Fluid servo valve and fluid servo device

Abstract

To provide a fluid servo valve in which the supporting rigidity of a movable plate is less affected by assembly accuracy and component accuracy etc, and which causes less variations in basic valve properties during mass production.SOLUTION: A fluid servo device includes: a supply-side valve body 1 being in communication with a supply-side flow path 12 and having a supply nozzle 11; a discharge-side valve body 2 being in communication with a discharge-side flow path 22 and having a discharge nozzle 21; a thin plate-shaped movable plate 3 provided at respective tip ends of the supply nozzle 11 and the discharge nozzle 21; an electromagnet 4 that deforms a movable plate 3 and displaces it between the supply nozzle 11 and the discharge nozzle 21; and a pinching structure P that is provided between the supply-side valve body 1 and the discharge-side valve body 2 and presses and pinches an outer edge part of the movable plate 3 in a thickness direction. With the supply-side valve body 1 fixed to the discharge-side valve body 2, the pinching structure P includes: a reference face P1 which is apart from the movable plate 3 at a predefined distance; and a pressing face P2 which projects from the reference face P1 toward the movable plate 3 to press the movable plate 3.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a fluid servo valve that controls the pressure or flow rate of a fluid by displacing a movable plate between a pair of nozzles, and a fluid servo device equipped with the fluid servo valve. [Background technology]

[0002] For example, active vibration isolation tables using pneumatic actuators are used to control micro-vibrations in ultra-precision equipment, etc. In such active vibration isolation tables, various sensors detect the position, speed, and acceleration of a stage on which the ultra-precision equipment, etc. is placed, and the internal pressure of the pneumatic actuator is controlled based on the output signals of the sensors.

[0003] Furthermore, to control the internal pressure of the pneumatic actuator, the flow rate of compressed air is adjusted by changing the valve drive current applied to the electromagnet of the fluid servo valve and displacing the position of the movable plate between the nozzles.

[0004] The applicant has already proposed a fluid servo valve in which the control pressure or control flow rate with respect to the valve drive current has better linearity than before (see Patent Document 1). This fluid servo valve comprises a supply-side valve body with a supply nozzle that supplies fluid, an exhaust-side valve body with an exhaust nozzle that is arranged coaxially opposite the supply nozzle, a movable plate disposed between the supply nozzle and the exhaust nozzle, a disk having a thickness equal to or less than a predetermined value, and an electromagnet disposed within the exhaust-side valve body that magnetically attracts the disk.

[0005] The outer edge of the disk is sandwiched between the inner end surfaces of the supply-side valve body and the exhaust-side valve body, where the tip ends of the nozzles are exposed, and is clamped and ideally rigidly supported by fastening the supply-side valve body and the exhaust-side valve body together with a plurality of bolts.

[0006] In mass-producing the above-described fluid servo valve, the inventors of the present application prototyped multiple fluid servo valves under sufficient precision control conditions for each component, and discovered that there was variation in the basic valve characteristics, such as the control pressure and control flow rate, of each fluid servo valve.

[0007] The present inventors have conducted extensive research into the cause of this problem and have found the following problems.

[0008] That is, the inventors of the present application discovered for the first time that (1) the variation in the basic valve characteristics is mainly due to the variation in the disk displacement characteristics in response to the valve drive current, and (2) the constraint conditions at the outer edge of the disk vary depending on the fastening state of multiple bolts and the precision of part processing, resulting in a slightly elastic support rather than a rigid support, which causes the variation in the disk displacement characteristics. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-148373 Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a fluid servo valve in which the support rigidity of the movable plate is less susceptible to the effects of assembly accuracy, component accuracy, etc., and in which the basic characteristics of the valve vary little during mass production. [Means for solving the problem]

[0011] That is, the fluid servo valve according to the present invention comprises a supply-side valve body connected to a supply-side flow path and having a supply nozzle at its tip from which a fluid is ejected; an exhaust-side valve body connected to an exhaust-side flow path and having an exhaust nozzle at its tip from which a fluid is sucked; a thin, plate-like movable plate provided between the tips of the supply nozzle and the exhaust nozzle; an electromagnet that deforms at least a portion of the movable plate and displaces it between the supply nozzle and the exhaust nozzle; and a clamping structure provided between the supply-side valve body and the exhaust-side valve body and that presses and clamps an outer edge of the movable plate in the thickness direction, wherein the clamping structure comprises, when the exhaust-side valve body is fixed to the supply-side valve body, a reference surface spaced a predetermined distance from the movable plate, and an annular pressing surface having a width dimension not greater than a predetermined value that protrudes further toward the movable plate than the reference surface and presses the movable plate.

