JPH05272536A - Bearing device - Google Patents

Abstract

PURPOSE:To provide a bearing device capable of increasing the support rigidity of a mobile body supported on a bearing body by the fluid pressure in the noncontact state. CONSTITUTION:A bearing device is provided with a bearing body 1, a mobile body 4 supported on the bearing body 1, a feed hole 6 feeding a fluid between the opposite faces of the bearing body 1 and mobile body 4 and supporting the mobile body on the bearing body 1 in the noncontact state via the fluid pressure, and a power source 9 applying the voltage across the bearing body 1 and mobile body 4 to generate electrostatic force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing device for supporting a movable body in a non-contact state by utilizing the pressure of fluid.

[0002]

2. Description of the Related Art There are various types of bearing devices. One of them is a movable body such as a shaft which utilizes static pressure, dynamic pressure or squeeze pressure of fluid against the bearing body. There is known a so-called hydrodynamic bearing device which is supported in a non-contact state.

Such a bearing device has many advantages in terms of supporting accuracy, coefficient of friction, wear, etc. due to the structure in which the movable body is supported in a non-contact state with respect to the bearing body, but in the non-contact state. Therefore, the movable body may be affected by an external force such as vibration, and the supporting state may become unstable. Especially, when a compressible gas is used as the fluid, the tendency becomes remarkable.

On the other hand, recently, along with the progress of semiconductor fine processing technology and extreme mechanical processing technology, various actuators have been developed.
Is being developed. In the bearing device used for such an actuator, it is sometimes required not only to support the movable body but also to drive it back and forth along the axial direction.

However, the conventional bearing device utilizing the fluid pressure has a structure of simply supporting the movable body in a non-contact state. Therefore, in order to drive the movable body forward and backward, a drive means dedicated for the movable body may be required.

[0006]

As described above, in the conventional non-contact type bearing device using the fluid pressure, the supporting state of the movable body may become unstable with respect to the external force. Also,
Since the movable body is simply supported, there is a case where a driving means dedicated to the movable body is required to drive the movable body in the axial direction.

A first object of the present invention is to support a movable body in a non-contact state by utilizing fluid pressure so that the supporting state can be kept stable without being affected by an external force. Another object of the present invention is to provide such a bearing device.

A second object of the present invention is that, when a movable body is supported by utilizing fluid pressure, the supporting state can be made stable without being affected by external force, and it can be used exclusively. Another object of the present invention is to provide a bearing device capable of driving the movable body to move back and forth in the axial direction without using the driving means.

[0009]

In order to solve the above-mentioned problems, a first aspect of the present invention is to provide a bearing body, a movable body supported by the bearing body, and a fluid between a facing surface of the bearing body and the movable body. And a fluid supply means for supporting the movable body in a non-contact state with the bearing body by the fluid pressure, and an electrostatic force generation for applying an electric voltage between the bearing body and the movable body to generate an electrostatic force. And means.

According to a second aspect of the present invention, a bearing body having an inner peripheral surface formed on the bearing surface, and a shaft-shaped movable body inserted into the bearing body,
Fluid supplying means for supplying a fluid between the bearing surface of the bearing body and the outer peripheral surface of the movable body, and supporting the movable body in a non-contact state with the bearing body by the fluid pressure, and a bearing of the bearing body. Applied between a plurality of bearing-side electrodes provided in a predetermined arrangement along the axial direction of the surface and the bearing-side electrodes provided in a predetermined arrangement along the axial direction on the outer peripheral surface of the movable body. A plurality of movable electrodes that generate an electrostatic force by the applied voltage.

[0011]

According to the first aspect of the invention, the movable body can be supported not only in a non-contact state with the bearing body by fluid pressure but also by a suction force by an electrostatic force, so that the supporting state is stable. Can be measured.

According to the second aspect of the invention, the attraction force due to the electrostatic force generated between the electrodes of the movable body and the bearing body is controlled so as to move along the axial direction, so that the fluid pressure causes no contact. An axial thrust can be applied to the supported movable body.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a thrust type hydrostatic bearing device according to a first embodiment of the present invention. The hydrostatic bearing device has a bearing body 1. The bearing surface 2 of the bearing body 1 is provided with a bearing side electrode 3 which is electrically insulated from the bearing body 1 path. A thick plate-shaped movable body 4 is arranged above the bearing surface 2. On the lower surface of the movable body 4 facing the bearing surface 2, the movable side electrode 5 is electrically insulated from the movable body 4.
Is provided. The bearing-side electrode 3 and the movable-side electrode 5 are formed, for example, by depositing Cr (chrome), Ni (nickel), or the like in a thickness of 1 to 2 microns.

