Air bearing control mechanism

Abstract

To provide a control mechanism which instantaneously corrects misalignment of a supporting position of a movable body with a simple structure in an air bearing capable of supporting the movable body with respect to a support face of a support body in a contactless manner so as to form an air layer between the movable body and the support body through supplying compressed air.SOLUTION: At a throat section where a cross-sectional area of a flow passage of a diffuser, having high-pressure air generation means injecting high pressure air, is minimized, an air bearing control mechanism displaces a piezo element installed on the throat section by applying voltage thereto with high pressure air P0 having pressure 1.89293 times air pressure Pb at an opening section of the diffuser injected into the flow passage of the diffuser through the high-pressure air generation means installed at a closed section on an upstream side of the diffuser, thereby causing the high pressure air flowing in the diffuser to be injected toward a movable body so as to correct misalignment of a supporting position of the movable body.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an air bearing, and more particularly to a control mechanism capable of instantly correcting deviations in the support position of a movable body in an existing air bearing with a simple structure. [Background technology]

[0002] 2. Description of the Related Art Conventionally, air bearings are known in which compressed air is supplied between a movable body and a support to form an air layer, thereby enabling the movable body to be supported in a non-contact manner from the support surface of the support. Since there is no resistance when driving a movable body that is supported without contact, high responsiveness is obtained and highly precise control is possible. Therefore, in recent years, this type of actuator has been used in a variety of devices such as processing equipment and component mounting equipment, which require more precise control. However, there has been a problem in that the support position or axis of the movable body may become misaligned when the movable body is driven or when the movable body is subjected to a force from outside the device.

[0003] To address this problem, Patent Document 1 discloses a locking mechanism in a linear air bearing in which a voltage is applied from a control means to a piezoelectric element when the air slider member is stopped at a guide rail member, driving the piezoelectric element by the inverse piezoelectric effect. According to this invention, the tip of the piezoelectric element presses against the upper and lower surfaces of the guide rail member, and this pressing force fixes the air slider member to the guide rail member via the piezoelectric element, so that the air slider member can be reliably locked to the guide rail member in a short period of time. In addition, by arranging piezoelectric elements on both sides of the air slider member in the direction of movement, and by arranging sensors capable of measuring the upper and lower gaps between the air slider member and the guide rail member on both sides of the direction of movement of the air slider member, the inclination angle of the air slider member relative to the guide rail member can be calculated based on the upper gap information and lower gap information from each sensor, and the inclination angle can be corrected by controlling the amount of voltage applied to each piezoelectric element, thereby locking the air slider member in a parallel state to the guide rail member.

[0004] However, it is extremely difficult to control the amount of displacement with high precision by controlling the amount of voltage applied to the piezoelectric element, and it is not realistic to use multiple piezoelectric elements to not only press the movable member to restrict its movement but also to prevent misalignment of the axis. Furthermore, since the air slider member has an extremely sophisticated surface treatment, direct contact of the piezoelectric element with this member leads to deterioration of the precision of the member. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 06-050339 Summary of the Invention [Problem to be solved by the invention]

[0006] In response to these problems, the inventors of the present application have discovered a method for controlling high-pressure air by utilizing the principle that, when the air pressure at the throat of a diffuser, which is a flow path through which high-pressure air flows from the upstream side toward the downstream side of atmospheric pressure, reaches a critical state where the Mach number is 1, due to the isentropic relationship in supersonic flow, a minute change in the flow path cross-sectional area at the throat has an extremely large effect on the flow field. According to this, by changing the cross-sectional area of ​​the diffuser, which is the flow passage through which transonic high-pressure air passes, at a position where the cross-sectional area is at its smallest, regardless of the position of the generated shock wave, it is possible to control the shock wave and the associated pressure fluctuations in the flow field and reduce the vibration of the shock wave.

[0007] In particular, if the pressure of the upstream high-pressure air in the flow passage can be made 1.89293 times the downstream air (atmospheric pressure) in the flow passage (specific heat ratio of air γ = 1.4), as shown in Equation 1, so that the pressure of the high-pressure air flowing at the position where the cross-sectional area of ​​the diffuser is smallest is equal to the downstream air (atmospheric pressure) in the flow passage, then even if a gap communicating with the outside of the diffuser is provided in the throat where the cross-sectional area of ​​the flow passage is smallest, there will be no pressure difference between the inside and outside of the flow passage in the throat and a virtual air film will be formed in the gap, and the high-pressure air flowing in the flow passage will not leak out of the diffuser from the gap provided in the throat.