[0012] With this configuration, the pressing surface can concentrate pressure on a specific area on the outer edge of the movable plate, thereby sandwiching the outer edge of the movable body between the supply-side valve body and the exhaust-side valve body. This makes it easier to increase the surface stress generated on the outer edge of the movable plate than in the past, making it easier to achieve a completely rigid support state. Therefore, even if there are variations in the restraint state of bolts or the machining accuracy of each valve body, the restraint state of the outer edge of the movable plate can be kept constant without being affected by these variations, thereby suppressing variations in valve characteristics. As a result, the yield rate is improved during mass production of fluid servo valves.

[0013] For example, even if the reference surface comes into contact with the outer edge of the movable plate due to problems such as assembly errors or processing errors, and the support state of the movable plate deviates from the expected state, the rigidity of the movable plate can be less affected if the pressing surface is located closer to the inner periphery than the reference surface.

[0014] In order to absorb the effects of assembly errors and processing errors by deforming the pressing surface itself and further reduce the likelihood of variation in valve characteristics, it is sufficient that the elastic modulus of the outer edge of the movable plate is higher than the elastic modulus of the pressing surface.

[0015] A specific example of a form in which the pressing surface can sufficiently press the outer edge of the movable plate to achieve a rigid support state is one in which the pressing surface is annular and has a width dimension of 5 mm or less in the radial direction.

[0016] In order to enable the pressing surface to uniformly press the outer edge of the movable plate so as to rigidly support the movable plate simply by combining the supply side valve body and the exhaust side valve body, the pressing and clamping structure may further include a threaded portion consisting of a male screw and a female screw formed between the supply side valve body and the exhaust side valve body.

[0017] In order to make it possible to adjust the relative distance between the tip of the supply nozzle and the movable plate, or the relative distance between the tip of the exhaust nozzle and the movable plate during assembly, thereby absorbing manufacturing errors and the like in the supply side valve body or the exhaust side valve body and obtaining a desired control pressure or control flow rate, it is sufficient to further provide a gap-adjusting spacer that is arranged between the supply side valve body and the exhaust side valve body and overlaps the movable plate.

[0018] In order to configure the entire fluid servo valve compactly and increase the integration density when used in, for example, a fluid servo device, it is sufficient that the supply side valve body and the exhaust side valve body are each formed in an approximately cylindrical shape.

[0019] In order to improve the linearity of the control flow rate or control pressure relative to the valve drive current applied to the electromagnet, it is sufficient that the magnetic characteristics of a magnetic material component forming the closed loop magnetic circuit, which is formed so that the magnetic flux generated by the electromagnet passes at least through the movable plate, have a linear region in which the magnetic flux density characteristic is roughly proportional to the magnetizing force, and a magnetic saturation region, which is a region in which the slope angle of the magnetic flux density relative to the magnetizing force changes more slightly than in the linear region, and that the magnetic flux density of the magnetic flux flowing through the magnetic material component falls within the magnetic saturation region when the current passing through the electromagnet is increased within the displacement range of the movable plate.

[0020] For example, in order to easily utilize the magnetic saturation phenomenon by adjusting the shape and dimensions of the components, the movable plate may be configured so that the magnetic flux density of the magnetic flux falls within the magnetic saturation region.

[0021] A fluid servo device comprising a fluid servo valve according to the present invention, a pneumatic actuator connected to the fluid servo valve, a sensor for detecting the displacement or vibration state of a controlled object, and a controller for controlling the fluid servo valve based on the output of the sensor, enables the fluid servo valve to achieve linearity in flow rate or pressure over a wide range of valve drive current, thereby (1) obtaining a wide control range centered on the operating point, (2) generating a highly accurate feedforward signal that cancels disturbances, thereby achieving highly accurate vibration suppression control, and (3) reducing the amplitude dependency of gain-phase characteristics near the operating point. [Effects of the Invention]