A supply hole 6 for compressed air as a fluid is formed in the movable body 4 in the thickness direction. The tip of the supply hole 6 is opened to the lower surface of the portion of the movable body 4 where the movable-side electrode 5 is provided via a diaphragm 7 having a diameter sufficiently smaller than that of the supply hole 6. One end of a supply hose 8 is connected to the rear end of the supply hole 6. The other end of the supply hose 8 communicates with a compressed air supply source (not shown). When the compressed air from the supply source is ejected from the throttle 7, the movable body 4 is supported by the static pressure of the compressed air so as to float from the bearing surface 2 in a non-contact state.

The bearing side electrode 3 and the movable side electrode 5 are connected to a power source 9, respectively. When the power source 9 is turned on and a voltage is applied between the bearing-side electrode 3 and the movable-side electrode 5, electric charges are charged on the electrodes 3 and 5, so that electrostatic attraction is applied between these electrodes. Power is generated.

According to the bearing device having the above structure, the movable body 4 is subjected to F ₂ by the static pressure of the compressed air jetted from the throttle 7.
Therefore, the movable body 4 is levitationally supported on the bearing surface 2 of the bearing body 1 in a non-contact state. Further, the movable body 4 levitated by the compressed air is kept in a levitated state by the attractive force F ₁ due to the electrostatic force generated between the bearing side electrode 3 and the movable side electrode 5.

The support in a state where the movable body 4 is floated by the compressed air is unstable because the support rigidity is not sufficiently high.
However, since the floating state of the movable body 4 is maintained by the attractive force of the electrostatic force, the supporting rigidity is increased by the attractive force. Therefore, the movable body 4 is unlikely to be affected by external vibrations and the like, so that the supporting state can be stabilized. The electrostatic force (suction force) F ₁ generated between the bearing-side electrode 3 and the movable-side electrode 5 is F ₁ = ε ₀ · ε _r · W · L · (V ² / 2D ² )… Equation (1)

It is represented by Where ε ₀ is the permittivity in vacuum, ε _r is the relative permittivity of the substance satisfying the gap G between the electrodes, and W
Is the electrode width, L is the electrode length, D is the distance between the electrodes, and V is the applied voltage. That is, from the above formula (1), the smaller the distance D between the electrodes, the larger F ₁ can be made. F ₁ can also be increased by using a fluid having a high relative dielectric constant. FIG. 2 shows a second embodiment of the present invention. In addition,
The same parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

This embodiment is a hydrodynamic bearing device, and a step portion for changing a gap G between the upper surface of the bearing body 1 and the bearing surface 2 on the lower surface of the movable body 4a at one end in the width direction in a wedge shape. 11 is provided. A movable-side electrode 5 is provided on the lower surface of the movable body 4a, and compressed air is present in the step portion 11 of the movable body 4a in a gap G between the bearing body 1 and the movable body 4a.
It is adapted to be supplied from the side, that is, one end side where the gap G is large.

The compressed air supplied to the gap G produces dynamic pressure as the gap G becomes gradually narrower. Therefore, the movable body 4a is levitationally supported by the bearing body 1 in a non-contact state by its dynamic pressure, and the floating state is maintained by the suction force generated between the bearing side electrode 3 and the movable side electrode 5. FIG. 3 shows a third embodiment of the present invention. The same parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

This embodiment is a bearing device utilizing squeeze pressure, and the construction is almost the same as that of the first embodiment,
In order to hold the movable body 4b in a non-contact state with the bearing surface 2 of the bearing body 1, the movable body 4b is oscillated and driven in a direction of approaching and separating from the bearing surface 2 as shown by an arrow.

As a result, the air pressure in the gap G between the bearing surface 2 and the lower surface of the movable body 4b becomes higher than the surrounding air pressure, so that the movable body 4b is held in a non-contact state by the pressure. Is becoming

That is, according to the present invention, the fluid pressure for floating and supporting the movable bodies 4, 4a, 4b on the bearing body 1 in a non-contact state is any of static pressure, dynamic pressure and squeeze pressure. Good. Hereinafter, another embodiment of the present invention utilizing static pressure will be described.

