JP7262559B2 - Actuator for valve and diaphragm valve with same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a valve actuator and a diaphragm valve including the same, and more particularly to a valve actuator and a diaphragm valve which are configured extremely suitably for miniaturization of the entire valve structure while exhibiting high valve closing performance even for high-pressure fluids. diaphragm valve.

In general, so-called direct-touch diaphragm valves are mainly used as control valves for gas supply systems in semiconductor manufacturing processes. A direct diaphragm valve is a metal diaphragm that is used as a sealing material for the outside, and it also directly closes the seat. The advantage is that there are no metal-to-metal sliding parts in the part, and that the structure is optimal for cleaning the fluid. However, there is a limit to the stroke that can be secured, and compared to other valve types such as bellows valves, it is structurally difficult to secure a large flow rate.

Diaphragm valves used in the semiconductor manufacturing process as described above are often equipped with air-driven actuators for automatic control and the like. Air-driven actuators are excellent in terms of cleanliness and cost, and are extremely suitable for use in semiconductor manufacturing equipment. Due to the compact footprint area occupied by , it is required to be compactly miniaturized to fit within this area. In particular, in an integrated gas system in which piping is blocked as a base block without using joints, the actuator can be detachably attached to the upper part of the base block via an interface. The high maintainability is also demonstrated, and it is used in many situations.

Furthermore, in order to manufacture highly precise devices such as semiconductor devices with high quality, the semiconductor manufacturing process equipment such as the gas supply system as described above must all be housed in a so-called clean room. In the clean room, airborne particles and microorganisms are managed to a specified level of cleanliness (contamination control), and a specified level of cleanliness is ensured for the materials, chemicals, water, etc. brought into the room as well as for the workers entering the room. , is a sealed space where environmental conditions such as temperature, humidity, and pressure can be controlled as needed. Cost is necessary, and it becomes a big burden as a production facility cost. For this reason, when introducing a clean room, it must be designed and constructed in such a way that the volume and configuration are optimal and minimal according to the intended use without causing waste.

On the other hand, in recent years, the demand for higher performance, power saving, performance improvement, etc. of devices equipped with semiconductors such as smartphones has increased more and more. Along with the demand, the diversification of semiconductor manufacturing processes has progressed remarkably. For this reason, the various process gases used in the manufacturing process are accompanied by high temperatures and high pressures depending on the individual application. A further increase in the supply flow rate (high flow) has become a basic demand in response to the enlargement of production systems and changes to special gas supply systems. For this reason, the above diaphragm valve used as a supply gas control valve also requires the development of an optimum valve for each application, and in particular, the demand for a large flow rate (increased Cv value) is increasing more and more. ing.

While the gas supply system or the semiconductor manufacturing equipment is all housed in a clean room, the clean room must be compactly optimized to the minimum necessary volume. Valves are also required to be made smaller and more compact. For this reason, there is an increasing demand for the diaphragm valve as described above to achieve both miniaturization and high flow. Furthermore, along with the diversification of process gases and the demand for high flow, the demand for high pressure compatibility is also increasing.

Here, in a diaphragm valve equipped with an actuator, there is a type in which the piston of the actuator is biased by a spring, and this biasing force causes the diaphragm to sit on the seat to close the valve. Therefore, even though a larger closing force is required, as the valve becomes smaller, the size of the actuator spring cannot be avoided. A problem of degradation arises. If the closing force of the valve is compromised, the precise fluid control of the process gas may be compromised, resulting in serious product quality defects. But it can be a big problem. In addition, when the installation area is limited due to the miniaturization of the valve, the applicable springs are limited to those with small wire diameters and spring diameters, and the stress applied to each spring increases, reducing the durability of the spring. A problem arises.

In order to maintain or increase the closing force of the valve as described above, for example, a structure in which a plurality of pistons are arranged in multiple stages to alternately form air chambers and springs in the vertical direction is conceivable. There is a problem that the valve is enlarged by extending in the height direction.

Diaphragm valves are integrated with other equipment as described above, and are usually installed in multiple locations. Therefore, if they are made larger, the installation area and height will increase, and the space occupied by the semiconductor manufacturing equipment in the clean room will also increase. However, this leads to problems such as an increase in the manufacturing cost of semiconductors due to an increase in the size of clean rooms and the like. In particular, an increase in the valve size in the width direction increases the foot space, which is a fatal flaw in designing a compact and optimal space filling gas supply system. There is a risk of interference with other equipment/devices installed in the space and obstacles to securing the required space. Therefore, it is difficult to adopt a structure in which the valve size cannot be avoided to increase in the horizontal or vertical direction.