[0022] As described above, in the fluid servo valve according to the present invention, the outer edge of the movable plate is pressed and clamped by an annular pressing surface that protrudes toward the movable plate from the reference surface and has a width equal to or less than a predetermined value. This concentrates the surface stress generated at the outer edge of the movable plate, making it easier to achieve a rigid support state. As a result, variations in the support state of the movable plate and variations in the displacement characteristics of the movable plate are reduced. As a result, variations in valve characteristics such as control pressure and control flow rate in response to valve drive current are reduced among multiple fluid servo valves, enabling higher yields in mass production. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a schematic exploded perspective view of a fluid servo valve according to a first embodiment of the present invention. [Figure 2] FIG. 1 is a schematic vertical cross-sectional view of a fluid servo valve according to a first embodiment. [Figure 3] FIG. 2 is a schematic partial enlarged view showing a closed loop magnetic circuit of the fluid servo valve according to the first embodiment. [Figure 4] 5A and 5B are schematic diagrams showing the difference between the analytical models of a conventional fluid servo valve and the fluid servo valve according to the first embodiment. [Figure 5] 10 shows analysis results regarding the fixed state of the movable plate of a conventional fluid servo valve and the fluid servo valve according to the first embodiment. [Figure 6] FIG. 6 is a schematic exploded perspective view of a fluid servo valve according to a second embodiment of the present invention. [Figure 7] FIG. 10 is a schematic vertical cross-sectional view of a fluid servo valve according to a second embodiment. [Figure 8] FIG. 10 is a schematic diagram showing a fluid servo device according to a third embodiment of the present invention. [Figure 9] FIG. 10 is a schematic perspective view showing an attached state of a fluid servo valve in a fluid servo device according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0024] A fluid servo valve 100 according to a first embodiment of the present invention will be described with reference to the drawings.

[0025] <Configuration of fluid servo valve 100> This fluid servo valve 100 is used to control the flow rate of compressed air to control the internal pressure of a pneumatic actuator provided in an active vibration isolation table, for example.

[0026] As shown in the exploded perspective view of FIG. 1, the fluid servo valve 100 is provided with a supply-side valve body 1 formed in a roughly rectangular parallelepiped shape and having a supply-side flow path 12 for supplying compressed air into the interior of the fluid servo valve 100, an exhaust-side valve body 2 formed in a roughly two-stage cylindrical shape and having an exhaust-side flow path 22 for exhausting a portion of the supplied compressed air to the outside, and a movable plate 3 sandwiched between the supply-side valve body 1 and the exhaust-side valve body 2.

[0027] As shown in the cross-sectional view of Figure 2, the supply-side valve body 1 has a supply-side flow passage 12, which is a through-hole formed along the central axis, and a control flow passage 13, which is a through-hole offset a predetermined distance radially outward from the central axis and extending parallel to the supply-side flow passage 12. A roughly thin, disc-shaped recess is formed on the inner surface of the supply-side valve body 1, forming a supply-side gap 14 between the supply-side flow passage 12 and the movable plate 3. A supply nozzle 11 is provided on the side of the supply-side flow passage 12 facing the movable plate 3.

[0028] On the other hand, the exhaust-side valve body 2 is provided with an exhaust-side flow path 22, which is a through hole formed along the central axis. An exhaust nozzle 21 is provided on the inner surface of the exhaust-side valve body 2 in the exhaust-side flow path 22 so as to face the movable plate 3. That is, the supply nozzle 11 and the exhaust nozzle 21 are arranged coaxially, and the center of the movable plate 3 is located between the tips of the nozzles. The exhaust-side valve body 2 also comprises a roughly cylindrical electromagnet 4, the central axis of which is formed with the exhaust nozzle 21 and the exhaust-side flow path 22, and a roughly cylindrical outer cover 2C that houses the electromagnet 4 and is fixed to the supply-side valve body 1 to sandwich the movable plate 3.

[0029] Here, the supply nozzle 11 and the exhaust nozzle 21 have the same inner diameter, and they form a symmetric nozzle.

[0030] 2 and 3, the electromagnet 4 includes a coil bobbin 41, a coil 42 wound around the coil bobbin 41, and a yoke 43 that forms a closed-loop magnetic circuit MC of magnetic flux generated when a valve drive current is applied to the coil 42. The coil bobbin 41 is made of a non-magnetic material, and the yoke 43 is made of a magnetic material.

