Valve diaphragm fixing structure and diaphragm valve

Abstract

To provide a valve diaphragm fixing structure and a diaphragm valve that improve the durability of the diaphragm and the sealing performance at the outer peripheral edge of the diaphragm that is clamped and fixed to the body, and that can stabilize the Cv value. [Solution] The valve diaphragm fixing structure 10 has a body 50 in which a diaphragm 61 with an outer circular shape that can open and close two passages 51 and 52 is arranged inside a cylindrical portion 53 with a circular inner surface provided between a passage 51 and a passage 52, and a substantially cylindrical bonnet 70 that is tightened and fixed to the inside of the cylindrical portion 53 in the axial direction of the cylindrical portion 53. The outer peripheral edge portion 61a of the diaphragm 61 is clamped and fixed between a body-side annular clamping portion 54 and a bonnet-side annular clamping portion 74 provided inside the cylindrical portion 53, and the body-side annular clamping portion 54 receives a clamping load via the diaphragm 61, so as to increase the contact surface 54aa of the body-side annular clamping portion 54 that is in close contact with the diaphragm 61.

Description

Technical Field

[0001] The present invention relates to a valve for controlling the flow of a fluid, and particularly to a diaphragm fixing structure and a diaphragm valve of a valve having a diaphragm sandwiched and fixed by a body and a bonnet.

Background Art

[0002] For controlling the gas of a semiconductor manufacturing apparatus, for example, a diaphragm valve having a diaphragm sandwiched and fixed by a body and a bonnet is used. This type of diaphragm valve has a body in which an outer circular diaphragm capable of opening and closing two flow paths is disposed in a cylindrical portion provided between an inlet-side flow path and an outlet-side flow path, and a substantially cylindrical bonnet that is fastened and fixed in the axial direction of the cylindrical portion inside the cylindrical portion. By fastening and fixing the bonnet to the body, the outer peripheral edge portion of the diaphragm is brought into close contact with and fixed to a body-side annular sandwiching portion in the cylindrical portion of the body.

[0003] In such a diaphragm fixing structure of a valve, since the deformation of the diaphragm due to the opening and closing of the valve is repeated with the outer peripheral edge portion of the diaphragm being sandwiched and fixed, durability of the diaphragm and sealing performance at the outer peripheral edge portion of the diaphragm sandwiched and fixed to the body are required.

[0004] In particular, a diaphragm valve used in a semiconductor manufacturing apparatus is required to have extremely high durability when used in a process such as ALD (Atomic Layer Deposition) that opens and closes the valve at high speed.

[0005] In addition, a diaphragm valve used in a semiconductor manufacturing apparatus uses a large amount of toxic gas as a control fluid. To prevent such toxic gases from leaking out of the diaphragm valve, improving the sealing performance of the outer edge of the diaphragm, which is clamped and fixed to the body, is important from a safety standpoint, and product inspection standards regarding sealing performance tend to become stricter. For example, inspections using leak detection devices called helium leak detectors may require meeting extremely strict acceptance criteria, such as a helium gas leakage rate of 1.0E-10 (Pa·m3 / s) or less.

[0006] To meet the above-mentioned durability or sealing requirements, the following diaphragm valves have been proposed, for example.

[0007] For example, in the diaphragm valve described in Patent Document 1, the upper surface of the outer peripheral edge of the diaphragm is in surface contact with the tapered lower surface of the retaining adapter, and the lower surface of the outer peripheral edge of the diaphragm is in line contact with the outer circumference of the flat part of the bottom surface of the recess of the body. In a state where the fluid passage is open (usually a spherical shell shape that is convex upwards), the upper surface of the outer peripheral edge of the diaphragm is in surface contact with the lower surface of the retaining adapter, thereby minimizing deformation from the natural spherical shell shape. Furthermore, because the lower surface of the outer edge of the diaphragm makes line contact with the outer circumference of the flat bottom surface of the recess in the body, the diaphragm maintains a state in which deformation from its natural spherical shell shape is kept to a minimum, even when held by the retaining adapter and the body. In other words, the diaphragm valve described in Patent Document 1 has no non-deformable, flat portion that bends relative to the spherical portion at the outer edge of the elastically deformable spherical shell-shaped diaphragm, thus avoiding localized stress concentration, optimizing the deformation of the diaphragm, and improving the durability of the diaphragm.