[0008]

number

[0009] By utilizing this phenomenon, the following becomes possible: In other words, when a virtual air film is formed in the gap, a slight displacement caused by a piezoelectric element on the wall of the throat portion facing the gap causes a pressure fluctuation. By oscillating this pressure vibration, the virtual air film separating the gap and the flow path is broken only at the moment when the pressure fluctuation occurs, and the high-pressure air in the flow path can be ejected or flowed into the outside of the diffuser through the gap provided in the throat portion. As a result, it is possible to instantaneously levitate an object located close to the nozzle of the gap communicating with the outside of the diffuser, in the same time and on the same scale as the response speed of the piezoelectric element. Additionally, the pressure within the flow passage can be reduced relative to the pressure outside the diffuser using the displacement of the piezoelectric element. In this case, it is also possible to take air into the flow passage from outside the diffuser through a gap communicating with the outside of the diffuser. This allows the sonic line in the flow passage to move upstream and downstream. In addition, since the pressure is lower downstream of the sonic line within the flow path, in order to cause flow from the outside to flow into the diffuser side, it is possible to displace the piezoelectric element to move the sonic line upstream and lower the local pressure near the outflow hole. This action reduces the pressure at the throat compared to atmospheric pressure, thus creating a negative pressure in the atmosphere.

[0010] Therefore, the present invention aims to provide a control mechanism that utilizes the phenomenon of a virtual air film being formed in the throat of an existing air bearing, which can support a movable body without contacting the support surface of the support by supplying compressed air between the movable body and the support to form an air layer, and uses a highly responsive piezoelectric element at a position where the cross-sectional area of ​​the throat of the diffuser is smallest, and sprays high-pressure air in the flow path towards the outside through the gap in the throat, thereby instantly correcting any deviation in the support position of the movable body with a simple structure. [Means for solving the problem]

[0011] The air bearing control mechanism according to the present invention comprises: An air supply means for supplying compressed air to a gap between the movable body and the support; an exhaust means for exhausting compressed air from a gap between the movable body and the support; a support that supports the movable body without contacting the support surface by forming an air layer by compressed air in a gap between the movable body and the support; In an air bearing comprising: The support is The support has one or more high-pressure air outlets formed to penetrate the support and for ejecting high-pressure air from the rear side of the support toward the gap between the movable body and the support for correcting a deviation in the support position of the movable body; A control mechanism for correcting a deviation in the support position of the movable body by ejecting high-pressure air is connected to the back side of the support on which the high-pressure air ejection ports are formed, the number of which is equal to the number of the high-pressure air ejection ports; The control mechanism is a diffuser having a closed tip on an upstream side of the air flow and an open tip on a downstream side of the air flow, the diffuser having a cross-sectional area that decreases in a direction along which the air flows; a high-pressure air generating means provided at a closing portion of the diffuser for causing high-pressure air to flow downstream through a flow passage of the diffuser; It consists of: The diffuser is a high-pressure air leakage port communicating with the high-pressure air outlet of the support body is formed in a throat portion where the flow passage cross-sectional area is smallest; A piezoelectric element is attached to the wall portion of the flow passage facing the high-pressure air leak port, A voltage application means is provided for applying a voltage to the piezoelectric element, As shown in formula 1, the air pressure at the opening of the diffuser, P b High pressure air P with a pressure of 1.89293 times 0 The high-pressure air generating means causes the high-pressure air to flow downstream in the flow passage of the diffuser, When the pressure of the high-pressure air flowing near the high-pressure air leak port of the throat of the diffuser is made equal to the air pressure at the downstream opening of the diffuser, By applying a voltage to the piezoelectric element and displacing it, high-pressure air flowing near the high-pressure air leak port of the diffuser is ejected from the high-pressure air leak port through a high-pressure air outlet of the support; Correct the misalignment of the support position of the movable body It is characterized by:

[0012]

number

[0013] The present invention is a control mechanism that can instantly correct any deviation in the support position of a movable body with a simple structure in an existing air bearing that can support the movable body non-contact from the support surface of the support by supplying compressed air between the movable body and the support to form an air layer. Therefore, the air supply means and the exhaust means can be any known means. For example, the air supply means can be a compressor.

[0014] The movable body may have any shape as long as it can be supported by compressed air without contacting the support surface of the support, and any of a long shaft shape, a plate shape, and a spherical shape can be supported. The support may take various shapes, such as a bearing type that surrounds the periphery of a shaft, a plate type, or a spherical type, depending on the shape of the movable body.

[0015] The support has one or more high-pressure air outlets formed therein through which high-pressure air from the control mechanism is ejected. The high pressure air outlet is formed to extend through the support. Control mechanisms are connected to the back surface side of the support body on which the high-pressure air outlets are formed, the control mechanisms being equal in number to the high-pressure air outlets. By connecting the control mechanism to the high-pressure air outlet, high-pressure air from the control mechanism is ejected from the rear side of the support toward the gap between the movable body and the support. This makes it possible to correct any deviation in the support position of the movable body.