[0031] The yoke 43 is generally cylindrical and comprises a central shaft portion 44 on whose outer peripheral surface the coil bobbin 41 is fitted, a bottom surface portion 45 which extends radially outward from the base end of the central shaft portion 44 and has a thin, disk-like shape and is fixed to the outer cover with bolts, a generally thin, cylindrical outer peripheral portion 46 which extends axially from the outer periphery of the bottom surface portion 45, and a generally thin, two-stage cylindrical top surface portion 47 which extends radially inward from the tip end of the outer peripheral portion 46. An exhaust-side gap 23 is formed between the top surface portion 47 and the movable plate 3.

[0032] The central shaft 44 has a hollow cylindrical shape, and the internal cavity forms the exhaust-side flow path 22. The aforementioned exhaust nozzle 21 is formed at the tip of the central shaft 44. Furthermore, as shown in FIG. 3(b), a first magnetic pole 48 is formed by an annular ridge with three notches formed around the periphery of the exhaust nozzle 21. Additionally, as shown in FIG. 3(a), a second magnetic pole 49 is formed by an annular ridge protruding from the center of the top surface 47 so as to protrude toward the movable plate 3. That is, the magnetic flux generated by the coil 42 circulates through the following path: "inside the central shaft 44 → first magnetic pole 48 → exhaust-side gap 23 → movable plate 3 → exhaust-side gap 23 → second magnetic pole 49 → top surface 47 → outer periphery 46 → bottom surface 45 → central shaft 44," forming a closed-loop magnetic circuit MC. Furthermore, the movable plate 3 is configured so that the magnetic flux density of the magnetic flux within the movable plate 3 causes magnetic saturation depending on the material, thickness, shape, etc. of the movable plate 3.

[0033] More specifically, the magnetic characteristics of the magnetic material components that form the closed-loop magnetic circuit MC have a linear region in which the magnetic flux density characteristic is roughly proportional to the magnetizing force, and a magnetic saturation region in which the gradient of the magnetic flux density to the magnetizing force changes less than in the linear region. The thickness and shape of the movable plate 3, which forms part of the closed-loop magnetic circuit MC, are set so that the magnetic flux density characteristic to the magnetizing force in the movable plate 3 falls within the magnetic saturation region when the valve drive current is within a predetermined range. When the movable plate 3 is closer to the electromagnet 4 than a predetermined position between the supply nozzle 11 and the exhaust nozzle 21, magnetic saturation is generated in the movable plate 3 so that the displacement of the movable plate 3 changes roughly proportionally to changes in the valve drive current.

[0034] 1 and 2, the movable plate 3 is a thin, circular disk that is configured to be displaced between the tips of the supply nozzle 11 and the exhaust nozzle 21 by the magnetic attraction of the electromagnet 4. More specifically, the outer edge of the movable plate 3 is sandwiched and fixed between the supply-side valve body 1 and the exhaust-side valve body 2, and the maximum displacement occurs in the center due to elastic deformation of the unfixed portion.

[0035] That is, the displacement portion 31, which is the center of the movable plate 3, is the location that is most displaced by the magnetic attractive force of the electromagnet 4. The outer edge of the movable plate 3 is a fixed portion 32 whose position is fixed relative to the supply nozzle 11 and the exhaust nozzle 21. Specifically, the fixed portion 32 is a portion that is pressed and held between the supply-side valve body 1 and the exhaust-side valve body 2, and is a portion that is supported at the fixed end of the movable plate 3. The displacement portion 31 is a portion where displacement occurs due to membrane deformation caused by the action of the force generated by the pressure on the supply side and the exhaust side and the magnetic attractive force of the electromagnet 4.

[0036] In addition, four fluid flow holes 34 are formed in the face plate portion of the movable plate 3 to allow the fluid, compressed air, to pass from the supply side gap portion 14 to the exhaust side gap portion 23, and each fluid flow hole 34 is arranged spirally around the center of the movable plate 3.

[0037] The fluid flow holes 34 are formed so that the slit width becomes smaller as they move from the outer edge toward the center. In this fluid servo valve 100, the movable plate 3 is driven solely by the magnetic attraction force of the electromagnet 4. Therefore, no permanent magnets are provided inside the supply-side valve body 1 or the exhaust-side valve body. As a result, assembly can be achieved simply by lining up the supply-side valve body 1, movable plate 3, and exhaust-side valve body 2 along the central axis and fastening them together with bolts.