In addition, for example, a structure in which two springs are provided for one piston is conceivable, but in this case, there is a structural limit to miniaturization, and there is a problem that the valve cannot be appropriately miniaturized. Furthermore, in the case of a structure using a large number of pistons and springs as described above, the diaphragm is energized by interlocking through a large number of parts, so the valve closing force tends to be unstable due to variations in the state of each part. and the precise fluid control function may be impaired.

Therefore, in order to appropriately reduce the size of the valve and at the same time maintain or increase the biasing force of the spring to secure a sufficient valve closing force, it is conceivable to adopt a booster mechanism having a simple structure. Patent Documents 1 to 3 have been proposed as prior art of this type.

In the controller disclosed in Patent Document 1, the casing is composed of an upwardly opening hollow lower casing and a downwardly opening hollow upper casing, and a partition plate is provided on the inner circumference of the butted portion of these casings. A cylinder chamber with a circular horizontal cross section is formed above the partition plate fixed in the casing, and a power amplifier storage chamber with a square horizontal cross section is formed below the partition plate. Further, the power amplifying means is arranged to face a tapered member having a predetermined structure and a disk-shaped member via the tapered member, and is capable of swinging around a swing shaft penetrating through the lower portion. and a first and a second rocking body. Also, the lower contact surface of each rocking body is an arc-shaped cam surface centered on the center line at a position eccentric from the axis of the rocking shaft. Furthermore, the lower portions of the first and second oscillating bodies are overlapped with each other, and the oscillating axis of both is shared.

Patent Literature 2 discloses an actuator whose sealing portion is excellent in durability against heat load and repeated operation, and has a built-in cam that moves a shaft in the direction opposite to the moving direction of the piston. Specifically, a shaft coupled to the other end of the stem is provided with a flange, and one end of a cam that is rotatably provided on the bonnet by a pin is engaged with the flange. A roller is provided at the other end of the cam and is in contact with the lower surface of the piston. When high-pressure air is introduced into the air chamber, the piston is pushed downward along with the expansion of the bellows, which pushes the roller at the other end of the cam to rotate around the pin. The flange is pushed up to move the shaft in the direction opposite to the pushing direction of the piston.

Patent Document 3 shows the structure of the power multiplier mechanism (116) in FIGS. Rod-shaped levers (118, 120) are rotatably attached to two pins (122, 128) provided to intersect the two pins (122, 128). ), and the intermediate portions (134, 136), which are the lower end positions, form so-called cam surfaces that contact the upper surface of the pressure receiving plate (140). It is configured to be slidable.

With this configuration, in FIGS. 1 and 2 of the document, the power of the piston (98) pushed down by the springs (110, 112) is increased by the lever principle of the two levers (118, 120), and the pressure receiving plate (140) is increased. through the rod (78) to close the valve. When the valve is opened, air from the air supply source (94) is supplied through the flow paths (92, 104) to the sealed space formed in the lower part of the chamber (106). be pushed up.

1 and 2 of the same document, the rod (78) has a spherical head (142) at the upper end that engages a tapered portion (144) that is open to the lower side of the pressure receiving plate (140), and a shoulder portion (156). is engaged with a compression spring (154) that supports lifting, and is slidable up and down as a sealing member between it and a neck (148) provided below the bottom wall (86). is provided with a sealing ring (150).

Japanese Patent No. 4529023 JP-A-9-26052 U.S. Pat. No. 5,253,671

However, in Patent Document 1, since the cylinder chamber and the power amplifier storage chamber are vertically stacked in series in the casing via partition plates, the structure inevitably increases the size of the valve in the vertical direction. ing. In addition, the configuration of the power amplifying means is also such that the arc-shaped upper contact surface of the oscillating body slides on a tapered member that extends vertically downward and is integrally provided at the lower end of the operating shaft provided near the axial position of the valve. Since it is configured to double the power from the piston by moving, the long plate-like main body must always maintain a vertical standing posture, and the valve as a whole It has to be long in the height direction. Furthermore, the structure of this power amplifying means is excessively complicated with a tapered member, a rocking body with a predetermined structure, etc., and is not suitable for miniaturization as a whole.

In the force boosting mechanism as shown in Patent Document 2, a plurality of plate-like cams are horizontally tilted and arranged to face each other symmetrically with respect to the axis of the valve. Since it is configured to rotate to double the power from the piston, in order to accommodate a plurality of these cams, it is necessary to secure a wide accommodation space in the lateral direction inside the actuator. The cam mechanism is accommodated in the large-diameter portion on the other end side of the housing, and it can be said that this structure is unsuitable for reducing the size of the valve. Furthermore, since the cam mechanism is vertically connected to the air chamber in the large-diameter portion via the piston, the valve size tends to increase in the vertical direction as well.