[0008] Furthermore, the diaphragm valve described in Patent Document 2 comprises a fluid control device comprising a first body and a second body, a threaded engagement portion that fastens the bodies together in an axially aligned relationship, and a diaphragm seal axially positioned between the first body and the second body to form a seal between them. The first body and the second body each have a generally flat surface portion near their outer circumference, at least one of which is adjacent to the outer corner, and the diaphragm is clamped alone between the generally flat portions, and the diaphragm has an outer surface portion adjacent to the generally flat surface which bends above the corner to seal it. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2016-11743 [Patent Document 2] WO98 / 34056 [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] However, in the diaphragm valve described in Patent Document 1, the degree of contact between the outer edge of the diaphragm and the body is reduced due to the surface condition of the body to which the lower surface of the outer edge of the diaphragm contacts, for example, the surface roughness of the body, which reduces the sealing performance. To minimize the impact of the surface finish precision of the body, the sealing performance can be prevented by pressing the retaining adapter firmly against the diaphragm to create a tighter seal between the diaphragm and the body. However, pressing the retaining adapter firmly against the diaphragm could cause the contact surface of the body that is in contact with the diaphragm to be crushed, potentially lowering the diaphragm below its designed position and reducing the Cv value. Furthermore, in the diaphragm valve described in Patent Document 1, if the retaining adapter is pressed firmly against the diaphragm to suppress the influence of the surface processing accuracy mentioned above, there is a risk that not only the body but also the diaphragm may deform. If the diaphragm is deformed, it may also affect the durability of the diaphragm.

[0011] In the diaphragm valve described in Patent Document 2, when the bonnet is pressed against the diaphragm, the outer edge of the diaphragm is deformed by bending downwards, which may reduce the durability of the diaphragm due to the effects of bending stress. Furthermore, in the diaphragm valve described in Patent Document 2, the bonnet is pressed firmly against the diaphragm with a load large enough to bend the outer edge of the diaphragm. Therefore, similar to the diaphragm valve in Patent Document 1, the contact surface of the body that is in close contact with the diaphragm is crushed, causing the diaphragm to drop below its designed position, which could lead to a decrease in the Cv value.

[0012] The present invention was developed to solve the problems of the prior art, and its objective is to provide a valve diaphragm fixing structure and a diaphragm valve that can improve the durability of the diaphragm and the sealing performance at the outer peripheral edge of the diaphragm that is clamped and fixed to the body, and stabilize the Cv value. [Means for solving the problem]

[0013] To achieve the above objective, the invention according to claim 1 is a valve diaphragm fixing structure having a body in which a circular outer diaphragm capable of opening and closing two passages is arranged in a cylindrical portion with a circular inner surface provided between an inlet passage and an outlet passage, and a substantially cylindrical bonnet that is tightened and fixed to the inside of the cylindrical portion in the axial direction of the cylindrical portion, wherein the outer peripheral edge of the diaphragm is clamped and fixed between a body-side annular clamping portion provided inside the cylindrical portion and a bonnet-side annular clamping portion provided at the lower end of the bonnet, and at least one of the body-side annular clamping portion or the bonnet-side annular clamping portion is provided so as to be elastically flexible and deformable so as to increase the contact surface of the body-side annular clamping portion that is in close contact with the diaphragm by receiving the tightening load when clamping and fixing the outer peripheral edge of the diaphragm via the diaphragm.

[0014] The invention according to claim 2 is a valve diaphragm fixing structure in which the body-side annular clamping portion is provided to protrude upward at an acute angle with respect to the inner circumferential surface of the cylindrical portion of the body, and elastically flexes to increase the angle with respect to the inner circumferential surface due to the clamping load.

