High-temperature valve actuators and high-temperature diaphragm valves

Abstract

To provide a high-temperature valve actuator and a high-temperature diaphragm valve that have simple structures and can enhance durability against a thermal load and assembling properties.SOLUTION: A high-temperature valve actuator 1 is provided with a piston unit 10, comprising a piston 15 energized by an elastic member 50 in one direction of a stroke, in a cylinder 30, and the piston unit 10 consists of a unit body 11 having an air flow passage 13a, a piston 15 connected to the unit body 11 through bellows 14 having a flow passage, a corrugated diaphragm 22 fixed hermetically to a planar part 16a of the piston 15, and an air chamber 20 provided between the planar part 16a and corrugated diaphragm 22, wherein driving air is supplied to and exhausted from the air chamber 20 to enable the piston 15 to have strokes, and the corrugated diaphragm 22 is brought into contact with a press-contact surface 31a provided in the cylinder 30 when the driving air is supplied to the air chamber 20.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a valve actuator for high temperatures and a diaphragm valve for high temperatures, and particularly to a valve actuator for high temperatures and a diaphragm valve of a normal close type or a normal open type provided with a piston biased in one direction of stroke by an elastic member.

Background Art

[0002] Conventionally, a valve actuator of a normal close type or a normal open type for operating a valve has been used for a valve in a gas supply system of a semiconductor manufacturing apparatus. This valve actuator includes a piston biased in one direction of stroke by an elastic member such as a spring inside a cylinder, and a pressing force is applied to the diaphragm in a pressing force application direction in which this piston is connected to a stem and deformed so that the diaphragm abuts against a valve seat, and the pressing force applied to the diaphragm is released in a pressing force release direction in which the diaphragm is separated from the valve seat and restored, and the piston moves. [[ID=__15]]

[0003] Such a valve actuator moves to an open position or a closed position against the biasing force of the elastic member by using the pressure of driving air supplied to an air chamber provided inside the cylinder. And in order to make this air chamber airtight, the periphery around the shaft guiding the movement of the piston and the piston is sealed. For example, a resin seal member made of a resin such as a polymer, silicon, or rubber is provided on the outer peripheral surface of the piston which becomes a portion sliding on the inner wall surface of the cylinder.

[0004] [[ID=__25]] Incidentally, in recent years, the gases supplied to semiconductor manufacturing equipment have tended to be at higher temperatures, and there is a need for valve actuators that can be used with gases exceeding 300°C. However, when valve actuators are applied to high-temperature gases exceeding 300°C, there is a problem that the durability of the aforementioned resin sealing members is reduced due to damage caused by thermal expansion and depletion of lubricants. To address these problems, various types of valve actuators have been proposed.

[0005] For example, Patent Documents 1 and 2 describe actuators in which a piston slides without rubbing against the inner wall surface of a cylinder. The actuator described in Patent Document 1 is an actuator for controlling a valve exposed to high temperatures in relation to air pressure, wherein a piston is provided in a housing, a heat-resistant bellows is connected in a sealed state so as to be expandable and contractible between the housing cap and the peripheral edge of the piston so as to be able to move the piston by high-pressure air introduced from the cap, and cams are provided radially at approximately equiangled positions to move a valve stem for opening and closing the valve body against a spring as the piston moves due to the introduction of high-pressure air.

[0006] Furthermore, the actuator described in Patent Document 2 is an actuator for operating a plunger, comprising a main inlet and a main outlet, and a main actuation assembly provided between the first and second hollow caps, the second cap of which is provided with a cap channel extending through it, the first and second hollow caps, and a deformable diaphragm having first and second diaphragm surfaces on opposite sides, a first chamber limited by the first diaphragm surface and in fluid communication with the main inlet, and the second diaphragm surface The main actuating assembly comprises a static sealing element for fluidly sealing a second chamber, a first chamber, and a second chamber that communicates with the main outlet, and a main piston that is movable between an operating position and a non-operating position and includes a piston surface that can be attached to a second diaphragm surface; an actuating stem, the portion of which extends outside the second cap and is connectable to a plunger, and which cooperates with the main piston to slide within the cap channel when the main piston moves between an operating position and a non-operating position; and a biasing mechanism for biasing the piston to the non-operating position. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 9-26052 [Patent Document 2] International Publication No. 2013010269 [Overview of the project] [Problems that the invention aims to solve]

[0008] However, the actuator described in Patent Document 1 has a power-enhancing mechanism composed of a cam, which has the problem of a complex structure and reduced durability due to wear of the power-enhancing mechanism. Furthermore, the actuator described in Patent Document 2 has the problem of poor assembly because the diaphragm used to drive the piston must be fixed to two components, such as the piston and a second cap, which is a separate component from the piston. Furthermore, the actuator described in Patent Document 2 has a problem of having a complex structure because it has multiple diaphragms that seal around the shaft that guides the movement of the piston. Furthermore, in the actuator described in Patent Document 2, since the expanded diaphragm comes into contact with a piston that is movable in the stroke direction, it is difficult for the diaphragm to expand uniformly in contact with the contact surface of the piston. This makes the movement of the piston unstable and prone to contact with the part that guides the movement of the piston, and as a result the contact part wears down, durability is reduced.

[0009] The present invention was developed to solve the problems of the past, and its objective is to provide a high-temperature valve actuator and a high-temperature diaphragm valve that have a simple structure and can improve durability against thermal load and ease of assembly. [Means for solving the problem]

[0010] To achieve the above objective, the invention according to claim 1 is a high-temperature valve actuator in which a piston unit is provided inside a cylinder, the piston unit having a piston biased in one direction of stroke by an elastic member, the piston unit comprising a unit body having an air passage, a piston connected to the unit body via a bellows having a passage, a corrugated diaphragm sealed and fixed to the planar portion of the piston, and an air chamber provided between the planar portion and the corrugated diaphragm, the piston is provided to move freely by supplying and exhausting drive air to the air chamber, and the corrugated diaphragm comes into contact with a pressure contact surface provided inside the cylinder when drive air is supplied to the air chamber.