[0016] The control mechanism consists of a diffuser fitted with a high pressure air generating means. The diffuser has a closed end on the upstream side of the air flow and an open end on the downstream side of the air flow. The diffuser has a shape in which the cross-sectional area decreases in the direction of the air flow. The high-pressure air generating means is provided at the closing portion of the diffuser and causes high-pressure air to flow into the flow passage of the diffuser. For example, a micro-compressor can be used.

[0017] The diffuser has a high-pressure air leakage port formed in the throat portion where the flow passage cross-sectional area is minimum. The high pressure air leak communicates with the high pressure air outlet of the support. For this purpose, a control mechanism consisting of a diffuser to which a high pressure air generating means is attached is mounted so that its high pressure air leak port communicates with the high pressure air outlet port of the support. The diffuser has a piezoelectric element attached to a wall portion within the flow passage facing the high-pressure air leak port. Further, a voltage application means for applying a voltage is attached to the piezoelectric element. When a voltage is applied to the piezoelectric element, the piezoelectric element is displaced, and high-pressure air flowing near the high-pressure air leak port is ejected from the high-pressure air leak port toward the high-pressure air ejection port of the support body. In other words, the control mechanism of the air bearing of the present invention displaces the piezoelectric element to eject high-pressure air flowing near the high-pressure air leak port from the high-pressure air leak port towards the high-pressure air outlet of the support body, thereby correcting any deviation in the support position of the movable body.

[0018] However, the high pressure air near the high pressure air leak port is maintained at a pressure equal to the air pressure at the downstream opening of the diffuser when the piezoelectric element is not displaced. In other words, the high-pressure air generating means attached to the diffuser generates the air pressure P at the opening of the diffuser as shown in Equation 1. b High pressure air P with a pressure of 1.89293 times 0 The air flows downstream through the flow passage of the diffuser. As a result, at the throat portion where the cross-sectional area of ​​the flow passage is the smallest, there is no pressure difference between the inside and outside of the flow passage, and a virtual air film is formed between the high-pressure air leak outlet and the flow passage, so that the high-pressure air flowing through the flow passage does not leak from the high-pressure air leak outlet toward the high-pressure air outlet of the support body.

[0019] Therefore, by displacing the piezoelectric element only when it is necessary to correct the deviation in the support position of the movable body, the high-pressure air flowing near the high-pressure air leak port can be instantly ejected from the high-pressure air leak port toward the high-pressure air outlet of the support body, thereby correcting the deviation in the support position of the movable body. Furthermore, by providing high-pressure air outlets and control mechanisms connected to these at multiple locations on the support, high-pressure air can be ejected from multiple locations and the movable body can be pushed in the ejection direction at the ejection location, correcting any deviation in the support position, making it possible to control the support position of the movable body in the air bearing.

[0020] The control mechanism may also be of a so-called recirculation type, in which the high-pressure air discharged from the downstream opening of the diffuser is circulated to the upstream closing portion of the diffuser.

[0021] The air bearing control mechanism according to the present invention comprises: An air supply means for supplying compressed air to a gap between the movable body and the support; an exhaust means for exhausting compressed air from a gap between the movable body and the support; a support that supports the movable body without contacting the support surface by forming an air layer by compressed air in a gap between the movable body and the support; In an air bearing comprising: The support is The support has one or more high-pressure air outlets formed to penetrate the support and for ejecting high-pressure air from the rear side of the support toward the gap between the movable body and the support for correcting a deviation in the support position of the movable body; A control mechanism for correcting a deviation in the support position of the movable body by ejecting high-pressure air is connected to the back side of the support on which the high-pressure air ejection ports are formed, the number of which is equal to the number of the high-pressure air ejection ports; The control mechanism is a diffuser having a closed tip on an upstream side of the air flow and an open tip on a downstream side of the air flow, the diffuser having a cross-sectional area that decreases in a direction along which the air flows; a high-pressure air generating means provided at a closing portion of the diffuser for causing high-pressure air to flow downstream through a flow passage of the diffuser; It consists of: The diffuser is a high-pressure air leakage port communicating with the high-pressure air outlet of the support body is formed in a throat portion where the flow passage cross-sectional area is smallest; Two or more stacked piezoelectric elements are attached to the wall surface of the flow passage facing the high-pressure air leak port, A voltage application means is provided for applying a voltage to the piezoelectric element, As shown in formula 1, the air pressure at the opening of the diffuser, P b High pressure air P with a pressure of 1.89293 times 0 The high-pressure air generating means causes the high-pressure air to flow downstream in the flow passage of the diffuser, When the pressure of the high-pressure air flowing near the high-pressure air leak port of the throat of the diffuser is made equal to the air pressure at the downstream opening of the diffuser, By applying a voltage to the piezoelectric element and displacing it, high-pressure air flowing near the high-pressure air leak port of the diffuser is ejected from the high-pressure air leak port through a high-pressure air outlet of the support; Correct the misalignment of the support position of the movable body It is characterized by:

