JPH02278009A - Static pressure gas bearing - Google Patents

Abstract

PURPOSE:To attempt to compact the above bearing by detecting the pressure variation in a shaft bearing space with a piezoelectric element on one side and further deforming a piezoelectric element on the other side interlocking with the piezoelectric element, and adjusting the contracting volume of feed air to control the pressure of said space. CONSTITUTION:Compressed air introduced from an air inlet 7 enters a shaft bearing space 4 passing the throughout hole 10 of a throttle plate 11 from a throttle space 5 to levitate/support a slide member 1. When the space in the shaft bearing space 4 lowered from the equilibrium state, the passage resistance of the shaft bearing space 4 increases raising pressure. In response to it, the throttle plate 11 mechanically strains, electric potential difference generates at its both end parts, this potential difference is conducted to an actuator 12 through a lead wire 9, the pressure element that is an integral part of it shrinks, and the throttle space 5 becomes large. Because of this, compressed air becomes easy to enter the shaft bearing space 4 and the pressure is further raised, and returns to the former equilibrium state. Reversely, if the space 4 becomes large, an action reverse to that mentioned above occurs, the pressure in the shaft bearing space 4 is decreased, and becomes the former equilibrium state.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to static pressure gas bearings such as air slides and air spindles, and more particularly to a supply air throttle structure for adjusting the pressure within the bearing gap. It is.

[Conventional technology]

Conventional static pressure gas bearings have a structure in which an orifice or the like is installed in the air supply hole between the bearing gaps to throttle the air supply, but controlling the bearing gap to an appropriate amount requires changing the supply pressure of the air supply. A method is used to reduce the pressure within the gap by 181 points.

However, this method of changing the supply pressure has the disadvantage that it takes time to change the pressure in the gap to the required pressure due to the time lag in the pressure change characteristics of the pressure pump, and the responsiveness is poor.

On the other hand, in a laboratory or the like, as shown in FIG.
It has been proposed to provide a throttle device 22 and adjust the amount of air supply to adjust the pressure within the gap to m nodes.

This throttle device 22 has a bearing clearance 2, as shown in the same figure.
A throttle plate 2 having a valve hole 23 in an air supply hole 21 opening at 0
5 and a piston 26 that changes the opening amount of the valve hole 23, and a sensor 27 that detects the gap in the bearing gap 20.
Based on the signal from the sensor 27, the piston 26 of the actuator 24 is expanded or contracted to change the amount of opening of the valve hole 23, thereby adjusting the amount of air supplied. In this case, the actuator 24 contracts to increase the amount of opening of the valve hole 23, increasing the amount of air supply and increasing the pressure inside the gap 20.
to return to equilibrium.

However, in the aperture device having the above structure, space is required for the drive mechanism of the actuator 24 and the piston 26, and the sensor 27 and the amplifier 28 for amplifying its output signal are required. etc., the bearing part is thick (this is a drawback that can easily occur).

Further, since the signal from the sensor 27 is amplified by an amplifier and transmitted to the actuator 24, there is a delay in the operation of the actuator 24, resulting in poor responsiveness.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and provide a compact hydrostatic gas bearing with excellent responsiveness.

[Means to solve the problem]

In order to solve the above problems, the present invention provides an air supply throttle device in the air supply hole that opens in the bearing gap, and uses this throttle device to increase the amount of air supply. J111ff In a static pressure gas bearing that controls the pressure in a bearing gap, the throttle device is composed of a throttle plate having a gas insertion hole and an actuator that is arranged at intervals in the insertion holes and expands and contracts the intervals. The aperture plate is formed by a piezoelectric element that converts mechanical strain into a potential difference, and the actuator is formed by a piezoelectric element that converts a potential difference into mechanical strain.The mutual electrodes of the aperture plate and actuator are connected by lead wires. That's what I did.

[Effect]

According to the above structure, when the size of the bearing gap becomes larger than the equilibrium state and the pressure in the bearing gap decreases, the aperture plate is distorted by the pressure and a potential difference is generated inside the aperture. This potential difference is It is transmitted to the electrode of the actuator through the wire, and the actuator deforms to reduce the distance between it and the insertion hole.For this reason, the amount of air supplied decreases,
The pressure inside the bearing gap is further reduced and the bearing gap is returned to equilibrium.

Conversely, when the pressure in the bearing gap increases, the actuator increases the distance between the actuator and the insertion hole by an operation opposite to the above, increases the amount of air supply, and adjusts the bearing gap to a constant value.

[Example] Hereinafter, an example of the present invention will be described based on the accompanying drawings.

1 and 2 show an example of application to a static pressure gas bearing of an air slide.

The slide member 1 is connected to the guide member 2 through the bearing gap 4.
It is supported by floating. This slide member 1 has
An air supply path 6 and an air suction lower connected to a compressed air supply source are formed. Further, the slide member 1 is formed with an air supply hole 8 that communicates a large number of air supply passages 6 and the bearing gap 4 in the circumferential direction, and this air supply hole 8 is formed in the guide member 2.
A plurality of rows are formed at predetermined intervals in the length direction (direction toward the page).