[0011] The invention according to claim 2 is a high-temperature valve actuator in which the piston unit is integrated by welding a planar portion and a diaphragm, welding one end of the bellows to the unit body, and welding the other end of the bellows to the piston.

[0012] The invention according to claim 3 is a high-temperature valve actuator in which the unit body is formed by welding together an air joint base and an air introduction joint.

[0013] The invention according to claim 4 is a high-temperature valve actuator in which the contact surface is the inner wall surface of a cylinder, and the corrugated diaphragm has a plurality of contact points that are dispersed and expanded on the contact surface and made contact with the air chamber when driving air is supplied to the air chamber.

[0014] The invention according to claim 5 is a high-temperature valve as described in claim 1. Bua Equipped with a cutter, high temperature valve Bua This is a high-temperature diaphragm valve that uses a ductor to stroke a piston, thereby opening and closing a diaphragm located in a flow path within the valve body. [Effects of the Invention]

[0015] According to the invention of claim 1, the piston unit comprises a unit body having an air passage, a piston connected to the unit body via a bellows having a passage, a corrugated diaphragm sealed and fixed to the planar portion of the piston, and an air chamber provided between the planar portion and the corrugated diaphragm. The piston is provided to move freely by supplying and exhausting drive air to the air chamber, and when drive air is supplied to the air chamber, the corrugated diaphragm comes into contact with a pressure contact surface provided inside the cylinder. This allows the piston to move in the stroke direction against the biasing force of the elastic member without using a power assist mechanism, by utilizing the expansion effect of the corrugated diaphragm caused by supplying drive air to the air chamber. Furthermore, the corrugated diaphragm expands while making contact with the pressure contact surface inside the cylinder, and the contact surface with the pressure contact surface deforms to spread uniformly along the pressure contact surface, thereby stably moving the piston in the stroke direction and suppressing contact with the part that guides the movement of the piston. Furthermore, supplying drive air to the air chamber expands the corrugated diaphragm; that is, the supply of drive air to the air chamber creates an airtight seal, eliminating the need for other sealing members to seal around the piston axis, and preventing the piston from moving while rubbing against the inner surface of the cylinder against the sealing members. Furthermore, the corrugated diaphragm can be assembled to a portion of the piston, and the unit body, which has an air passage that forms the main part of the actuator, can be connected to the bellows and piston to form a unit that can be assembled inside the cylinder. Therefore, according to the invention of claim 1, a simple structure can be used to improve durability against thermal load and ease of assembly.

[0016] According to the invention of claim 2, the piston unit is formed by welding a planar portion and a corrugated diaphragm, welding one end of the bellows to the unit body, and welding the other end of the bellows to the piston, thereby integrating them. As a result, the piston unit is firmly and airtightly connected, making it easier to handle as a single unit and ultimately improving ease of assembly.

[0017] According to the invention of claim 3, since the unit body is formed by welding the air joint base and the air introduction joint together, the piston unit can be handled as a single unit with the air introduction joint and the air joint base firmly connected, which are the connection parts to the external air supply destination. This improves assembly workability, durability, and airtightness.

[0018] According to the invention according to claim 4, the pressure contact surface is the inner wall surface of the cylinder, and when the corrugated diaphragm supplies driving air to the air chamber, the corrugated diaphragm has a plurality of grounding portions that are dispersed and expanded to be grounded on the pressure contact surface. As a result, when driving air is supplied to the air chamber, the corrugated diaphragm bulging toward the inner wall surface side of the cylinder is dispersed and expanded on the inner wall surface to ground the grounding portions, making it easier to receive the reaction force from the inner wall surface. Consequently, the thrust of the piston can be increased.

[0019] According to the invention according to claim 5, it includes a high-temperature valve Bua actuator, and by stroking the piston with the high-temperature valve Bua actuator to open and close the diaphragm provided in the flow path in the body, the piston is moved in the direction of the stroke against the biasing force of the elastic member by utilizing the expansion action of the corrugated diaphragm due to the supply of driving air to the air chamber, without using a force multiplying mechanism. Further, while the corrugated diaphragm bulges while being grounded on the pressure contact surface in the cylinder, the grounding surface against the pressure contact surface is deformed so as to uniformly spread along the pressure contact surface, thereby stably moving the piston in the stroke direction and suppressing contact with the portion guiding the movement of the piston. Also, when driving air is supplied to the air chamber, the corrugated diaphragm is expanded, that is, when driving air is supplied to the air chamber, the air chamber is in an airtight sealed state, and there is no need to seal around the axis of the piston with other sealing members, and the piston does not move while rubbing against the inner peripheral surface of the cylinder. Moreover, the corrugated diaphragm is assembled to only a part of the piston, and the unit body having an air flow path, the bellows, and the piston can be connected and unitized to assemble the main part of the actuator in the cylinder. Therefore, according to the invention according to claim 5, it has a simple structure and can enhance durability and assemblability against heat load.