On the other hand, in Patent Document 3, first, a sealed space that becomes an air chamber to which air is supplied is only provided in the lower part of the chamber. Further, in the structure of the actuator in the same document, there is no mention of increasing the volume of the air chambers or increasing the number of air chambers, and therefore, it is premised on a single air chamber structure. On the other hand, the air pressure that pushes up the piston when the valve is opened increases according to the volume of the space comprising the air chamber. , there is a risk that a sufficient air pressure cannot be ensured and the good valve opening performance of the valve is impaired.

Next, in the booster mechanism of the document, since the two levers are pivotally attached to respective pins, the structure is complicated, and a large capacity must be secured as a space to accommodate the actuator. However, it is disadvantageous in terms of cost, productivity, durability and maintainability, and it is a structure that is difficult to adopt especially from the viewpoint of miniaturization. In particular, a large accommodation space is indispensable in the width direction of the actuator, and there are many restrictions on miniaturization. In addition, the position where the intermediate portion of the two levers acts on the pressure receiving plate (contact position of the cam surface) is near the edge of the pressure receiving plate, which is far away from the axial center position of the valve where the rod is arranged. Moreover, the pressure-receiving plate and the rod are separate members and have a small contact area. This makes it difficult for the force to be transmitted from the lever to the rod, and the force transmission tends to be uneven and unstable, so that the valve may not close well, especially at high pressures.

Further, in the case of the structure shown in the same document, when air is supplied to the sealed space in the lower part of the chamber, the rod receives an internal pressure corresponding to the opening area of the bottom wall, so the rod is lowered as the air is supplied. There is a risk that the diaphragm will be pushed and the valve will not open properly, but no consideration, description or suggestion regarding this point is accepted. Furthermore, the rod is provided with a seal ring and a compression spring that urges the shoulder, which complicates the structure, and is completely inappropriate for miniaturization. In such a case, the valve opening force may be insufficient, but there is no mention of such a point. Moreover, the fact that the springs for urging the piston are provided in duplicate is also unsuitable for miniaturization.

Furthermore, the upper ends of the two levers slide on the scraping plate, and the pressure receiving plate also slides on the head at the upper end of the rod. As a result, the large frictional force between the members results in a loss of force transmission, and the members are easily damaged, leading to deterioration in durability and shortening of service life. be. Moreover, such a separate and complicated structure is completely unsuitable for miniaturization. Furthermore, the two contact positions between the upper ends of the two levers and the piston are left-right asymmetric when the piston is viewed from above, and the contact area is also small. As a result, the resultant force that the piston receives from the abutting points of the spring and the two levers is biased, making it easier to shift from the inner peripheral surface of the chamber. Besides, the durability against a large number of opening and closing operations is questionable, and the force is concentrated on a small contact area, and the sliding tends to generate dust and damage.

Accordingly, the present invention has been developed to solve the above problems, and its object is to provide a valve that has a simple structure, can be easily miniaturized, and is reliable even at high pressure. To provide a valve actuator having opening and closing properties and exhibiting high durability even when the valve is frequently opened and closed, and a diaphragm valve having the same.

In order to achieve the above object, the invention according to claim 1 provides an elastic member provided in an actuator main body comprising a cylindrical base and a casing, a piston urged by the elastic member, and an air pressure to move the piston. and a booster mechanism is housed in the air chamber, and the booster mechanism exerts an amplified force in the valve closing direction, wherein the booster mechanisms are a pair of opposingly arranged The holder is constructed by integrally forming the supporting portion of the ring with the annular portion, and the end portions of the pair of cam members are axially attached to a single rocking shaft, and both ends of the rocking shaft are rotated to the supporting portion of the holder, respectively. A booster mechanism is constructed by making it possible to support it, and the booster mechanism incorporated in the actuator main body has an annular part of the booster mechanism housed in the bottom of the base, and a male screw part provided in the casing is provided in the base. The lower end portion of the casing presses the annular portion of the holder with the tightening force of screwing it into the female screw portion, and the holder is clamped and fixed between the bottom portion of the base and the annular portion, thereby being housed and fixed in the air chamber. A valve actuator.

The invention according to claim 2 is a diaphragm valve provided with a valve actuator, wherein the diaphragm is pressed against a valve seat provided in the body via an output member to close the valve.

According to the first aspect of the invention, since the booster mechanism is housed in the air chamber, the occupied space required for both the air chamber and the booster mechanism is integrated. Therefore, the size of the actuator can be significantly reduced while ensuring a sufficient valve closing force. Moreover, since the annular portion and the supporting portion provided integrally therewith can be securely and easily clamped and fixed, the actuator itself can be formed compactly, and the boosting mechanism can be housed and held with high accuracy, thereby stabilizing the actuator. In this state, it is possible to provide a valve actuator that can not only be driven, but also contribute to overall compactness.

According to the second aspect of the invention, the actuator is sufficiently small and has a simple structure, and is equipped with an actuator that secures a sufficient valve closing force.・A diaphragm valve with usability can be provided.