[0022]

number

[0023] Piezoelectric elements have the property that their volume changes when voltage is applied, but the amount of displacement is extremely minute. Therefore, depending on the movable body to be controlled, a single piezoelectric element may not be able to obtain a sufficient amount of displacement to correct the misalignment of the support position of the movable body by ejecting the high-pressure air flowing near the high-pressure air leak port of the diffuser from the high-pressure air leak port through the high-pressure air outlet of the support body. Therefore, in the present invention, as a means for solving this problem, two or more piezoelectric elements are stacked. By increasing the number of piezoelectric elements and stacking them according to the movable body to be controlled, a displacement amount corresponding to the number of elements can be obtained, which is sufficient to correct the deviation of the support position of the movable body. The laminated type has higher responsiveness than the bimorph type, and overcomes the drawback of the bimorph type, which has large displacement but no responsiveness. Furthermore, a plurality of piezoelectric elements can be attached in a direction perpendicular to the flow path direction of the high-pressure air.

[0024] The air bearing control mechanism according to the present invention comprises: An air supply means for supplying compressed air to a gap between the movable body and the support; an exhaust means for exhausting compressed air from a gap between the movable body and the support; a support that supports the movable body without contacting the support surface by forming an air layer by compressed air in a gap between the movable body and the support; In an air bearing comprising: The support is The support has one or more high-pressure air outlets formed to penetrate the support and for ejecting high-pressure air from the rear side of the support toward the gap between the movable body and the support for correcting a deviation in the support position of the movable body; A control mechanism for correcting a deviation in the support position of the movable body by ejecting high-pressure air is connected to the back side of the support on which the high-pressure air ejection ports are formed, the number of which is equal to the number of the high-pressure air ejection ports; The control mechanism is a diffuser having a closed tip on an upstream side of the air flow and an open tip on a downstream side of the air flow, the diffuser having a cross-sectional area that decreases in a direction along which the air flows; a high-pressure air generating means provided at a closing portion of the diffuser for causing high-pressure air to flow downstream through a flow passage of the diffuser; It consists of: The diffuser is A high-pressure air leak port having a slit width of 0.3 mm in the flow path direction is formed in the throat portion where the flow path cross-sectional area is the smallest and communicates with the high-pressure air outlet of the support body, Two or more stacked piezoelectric elements are attached to the wall surface of the flow passage facing the high-pressure air leak port, A voltage application means is provided for applying a voltage to the piezoelectric element, As shown in formula 1, the air pressure at the opening of the diffuser, P bHigh pressure air P with a pressure of 1.89293 times 0 The high-pressure air generating means causes the high-pressure air to flow downstream in the flow passage of the diffuser, When the pressure of the high-pressure air flowing near the high-pressure air leak port of the throat of the diffuser is made equal to the air pressure at the downstream opening of the diffuser, By applying a voltage to the piezoelectric element and displacing it, high-pressure air flowing near the high-pressure air leak port of the diffuser is ejected from the high-pressure air leak port through a high-pressure air outlet of the support; Correct the misalignment of the support position of the movable body It is characterized by:

[0025]

number

[0026] If the diameter of the high-pressure air leak port in the flow path direction is too large, there is a risk that the high-pressure air flowing through the flow path of the diffuser will leak out of the high-pressure air leak port regardless of the operation of the piezoelectric element. Conversely, if the diameter of the high-pressure air leak port in the flow path direction is too small, even if the piezoelectric element operates, high-pressure air will not be ejected from the diffuser flow path toward the high-pressure air leak port (the imaginary air film will remain unbroken). In the present invention, therefore, as a means for solving this problem, the slit width in the flow path direction of the high-pressure air leak port is set to 0.3 mm. In addition, it is desirable that the diameter of the high-pressure air leak port in the direction perpendicular to the flow path direction is the same as the width of the piezoelectric element to be attached. For example, when two piezoelectric elements are attached side by side in a direction perpendicular to the flow path direction, the diameter of the high-pressure air leak port in the direction perpendicular to the flow path direction is the same as the overall width of the multiple piezoelectric elements. Effect of the Invention

[0027] By utilizing the property of a piezoelectric element, which changes in volume when pressure is applied to it, high-pressure air can be ejected onto the movable body in the air bearing, thereby correcting any deviation in the support position of the movable body. In particular, by providing a plurality of control mechanisms for ejecting high-pressure air, it is possible to eject high-pressure air onto the movable body from a plurality of directions, and thus to correct deviations in the support position of the movable body from a plurality of directions. Furthermore, if a means for detecting deviations in the support position of the movable body can be provided, then it is possible to correct the deviations in the support position of the movable body by displacing only the piezoelectric element of the control mechanism installed at a specific location and ejecting high-pressure air only from that specific location. Furthermore, by making it possible to jet high-pressure air onto the movable body from multiple directions, the movable body can be supported in a more accurate position. [Brief description of the drawings]