[0038] In the fluid servo valve 100 configured as described above, compressed air supplied from the supply nozzle 11 flows into the supply-side gap 14, and a portion of the compressed air flows out through the control flow path 13 to the pneumatic actuator. The remainder of the compressed air that flows into the supply-side gap 14 flows into the exhaust-side gap 23 through the fluid communication holes 34 of the movable plate 3. The compressed air in the exhaust-side gap 23 is sucked in through the exhaust nozzle 21 and exhausted to the outside through the exhaust-side flow path 22. The position of the movable plate 3 between the supply nozzle 11 and the exhaust nozzle 21 is controlled by the magnetic attractive force of the electromagnet 4, thereby controlling the flow rate of compressed air supplied from the control flow path 13 to the pneumatic actuator.

[0039] Next, the clamping structure P formed between the supply side valve body 1 and the exhaust side valve body 2 for pressing and clamping the fixed portion 32, which is the outer edge portion of the movable plate 3, will be described with reference to FIG.

[0040] The clamping structure P is formed between the end face of the supply-side valve body 1 on the side where the tip of the supply nozzle 11 is exposed and the end face of the exhaust-side valve body 2 on the side where the tip of the exhaust nozzle 21 is exposed. In the first embodiment, a portion of the end face of the supply-side valve body 1 contacts the movable plate 3, and almost the entire end face of the exhaust-side valve body 2 contacts the movable plate 3. More specifically, the clamping structure P includes an annular (ring-shaped) reference surface P1 that is spaced a predetermined distance from the movable plate 3 when the supply-side valve body 1 and the exhaust-side valve body 2 are fixed with bolts, and an annular pressing surface P2 that protrudes toward the movable plate 3 beyond the reference surface P1. In the first embodiment, as shown in FIG. 2 , the reference surface P1 and the pressing surface P2 are formed on the end face of the supply-side valve body 1. The pressing surface P2 is formed on the inner peripheral side of the reference surface P1, and its radial width is set to 5 mm or less. When the supply-side valve body 1 is fixed to the exhaust-side valve body 2 with the movable plate 3 sandwiched between them, the fastening force of the bolts causes this pressing surface P2 to press the movable plate 3 against the end face of the exhaust-side valve body 2, generating a surface stress of a predetermined value or greater. In other words, the outer edge of the movable plate 3 is rigidly supported by the supply-side valve body 1 and the exhaust-side valve body, and even if the magnetic attractive force of the electromagnet 4 is applied to the movable plate 3, no substantial displacement occurs in the fixed portion 32.

[0041] <Analysis results> Next, a stress analysis was performed based on the analytical model shown in FIG. 4 on the fixed state of the movable body 3 in a conventional fluid servo valve configuration and the fixed state of the movable plate 3 in the clamping structure P of the fluid servo valve 100 of this embodiment. As shown in FIG. 4, the fixed structure of the movable plate 3 in the conventional fluid servo valve has a pressing surface P2 in this embodiment that covers the entire end surface of the supply-side valve body 1 and does not have a reference surface P1 spaced apart from the movable plate 3. In other words, as shown in FIG. 4, the pressing surface P2 in this embodiment has a significantly smaller area that contacts the movable plate 3 than the conventional pressing surface P2. In the analysis, the Young's modulus of the movable plate 3 was set to stainless steel, while the Young's modulus of the outer case 2C of the supply-side valve body 1 and the exhaust-side valve body 2 was set to aluminum alloy. Furthermore, the analysis was unified to a case where the bolts were fastened at six locations with an axial force of 1050 N.

[0042] 5 shows the analysis results of the surface stress generated in the movable plate 3. Compared to the conventional structure, the structure of this embodiment makes it possible to concentrate stress on the part pressed by the annular pressing surface P2 at the outer edge of the movable plate 3. In other words, it can be seen that the pressing surface P2 fixes the movable plate 3 with sufficient pressing force, achieving ideal rigid support.

[0043] <Effects of the fluid servo valve 100> As described above, in the fluid servo valve 100 of the first embodiment, the annular pressing surface P2 having a limited width concentrates the reaction force of the bolt fastening force on the outer edge of the movable plate 3, thereby realizing a state of rigid support. As a result, even if there is an error in the parallelism or surface roughness of the end faces of the supply-side valve body 1 and the exhaust-side valve body 2 that sandwich the movable plate 3, variations in the support rigidity of the movable plate 3 are unlikely to occur.