Brief Description of the Drawings

[0020] [Figure 1]This is a cross-sectional view of a high-temperature diaphragm valve equipped with a high-temperature valve actuator according to an embodiment. [Figure 2] Figure 1 is a top view of the high-temperature valve actuator shown. [Figure 3] Figure 1 is a side view of the high-temperature diaphragm valve. [Figure 4] Figure 1 is a cross-sectional view of a high-temperature diaphragm valve showing the state when the high-temperature valve actuator is in the valve open position. [Figure 5] Figure 1 is an enlarged view of the piston unit shown. [Figure 6] This diagram illustrates the difference in piston thrust obtained by the bulge shape of the corrugated diaphragm. [Modes for carrying out the invention]

[0021] Embodiments of the high-temperature valve actuator 1 and high-temperature diaphragm valve 100 according to the present invention will be described in detail with reference to Figures 1 to 6. This disclosure is not limited to the embodiments shown below. Furthermore, it should be noted that the drawings are schematic, and the dimensional relationships and proportions of each element may differ from reality. Additionally, there may be differences in dimensional relationships and proportions between drawings. Figure 1 is a cross-sectional view of a high-temperature diaphragm valve 100 equipped with a high-temperature valve actuator 1 according to an embodiment. Figure 2 is a top view of the high-temperature valve actuator 1 shown in Figure 1. Figure 3 is a side view of the high-temperature diaphragm valve 100 shown in Figure 1. Figure 4 is a cross-sectional view of the high-temperature diaphragm valve 100 showing the state when the high-temperature valve actuator 1 shown in Figure 1 is in the valve open state. Figure 5 is an enlarged view of the piston unit 10 shown in Figure 1. Figure 6 is a diagram for illustrating the difference in thrust of the piston 15 obtained by the bulging state of the corrugated diaphragm 22.

[0022] The high-temperature valve actuator 1 according to an embodiment of the present invention is provided in a high-temperature diaphragm valve 100. The high-temperature diaphragm valve 100 comprises a valve 70 and a high-temperature valve actuator 1 that drives the valve, and is used, for example, as an automatic valve in the gas supply system of a semiconductor manufacturing apparatus. Furthermore, as shown in Figure 1, the high-temperature valve actuator 1 drives the diaphragm 71, which is the valve body of the valve 70, to open and close, and is installed connected to the body 72 of the valve 70.

[0023] <Regarding the valve 70 driven by the high-temperature valve actuator 1> First, we will describe the valve 70 driven by the high-temperature valve actuator 1. Valve 70 is a diaphragm valve that uses a diaphragm 71 as the valve body, and a valve seat 73 is provided in the middle of a flow path 72a formed inside the body 72, extending from the upstream end which is the gas inlet to the downstream end which is the gas outlet. Furthermore, the valve 70 has an actuator connecting portion 74 that is integrally provided with the body 72 at the upper part of the body 72 and serves as the connecting portion with the cylinder 30 of the high-temperature valve actuator 1. Inside the actuator coupling portion 74, the diaphragm 71 is held in place by the stepped portion of the body 72 and the bonnet 75, with its outer peripheral edge clamped between them, allowing it to freely contact the valve seat 73. Furthermore, the diaphragm piece 76 is supported by the bonnet 75 so as to be able to press the diaphragm 71 in a direction that brings it into contact with the valve seat 73.

[0024] <About High-Temperature Valve Actuator 1> Next, we will describe the high-temperature valve actuator 1. In this embodiment, the high-temperature valve actuator 1 is of the normally closed type and is equipped with a piston 15 inside the cylinder 30 that is biased in one direction of stroke by a spring 50 which is an elastic member. This high-temperature valve actuator 1 moves in a pressing force application direction, where the piston 15 is connected to the stem portion 16b and a pressing force is applied to the diaphragm 61 so that the diaphragm 71 contacts the valve seat 73 together with the stem portion 16b, and in a pressing force release direction, where the pressing force applied to the diaphragm 71 is released so that the diaphragm 71 returns to its original position away from the valve seat 73.

[0025] The high-temperature valve actuator 1 includes a piston unit 10, a cylinder 30 to which the piston unit 10 is assembled, and a cylinder cover 40 that closes the opening 30a of the cylinder 30.

[0026] <About the piston unit 10> First, let's describe the piston unit 10. The piston unit 10 comprises a unit body 11 with an upper nut 12a at one end which serves as an air connection part connected to an air supply source, a bellows 14 that extends and retracts between the other end of the unit body 11 and the piston 15, and a piston 15 that is integrally provided with the stem portion 16b. This piston unit 10 is an integrated unit in which the unit body 11, bellows 14, and piston 15 are connected from the upstream side to the downstream side in the direction of air introduction.

[0027] <Regarding the unit body 11 of the piston unit 10> The unit body 11 includes an air inlet fitting 12 and an air fitting base 13, and the air fitting base 13 and the air inlet fitting 12 are welded together to form a unit. In this embodiment, the air introduction fitting 12 is, for example, a commercially available metal pipe fitting having an air connection portion at one end that connects to an air pipe such as an air tube connected to an air supply source. In this embodiment, the air introduction joint 12 has an upper nut 12a that is rotatably mounted on the joint body 12c as an air connection part to fasten the air piping, and a lower nut 12b that is fixed to the joint body 12c.

[0028] The air joint base 13 is made of metal, for example, stainless steel, and is installed between the air introduction joint 12 and the bellows 14. A flow path 13a is formed inside the base, through which the drive air introduced from the air introduction joint 12 is guided into the interior of the bellows 14. Furthermore, the air coupling base 13 has a step portion 13b against which the push-butt portion 46 of the cylinder cover 40, which will be described later, abuts when the cylinder cover 40 is assembled to the cylinder 30.

[0029] <Regarding the bellows 14 of the piston unit 10> In this embodiment, a commercially available metal bellows 14 is used, and the air introduced into the bellows 14 from the unit body 11 is guided into the air passage 18 provided on the piston 15. As the bellows 14 extends and retracts, the piston 15 moves relative to the unit body 11, which is fixedly positioned in the cylinder 30.