Each of the air supply holes 8 is provided with a throttle device 3 that throttles the amount of air supplied. This diaphragm device 3, as shown in FIG.
It is attached to the outlet of the air supply hole 8, and has an air insertion hole 10 in the center.
It is composed of a throttle plate 11 having a diaphragm plate 11, and an actuator 1'2 installed inside the air supply hole 8. They are close to each other, and a throttle gap 5 is formed between the tip and the air passage hole 10 .

The diaphragm plate 11 is formed of a piezoelectric element that converts mechanical strain into a potential difference, and when the pressure within the bearing gap 4 changes and the diaphragm plate 11 is distorted in response to the pressure change, a potential difference is created at both ends of the diaphragm plate 11. It's starting to happen.

On the other hand, the actuator 12 is formed of a piezoelectric element that converts a potential difference into mechanical strain, and when it receives a potential difference, mechanical strain is generated and it expands and contracts in the length direction, reducing the aperture gap 5 between it and the aperture plate 11. change.

The actuator 12 and the aperture plate 11 have their electrodes connected to each other by a lead wire 9, so that they operate in conjunction with each other. That is, when a potential difference occurs between the electrodes of the aperture plate 11, the potential difference is transmitted to the actuator 12 via the lead wire 9, creating a potential difference between the electrodes of the actuator 12, and deforming the actuator 12. In this case, the potential change caused by the distortion of the aperture plate 1.1 due to the increase in pressure within the bearing gap 4 is polarized with the potential change that deforms the actuator 12 in the direction of shortening it, that is, in the direction of enlarging the aperture gap 5. It is set as follows.

This embodiment has the structure described above, and its operation will be explained next.

When compressed air is introduced into the air supply path 6 from the air suction lower, the compressed air is introduced into the bearing gap 4 from the throttle gap 5 in the air supply hole 8 through the insertion hole 10 of the throttle plate 11, and is guided into the bearing gap 4. The slide member 1 is floated and supported relative to the member 2.

Now, if the bearing gap 4 determined by the positional relationship between the slide member 1 and the guide member 2 decreases from the equilibrium state, the flow path resistance within the bearing gap 4 increases and the pressure increases. When the pressure within the bearing gap 4 increases in this way, the diaphragm plate 11 is mechanically strained in response to the increase, creating a potential difference between its two ends.

When this potential difference is transmitted to the actuator 12 via the lead wire 9, the piezoelectric element forming the actuator 12 is strained in the direction of contraction, and the aperture plate 11 and the actuator 12
The aperture gap 5 between the two becomes larger. Therefore, compressed air easily enters the bearing gap 4, and the pressure therein further increases, and the gap 4 is quickly returned to an equilibrium state, returning to the original pressure in the equilibrium state.

On the other hand, when the bearing gap 4 increases and the pressure within the bearing gap 4 decreases, the throttle plate 11. The actuator 12 operates in the opposite manner to the above, the throttle gap 5 becomes smaller, it becomes difficult for compressed air to enter the bearing gap 4, and the pressure in the bearing gap 4 further decreases. Therefore, the bearing gap 4 is quickly returned to an equilibrium state, and the pressure is returned to the original equilibrium state.

Note that 13 in the figure is a resin or ceramic layer, and if the aperture slope 11 is covered with resin or the like in this way, there is an advantage that self-excited vibration can be suppressed.

FIG. 3 shows another embodiment, in which the actuator 12' is mounted in a cantilevered manner.

If the end portion of the actuator 12' is supported in this manner, the amount of displacement thereof can be increased, and there is an advantage that the amount of control can be increased. Note that the actuator is connected to the air supply hole 8'.
It may be installed internally with support at both ends.

(Effects of the Invention) As described above, the present invention forms a supply air throttling device using piezoelectric elements with different properties, detects pressure changes in the bearing gap with one piezoelectric element, and works in conjunction with that piezoelectric element. Since the other piezoelectric element is deformed to change the amount of air supply throttling, there is no need to use sensors, amplifiers, etc. as in the past, and it can be incorporated into the bearing in an extremely compact manner.

Furthermore, since the relationship between the strain and potential difference of the piezoelectric element is utilized, the amount of supplied air can be adjusted instantaneously, and a hydrostatic gas bearing with excellent response characteristics can be obtained.

[Brief explanation of drawings]

FIG. 1 is a longitudinal side view of the embodiment, FIG. 2 is a longitudinal side view showing the main parts of the same, and FIG. 3 is a longitudinal side view of another embodiment.
FIG. 4 is a longitudinal sectional side view showing a conventional example. 1...Slide member, 2...Effective member, 3...Aperture device, 4. Curve/bearing clearance, 5...Aperture clearance, 6.・Curved air supply path, 8.8'...Curved air supply hole, S...-, lJ
- lead wire, 10.10'... air insertion hole, 11.
11'...Aperture plate, 12.12'...River actuator. Figure 1 Figure 3

Claims (1)

[Claims] (1) In a static pressure gas bearing, a supply air throttle device is provided in the air supply hole opening in the bearing gap, and the throttle device adjusts the amount of air supply to control the pressure in the gap. The diaphragm plate is composed of a diaphragm plate having an insertion hole, and an actuator arranged at intervals in the insertion hole to expand and contract the interval. 1. A static pressure gas bearing, characterized in that each electrode is formed by a piezoelectric element that converts a potential difference into mechanical strain, and the mutual electrodes of the aperture plate and the actuator are connected by a lead wire.