[0044] Furthermore, since there is little variation in the support rigidity of the movable plate 3, it is also possible to suppress variation in the rigidity of the movable plate 3. Therefore, there is less variation in the displacement characteristics with respect to the valve drive current applied to the electromagnet 4, and as a result, it is possible to reduce variations in the control pressure and control flow rate of the compressed air output from the control flow path 13.

[0045] Furthermore, since the modulus of longitudinal elasticity of the pressing surface P2 is smaller than that of the movable body 3, minute deformations of the pressing surface P2 or the end face of the exhaust side valve body 2 can absorb error factors in the valve characteristics such as assembly errors and surface roughness.

[0046] As a result, when the fluid servo valve of the first embodiment is mass-produced, the yield can be improved compared to the conventional method.

[0047] Next, a fluid servo valve 100 according to a second embodiment of the present invention will be described with reference to Fig. 6. Note that members corresponding to those described in the first embodiment will be given the same reference numerals.

[0048] The fluid servo valve 100 of the second embodiment is different from the first embodiment in the shapes of the supply side valve body 1 and the exhaust side valve body 2, and also in the configuration of the clamping structure P.

[0049] <Configuration of fluid servo valve 100> In the second embodiment, as shown in FIG. 6 , the supply-side valve body 1 and the exhaust-side valve body 2 have generally cylindrical outer shapes. Furthermore, the supply-side valve body 1 is fixed to the exhaust-side valve body 2 not with bolts but with male and female threads formed on the supply-side valve body 1 and the exhaust-side valve body 2, respectively. That is, the supply-side valve body 1 is generally cylindrical with a bottom, and a female thread is formed on the inner circumferential surface on the tip opening side. A shim ring S and a movable plate 3 are housed inside the opening of the supply-side valve body 1. Meanwhile, the exhaust-side valve body 2 is generally cylindrical, and a male thread is formed on the outer circumferential surface on the side where the tip of the exhaust nozzle 21 is exposed. When the exhaust-side valve body 2 is screwed onto the supply-side valve body 1, the fluid servo valve 1 is configured to form a single cylinder.

[0050] The clamping structure P of the second embodiment will be described in detail with reference to Fig. 7. The clamping structure P of the second embodiment includes a reference surface P1 and a pressing surface P2 formed on the exhaust-side valve body 2, and further includes a threaded portion SC consisting of a male thread and a female thread formed between the supply-side valve body 1 and the exhaust-side valve body.

[0051] In the second embodiment, the reference surface P1 is formed as an outer end surface formed in the axial center of the cylindrical exhaust-side valve body 2, and an annular pressing surface P2 having a predetermined width in the radial direction is provided which is formed tip-side of the reference surface P1. Specifically, the reference surface P1 is formed so as to extend radially outward from the base end side of the male thread formed in the exhaust-side valve body 2, and the pressing surface P2 is formed on the tip-side surface of the male thread.

[0052] The supply-side valve body is formed with a step that extends radially inward from the base end of the female thread in a ring shape. A shim ring S, which is a gap adjustment spacer, and the outer edge of the movable plate 3 are placed on this step.

[0053] The shim ring S is a ring-shaped spacer used to adjust gaps in precision equipment. Shim rings S with a variety of thicknesses are prepared in advance. By selecting the appropriate thickness of the shim ring S, it is possible to finely adjust the relative distance between the tip of the supply nozzle 11 and the center 31 of the movable plate 3, and the relative distance between the tip of the exhaust nozzle 21 and the center 31 of the movable plate 3, in the final assembly stage. Note that the shim ring S may be used to adjust only one of the above-mentioned relative distances.

[0054] <Adjusting the gap with Shim Ring S> When the exhaust-side valve body 2 is in a separate state before being assembled to the supply-side valve body 1, the axial position of the tip of the exhaust nozzle 21 can be precisely measured using the ring-shaped protruding pressing surface P2, which is the surface that comes into contact with the fixed portion 32 of the movable plate 3, as a reference. This is because the pressing surface P2 and the exhaust nozzle 21 are provided on the inner surfaces of the exhaust valve body 2. Similarly, when the supply-side valve body 1 is in a separate state, the axial position of the tip of the supply nozzle 11 can be precisely measured using the ring-shaped support surface SS, which is the surface on which the shim ring S is attached. By adjusting the thickness of the shim ring S based on these obtained measurements, the distance between the center portion 31 of the movable plate 3 and the tip of the supply-side nozzle 11 and the distance between the center portion 31 of the movable plate 3 and the tip of the exhaust-side nozzle 21 can be adjusted.