[0030] <Regarding the piston 15 of the piston unit 10> The piston 15 is made of a metal material and has a head portion 16 whose cross-section perpendicular to the stroke direction is substantially circular and whose outer diameter is adjusted to a size that provides a gap with respect to the inner circumferential surface 31e of the cylinder 30, and a stem portion 16b which is integrally provided with the head portion 16 and functions as the stem of the valve 70.

[0031] The head portion 16 is provided with a connected portion 17 (see Figure 5) at one end which is connected to the end of the bellows 14, and an air passage 18 is formed from the end connected to the bellows 14 through the interior and connected to the air chamber 20 described later. Furthermore, the head portion 16 is provided with a spring set recess 19 into which the end of the spring 50 is fitted and which holds one end of the spring.

[0032] <Regarding the air chamber 20 provided in the piston 15> An air chamber 20 is provided in the head portion 16 of the piston 15. The air chamber 20 is located between the planar portion 16a of the head portion 16 and the corrugated diaphragm 22 described later, specifically between the surface oriented in the direction of biasing by the spring 50 and the corrugated diaphragm 22 described later. This air chamber 20 is a recess having an opening surface 21a that faces the inner wall surface 31a of the cylinder 30 in the direction of biasing by the spring 50. The corrugated diaphragm 22 is fixed to the planar portion 16a so as to block the opening surface 21a of the air chamber 20.

[0033] The air chamber 20 is an annular recess with an inner circumference around the base end of the stem portion 16b and an outer circumference around the outer edge of the head portion 16, and is provided with a vent 21b inside that connects to the flow path 18 of the head portion 16 for introducing drive air. Furthermore, as shown in Figure 5, mounting steps 16aa and 16ab for welding the corrugated diaphragm 22 are provided along the circumferential direction on the planar portion 16a, which is the upper end surface on both the inner and outer sides of the air chamber 20.

[0034] <Regarding the wave-shaped diaphragm 22 provided on the piston 15> In this embodiment, the corrugated diaphragm 22 is made of metal, for example, a cobalt alloy, and is sealed and fixed to the planar portion 16a of the piston 15 so as to be able to expand toward the inner wall surface 31a of the cylinder 30. This corrugated diaphragm 22 has an annular shape with a stem through-hole 22a formed in the center through which the stem portion 16b passes, and both ends on the inner and outer circumferences are welded and fixed to the respective mounting steps 16aa and 16ab of the planar portion 16a. In this embodiment, the corrugated diaphragm 22 can be attached to the piston 15 to hermetically seal the opening surface 21a of the air chamber 20, and may also be attached to the head portion 16 by methods other than welding, provided that it has high heat resistance. For example, the corrugated diaphragm 22 may be attached to the head portion 16 using a highly heat-resistant adhesive. Furthermore, the corrugated diaphragm 22 may be made of a material other than metal, as long as it has high heat resistance. For example, a highly heat-resistant resin material may be used.

[0035] In this manner, the air chamber 20 provided in the piston 15 has its opening surface 21a blocked by the corrugated diaphragm 22, and is filled with air by introducing drive air through the vent 21b provided inside. Therefore, when drive air is introduced into the air chamber 20 from an external air supply source through the unit body 11, the air filling the air chamber 20 causes the corrugated diaphragm 22 to expand toward the inner wall surface 31a of the cylinder 30. On the other hand, when the supply of drive air from the air source is stopped, the air in the air chamber 20 flows out through the vent 21b, causing the corrugated diaphragm 22 to return to its deflated state before air was introduced.

[0036] <Regarding the stem portion 16b provided on the piston 15> The stem portion 16b is integrally attached to the piston 15 along the axial direction from the center of the planar portion 16a, and its tip is capable of contacting the diaphragm piece 76 of the valve 70. This stem portion 16b also serves to guide the piston 15 in the stroke direction by passing through the stem guide hole 32c provided in the cylinder 30, which will be described later. In this embodiment, the stem portion 16b is shown as being integrally attached to the piston 15, but the stem portion 16b may be provided separately from the piston 15 as long as it moves in cooperation with the piston 15.

[0037] <Regarding the piston unit 10 integrated as a unit> Here, we will describe the piston unit 10, which is integrated as a single unit. As shown in Figure 5, the piston unit 10 is constructed by welding together the unit body 11, the bellows 14, and the piston 15. Furthermore, the air introduction joint 12 and the air joint base 13, which constitute the unit body 11, are also welded together. Therefore, the piston unit 10 is integrated from an air connection part 12a connected to an external air supply to a stem part 16b that transmits a pressing force to the valve 70 side to press the diaphragm 71 of the valve 70, and includes an air chamber 20 and a corrugated diaphragm 22 that function to move the piston 15 in the stroke direction against the biasing force of the spring 50. In other words, the piston unit 10 integrates the main parts of the actuator. In this embodiment, the unit body 11, bellows 14, and piston 15 are shown as being connected by welding, but other connection methods may be used as long as the unit body 11, bellows 14, and piston 15 can be connected in a way that integrates them as a single unit. For example, they may be connected using a high heat-resistant adhesive.

[0038] <Regarding cylinder 30> Next, we will describe the cylinder 30. The cylinder 30 has a case portion 31 that houses the main part of the high-temperature valve actuator 1, including the piston unit 10, and a base portion 32 that is connected to the valve 70.

[0039] <Regarding the case portion 31 of the cylinder 30> The case portion 31 is assembled with the piston unit 10 having its upper end, including the upper nut 12a which serves as the connection point to the air supply source, protruding outwards. Inside this case portion 31, a space is formed through which the piston 15 of the piston unit 10 moves through the stroke while assembled to the cylinder 30. The case portion 31 is equipped with a spring 50 inside, and this spring 50 applies a force to the piston 15 that presses the diaphragm piece 76 so that the diaphragm 71 comes into contact with the valve seat 73.