[0015] The invention according to claim 3 is a valve diaphragm fixing structure in which the bonnet-side annular clamping portion is provided with a flexible and deformable annular groove formed along the circumferential direction on the outer circumferential surface near the lower end surface of the bonnet, and the annular groove is formed on the outer circumferential surface near the lower end surface of the bonnet.

[0016] The invention according to claim 4 is a valve diaphragm fixing structure in which the body-side annular clamping portion is provided to be elastically flexible and deformable so as to increase the contact surface with the diaphragm by receiving the tightening load when clamping and fixing the outer peripheral edge of the diaphragm via the diaphragm, and the coefficient of linear expansion of the body is greater than the coefficient of linear expansion of the diaphragm.

[0017] The invention according to claim 5 is a valve diaphragm fixing structure having a fastening member that fastens and fixes the hood to the body by screwing into the cylindrical portion between the hood and the cylindrical portion.

[0018] The invention according to claim 6 is a diaphragm valve having the diaphragm fixing structure of the valve described in claims 1 to 5. [Effects of the Invention]

[0019] According to the invention of claim 1, when clamping and fixing the outer peripheral edge of the diaphragm between the body-side annular clamping portion provided inside the cylindrical portion and the bonnet-side annular clamping portion provided at the lower end of the bonnet, at least one of the body-side annular clamping portion or the bonnet-side annular clamping portion receives the tightening load when clamping and fixing the outer peripheral edge of the diaphragm via the diaphragm, and is elastically deformed to increase the contact surface of the body-side annular clamping portion that is in close contact with the diaphragm. Therefore, according to the invention according to claim 1, by adjusting the deflection amount of at least one of the body-side annular clamping portion or the bonnet-side annular clamping portion, the tightening load is appropriately released, the deformation of the diaphragm is suppressed, and the contact surface of the body-side annular clamping portion that adheres to the diaphragm is prevented from being crushed. The outer peripheral edge portion of the diaphragm can be closely adhered to and clamped and fixed at a predetermined position between the body-side annular clamping portion and the bonnet-side annular clamping portion. As a result, the durability of the diaphragm and the sealing performance at the outer peripheral edge portion of the diaphragm clamped and fixed to the body can be improved, and the Cv value can be stabilized.

[0020] According to the invention according to claim 2, the body-side annular clamping portion is provided so as to project upward at an acute angle with respect to the inner peripheral surface of the cylindrical portion of the body and is elastically deflected so as to expand the angle with respect to the inner peripheral surface by the tightening load. Thus, processing for thickness adjustment can be easily performed so that a processing tool can be inserted from the upper opening of the cylindrical portion of the body and the body-side annular clamping portion inside the cylindrical portion can be elastically deflected and deformed.

[0021] According to the invention according to claim 3, the bonnet-side annular clamping portion is provided so as to be elastically deflectable toward the annular groove side by an annular groove formed along the circumferential direction on the outer peripheral surface near the lower end surface of the bonnet. Thus, processing can be easily performed so that the bonnet-side annular clamping portion can be elastically deflected and deformed from the outer peripheral surface side of the bonnet.

[0022] According to the invention according to claim 4, the body-side annular clamping portion is provided so as to be elastically deflectable so as to increase the contact surface with the diaphragm by receiving the tightening load when clamping and fixing the outer peripheral edge portion of the diaphragm through the diaphragm, and the linear expansion coefficient of the body is larger than the linear expansion coefficient of the diaphragm. As a result, even if the outer peripheral edge of the diaphragm is pulled radially outward by the body due to the difference in the linear expansion coefficients of the body and the diaphragm in a high-temperature environment, the body-side annular clamping portion flexes and acts to release the radially outward pulling force, thereby keeping the outer peripheral edge of the diaphragm at the initial clamping and fixing position, preventing the outer peripheral edge of the diaphragm from being pulled radially outward by the body and the central portion of the diaphragm from dropping. Consequently, it is possible to prevent a decrease in the Cv value even when used in a high-temperature environment.