4 and 5 show a fourth embodiment of the present invention applied to a journal bearing device, and 21 in the figures is a cylindrical bearing body. The inner peripheral surface of the bearing body 21, that is, the bearing surface 21
Four bearing-side electrodes 22 are provided at a at 90 ° intervals in the circumferential direction so as to be electrically insulated from the bearing body 21. A supply hole 23 is formed in a portion of the peripheral wall of the bearing body 21 corresponding to each bearing side electrode 22 along the thickness direction (radial direction). The tip of the supply hole 23 is opened in the bearing surface 21a of the bearing body 21 through the throttle 24, and the rear end is in communication with a compressed air supply source (not shown).

A shaft-shaped movable body 25 is inserted through the bearing body 21. The movable body 25 is made of a conductive material and is connected to the power source 9. The bearing side electrode 22 is also connected to the power source 9.

According to the bearing device having the above structure, the bearing body 21
Compressed air is supplied from the four supply holes 23 formed in
If jetted from each throttle 24, the movable body 25 can be held in a non-contact state with the bearing surface 21a of the bearing body 21 by the static pressure of the compressed air. In that state, the bearing-side electrode 22
When a voltage is applied between the movable body 25 and the movable body 25, the attraction force due to the electrostatic force generated between the movable body 25 and the movable body 25 acts on the movable body 25 substantially uniformly in the circumferential direction. Therefore, the movable body 25 can be held in a stable state by the static pressure of compressed air and the suction force of electrostatic force.

FIG. 6 shows a fifth embodiment of the present invention applied to a journal bearing device, and 31 in the drawing is a rectangular cylindrical bearing body. The base ends of four pads 32 are attached to the inner surface of the bearing body 31. The tip end surface of each pad 32 is formed into an arc surface 32a forming a cylindrical bearing surface, and each arc surface 32a has first to fourth bearing side electrodes 33a to 33a.
33d is electrically insulated and attached.

A shaft-shaped movable body 34 is inserted into the bearing surface formed by the circular arc surfaces 32a of the four pads 32. The movable body 34 is made of a conductive material and is connected to the power source 9.

The bearing-side electrodes 33a to 33d are connected to the power source 9 via a switch 35 and a variable resistor 36, respectively. If the resistance value of the variable resistor 36 is controlled by turning on the switch 35, each bearing side electrode 33
The voltage applied to a to 33d can be changed. Compressed air supply holes 37 are formed in each of the four pads 32, and these supply holes 37 are formed by the throttle 3
8 to the circular arc surface 32a.

According to such a configuration, each variable resistor 3
6 to adjust the first to fourth bearing side electrodes 33a to 33d
If the voltage flowing to the bearings is controlled, the bearing side electrodes 33a to 33a
The suction force generated between d and the movable body 34 can be changed. Thereby, the distance between each of the bearing side electrodes 33a to 33d and the movable body 34 can be controlled, so that the supporting position of the movable body 34 with respect to the bearing body 31 can be corrected. That is, when the movable body 34 is eccentric,
The eccentricity can be corrected.

FIG. 7 shows a sixth embodiment of the present invention applied to a journal bearing device, and 41 in the drawing is a cylindrical bearing body. In this bearing body 41, four supply holes 42 are formed in the circumferential direction in the thickness direction of the peripheral wall. The tip of each supply hole 42 is opened to the inner peripheral surface 41a, which serves as the bearing surface of the bearing body 41, through the throttle 43, and the base end communicates with a compressed air supply source (not shown).

On the inner peripheral surface 41a of the bearing body 41, two pairs of first to fourth bearing side electrodes 44a to 44d are electrically insulated from the bearing body 41 on both sides of each supply hole 42. Are provided. The bearing body 41 includes a shaft-shaped movable body 4
5 is inserted. On the outer peripheral surface of the movable body 45, four movable-side electrodes 46a to 46d are provided at 90 degree intervals in the circumferential direction so as to be electrically insulated from the movable body 45. That is, the pair of bearing-side electrodes 44a to 44d are symmetrically opposed to the respective movable-side electrodes 46a to 46d. Although not shown in detail, the bearing side electrode 44a
44d are connected to the DC power supply 9, and the movable electrode 46 is
Similarly, a to 46d are connected to the power source 9.

According to this structure, compressed air is supplied from each supply hole 42 to hold the movable body 45 in a non-contact state with the bearing body 41. In this state, the bearing side electrodes 44a to 44d and the movable side electrode are held. When a DC voltage is applied between 46a to 46d, the movable body 45 is also held by the attractive force of electrostatic force.

The attraction force due to the electrostatic force is generated substantially symmetrically between the one movable electrode and the two bearing side electrodes as shown by the arrow in the figure, and the attraction force is inclined with respect to the diametrical direction. To work. That is, since a suction force is generated between one movable side electrode and the pair of bearing side electrodes, the movable body 45
Is hard to rotate against an external force in the rotating direction.