[0040] As shown in Figure 1, a retaining ring retaining groove 31b is formed on the inner circumferential surface 31e of the case portion 31, which fits and holds the outer circumferential end of the retaining ring 60 that restricts the stroke range of the piston 15. In this embodiment, the area of ​​the inner wall surface 31a facing the air chamber 20 is a protruding surface area 31aa that protrudes toward the air chamber 20, and this protruding surface area 31aa can be positioned inside the air chamber 20 by fitting its outer peripheral stepped portion into the mounting stepped portions 16aa and 16ab for welding the corrugated diaphragm 22.

[0041] <Regarding the base portion 32 of the cylinder 30> The base portion 32 is the connection portion with the valve 70. A male threaded portion 32a is formed on the outer circumferential surface of the base portion 32, which screws into a female threaded portion 72b formed on the body 72 of the valve 70. Furthermore, the base portion 32 has a bonnet pressing surface 32b formed on the tip surface on the side connecting to the valve 70, which presses against the bonnet 75 on the side that holds the diaphragm 71. Furthermore, the base portion 32 is formed with a stem guide hole 32c that guides the stem portion 16b in the stroke direction of the piston 15. This stem guide hole 32c allows the stem portion 16b protruding from the piston 15 to pass through from inside the cylinder 30 towards the space where the diaphragm piece 76 of the valve 70 is located. Furthermore, an air outlet 31c is formed on the inner wall surface 31a of the cylinder 30 to allow air inside the cylinder 30 to flow out to the outside.

[0042] <Regarding cylinder cover 40> Next, we will describe the cylinder cover 40. The cylinder cover 40 closes the opening 30a of the cylinder 30, which serves as the insertion point for the piston unit 10, when the piston unit 10 is assembled inside the cylinder 30, with the upper part of the piston unit 10 protruding outwards.

[0043] The cylinder cover 40 has an upper surface that slopes downward in a stepped manner from the inner diameter side to the outer diameter side, and includes an upper section 41 where the uppermost surface is formed, a middle section 42 that is one step lower than the upper section 41 and protrudes outward in a flange-like manner in the outer diameter direction, and a lower section 43 that is one step lower than the middle section 42 and protrudes outward in a flange-like manner in the outer diameter direction. Furthermore, the cylinder cover 40 has a through-hole 44 in the center of the upper part of the unit, which is formed to allow the upper part of the piston unit 10 to pass through. As shown in Figure 2, the upper through-hole 44 of this unit has a rectangular shape with two faces 44a and 44b on its inner surface that face each other in a direction perpendicular to the axis of the lower nut 12b of the piston unit 10.

[0044] The upper section 41 has two screw holes 41a formed on its circumferential surface, extending through to the upper through hole 44 of the unit, for screwing in two set screws S1. By screwing the set screws S1 into the two screw holes 41a formed in the upper section 41, the tips of the set screws S1 come into contact with the two surfaces of the lower nut 12b of the piston unit 10. Therefore, the piston unit 10 is fixed to the cylinder 30 in a state where it cannot rotate and is prevented from moving downward by the two surfaces 44a and 44b of the through hole 44 at the top of the unit and the two set screws S1.

[0045] An annular gap G is provided between the outer circumferential surface of the middle section 42 and the inner circumferential surface 31e of the cylinder 30, and the spring nut N is screwed onto the cylinder 30 and positioned in this gap G. When the spring nut N is screwed onto the cylinder 30, the lower surface of the spring nut N comes into contact with the upper surface of the lower portion 43 of the cylinder cover 40, thereby fixing the cylinder cover 40 to the cylinder 30.

[0046] The lower section 43 has three screw holes 43a formed on its circumferential surface, spaced evenly along the circumferential direction, for screwing in three anti-rotation screws S2. These three screw holes 43a are formed in positions corresponding to three screw insertion holes 31d formed on the circumferential surface of the cylinder 30, and the cylinder cover 40 can be fixed to the cylinder 30 in a non-rotatable manner by anti-rotation screws S2 that are screwed through these screw insertion holes 31d. In this embodiment, the anti-rotation screw S2 is a very low-profile hex socket head bolt, which is screwed into the circumferential surface of the cylinder 30 in an embedded state. Furthermore, the anti-rotation screws S2 can be installed in any number other than three locations, as long as they can prevent the rotation of the cylinder cover 40, and the spacing between them can also be uneven. In other words, the number of anti-rotation screws S2 and their spacing should be adjusted as appropriate according to the specifications.

[0047] Furthermore, on the lower surface of the cylinder cover 40, there is a spring set recess 45 that holds the other end of the spring 50, in conjunction with a spring set recess 19 provided on the piston 15 to hold one end of the spring 50. Furthermore, a push-butt portion 46 is provided on the lower surface of the cylinder cover 40, which abuts against the abutting step portion 13b of the air coupling base 13. The surface of this push-in abutment portion 46 that abuts against the abutted step portion 13b is the upper surface on the inner circumference side of the spring set recess 45. In other words, the push-in stopper portion 46 is provided using the upper surface of the spring set recess 45.

[0048] <Procedure for assembling the piston unit 10 to the cylinder 30> Here, we will explain the procedure for assembling the piston unit 10 into the cylinder 30. First, the worker inserts the piston unit 10 into the cylinder 30 through the opening 30a of the cylinder 30, with the stem portion 16b side as the tip. At this time, the worker inserts the piston unit 10 toward the inside of the cylinder 30 while inserting the stem portion 16b into the stem guide hole 32c of the cylinder 30. In other words, the piston unit 10 is inserted into the cylinder 30 using the stem guide hole 32c as a positioning guide when assembling it into the cylinder 30.