FIG. 2 is a cross-sectional view of a diaphragm valve provided with the valve actuator of this example, the left side of the center line showing the fully closed state and the right side showing the fully open state. FIG. 2 is a schematic cross-sectional view schematically showing a cross section taken along the line AA in FIG. 1; FIG. 3 is a schematic perspective cross-sectional view schematically showing the half-split structure of the force boosting mechanism of the present example, corresponding to the BB line cross section in FIG. 2 ; FIG. 5 is an explanatory view schematically explaining the force boosting action of the cam member of the present example;

Hereinafter, the structure of one embodiment of the present invention will be described in detail based on the drawings. FIG. 1 is a cross-sectional view of a valve actuator of this embodiment (this example) and a diaphragm valve of this example equipped with the same, and the left half of the center line of the figure shows the fully closed state of the valve of this example. , and the right half shows the fully open state of the valve in this example.

In FIG. 1, the valve actuator of this example includes a piston 2 biased by an elastic member 8 (spring 8) provided in an actuator body 100, and at least two air chambers for moving the piston 2 by air pressure. 3 (3a, 3b) and a booster mechanism 1 for exerting an amplified force in the valve closing direction is housed in any one of the air chambers 3.

The cover 4 has a substantially cylindrical external appearance, and is provided with a connection portion 5 for connection with an air source (not shown) provided outside, at the axial center position, and a flow path 5a connected thereto is formed, Further, a fitting portion 10 that can be fitted with the piston 2 connected thereto is provided. The lower end of the cover 4 is provided with a male threaded portion 9 that can be screwed onto the female threaded portion 7 of the casing 6 . A receiving portion 11 for urging the spring 8 is recessed inside the cover 4 .

The casing 6 is formed to have a cylindrical appearance having substantially the same diameter as the cover 4, and has the above-described female screw portion 7 formed at its upper end, and a male screw screwable to the female screw portion 13 of the base 12 at its lower end. A portion 14 is formed. An O-ring 15 is interposed to seal between the female threaded portion 13 and the male threaded portion 14 . A stepped portion 17 that engages with the sub-base 16 is formed on the inner peripheral surface of the casing 6 .

The base 12 has a cylindrical upper portion having substantially the same diameter as the casing 6, and a lower portion whose diameter is stepwise reduced from that of the upper portion. 20 are formed. A mounting hole 22 that can be fitted and mounted to the output member 21 (disk member 21) is opened at the central axial position, and an O-ring 23 is provided on the inner peripheral surface of the mounting hole 22. is provided.

The body 18 has an inlet flow path 24 and a primary side flow path 25 connected thereto at an angle. It communicates with the secondary side space 27 (valve chamber) via the secondary side space 27 . A valve seat 28 made of PCTFE is fixed to the periphery of the opening 26, and the lower surface of the diaphragm 29 is flexibly deformed on the upper surface so that it can be brought into close contact (seated). The secondary space 27 has a substantially rectangular cross section and is formed to have a deep annular groove shape. Thus, a high Cv value can be achieved by ensuring a flow path space that has as large a capacity and as low a fluid resistance as possible. Further, a part of the secondary space 27 is open and communicates with the linearly formed outlet channel 30 .

The diaphragm 29 is formed in a substantially circular shape, and in this example, is constructed by stacking nine sheets of Co alloy diaphragms. A peripheral portion of the diaphragm 29 is clamped and fixed between a convex portion 31 formed on the outer peripheral portion of the secondary space 27 and the lower surface of the bonnet 32 to form a valve chamber of the valve.

The bonnet 32 is formed in a substantially cylindrical shape, and is provided between the base 12 and the body 18 when assembling the valve of this embodiment, and is used for tightening when the female threaded portion 19 is screwed to the male threaded portion 20 . The lower end surface of the base 12 presses the bonnet 32 due to the applied force, and the peripheral edge portion of the diaphragm 29 is sandwiched between the lower surface of the bonnet 32 and the convex portion 31 by this pressing force and fixed in the valve chamber. The inner peripheral surface of the bonnet 32 is a cylindrical space formed with substantially the same diameter, and the substantially cylindrical diaphragm piece 33 slides on the inner peripheral surface with almost no resistance. mated as possible. Further, the upper surface of the diaphragm piece 33 is provided so that the lower end surface of the disk member 21 fitted in the mounting hole 22 can come into contact.

The actuator of the present invention has at least two air chambers, and solves the shortage of air driving force (valve opening force) that accompanies miniaturization. The structure of the plurality of air chambers can be selected arbitrarily according to the implementation, but in this example, as shown in FIGS. With the configuration in which the sub-base 16 is arranged on the stepped portion 17, two air chambers 3 for moving the piston 2 by supplied air are added.