[0055] <Effects of the fluid servo valve 100> With the fluid servo valve 100 of the second embodiment configured as described above, the exhaust-side valve body 2 can be screwed onto the supply-side valve body 1 with the shim ring S and the movable plate 3 housed inside the supply-side valve body 1, allowing the pressure surface P2 formed on the tip surface of the male thread to apply a uniform pressure and clamp. Therefore, compared to the first embodiment in which the supply-side valve body 1 and the exhaust-side valve body 2 are fixed together with multiple bolts, it is easier to apply a uniform force to the pressure surface P2 regardless of the skill of the assembly worker.

[0056] Furthermore, simply by turning the exhaust side valve body 2 until it is completely screwed into the supply side valve body 1, a predetermined surface stress is generated, creating a state in which the movable body 3 is completely rigidly supported.

[0057] Therefore, the variation in the support state of the movable plate 3 can be further reduced compared to the first embodiment, and the variation in the control flow rate and control pressure output from the control flow path 13 relative to the valve drive current can also be eliminated.

[0058] Next, a fluid servo device 200 according to a third embodiment will be described. As shown in Fig. 8, an active vibration isolation table, which is the fluid servo device 200, may be configured using the fluid servo valve 100 described in the second embodiment. Specifically, the active vibration isolation table includes a table ST on which an object to be isolated or controlled is placed, a pneumatic actuator AS provided on the leg of the table ST and connected to the fluid servo valve 100, a sensor SN that detects the displacement or vibration state of the table ST, which is the object to be controlled, and a controller CN that controls the fluid servo valve 100 based on the output of the sensor SN.

[0059] The position, speed, and acceleration of the table ST are detected by a plurality of sensors SN provided on the table ST and the foundation, and their output signals are input to a controller CN. The controller CN, whose functions are realized using, for example, a computer, controls the fluid servo valve 100 by feedforward control based on the outputs of the sensors SN so as to cancel the influence of disturbances such as vibrations in the foundation. In other words, the controller CN controls the pressure or flow rate of compressed air supplied to the pneumatic actuator AS from the fluid servo valve 100, which is connected to a compressed air supply source, via a control flow path 13.

[0060] In such a fluid servo device 200, the fluid servo valve 100 has linearity in the pressure or flow rate of the fluid output over a wide range of valve drive currents, making it possible to achieve highly accurate feedforward control so as to cancel various disturbances to the table ST. Furthermore, since the fluid servo valve 100 of the second embodiment has a cylindrical shape and can be configured compactly, it is possible to provide multiple fluid servo valves 100 in a compact configuration, which allows them to be integrated on the side of the pneumatic actuator AS, as shown in the perspective view of Fig. 9. In other words, by providing five fluid servo valves 100 as shown in Fig. 9, it is possible to increase the controlled flow rate and increase the degree of freedom in control.

[0061] Other embodiments will now be described. The fluid servo valve may have an electromagnet provided in the supply-side valve body. In such a case, the effective cross-sectional area of ​​the exhaust nozzle provided on the opposite side of the movable plate from the electromagnet may be made larger than the effective cross-sectional area of ​​the supply-side nozzle. In other words, by making the effective cross-sectional area of ​​the nozzle on the side farther from the electromagnet relative to the movable plate larger than the effective cross-sectional area of ​​the other nozzle, it is possible to linearize the displacement when the movable plate is displaced to a position farther from the electromagnet than the operating point.

[0062] The movable plate is not limited to a thin circular disk or a thin rectangular parallelepiped plate member, and may have various shapes. Furthermore, the fluid servo valve according to the present invention may be configured so that magnetic saturation does not occur in the closed loop magnetic circuit.

[0063] The pressing surface in the clamping structure may be a surface formed in a ring shape having a predetermined width, i.e., it is not limited to a circular ring shape, but may be a square ring shape with rounded corners, or the like.