[0028] [Figure 1] FIG. 1 is a side view showing the outline of the configuration of the air bearing control mechanism. [Diagram 2] FIG. 13 is a side view showing an outline of a configuration in which the control mechanism also serves as an air supply means for supplying compressed air and supports a spherical movable body. [Diagram 3] A horizontal cross-sectional view of a conventional air bearing that supports a rod-shaped movable body with a horizontal axis of rotation. [Figure 4] FIG. 1 is a horizontal cross-sectional view of an embodiment in which a plurality of control mechanisms are provided in an air bearing that supports a rod-shaped movable body having a horizontal rotation axis. [Diagram 5] A schematic diagram showing one embodiment of a vibration isolation table for precision laser measurement that uses air bearings to control and isolate vibrations transmitted from the base at high speed. [Figure 6] A schematic diagram showing an embodiment of a milling bed device for precision machining that uses air bearings to control vertical movement at high speed while allowing frictionless feeding. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

[0030] FIG. 1 is a side view showing the outline of the configuration of an air bearing control mechanism. The diffuser 1 is closed on the upstream side (the left side in FIG. 1) where the air flows, and is open on the downstream side. A high-pressure air generating means 2 is attached to the upstream closed portion of the diffuser 1. The diffuser 1 is shaped so that the cross-sectional area decreases in the direction of the air flow. The high-pressure air generating means 2 is for causing high-pressure air to flow into the flow passage of the diffuser, and for example, a micro-compressor can be used.

[0031] The diffuser 1 has a high-pressure air leakage port 3 formed in a throat portion where the flow passage cross-sectional area is minimum. The support 4 is formed with a high-pressure air outlet 5 through which high-pressure air is ejected from the high-pressure air leak outlet 3 of the control mechanism. The high-pressure air outlet 5 is formed so as to penetrate the support 4 , and the high-pressure air leak port 3 communicates with the high-pressure air outlet 5 of the support 4 . A diffuser 1 serving as a control mechanism is connected to the high-pressure air outlet 5 on the rear side of the support 4 on which the high-pressure air outlet 5 is formed. Therefore, when a plurality of control mechanisms are provided, the support 4 is formed with the same number of high-pressure air nozzles 5 . In other words, the multiple control mechanisms are connected in a state in which the high-pressure air leak ports 3 formed in the respective diffusers 1 are communicated with the high-pressure air outlets 5 of the support body 4, one by one.

[0032] By connecting the control mechanism to the high-pressure air outlet 5 , high-pressure air from the control mechanism is ejected from the rear side of the support 4 toward the gap between the movable body 7 and the support 4 . This makes it possible to correct any deviation in the support position of the movable body 7.

[0033] The diffuser 1 has a piezoelectric element 6 attached to a wall portion in the flow passage facing the high-pressure air leak port 3. Furthermore, a voltage application means for applying a voltage is attached to the piezoelectric element 6. When a voltage is applied to the piezoelectric element 6 , it is displaced, causing the high-pressure air (arrow in FIG. 1) flowing near the high-pressure air leak port 3 to be ejected from the high-pressure air leak port 3 towards the high-pressure air ejection port 5 in the support 4 . In this manner, the piezoelectric element 6 is displaced, thereby correcting the deviation of the support position of the movable body 7.

[0034] When the piezoelectric element 6 is not displaced, the high pressure air near the high pressure air leak port 3 is kept at a pressure equal to the air pressure (atmospheric pressure) at the downstream opening of the diffuser 1. In other words, the high-pressure air generating means 2 attached to the diffuser 1 generates the air pressure P b High pressure air P with a pressure of 1.89293 times 0 The air flows downstream in the flow passage of the diffuser 1.

[0035]

number

[0036] At this time, at the throat portion where the flow passage cross-sectional area of ​​the diffuser 1 is the smallest, the pressure difference between the inside and outside of the flow passage disappears and an imaginary air film is formed between the high-pressure air leakage outlet 3 and the flow passage, so that the high-pressure air flowing in the flow passage of the diffuser 1 does not leak from the high-pressure air leakage outlet 3 toward the high-pressure air outlet 5 of the support 4.

[0037] Therefore, the piezoelectric element 6 is displaced only when it is necessary to correct the deviation of the supporting position of the movable body 7. This allows the high-pressure air flowing near the high-pressure air leak port 3 to be instantly ejected from the high-pressure air leak port 3 toward the high-pressure air outlet 5 of the support body 4, thereby correcting the deviation of the support position of the movable body 7.