Specifically, the piston 2 has circular flange-like piston portions 2a and 2b that extend in parallel, and cylindrical extension portions 2c and 2d that connect the central axis positions of the piston portions 2a and 2b. A flow path 34 is formed in the interior of 2c and opens to the outside to conduct the supplied air, and communicates with this flow path 34. A flow path 35 opens in the lateral direction also in the extended portion 2d and a flow path in the vertical direction. 36 is formed, and this flow path 36 opens to the outside of the piston 2 .

The piston 2 is configured by integrally forming the piston portion 2a and the extension portion 2d, and the piston portion 2b and the extension portion 2c, respectively, and combining these two members. Specifically, in the case of the piston portion 2a and the extension portion 2c, the disk-shaped piston portion 2a and the cylindrical extension portion 2d having the flow path 36 therein are integrally formed in an umbrella shape, and the extension portion 2d is circular. A channel 35 is formed by notching a groove so as to pass through the opening of the channel 36 at the center position on the end face, and the piston part 2b and the extension part 2c having the channel 34 inside are similarly umbrella-shaped. is integrally formed. After that, the end surface of the extended portion 2d with the flow path 35 notched is combined with the center position of the piston portion 2b so that the flow paths 34 and 35 communicate with each other, and the piston 2 is composed of two members. , the entire piston 2 may be integrally constructed from a single member.

Further, O-rings 37 and 38 are provided on the outer peripheral edge portions of the piston portions 2a and 2b, respectively, so that they can seal with the inner peripheral surface of the casing 6 while sliding therebetween. The outer diameters of the piston portions 2a and 2b are adapted to the inner diameters above and below the stepped portion 17 of the casing 6, respectively. The valve stroke operation of the piston 2 within the actuator main body 100 is possible while maintaining the internal sealing performance.

Due to the above structure, when the assembly of the actuator of this example is completed, the sealed space formed between the lower surface side of the piston portion 2a and the inner peripheral surface of the base 12 is filled with air supplied from the flow path 36. A sealed space formed between the lower surface side of the piston portion 2b and the upper surface side of the sub-base 16 serves as a second air chamber into which the supply air from the flow path 35 is introduced. 3b. Thus, in this example, two air chambers 3, ie, the first air chamber 3a and the second air chamber 3b are added. Since a plurality of air chambers are compactly provided by such a configuration of the piston 2 and the casing 6, in this example, an excessively large actuator body 100 and an increase in the number of parts can be avoided, and a reliable air driving force can be obtained. can be secured. In addition, as long as the height of the actuator main body 100 is allowed under the conditions, for example, the casing 6 may be provided long and the piston 2 may be arranged in three or more stages.

1 and 3, the disk member 21 includes a substantially disk-shaped large diameter portion 39 that abuts on cam surfaces 42b and 43b of cam members 42 and 43, which will be described later, respectively, and a mounting hole formed in the base 12 below the actuator. 22, and a substantially cylindrical small-diameter portion 40 that can be fitted to 22. In this example, these are integrally formed. Specifically, as shown in FIG. 1, the disk member 21 incorporated in the actuator of this example has the small diameter portion 40 fitted in the mounting hole 22 so as to be vertically slidable, and the peripheral edge of the large diameter portion 39. The portion engages with a step portion surface 41 formed on the inner bottom surface of the base 12 so as to match the shape of the large-diameter portion 39 so as to be vertically movable. The disk member 21 of this example is made of steel for mechanical structure (S45C-H HRC40) coated with MoS2 (film thickness: about 10 μm).

An O-ring 23 is attached to the inner peripheral surface of the mounting hole 22 to seal the small-diameter portion 40 . In the operation of this example, as will be described later, the base 12 serves as a stationary side member and the disk member 21 serves as a movable side member. Therefore, it is suitable for reducing the size of the valve.

In FIG. 1, the booster mechanism 1 of this example has a pair of cam members 42 and 43 pivotally attached to a single common swing shaft 44 (camshaft), and the pair of cam members 42 and 43 These cam members 42 and 43 are provided at their upper ends with contact portions 42a and 43a for contacting the piston 2, respectively, and have discs at their lower ends. Convex cam surfaces 42b and 43b that come into contact with the member 21 are formed respectively. 47a and 47b are constituent members of a holder 47 which will be described later with reference to FIGS.

The contact portions 42a and 43a are provided with roller portions 45 and 46, respectively. The rollers 45a and 46a of the roller portions 45 and 46 are rotatably provided on roller shafts 45b and 46b, respectively. The abutment portions 42a and 43a are formed by abutting on the . The abutting portion does not have the roller portion as described above, and for example, as schematically shown in FIG. may be configured to directly contact and slide on the lower surface of the piston.