[0023] According to the invention according to claim 5, by having a tightening member that tightens and fixes the bonnet by screwing the bonnet onto the cylindrical portion between the bonnet and the cylindrical portion, when tightening and fixing the bonnet to the body while rotating the tightening member, if the bonnet rotates in the rotation direction of the tightening member and unevenly presses against the outer peripheral edge of the diaphragm, the diaphragm may be twisted. However, at least one of the body-side annular clamping portion or the bonnet-side annular clamping portion elastically flexes to release a part of the tightening load, thereby preventing the diaphragm from being twisted. As a result, it is possible to prevent malfunction caused by the twisting of the diaphragm.

[0024] According to the invention according to claim 6, by having the inventions according to claims 1 to 5, the same effects as the inventions according to claims 1 to 5 can be achieved.

Brief Description of the Drawings

[0025] [Figure 1] It is a perspective view of a diaphragm valve according to Embodiment 1 of the present invention. [Figure 2] It is a cross-sectional view of the diaphragm valve shown in FIG. 1. [Figure 3] It is an enlarged view of the vicinity of the outer peripheral edge of the diaphragm of the diaphragm valve shown in FIG. 2. [Figure 4] It is an exploded perspective view of the diaphragm valve shown in FIG. 1. [Figure 5] It is a perspective cross-sectional view of the body shown in FIG. 2. [Figure 6] This diagram illustrates the elastic bending of the annular clamping portion on the body side when the hood is tightened and secured to the body. [Figure 7] The upper diagram shows the area around the outer edge of the diaphragm before the hood is pushed downward by the clamping member, and the lower diagram shows the area around the outer edge of the diaphragm after the hood has been pushed downward by the clamping member and is clamped and fixed between the annular clamping portion on the body side and the annular clamping portion on the hood side. [Figure 8A] This diagram illustrates the movement in the conventional technology where the central part of the diaphragm lowers due to the difference in the coefficients of thermal expansion between the diaphragm and the body. [Figure 8B] This diagram illustrates the operation of a diaphragm valve according to Embodiment 1, which prevents the central portion of the diaphragm from sagging due to the difference in the coefficients of thermal expansion between the diaphragm and the body. [Figure 9] This is a cross-sectional view of a diaphragm valve according to Embodiment 2 of the present invention. [Figure 10] This is a magnified view of the area around the outer edge of the diaphragm of the diaphragm valve shown in Figure 9. [Figure 11] This is a cross-sectional view of a modified diaphragm valve. [Modes for carrying out the invention]

[0026] (Embodiment 1) Embodiment 1 of the valve diaphragm fixing structure 10 and diaphragm valve 1 according to the present invention will be described in detail with reference to Figures 1 to 5. 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 perspective view of a diaphragm valve 1 according to Embodiment 1 of the present invention. Figure 2 is a cross-sectional view of the diaphragm valve 1 shown in Figure 1. Figure 3 is an enlarged view of the area around the outer peripheral edge 61a of the diaphragm 61 of the diaphragm valve 1 shown in Figure 2. Figure 4 is an exploded perspective view of the diaphragm valve 1 shown in Figure 1. Figure 5 is a perspective cross-sectional view of the body 50 shown in Figure 2. The diaphragm valve 1 according to Embodiment 1 of the present invention comprises an actuator 20, a valve body 40 which is the main body of the diaphragm valve 1, and a fastening member 80 which fastens and connects the actuator 20 and the body 50 of the valve body 40. Furthermore, the valve diaphragm fixing structure 10 according to Embodiment 1 of the present invention comprises a body 50, a diaphragm 61, and a bonnet 70.

[0027] <About Actuator 20> First, let me explain the actuator 20. The actuator 20 functions as a drive source for the stem 60 that drives the diaphragm 61, which acts as a valve body, to open and close, and in this embodiment 1, an air actuator is used.

[0028] The drive mechanism 30 is housed inside the case 21 of this actuator 20. The drive mechanism 30 includes a piston 31 that presses the stem 60 in the valve closing direction, a spring 32 that biases the piston 31 in the valve closing direction, and an air connection part 33 that serves as the connection point to the air supply source. The case 21 has an enlarged diameter cylindrical portion 21a in which the drive mechanism 30 is housed, and a reduced diameter cylindrical portion 21b which is connected to the body 50 via a fastening member 80.