FIG. 8 shows a seventh embodiment of the present invention applied to a journal bearing device, and 51 in the figure is a cylindrical bearing body. The bearing body 51 has an inner peripheral surface 51a serving as a bearing surface.
In addition, a plurality of supply holes 53, the ends of which communicate with each other via the diaphragm 52, are formed at predetermined intervals in the axial direction and at 180 ° intervals in the circumferential direction. The rear end of each supply hole 53 communicates with a compressed air supply source (not shown). Inner peripheral surface 51a of the bearing body 51
, Are provided with a plurality of bearing-side electrodes 54a, 54b, ..., Which are sequentially displaced by 180 degrees in the circumferential direction, at predetermined intervals in the form of a strip in the axial direction.

On the outer peripheral surface of the shaft-shaped movable body 55 inserted through the bearing body 51, a plurality of first to n-th movable side electrodes 55a, 55b, ... Are movable at predetermined intervals along the axial direction. It is provided so as to be electrically insulated from the body 55. The bearing side electrodes 54a, 54b, ... Are connected to the power source 9 via the drive control unit 56, and the movable side electrodes 55a, 55b ,. The drive control unit 56
Controls the application of voltage to the bearing side electrodes 54a, 54b, .... That is, the drive control unit 56
By the operation, a plurality of movable electrodes 55a, 55
voltage is simultaneously applied to b, ...
Control such as sequentially applying a voltage from 5a to the second, third, ...

In such a structure, compressed air is jetted from each supply hole 53, and the pressure causes the movable body 55 to move to the bearing body 5.
1 is supported in a non-contact state, a plurality of bearing-side electrodes 5
If a voltage is applied to the movable side electrodes 55a, 55b, ..., The attraction force by the electrostatic force generated thereby also acts as a holding force, so that the holding state of the movable body 55 can be stabilized. it can.

On the other hand, when the drive controller 56 is operated to sequentially apply a voltage to the plurality of bearing side electrodes 54a, 54b, ..., A thrust force can be generated in the movable body 55 in the axial direction. That is, in the state shown in FIG. 8, when considering 55a, which is one of the plurality of movable electrodes, first,
When a voltage is applied only to the first bearing side electrode 54a, the movable body 55 causes the electrodes 54a and 55a to move by the attractive force generated between the electrode 54a and the movable side electrode 55a.
Slide in the axial direction indicated by the arrow until they face each other (state of FIG. 8). In this state, only a part of the movable side electrode 55a faces the second bearing side electrode 54b.

Next, the energization to the first bearing side electrode 54a is cut off, and the second bearing side electrode 54b is energized. Thereby, the second bearing side electrode 54b and the movable side electrode 55
Since a suction force is generated between the movable body 55 and a, the movable body 55 is axially driven by the suction force until the electrodes face each other. The movable side electrode 55a and the second bearing side electrode 5
4b, a part of the movable electrode 55a faces the third bearing electrode 54c.
If a voltage is applied to the bearing side electrode 54c of the movable body 5,
5 can be driven similarly.

That is, electrodes are provided on the bearing body 51 and the movable body 55, respectively, and an electrostatic force is generated between these electrodes to stabilize the supporting state of the movable body 55 in the non-contact state by the compressed air. In addition to being able to do, movable body 5
The movable body 55 can be driven in the axial direction by controlling the energization of the plurality of movable-side electrodes 55a, 55b, ...

Therefore, not only the movable body 55 can be driven in a non-contact state, but also a dedicated drive means therefor is not required. The driving accuracy of the movable body 55 can be controlled by changing the distance between the bearing-side electrodes 54a, 54b, ....

9 and 10 show an eighth embodiment of the present invention applied to a slide bearing device. In the figure, reference numeral 61 denotes a bearing body having a rectangular guide groove 62 whose upper surface is open. A bearing side electrode 63 is provided on the entire inner surface of the guide groove 62 of the bearing body 61 so as to be electrically insulated from the bearing body 61.

The movable body 64 slidably supported in the guide groove 62 of the bearing body 61 along the groove direction is
It has a rectangular plate shape with a predetermined thickness. A movable electrode 65 is provided on the outer surface of the movable body 64 excluding the upper surface and the end surface in the front-rear direction so as to be electrically insulated from the movable body 64. A supply hole 66 is formed in the movable body 64.
The supply hole 66 is branched in a substantially cross shape as shown in FIG. 9, and the tip end is opened to the lower surface and both side surfaces of the movable body 64 through the diaphragm 67, respectively. The rear end of the supply hole 66 communicates with a compressed air supply source (not shown). By supplying compressed air from this supply source and ejecting it from the three throttles 67, the movable body 64 can be supported by the bearing body 61 in a non-contact state.