[0038] Furthermore, by providing high-pressure air outlets 5 and control mechanisms connected to these in multiple locations on the support 4, high-pressure air can be ejected from the multiple locations and, at the ejected location, the movable body 7 can be pushed in the direction of the high-pressure air being ejected, thereby correcting any deviation in the support position of the movable body 7. As a result, it becomes possible to control the support position of the movable body 7 in the air bearing.

[0039] Two or more piezoelectric elements 6 can also be stacked. By increasing and stacking the number of piezoelectric elements 6 according to the movable body 7 to be controlled, a displacement amount corresponding to the number of elements can be obtained, so that a displacement amount sufficient to correct the deviation of the support position of the movable body 7 can be obtained. Furthermore, a plurality of piezoelectric elements 6 may be attached in a direction perpendicular to the flow path direction of the high-pressure air.

[0040] If the diameter of the high-pressure air leak port 3 in the flow path direction is too large, the high-pressure air flowing through the flow path of the diffuser 1 may leak out to the high-pressure air leak port 3 regardless of the operation of the piezoelectric element 6. Conversely, if the diameter of the high-pressure air leak port 3 in the flow path direction is too small, even if the piezoelectric element 6 operates, the high-pressure air will not be ejected from the flow path of the diffuser 1 toward the high-pressure air leak port 3 (the imaginary air film will remain unbroken). Therefore, it is desirable that the slit width of the high-pressure air leak port 3 in the flow path direction is 0.3 mm. Moreover, it is desirable that the diameter of the high-pressure air leak port 3 in the direction perpendicular to the flow path direction is the same as the width of the piezoelectric element 6 to be attached. For example, when two piezoelectric elements 6 are attached side by side in a direction perpendicular to the flow path direction, the diameter of the high-pressure air leak port 3 in the direction perpendicular to the flow path direction is the same as the overall width of the piezoelectric elements 6.

[0041] The control mechanism may also be of a so-called recirculation type, in which the high-pressure air discharged from the open portion on the downstream side of the diffuser 1 is circulated to the closed portion on the upstream side of the diffuser 1.

[0042] A plurality of the above control mechanisms can be provided, and if high-pressure air can be ejected from a plurality of directions onto the movable body 7, deviations in the support position of the movable body 7 can be corrected from a plurality of directions. Furthermore, if a means for detecting deviation in the support position of the movable body 7 can be provided, then it is possible to correct the deviation in the support position of the movable body 7 by displacing only the piezoelectric element 6 of the control mechanism installed at a specific location and ejecting high-pressure air only from that specific location. Furthermore, by making it possible to eject high-pressure air onto the movable body 7 from multiple directions, it becomes possible to support the movable body in a more accurate position.

[0043] By using the above control mechanism, compressed air is supplied between the movable body 7 and the support body 4 to form an air layer, so that the displacement of the support position of the movable body 7 can be instantly corrected with a simple structure in an existing air bearing that can support the movable body 7 non-contact from the support surface of the support body 4. Therefore, the air supply means and the exhaust means can be any known means. For example, the air supply means can be a compressor.

[0044] The movable body 7 may have any shape as long as it can be supported by compressed air without contacting the support surface of the support, and any of a long shaft shape, a plate shape, and a spherical shape can be supported. The support 4 can have various shapes, such as a bearing type surrounding a shaft, a plate type, or a spherical type, depending on the shape of the movable body 7.

[0045] FIG. 2 is a diagram showing the configuration of an embodiment in which a spherical or cylindrical movable body 7 is supported using a control mechanism, and shows an embodiment in which the high-pressure air ejected by the control mechanism also serves as an air supply means for supplying compressed air to the gap between the movable body and the support. Therefore, the embodiment in Figure 2 is not described as an embodiment for correcting the deviation of the support position of the spherical movable body 7, but is a diagram for explaining how the high-pressure air ejected from the control mechanism is ejected toward the spherical movable body 7.

[0046] The control mechanism has a diffuser 1 in which the flow passage cross-sectional area is minimized at the throat portion where the piezoelectric element 6 is attached. A high-pressure air generating means 2 is provided upstream of the diffuser 1 , and high-pressure air flows from the high-pressure air generating means 2 into the flow passage of the diffuser 1 . The downstream side of the diffuser 1 is open. A high-pressure air leak port 3 is formed in the throat portion facing the piezoelectric element 6 , and the high-pressure air leak port 3 communicates with a high-pressure air outlet 5 formed in the support 4 . Therefore, the high pressure air ejected from the high pressure air leak port 3 is ejected from the high pressure air ejection port 5 formed in the support body 4 toward the movable body 7 . The spherical movable body 7 is supported in a non-contact manner against a support surface formed in a semi-spherical recess in the support body 4 by an air layer of compressed air formed in the gap between the movable body and the support body.