2 and 3 schematically show the structure of the booster mechanism 1 of this example, and FIG. 2 is a schematic cross-sectional view when the booster mechanism 1 is viewed from the AA line cross section in FIG. . 3(a) and 3(b) are schematic diagrams of the booster mechanism 1 corresponding to the BB line cross section shown in FIG. It is a perspective sectional view explained.

As shown in FIGS. 2 and 3, a pair of cam members 42 and 43 are hingedly attached to a single swing shaft 44, and the cam member 42 is formed in a bifurcated U-shape. A single shaft mounting portion 61 of the cam member 43 is shaft mounted between the shaft mounting portions 60 , 60 . Therefore, as shown in FIG. 2, the area where the cam surface 42b of the cam member 42 contacts the disk member 21 is near the area 42c in plan view of the actuator, and the cam surface 43b of the cam member 43 contacts the disk member 21. The contact area is near the area 43c in the figure. Similarly, the area where the cam member 42 (roller 45a) contacts the lower surface of the piston 2a is near the area 42d, and the area where the cam member 43 (roller 46a) contacts the lower surface of the piston 2a is near the area 43d.

As shown in FIG. 2, the three regions 42c and 43c are positioned close to the axial center position (small diameter portion 40) of the disk member 21, and are substantially symmetrical vertically in the figure. , the pressing force received from the cam surfaces 42b and 43b is evenly transmitted to the disc member 21 and is easily transmitted directly to the small diameter portion 40, so that the transmission of force is extremely good. In addition, since the two regions 42d and 43d are positioned substantially symmetrical to the left and right in FIG. Core force does not work.

As shown in FIG. 3, both end portions of the swing shaft 44 are inserted into the inner side surfaces of the opposed support portions 47b and rotatably fixed. The holder 47 of this example shown in FIGS. 1 and 3 has an annular portion 47a formed in an annular shape so as to fit the lower side surface of the base 12, and an annular portion 47a integrally formed on the inner peripheral side of the annular portion 47a and arranged opposite to each other. When assembling the actuator main body 100 of this example, the annular portion 47a is placed on the bottom surface of the base 12, and the male threaded portion 14 of the casing 6 is connected to the female threaded portion of the base 12. It is pressed against the lower end of the casing 6 by the tightening force when it is screwed to the casing 13, and is clamped and fixed between the casing 6 and the bottom surface of the base 12. As shown in FIG.

Next, the action of the valve actuator of this example shown in FIG. 1 and the diaphragm valve including the same will be described. The left side of the figure shows the fully closed state of the valve, and the right side of the same figure shows the fully opened state of the valve. In the following, the action when the air is removed from the air chamber 3 in the fully open state will be described.

As the air is released from the air chamber 3, the internal pressure of the first air chamber 3a and the second air chamber 3b, which had been at a predetermined pressure, decreases to the outside pressure, and the pressure received by the piston 2 from the air chamber 3 decreases, it is pushed downward by the biasing force of the spring 8. The lower surface of the pushed-down piston 2 contacts and presses the contact portions 42a and 43a of the force boosting mechanism 1 to rotate the cam members 42 and 43 around the swing shaft 44, respectively. Accordingly, the cam surfaces 42b and 43b press the large diameter portion 39 of the disc member 21 to push the disc member 21 downward. The effect of amplifying the force at this time will be described later.

Since the lower end of the small diameter portion 40 of the disk member 21 is in contact with the upper surface of the diaphragm piece 33, the diaphragm piece 33 is also pushed down as the disk member 21 is pushed down. Since the lower surface of the diaphragm piece 33 is in contact with the diaphragm 29, when the diaphragm piece 33 descends, the upper surface of the diaphragm 29 is pressed by the lower surface and flexibly deformed. The lower surface of the diaphragm piece 33 is deformed so as to dent the diaphragm 29 downward, and the lower surface of the diaphragm 29 is crimped to the upper surface of the valve seat 28 with a predetermined pressure. , and the primary side passage 25 and the secondary side space 27 of the valve chamber are separated from each other, so that the valve is in a fully closed state.

Next, the operation of filling air into the air chamber 3 in this fully closed state to bring it into a fully open state will be described. When air is introduced into the air chamber 3, air injected from an air source (not shown) passes through a flow path 34 provided in the extension 2c of the piston 2 and then through a flow path 35 provided in the extension 2d. It passes through and is press-fitted into the second air chamber 3b. At the same time, it is also press-fitted into the first air chamber 3a through the flow path 36 provided in the extended portion 2d.