[0029] <Regarding the piston 31 of actuator 20>

[0030] The piston 31 has a flange portion 31a, an upper protruding shaft portion 31b that protrudes from the central upper surface of the flange portion 31a, and a lower protruding shaft portion 31c that protrudes from the central lower surface of the flange portion 31a.

[0031] The upper protruding shaft portion 31b is guided by a guide cylinder portion 21aa provided in the center of the case 21, and is configured to move up and down along axis A.

[0032] The lower protruding shaft portion 31c passes through a guide hole 31d that penetrates the wall forming the boundary between the enlarged diameter cylindrical portion 21a and the reduced diameter cylindrical portion 21b of the case 21, and its tip surface contacts the stem 60 while being guided vertically by the guide hole 31d.

[0033] In this type of piston 31, O-rings 31e are fitted onto the outer circumferential surfaces of the flange portion 31a, the upper protruding shaft portion 31b, and the lower protruding shaft portion 31c. The piston 31 is able to move up and down along axis A while hermetically sealing the space between it and the inner circumferential surface of the case 21, including the guide cylinder portion 21aa and the guide hole 31d, via the O-rings 31e.

[0034] Furthermore, the piston 31 forms a continuous flow path through the internally formed flow path 31f, connecting the air connection section 33 to the air chamber 21c. When the supply of air to the air chamber 21c is stopped, the piston 31 is moved downward in the valve closing direction via the flange portion 31a of the piston 31, which is pressed by the elastic force of the spring 32.

[0035] On the other hand, when air is supplied into the case 21 from an air supply source (not shown) via the air connection part 33, the air fills the air chamber 21c through the flow path 31f formed in the piston 31. As a result, the piston 31 is moved upward in the valve opening direction against the elastic force of the spring 32 by the pressure of the air filled in the air chamber 21c.

[0036] <Regarding valve body 40> The valve body 40 includes a body 50, a stem 60, a diaphragm 61, and a bonnet 70.

[0037] <About Body 50> The body 50 is made of, for example, stainless steel, and a cylindrical portion 53 with a circular inner surface 53a is provided between the inlet channel 51 through which the control fluid flows in and the outlet channel 52 through which the control fluid flows out. This cylindrical section 53 has a diaphragm 61 with an outer circular shape that can open and close two flow paths 51 and 52 on the inlet side and outlet side. Inside the cylindrical portion 53, as shown in Figure 2, the diaphragm 61, stem 60, and bonnet 70 are arranged concentrically with the shaft A.

[0038] Inside the body 50, an annular valve seat 56 is provided on the opening edge surface that opens toward the valve chamber 55 by passing the inlet-side flow path 51 upwards. The valve seat 56 is made of, for example, a perfluoroalkoxyalkane (PFA).

[0039] The cylindrical portion 53 has a threaded portion 53b formed on the inner circumferential surface 53a of the end on the opening 53c side into which the fastening member 80 is screwed, and a body-side annular clamping portion 54 is provided on the inner circumferential surface 53a below the threaded portion 53b.

[0040] <Regarding the body-side annular clamping portion 54> The body-side annular clamping portion 54 is designed to elastically flex and deform in such a way that it increases the contact surface 54aa with the diaphragm 61 by receiving the tightening load through the diaphragm 61 when clamping and fixing the outer peripheral edge portion 61a of the diaphragm 61. More specifically, the body-side annular clamping portion 54 is a portion that protrudes in an annular shape along the circumferential direction from the inner circumferential surface 53a of the cylindrical portion 53. For example, a stepped portion with a reduced diameter is formed on the inner circumferential surface 53a of the cylindrical portion 53 so that the outer peripheral edge 61a of the diaphragm 61 is placed on it, and recessed portions 54c and 54d are formed at the base of the stepped portion so that the stepped portion can elastically flex when subjected to a clamping load. This body-side annular clamping portion 54 can be broadly divided into two surfaces: a contact surface 54a, which is the surface on which the outer peripheral edge 61a of the diaphragm 61 is placed, and a flexible surface 54b, which is the surface that elastically bends when subjected to a clamping load. The body-side annular clamping portion 54 has recessed portions 54c and 54d at its base, formed by carving out the inner circumferential surface 53a of the cylindrical portion 53 radially from both sides of the contact surface 54a and the flexible surface 54b. In this embodiment, the clamping load is the load applied in the direction of axis A when the bonnet 70 is clamped and fixed to the body 50.