[0047] FIG. 3 is a cross-sectional view showing a horizontal section of a conventional air bearing that supports a rod-shaped movable body 7 having a horizontal axis of rotation. Conventional air bearings are provided with an air supply means 8 that supplies compressed air to the gap between the movable body 7 and the support 4, and an exhaust means 9 that exhausts the compressed air from the gap between the movable body 7 and the support 4. An air layer is formed by the compressed air in the gap between the movable body 7 and the support 4, thereby supporting the movable body 7 without contacting the support surface of the support 4. However, when the movable body 7 is driven, or when the air bearing device receives a force from outside, the support position or rotation axis of the movable body 7 may become misaligned.

[0048] In FIG. 3, the right side of the figure is in a high pressure state, and the left side of the figure is in a low pressure state, so that the rotation axis of the movable body 7 is shifted to the left side of the figure. In conventional air bearings, the misalignment of the rotation axis of the movable body 7 cannot be corrected simply by supplying compressed air to the gap between the movable body 7 and the support 4 using the air supply means 8.

[0049] FIG. 4 is a horizontal cross-sectional view of an embodiment in which a plurality of control mechanisms 10 as shown in FIG. 1 are provided on a support 4 in the air bearing of FIG. 3 that supports a rod-shaped movable body 7 having a horizontal axis of rotation. Since multiple control mechanisms 10 as described above are connected to multiple directions of the support 4, no matter in which direction the movable body 7 moves and the rotation axis becomes misaligned, the movable body 7 can be returned to its normal position by jetting high-pressure air from the control mechanism 10. In Figure 4, the right side of the figure shows a high-pressure state, and the left side of the figure shows a low-pressure state. By driving the control mechanism 10 connected to the left side of the figure, which shows the low-pressure state, and spraying out high-pressure air, the movable body 7 can be returned to the right side of the figure.

[0050] Furthermore, if a means for detecting deviations in the support position of the movable body can be provided, then it is possible to correct the deviations in the support position of the movable body by displacing only the piezoelectric element of the control mechanism installed at a specific location and ejecting high-pressure air only from that specific location. Furthermore, by making it possible to jet high-pressure air onto the movable body from multiple directions, the movable body can be supported in a more accurate position.

[0051] FIG. 5 is a schematic diagram showing an embodiment of a vibration isolation table for precision laser measurement on which a plurality of control mechanisms 10 shown in FIG. 1 are installed. The control mechanism 10, which functions as an air bearing, can control and isolate vibrations at high speed so that vibrations generated on the ground or on the vibration isolation table for precision laser measurement are not transmitted to the stationary table for the laser.

[0052] FIG. 6 is a schematic diagram showing an embodiment of a milling bed device for precision machining in which a plurality of the control mechanisms 10 shown in FIG. 1 are installed. The control mechanism 10, which functions as an air bearing, controls and dampens the vibrations at high speed so that the vertical vibrations generated by the precision milling bed are not transmitted to the table, enabling frictionless feeding, enabling stable, highly accurate precision machining. [Explanation of symbols]

[0053] 1 Diffuser 2. High-pressure air generating means 3 High pressure air leak 4 Support 5 High pressure air outlet 6 Piezo element 7 Movable body 8 Air supply means 9 Exhaust means 10 Control Mechanism 11. Vibration isolation table for precision laser measurement 12 Laser stationary stand 13 Milling bed for precision machining 14 Tables

Claims

1. An air supply means for supplying compressed air to a gap between the movable body and the support; an exhaust means for exhausting compressed air from a gap between the movable body and the support; a support that supports the movable body without contacting the support surface by forming an air layer by compressed air in a gap between the movable body and the support; In an air bearing comprising: The support is The support has one or more high-pressure air outlets formed to penetrate the support and for ejecting high-pressure air from the rear side of the support toward the gap between the movable body and the support for correcting a deviation in the support position of the movable body; A control mechanism for correcting a deviation in the support position of the movable body by ejecting high-pressure air is connected to the back side of the support on which the high-pressure air ejection ports are formed, the number of which is equal to the number of the high-pressure air ejection ports; The control mechanism is a diffuser having a closed tip on an upstream side of the air flow and an open tip on a downstream side of the air flow, the diffuser having a cross-sectional area that decreases in a direction along which the air flows; a high-pressure air generating means provided at a closing portion of the diffuser for causing high-pressure air to flow downstream through a flow passage of the diffuser; It consists of: The diffuser is a high-pressure air leakage port communicating with the high-pressure air outlet of the support body is formed in a throat portion where the flow passage cross-sectional area is smallest; A piezoelectric element is attached to the wall portion of the flow passage facing the high-pressure air leak port, A voltage application means is provided for applying a voltage to the piezoelectric element, As shown in Equation 1, the air pressure at the opening of the diffuser P ｂ Compressed air P with a pressure of 1.89293 times ０ The high-pressure air generating means causes the high-pressure air to flow downstream in the flow passage of the diffuser, When the pressure of the high-pressure air flowing near the high-pressure air leak port of the throat of the diffuser is made equal to the air pressure at the downstream opening of the diffuser, By applying a voltage to the piezoelectric element and displacing it, high-pressure air flowing near the high-pressure air leak port of the diffuser is ejected from the high-pressure air leak port through a high-pressure air outlet of the support; Correct the misalignment of the support position of the movable body 2. An air bearing control mechanism comprising: [0010] (γ: specific heat ratio of air = 1.4, Pb: air pressure at the opening of the diffuser)