The piston 2 is urged downward by the spring 8. However, in the first air chamber 3a, the only movable member is the piston portion 2a, excluding the disk member 21, which will be described later. When the air pressure rises and exceeds the biasing force of the spring 8, this air pressure acts to push up the piston portion 2a. Similarly, in the second air chamber 3b, since the sub-base 16 is fixed to the inner peripheral surface of the casing 6, the only movable member is the piston portion 2b, and the air pressure in the air chamber 3b rises. When the biasing force of the spring 8 is exceeded, the piston portion 2b is pushed upward. Therefore, the entire piston 2 slides and is pushed upward while maintaining a hermetic seal with the inner peripheral surface of the casing 6 .

Here, the air pressure acting on the piston 2 is proportional to the area of the piston 2 facing the inside of the air chamber 3. In this example, the air chamber 3 is added to the first air chamber 3a, By constructing the second air chamber 3b compactly in two stages via a thin sub-base 16, a sufficient piston area is ensured while avoiding an increase in size of the actuator.

On the other hand, since the diaphragm 29 has a shape self-restoring force, the contact portions 42a and 43a of the cam members 42 and 43 are moved by the piston 2 as the pressure inside the air chambers 3a and 3b increases as described above. When the pressing force is released, the diaphragm 29 can return to its natural convex shape gently curved upward due to the self-restoring reaction force. Then, the valve is fully opened. More specifically, this reaction force pushes up the diaphragm piece 33, which in turn pushes up the disk member 21, which pushes up the cam surfaces 42b and 43b, causing the cam members 42 and 43 to swing. It rotates around the axis 44 .

Next, using FIG. 4, the principle of force amplification by the booster mechanism 1 of this example will be explained geometrically. FIG. 4 schematically shows a side view of one of the cam members of this example, and the force amplification principle described below is common to both the pair of cam members 42 and 43 .

In FIG. 4, 50 schematically shows the shape of the cam member of this example, and has a contact portion 51 at the upper end and a convex cam surface 52 at the lower end. The contact portion 51 in the figure is shown in a simplified manner, and has a simple circular arc shape without the roller portion as described above, and the point Q is the center position of this circular arc. The contact portion 51 contacts the piston lower surface 53 , and the cam surface 52 contacts the disk member upper surface 54 . 55 is a swing shaft, and point O is its axial center position. Further, the force that the contact portion 51 receives from the lower surface 53 is denoted by F, and since the contact portion 51 is arc-shaped, the force F is directed in the direction of the point Q vertically downward. Similarly, the force applied by the cam surface 52 to the upper surface 54 is denoted by N, and the point of contact is denoted by P. As shown in FIG.

Also, the length of the line segment OP is l, the length of the line segment OQ is L, and the intersection angle between the line segments OP and OQ is α. These are all constants inherent in the shape of the cam member. Also, the inclination angle of the line segment OQ from the horizontal direction is θ. In this case, according to the principle of leverage (relationship between F and N), the force amplification factor N/F is as follows.

Within the range of the valve stroke of this example, the range of variation of the angle .theta. is small. Therefore, it is possible to obtain a stable boosting action depending on the setting of the shape of the cam member.

With the above structure, the power of the piston 2 urged by the elastic member (spring 8) acts as a lever with the contact portions 42a and 43a as the power point, the swing shaft 44 as the fulcrum, and the cam surfaces 42b and 43b as the points of action. According to the principle, when the cam members 42 and 43 rotate around the swing shaft 44, the force is amplified and transmitted to the output member (disk member 21), and the valve seat provided in the body 18 is transmitted through this output member. 28 presses the diaphragm 29 to close the valve.

Further, as shown in FIG. 1, in the actuator of this example, roller portions 45 and 46 are provided on the contact portions 42a and 43a, respectively. For this reason, the rollers 45a and 46a of these roller portions are in contact with the lower surface (abutment surface) of the piston portion 2a so as to be biased. When the piston 2 moves up and down as the valve opens and closes as described above, the rollers 45a and 46a roll on the lower surface of the piston portion 2a with almost no resistance, and accordingly the cam members 42 and 43 move. It rotates around the swing shaft 44 .

Further, the diameter of the small-diameter portion 40 of the disk member 21 of this embodiment is smaller than the pressure at which the disk member 21 is pushed out of the air chamber 3a by the supplied air pressure when air is supplied into the first air chamber 3a. Also, the diameter is set to such an extent that the force to move toward the inner side of the air chamber 3a based on the self-returning reaction force of the diaphragm 29 becomes larger.

That is, when air is supplied to the first air chamber 3a and the internal pressure rises, the movable member on the inner peripheral surface of the air chamber 3a is fitted into the contact surface of the piston portion 2a, which is the upper surface, and the mounting hole 22. Since the disk member 21 is formed as a flat disk member 21, the internal pressure of the air chamber 3a, which is a sealed space, acts on the disk member 21 in addition to the piston portion 2a. It acts so as to push down the disc member 21 while sliding against it. Therefore, when air is introduced into the air chamber 3a in order to open the valve by the self-recovery reaction force of the diaphragm 29 by releasing the urging force of the diaphragm piece 33, this air pressure presses the disk member 21 to open the valve. It may interfere with the operation. This is a peculiar problem associated with accommodating the booster mechanism 1 together with the disk member 21 in the air chamber 3a.