The bearing side electrode 63 is grounded, and the movable side electrode 65 is connected to the power source 9. Therefore, if a DC voltage is applied between the bearing side electrode 63 and the movable side electrode 65 while the movable body 64 is supported in the guide groove 62 of the bearing body 61 in a non-contact state, the movable body 64 is compressed. It can be held not only by air but also by suction force by electrostatic force, and the holding state can be stabilized. Moreover, the movable body 64 can be slid along the guide groove 62 of the bearing body 61.

The present invention is not limited to the above embodiments and can be variously modified. For example, the fluid is not limited to compressed air, and may be an electrically insulating liquid or the like. In the fourth to seventh embodiments applied to the journal bearing, the fluid can be applied to the outer peripheral surface of each axial movable body. A groove may be formed to generate a dynamic pressure in the fluid supplied between the movable body and the bearing body, and the dynamic pressure may support the movable body in a non-contact state.

When the bearing body and the movable body are made of a conductive material, the movable body and the bearing body may be directly connected to a power source to apply a voltage without providing electrodes. An electrostatic force can be generated between and.

[0048]

As described above, according to the first aspect of the invention, when the fluid is supplied between the bearing body and the movable body to support the movable body in a non-contact state, A suction force by an electrostatic force is generated between the two.

Therefore, the reduction in the supporting rigidity that occurs when the movable body is supported by the fluid in a non-contact state can be compensated for by the attractive force of the electrostatic force. Can be supported.

According to the second aspect of the invention, when an electrode is provided to stabilize the supporting state of the movable body by the attractive force of electrostatic force, the electrode is provided along the axial direction of the movable body and the bearing body. Since they are provided in a predetermined arrangement state, the thrust in the axial direction can be applied to the movable body by controlling the application of the voltage to the electrodes.

Therefore, when it is used for an actuator or the like, not only can the movable body be accurately driven in a non-contact manner, but also a driving means dedicated to the driving of the movable body is not required. Can be simplified.

[Brief description of drawings]

FIG. 1 is a configuration diagram when applied to a hydrostatic bearing device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram when applied to a dynamic pressure bearing device showing a second embodiment of the present invention.

FIG. 3 is a configuration diagram when applied to a squeeze type bearing device showing a third embodiment of the present invention.

FIG. 4 is a sectional view taken along the axial direction when applied to a journal bearing device showing a fourth embodiment of the present invention.

FIG. 5 is a sectional view taken along line AA of FIG.

FIG. 6 is a sectional view in a direction orthogonal to the axial direction when applied to a journal bearing device showing a fifth embodiment of the present invention.

FIG. 7 is a cross-sectional view in a direction orthogonal to the axial direction when applied to a journal bearing device showing a sixth embodiment of the present invention.

FIG. 8 is a sectional view taken along the axial direction when applied to a journal bearing device showing a seventh embodiment of the invention.

FIG. 9 is a sectional view when applied to a slide bearing device showing an eighth embodiment of the present invention.

FIG. 10 is a sectional view taken along line BB of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Bearing body, 2 ... Bearing surface, 3 ... Bearing side electrode, 4 ... Movable body, 5 ... Movable side electrode, 6 ... Supply hole, 7 ... A diaphragm, 8 ... Power supply.

Claims (2)

[Claims] 1. A fluid is supplied between a bearing body, a movable body supported by the bearing body, and the facing surfaces of the bearing body and the movable body, and the fluid pressure prevents the movable body from being applied to the bearing body. A bearing device comprising: a fluid supply means for supporting in a contact state; and an electrostatic force generating means for applying a voltage between the bearing body and the movable body to generate an electrostatic force. 2. A bearing body having an inner peripheral surface formed on the bearing surface,
Fluid is supplied between the shaft-shaped movable body inserted in the bearing body and the bearing surface of the bearing body and the outer peripheral surface of the movable body, and the fluid pressure causes the movable body to be in non-contact with the bearing body. Fluid supply means for supporting in a state, a plurality of bearing-side electrodes provided in a predetermined arrangement along the axial direction of the bearing surface of the bearing body, and a predetermined number along the axial direction on the outer peripheral surface of the movable body. A bearing device comprising: a plurality of movable electrodes that are provided in an arranged state and that generate an electrostatic force by a voltage applied between the electrodes and the bearing electrodes.