[0041] When the body-side annular clamping portion 54 receives a tightening load while clamping and fixing the outer peripheral edge portion 61a of the diaphragm 61, it is designed to bend from the flexible side surface 54b towards the recessed portion 54d, which is a recess carved radially outward into the inner peripheral surface 53a of the cylindrical portion 53. In other words, the recessed portion 54d functions as a relief portion for the body-side annular clamping portion 54. The body-side annular clamping portion 54 is adjusted, for example, by the amount and shape of the recesses that are carved into the inner circumferential surface 53a of the cylindrical portion 53 from both sides of the contact surface 54a and the bending surface 54b, so that it can bend by a predetermined amount when subjected to a clamping load, while ensuring a predetermined strength at the base.

[0042] In this embodiment 1, the body-side annular clamping portion 54 is provided projecting upward at an acute angle with respect to the inner circumferential surface 53a of the cylindrical portion 53 of the body 50, and is designed to elastically flex in order to increase the angles B1 and B2 (see Figure 3) of the cylindrical portion 53 with respect to the inner circumferential surface 53a due to the clamping load.

[0043] In this embodiment 1, the angle of the body-side annular clamping portion 54 with respect to the inner circumferential surface 53a of the cylindrical portion 53 refers to the angle B1 formed between the inner circumferential surface 53a of the cylindrical portion 53, which extends in a substantially vertical direction, and the contact surface 54a of the body-side annular clamping portion 54, and the angle B2 formed between the inner circumferential surface 53a and the flexible surface 54b of the body-side annular clamping portion 54, as shown in Figure 3.

[0044] Furthermore, in this embodiment 1, the contact surface 54a and the flexible surface 54b each have a shape that includes a curved surface. Therefore, in this embodiment 1, for example, the angles B1 and B2 of the body-side annular clamping portion 54 with respect to the inner circumferential surface 53a of the cylindrical portion 53 are determined by linearly approximating the inclination of the contact surface 54a and the deflection surface 54b with respect to the inner circumferential surface 53a of the cylindrical portion 53. Furthermore, the inner circumferential surface 53a of the cylindrical portion 53 uses a plane in a substantially vertical direction as the reference for angles B1 and B2. Furthermore, angle B1 is an angle based on the inner circumferential surface 53a, which is above the contact surface 54a. Furthermore, angle B2 is an angle based on the inner circumferential surface 53a above the deflected side surface 54b. Therefore, the inner circumferential surface 53a of the cylindrical portion 53 can be easily processed to adjust the wall thickness of the cylindrical portion 53 by, for example, inserting a processing tool into the opening 53c at the top of the cylindrical portion 53 of the body 50 from diagonally above.

[0045] <About Stem 60> The stem 60 is a substantially cylindrical member in which one end 60a abuts against the shaft portion 31c protruding from the lower surface of the piston 31, and the other end 60b, which is provided with an enlarged diameter, abuts against the central part of the diaphragm 61. The stem 60 is guided vertically by the stem guide hole 70a of the bonnet 70, which will be described later.

[0046] <About diaphragm 61> The diaphragm 61 is provided so as to be able to move toward and away from the valve seat 56 disposed in the cylindrical portion 53 of the body 50, and functions as a valve body that contacts the valve seat 56 and seals the opening that connects the inlet side passage 51 and the outlet side passage 52. This diaphragm 61 is a metal plate-like member with a circular outer shape, such as a nickel-cobalt alloy. In this embodiment 1, the diaphragm 61 is constructed by stacking multiple thin metal plates and is provided in a gently curved shape that protrudes upward with the center being the apex when elastically neutral. The diaphragm 61 is then placed on the tip 54e of the body-side annular clamping portion 54, with its outer circumference extending radially outward from the contact point with the tip 54e of the body-side annular clamping portion 54.