At this time, the force with which the disc member 21 is pushed down by the air pressure in the air chamber 3a is the area obtained by subtracting the pressure receiving area of the large diameter portion 39 from the pressure receiving area of the large diameter portion 39 upper surface, that is, the area of the small diameter portion 40 lower surface. , multiplied by the air pressure. Therefore, except for the weight of the disc member 21, in principle, the valve opening operation is performed according to the size of the outer diameter of the small diameter portion 40 (or the corresponding inner diameter of the mounting hole 22). On the other hand, the force with which the disk member 21 is pushed down is determined by the air pressure in the air chamber 3a.

On the other hand, in the actuator of this example, the size of the outer diameter of the small diameter portion 40 (the size of the inner diameter of the mounting hole 22) is controlled by the diaphragm 29 pushing up the disk member 21 via the diaphragm piece 33 by the self-returning reaction force. Since the force is set within a range not exceeding the force that pushes down the disk member 21 as described above, the valve can be opened satisfactorily as the air is supplied to the air chamber 3a. Verbality is not hindered.

Specifically, in the diaphragm valve of this example, the relationship between the force pressing the top of the diaphragm 29 from above and the flow rate of the valve was investigated in advance, and it was found that the pressing force The flow rate of the valve was maintained almost equal to the flow rate in the fully open state because the sinking of the diaphragm 29 due to the pressure was small, but from around 30 N, the flow rate of the valve began to decrease gradually due to the sinking of the diaphragm 29. It has been found. It was also found that the diaphragm 29 was finally seated on the valve seat 28 with a pressing force of about 500 N, and the valve was completely closed.

For this reason, the disk member 21 is adversely affected by the air pressure introduced into the air chamber 3a during the valve opening operation, that is, it is pushed downward, which presses the diaphragm 29, which hinders the valve opening operation and reduces the flow rate. In order to prevent this from occurring, the air pressure acting on the disc member 21 should be set to 30N or less at maximum.

On the other hand, the diaphragm valve of this example is designed on the assumption that the maximum working pressure of air is 0.7 MPa. The pressing force due to the acting air pressure was about 15N. Therefore, if the diameter of the small diameter portion is set to this size, even if the maximum air pressure introduced into the air chamber 3a acts on the disk member 21 and pushes it down, the diaphragm 29 will not sink. , the problem that the valve opening operation is obstructed as described above does not occur.

In addition, the force that causes the flow rate to decrease as described above varies depending on the shape, material, thickness and number of diaphragms of the valve to be designed, the temperature and pressure of the valve and the fluid used, the air pressure used, etc. Therefore, the large-diameter portion and small-diameter portion of the disk member may be designed as appropriate in consideration of the value of the force that can cause the flow rate to decrease according to each condition.

Furthermore, the present invention is not limited to the description of the above embodiments, and various modifications can be made without departing from the gist of the invention described in the claims of the present invention.

1 booster mechanism 2 piston 3 (3a, 3b) air chamber 6 casing 8 spring (elastic member)
12 base 18 body 21 disk member (output member)
23 O-ring 28 Valve seat 29 Diaphragm 39 Large diameter portion 40 Small diameter portion 42, 43 Cam member 42a, 43a Contact portion 42b, 43b Cam surface 44 Swing shaft 45, 46 Roller portion 45a, 46a Roller 47a Annular portion 47b Support Part 100 Actuator main body

Claims (2)

An elastic member provided in an actuator main body consisting of a cylindrical base and a casing, a piston urged by the elastic member and an air chamber for moving the piston by air pressure are arranged, and a boosting mechanism is arranged in the air chamber. and exerts an amplified force in the valve closing direction by the force booster mechanism, wherein the force booster mechanism includes a pair of supporting portions arranged oppositely and integrally formed in the annular portion to form a holder wherein the end portions of a pair of cam members are axially attached to a single swing shaft, and both ends of the swing shaft are rotatably supported by the support portions of the holder to form the booster mechanism wherein the booster mechanism incorporated in the actuator main body has the annular portion of the booster mechanism housed and mounted on the bottom of the base, and the base is provided with a male threaded portion provided on the casing. The lower end portion of the casing presses the annular portion of the holder with the tightening force of screwing to the female screw portion, and is clamped and fixed between the bottom portion of the base and the annular portion, thereby accommodating the holder in the air chamber. A valve actuator, characterized in that it is fixed . A diaphragm valve comprising the valve actuator according to claim 1, wherein the diaphragm is pressed against a valve seat provided in the body via an output member to close the valve.

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