[0049] Next, the worker inserts and secures the retaining ring 60 into the retaining ring retaining groove 31b provided on the inner circumferential surface 31e of the cylinder 30. Then, the worker inserts one end of the spring 50 into the spring set recess 19 of the piston 15, which is facing the opening 30a of the cylinder 30, and inserts the other end of the spring 50 into the spring set recess 45 of the cylinder cover 40, while passing the top of the piston unit 10 through the through hole 44 at the top of the unit of the cylinder cover 40. Then, the worker compresses the spring 50 and pushes the cylinder cover 40 into the completed mounting position. At this time, the piston unit 10 is pushed into the cylinder 30 as the push-butt portion 46 of the cylinder cover 40 abuts against the abutted step portion 13b of the piston unit 10.

[0050] Next, the worker secures the cylinder cover 40 to the cylinder 30 by screwing the spring nut N onto the cylinder 30. Next, the worker completes the assembly of the piston unit 10 to the cylinder by screwing the set screw S1 and the anti-rotation screw S2 into their respective designated locations. When connecting an air tube to an air supply source to the piston unit 10 assembled to the cylinder 30, the end of the air tube is fastened and secured with an upper nut 12a. At this time, a force acts to rotate the air introduction coupling 12 around its axis, that is, a force that rotates the piston unit 10 axially relative to the cylinder 30. However, the rotation of the piston unit 10 is restricted by the two faces of the lower nut 12b fixed to the piston unit 10, the two faces 44a and 44b of the upper through hole 44 of the cylinder cover 40, and the set screw S1. As a result, the rotation of the piston unit 10 is prevented, and consequently, the bellows 14 is prevented from twisting.

[0051] <Regarding the operation of the high-temperature valve actuator 1> Next, the operation of the high-temperature valve actuator 1 will be described. When the high-temperature valve actuator 1 stops supplying air from the air source to the unit body 11 in response to the valve closing process of valve 70, as shown in Figure 1, the air in the air chamber 20 of the piston 15 flows out of the air chamber 20 through the vent 21b, causing the corrugated diaphragm 22 to deflate and not bulge toward the inner wall surface 31a of the cylinder 30. Therefore, the piston 15 is positioned at the bottom dead center position of the cylinder 30 by the biasing force of the spring 50, with the head portion 16 positioned at the bottom dead center position of the cylinder 30. Furthermore, when the piston 15 is in the bottom dead center position, the protruding surface region 31aa of the inner wall surface 31a of the cylinder 30 is recessed into the air chamber 20. Therefore, when the corrugated diaphragm 22 bulges out toward the inner wall surface 31a in this state, it is more likely to come into contact with the inner wall surface 31a. Furthermore, when the piston 15 is moved to the bottom dead center position, the air between the head portion 16 of the piston 15 and the inner wall surface 31a is released from the air outlet 31c provided on the inner wall surface 31a of the cylinder 30, so that the air that remains there does not obstruct the movement of the piston 15. Furthermore, when the piston 15 is moved to the bottom dead center position, the head portion 16 moves with respect to the inner circumferential surface 31e of the cylinder 30 with a gap between them and the inner circumferential surface 31e without any sealing material in between, so that it does not rub against the inner circumferential surface 31e of the cylinder 30. Then, the stem portion 16b of the piston 15, which has moved to the bottom dead center position, presses down on the diaphragm piece 76 of the valve 70. The diaphragm piece 76 presses down on the diaphragm 71 of the valve 70, causing it to contact the valve seat 73, and thus the valve 70 closes.

[0052] On the other hand, when drive air is supplied from the air supply source to the unit body 11 in response to the valve opening process of valve 70, the high-temperature valve actuator 1 receives drive air through the vent 21b to the air chamber 20, as shown in Figure 4, and the corrugated diaphragm 22 gradually expands and bulges out toward the inner wall surface 31a of the cylinder 30. At this time, the corrugated diaphragm 22 expands while making contact with the inner wall surface 31a of the cylinder 30, so that the air is evenly distributed and spread along the inner wall surface 31a. In other words, the corrugated diaphragm 22 expands while receiving a reaction force in the direction that moves the piston 15 from the surface that is evenly spread along the inner wall surface 31a. Therefore, the piston 15 moves to the top dead center position where it contacts the retaining ring 60 while resisting the biasing force of the spring 50 in a stable state that is less likely to tilt in the stroke direction due to the expansion of the corrugated diaphragm 22. When the piston 15 is moved to the top dead center position, the head portion 16 moves with respect to the inner circumferential surface 31e of the cylinder 30 with a gap between them and the inner circumferential surface 31e without any sealing material in between, so that it does not rub against the inner circumferential surface 31e of the cylinder 30. Then, when the piston 15 is moved to the top dead center position, the stem portion 16b separates from the diaphragm piece 76 of the valve 70, the pressing force of the diaphragm piece 76 on the diaphragm 71 is released, and the diaphragm 71 returns to a state where it is separated from the valve seat 73, causing the valve to open.