2. An air supply means for supplying compressed air to a gap between the movable body and the support; an exhaust means for exhausting compressed air from a gap between the movable body and the support; a support that supports the movable body without contacting the support surface by forming an air layer by compressed air in a gap between the movable body and the support; In an air bearing comprising: The support is The support has one or more high-pressure air outlets formed to penetrate the support and for ejecting high-pressure air from the rear side of the support toward the gap between the movable body and the support for correcting a deviation in the support position of the movable body; A control mechanism for correcting a deviation in the support position of the movable body by ejecting high-pressure air is connected to the back side of the support on which the high-pressure air ejection ports are formed, the number of which is equal to the number of the high-pressure air ejection ports; The control mechanism is a diffuser having a closed tip on an upstream side of the air flow and an open tip on a downstream side of the air flow, the diffuser having a cross-sectional area that decreases in a direction along which the air flows; a high-pressure air generating means provided at a closing portion of the diffuser for causing high-pressure air to flow downstream through a flow passage of the diffuser; It consists of: The diffuser is a high-pressure air leakage port communicating with the high-pressure air outlet of the support body is formed in a throat portion where the flow passage cross-sectional area is smallest; Two or more stacked piezoelectric elements are attached to a wall portion of the flow passage facing the high-pressure air leak port, A voltage application means is provided for applying a voltage to the piezoelectric element, As shown in Equation 1, the air pressure at the opening of the diffuser P ｂ Compressed air P with a pressure of 1.89293 times ０ The high-pressure air generating means causes the high-pressure air to flow downstream in the flow passage of the diffuser, When the pressure of the high-pressure air flowing near the high-pressure air leak port of the throat of the diffuser is made equal to the air pressure at the downstream opening of the diffuser, By applying a voltage to the piezoelectric element and displacing it, high-pressure air flowing near the high-pressure air leak port of the diffuser is ejected from the high-pressure air leak port through a high-pressure air outlet of the support; Correct the misalignment of the support position of the movable body 2. An air bearing control mechanism comprising: [0010] (γ: specific heat ratio of air = 1.4, Pb: air pressure at the opening of the diffuser)

3. An air supply means for supplying compressed air to a gap between the movable body and the support; an exhaust means for exhausting compressed air from a gap between the movable body and the support; a support that supports the movable body without contacting the support surface by forming an air layer by compressed air in a gap between the movable body and the support; In an air bearing comprising: The support is The support has one or more high-pressure air outlets formed to penetrate the support and for ejecting high-pressure air from the rear side of the support toward the gap between the movable body and the support for correcting a deviation in the support position of the movable body; A control mechanism for correcting a deviation in the support position of the movable body by ejecting high-pressure air is connected to the back side of the support on which the high-pressure air ejection ports are formed, the number of which is equal to the number of the high-pressure air ejection ports; The control mechanism is a diffuser having a closed tip on an upstream side of the air flow and an open tip on a downstream side of the air flow, the diffuser having a cross-sectional area that decreases in a direction along which the air flows; a high-pressure air generating means provided at a closing portion of the diffuser for causing high-pressure air to flow downstream through a flow passage of the diffuser; It consists of: The diffuser is a high-pressure air leak port having a length of 0.3 mm in the flow path direction and communicating with the high-pressure air outlet of the support body is formed in a throat portion where the flow path cross-sectional area is smallest; Two or more stacked piezoelectric elements are attached to a wall portion of the flow passage facing the high-pressure air leak port, A voltage application means is provided for applying a voltage to the piezoelectric element, As shown in Equation 1, the air pressure at the opening of the diffuser P ｂ Compressed air P with a pressure of 1.89293 times ０ The high-pressure air generating means causes the high-pressure air to flow downstream in the flow passage of the diffuser, When the pressure of the high-pressure air flowing near the high-pressure air leak port of the throat of the diffuser is made equal to the air pressure at the downstream opening of the diffuser, By applying a voltage to the piezoelectric element and displacing it, high-pressure air flowing near the high-pressure air leak port of the diffuser is ejected from the high-pressure air leak port through a high-pressure air outlet of the support; Correct the misalignment of the support position of the movable body 2. An air bearing control mechanism comprising: [0010] (γ: specific heat ratio of air = 1.4, Pb: air pressure at the opening of the diffuser)

Images