[0064] The fluid servo valve according to the present invention is not limited to use for controlling pneumatic actuators, but may also be used for other purposes requiring control of the pressure or flow rate of fluids.

[0065] The fluid servo device according to the present invention is not limited to an active vibration isolation table, but may be, for example, a passive vibration isolation table in which only feedback control is performed, or other devices.

[0066] In addition, various modifications may be made and parts of the embodiments may be combined together as long as they do not go against the spirit of the present invention. [Explanation of symbols]

[0067] 200 Fluid Servo Device 100···Fluid Servo Valve 11. Supply nozzle 21 Exhaust nozzle 3...Movable plate 4. Electromagnet

Claims

1. a supply-side valve body having a supply nozzle that communicates with the supply-side flow path and discharges a fluid from a tip thereof; an exhaust-side valve body having an exhaust nozzle that is connected to an exhaust-side flow path and through which fluid is drawn from a tip thereof; a thin movable plate provided between the tip ends of the supply nozzle and the exhaust nozzle; an electromagnet that adjusts the flow rate of the fluid by deforming at least a portion of the movable plate and displacing it between the supply nozzle and the exhaust nozzle; a clamping structure provided between the supply-side valve body and the exhaust-side valve body, for pressing and clamping an outer edge portion of the movable plate in a thickness direction, The clamping structure is an annular pressing surface having a width dimension equal to or smaller than a predetermined value that presses the movable plate; a threaded portion formed between the supply side valve body and the exhaust side valve body, a fluid servo valve configured such that, by turning the supply-side valve body relative to the exhaust-side valve body and screwing it together, the distance between the supply-side valve body and the exhaust-side valve body changes, causing the pressing surface to press against the outer edge of the movable plate.

2. a supply-side valve body having a supply nozzle that communicates with the supply-side flow path and discharges a fluid from a tip thereof; an exhaust-side valve body having an exhaust nozzle that is connected to an exhaust-side flow path and through which fluid is drawn from a tip thereof; a thin movable plate provided between the tip ends of the supply nozzle and the exhaust nozzle; an electromagnet that adjusts the flow rate of the fluid by deforming at least a portion of the movable plate and displacing it between the supply nozzle and the exhaust nozzle; a clamping structure provided between the supply-side valve body and the exhaust-side valve body, for pressing and clamping an outer edge portion of the movable plate in a thickness direction, The clamping structure is a reference surface spaced a predetermined distance from the movable plate when the exhaust-side valve body is fixed to the supply-side valve body; an annular pressing surface having a width dimension equal to or smaller than a predetermined value that protrudes toward the movable plate from the reference surface and presses the movable plate; A fluid servo valve, wherein the pressing surface is provided on the inner peripheral side of the reference surface.

3. 3. A fluid servo valve according to claim 1, wherein the elastic modulus of the outer edge of said movable plate is higher than the elastic modulus of said pressing surface.

4. 4. A fluid servo valve according to claim 1, wherein the pressing surface is annular and has a width of 5 mm or less in the radial direction.

5. 5. A fluid servo valve according to claim 1, wherein the supply side valve body and the exhaust side valve body are each formed in a generally cylindrical shape.

6. 6. The fluid servo valve according to claim 5, further comprising a gap adjusting spacer disposed between the supply side valve body and the exhaust side valve body so as to overlap the movable plate.

7. In a closed loop magnetic circuit formed so that the magnetic flux generated by the electromagnet passes through at least the movable plate, the magnetic characteristics of the magnetic material parts forming the closed loop magnetic circuit have a linear region in which the magnetic flux density characteristic is approximately proportional to the magnetizing force, and a magnetic saturation region in which the gradient angle of the magnetic flux density to the magnetizing force changes smaller than that in the linear region, 7. A fluid servo valve according to claim 1, wherein the magnetic flux density of the magnetic flux flowing through the magnetic material component falls within the magnetic saturation region when the current passing through the electromagnet is increased within the displacement range of the movable plate.

8. 8. The fluid servo valve according to claim 7, wherein the magnetic flux density of the magnetic flux in the movable plate is configured to fall within the magnetic saturation region.

9. A fluid servo valve according to any one of claims 1 to 8; a pneumatic actuator connected to the fluid servo valve; a sensor for detecting a displacement or vibration state of a controlled object; a controller that controls the fluid servo valve based on the output of the sensor.

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