[0053] <Regarding the difference in thrust of the piston 15 obtained by the bulging shape of the corrugated diaphragm 22> Here, the difference in thrust of the piston 15 obtained by the bulging shape of the corrugated diaphragm 22 will be explained using Figure 6. Figure 6 is a diagram illustrating the difference in thrust of the piston 15 obtained by the bulging shape of the corrugated diaphragm 22. In Figure 6, the magnitude of the thrust of piston 15 is represented by the size of the arrow. Figure 6 shows the wave-shaped diaphragms 22A, 22B, and 22C, in which the expansion shape is changed so that the thrust of the piston 15 increases in the order of (a) to (c). Comparing Figure 6(a) and Figure 6(b), although the shapes of the corrugated diaphragms 22A and 22B are substantially the same, the wave peaks that make contact with the inner wall surface 31a of the cylinder 30 are more numerous in the corrugated diaphragm 22B shown in Figure 6(b) compared to the corrugated diaphragm 22A shown in Figure 6(a). Therefore, the reaction force received from the inner wall surface 31a is greater in the corrugated diaphragm 22B shown in Figure 6(b) compared to the corrugated diaphragm 22A shown in Figure 6(a), and as a result, the thrust of the piston 15 is greater.

[0054] Next, looking at Figure 6(c), when the corrugated diaphragm 22C is in the expanded state, the area around the peak of the wave becomes flattened, and the overall shape becomes roughly rectangular, greatly enlarging the contact portion 22d that contacts the inner wall surface 31a of the cylinder 30. Therefore, the corrugated diaphragm 22C expands and comes into contact with the inner wall surface 31a of the cylinder 30, thereby obtaining a larger reaction force from the inner wall surface 31a. In other words, it is important to set the shape, dimensions, etc. of the corrugated diaphragm 22 so that when expanded, a larger surface area contacts the inner wall surface 31a of the cylinder 30, that is, so that it has multiple contact points 22d that are dispersed and expanded and made contact with the ground when expanded. It is advisable to take this point into consideration and make appropriate adjustments.

[0055] <Effects of the Embodiment> As described above, according to the high-temperature valve actuator 1 of the embodiment, the piston unit 10 is composed of a unit body 11 having an air passage 13a, a piston 15 connected to the unit body 11 via a bellows 14 having a passage 14a, a corrugated diaphragm 22 sealed and fixed to the planar portion 16a of the piston 15, and an air chamber 20 provided between the planar portion 16a and the corrugated diaphragm 22. The piston 15 is provided to move freely by supplying and exhausting drive air to the air chamber 20, and when drive air is supplied to the air chamber 20, the corrugated diaphragm 22 comes into contact with the inner wall surface 31a of the cylinder 30. As a result, the expansion of the corrugated diaphragm 22 caused by supplying drive air to the air chamber 20 is utilized to move the piston 15 in the stroke direction against the biasing force of the spring 50 without using a power assist mechanism. Furthermore, as the corrugated diaphragm 22 expands while making contact with the inner wall surface 31a of the cylinder 30, the contact surface with the inner wall surface 31a deforms so that it spreads uniformly along the contact surface, thereby allowing the piston 15 to move stably in the stroke direction and suppressing contact with the part that guides the movement of the piston 15, such as the stem guide hole 32c. Furthermore, supplying drive air to the air chamber 20 expands the corrugated diaphragm 22, meaning that the supply of drive air into the air chamber 20 creates an airtight seal within the air chamber 20. This eliminates the need for additional sealing members to seal the axis of the piston 15, and prevents the piston from moving while rubbing against the inner circumferential surface 31e of the cylinder 30. Furthermore, the corrugated diaphragm 22 is assembled to only a portion of the piston 15, and the unit body 11, which has an air passage 13a that forms the main part of the actuator, the bellows 14 and the piston 15 are connected to form a unit which can then be assembled into the cylinder 30. Therefore, according to the embodiment of the high-temperature valve actuator 1, a simple structure can be used to improve durability against thermal load and ease of assembly.

[0056] Furthermore, according to the high-temperature valve actuator 1 of the embodiment, the piston unit 10 is integrated by welding the planar portion 16a and the corrugated diaphragm 22, welding one end of the bellows 14 to the unit body 11, and welding the other end of the bellows 14 to the piston 15. As a result, the piston unit 10 is firmly and airtightly connected, making it easier to handle as a single unit, and consequently improving ease of assembly.

[0057] Furthermore, according to the high-temperature valve actuator 1 of this embodiment, the unit body 11 is formed by welding the air joint base 13 and the air introduction joint 12 together, so the piston unit 10 can be handled as a single unit with the air introduction joint 12 and the air joint base 13 firmly connected, which are the connection parts to the external air supply destination. This improves assembly workability, durability, and airtightness.

[0058] Furthermore, according to the high-temperature valve actuator 1 of the embodiment, the pressure contact surface to which the corrugated diaphragm 22 expands and makes contact is the inner wall surface 31a of the cylinder 30. The corrugated diaphragm 22 has a plurality of contact portions 22d that are dispersed and expanded on the inner wall surface 31a and made contact when drive air is supplied to the air chamber 20. As a result, when drive air is supplied to the air chamber 20, the corrugated diaphragm 22 that has expanded toward the inner wall surface 31a of the cylinder 30 disperses and expands on the inner wall surface 31a and makes contact with the inner wall surface 31a, making it easier to receive a reaction force from the inner wall surface 31a, and consequently, the thrust of the piston 15 can be increased.

[0059] Furthermore, according to the high-temperature diaphragm valve 100 of this embodiment, the piston 15 is moved in the stroke direction against the biasing force of the elastic member without using a power assist mechanism by utilizing the expansion action of the corrugated diaphragm 22 caused by supplying driving air to the air chamber 20. Furthermore, the corrugated diaphragm 22 expands while making contact with the inner wall surface 31a inside the cylinder 30, and its contact surface deforms so that it spreads uniformly along the inner wall surface 31a, thereby stably moving the piston 15 in the stroke direction and suppressing contact with the part that guides the movement of the piston 15, such as the stem guide hole 31c. Furthermore, supplying drive air to the air chamber 20 expands the corrugated diaphragm 22, meaning that the supply of drive air into the air chamber 20 creates an airtight seal within the air chamber 20. This eliminates the need for additional sealing members to seal the area around the piston 15's axis, and prevents the piston 15 from moving while rubbing against the inner circumferential surface 31e of the cylinder 30. Furthermore, the corrugated diaphragm 22 is assembled to only a portion of the piston 15, and the unit body 11, which has an air passage 13a that forms the main part of the actuator, the bellows 14 and the piston 15 are connected to form a unit which can then be assembled into the cylinder 30. Therefore, according to the high-temperature diaphragm valve 100 of the embodiment, it has a simple structure and can improve durability against thermal load and ease of assembly.

[0060] While embodiments of this disclosure have been described above, this disclosure is not limited to the embodiments described above, and various modifications are possible without departing from its spirit.

[0061] For example, in the above embodiment, the corrugated diaphragm 22 is shown to be in contact with the inner wall surface 31a of the cylinder 30 as the contact surface. However, as long as the corrugated diaphragm 22 can contact the wall surface inside the cylinder 30 when it expands, it may be made to contact a wall surface other than the inner wall surface 31a as the contact surface. For example, the contact surface of the corrugated diaphragm 22 may be formed by a plate-shaped member provided inside the cylinder 30.

[0062] For example, in the above embodiment, a corrugated diaphragm 22 was exemplified, but other shapes are also acceptable as long as they can expand toward the pressure contact surface inside the cylinder 30 and make contact with the pressure contact surface by introducing air into the air chamber 20. Furthermore, the material of the corrugated diaphragm 22 is not limited to metal; a highly heat-resistant resin may also be used.

[0063] Furthermore, although the above embodiment illustrates a case where the high-temperature valve actuator 1 is of the normally closed type, the high-temperature valve actuator 1 may also be of the normally open type. If the high-temperature valve actuator 1 is of the normally open type, a spring 50 is provided on the lower side of the head portion 16 of the piston 15, a corrugated diaphragm 22 is provided on the upper side of the head portion 16 to form an air chamber 20, and a pressure contact surface to which the expanded corrugated diaphragm 22 makes contact is provided inside the cylinder 30.

[0064] Furthermore, although a spring 50 was used as the elastic member in the above embodiment, other elastic members such as Belleville washers may also be used.

[0065] Furthermore, although the above embodiment illustrates the application of the high-temperature valve actuator 1 to a high-temperature diaphragm valve 100, the high-temperature valve actuator 1 can be applied to any valve that opens and closes the valve vertically using the stroke of a piston biased in one direction by an elastic member such as a spring, such as a bellows valve, needle valve, or other valve.

[0066] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The embodiments described above may be omitted, replaced, or modified in various forms without departing from the scope and spirit of the appended claims. [Explanation of Symbols]

[0067] 1. High-temperature valve actuator 10 Piston Unit 11 Unit body 12. Air inlet fitting 12a Upper nut (air connection part) 12b Lower nut 12c fitting body 13 Air fitting base 13a Flow channel 13b Stepped part to be abutted 13c Upstream connected part 13d Downstream connected part 14 Bellows 14a Flow channel 15 pistons 16 Head section 16a Planar part 16aa, 16ab Mounting step 16b Stem section 17 Connected part 18 channels 19 Spring set recess 20 Air chambers 21a Opening surface 21b Ventilation opening 22. Corrugated diaphragm 22A, 22B, 22C Corrugated diaphragm 22a Stem through hole 22d Grounding part 30 cylinders 30a opening 31 Case section 31a Inner wall surface (pressure contact surface) 31aa protruding surface area 31b Retaining ring groove 31c Air outlet 31d Screw insertion hole 31e Inner surface 32 Base section 32a Male threaded portion 32b Bonnet pressure surface 32c Stem guide hole 40 Cylinder Cover 41 Upper section 41a Screw hole 42 Middle section 43 Lower section 43a Screw hole 44 Unit upper through holes 44a, 44b side 45 Spring set recess 46 Push-in stopper 50 Springs (elastic components) 60 Retaining ring 70 valves 71 Diaphragm 72 Body 72a Flow channel 72b Female thread section 73 valve seats 74 Actuator connection section 75 Bonnet 76 Diaphragm Piece 100 High-temperature diaphragm valve

Claims

1. A piston unit is provided inside the cylinder, which includes a piston biased in one direction of stroke by an elastic member. The piston unit comprises a unit body having an air passage, a piston connected to the unit body via a bellows having a passage, a corrugated diaphragm sealed and fixed to the planar portion of the piston, and an air chamber provided between the planar portion and the corrugated diaphragm. By supplying and exhausting drive air to the aforementioned air chamber, the piston is provided to move freely. A high-temperature valve actuator characterized in that, when driving air is supplied to the air chamber, the corrugated diaphragm is brought into contact with a pressure contact surface provided inside the cylinder.

2. The high-temperature valve actuator according to claim 1, wherein the piston unit is integrated by welding the planar portion and the corrugated diaphragm, welding one end of the bellows to the unit body, and welding the other end of the bellows to the piston.

3. The unit body is a high-temperature valve actuator according to claim 1 or 2, formed by welding an air joint base and an air inlet joint together.

4. The aforementioned contact surface is the inner wall surface of the cylinder, The high-temperature valve actuator according to claim 1 or 2, wherein the corrugated diaphragm has a plurality of grounding portions that are dispersed and expanded on the pressure contact surface and grounded when driving air is supplied to the air chamber.

5. A high-temperature valve actuator as described in claim 1 is provided, A high-temperature diaphragm valve that opens and closes a diaphragm provided in a flow path inside the body by stroking the piston using the high-temperature valve actuator.

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