[0047] <About Bonnet 70> The bonnet 70 holds the stem 60 so that it can move up and down along axis A. Furthermore, as described above, the bonnet 70 also clamps and fixes the outer peripheral edge 61a of the diaphragm 61 between itself and the body 50. The bonnet 70 has a roughly annular cross-section perpendicular to axis A, and a stem guide hole 70a is formed in the center through which the stem 60 is inserted and guided. Furthermore, the bonnet 70 is formed so that its outer diameter expands in three stages from the actuator 20 side towards the body 50 side. The bonnet 70 has, in the direction of axis A, an upper end cylindrical portion 71 that constitutes the smallest outer diameter portion at the upper part facing the actuator 20, a lower end cylindrical portion 72 that constitutes the largest outer diameter portion at the lower part facing the body 50, and an intermediate cylindrical portion 73 that constitutes an intermediate size outer diameter portion between the upper end cylindrical portion 71 and the lower end cylindrical portion 72.

[0048] The upper cylindrical portion 71 is the part on its outer circumference where the reduced-diameter cylindrical portion 21b of the actuator 20 abuts against and fits against the stepped surface 73a between it and the intermediate cylindrical portion 73. In this embodiment 1, the actuator 20 and the bonnet 70 are connected by fixing the reduced diameter cylindrical portion 21b of the actuator 20 and the upper end cylindrical portion 71 of the bonnet 70 with a screw S.

[0049] The intermediate cylindrical portion 73 has an outer diameter slightly smaller than the inner diameter of the fastening member 80, and is a portion for positioning the bonnet 70 inside the fastening member 80 in a concentric position with the fastening member 80.

[0050] The lower end cylindrical portion 72 is provided with a bonnet-side annular clamping portion 74 that contacts the outer peripheral edge portion 61a of the diaphragm 61. The annular clamping portion 74 on the bonnet side has an annular contact surface 74a that contacts the outer peripheral edge 61a of the diaphragm 61. The lower end cylindrical portion 72 has a curved outer circumferential stepped surface 72a that forms the boundary with the intermediate cylindrical portion 73, and the tip 80a of the fastening member 80 comes into contact with this outer circumferential stepped surface 72a. In other words, the clamping member 80 moves downward along the shaft A while screwing into the threaded portion 53b of the cylindrical portion 53, and the tip portion 80a of the clamping member 80 comes into contact with the stepped outer surface 72a of the hood 70, pushing the hood 70 downward, thereby clamping and fixing the outer edge portion 61a of the diaphragm 61 between the body-side annular clamping portion 54 and the hood-side annular clamping portion 74.

[0051] <Regarding the valve diaphragm fixing structure 10> The valve diaphragm fixing structure 10 according to Embodiment 1 of the present invention comprises a body 50, a diaphragm 61, and a bonnet 70, and is structured to clamp and fix the outer peripheral edge 61a of the diaphragm 61 between a body-side annular clamping portion 54 provided inside a cylindrical portion 53 and a bonnet-side annular clamping portion 74 provided at the lower end of the bonnet 70.

[0052] The body-side annular clamping portion 54 is provided to be elastically flexible and deformable so as to increase the contact surface 54aa of the body-side annular clamping portion 54 that is in close contact with the diaphragm 61 by receiving the tightening load when clamping and fixing the outer peripheral edge portion 61a of the diaphragm 61 via the diaphragm 61.

[0053] The valve diaphragm fixing structure 10 according to Embodiment 1 of the present invention is configured such that the body-side annular clamping portion 54 elastically flexes to increase the contact surface 54aa that comes into close contact with the lower surface 61c of the diaphragm 61. Therefore, when the bonnet 70 is pushed downward by the tightening member 80, that is, when the diaphragm 61 is placed on the tip 54e of the body-side annular clamping portion 54 and the body-side annular clamping portion 54 is in contact with the lower surface 61c of the diaphragm 61 only at the tip 54e, the body-side annular clamping portion 54 is pushed downward by the tightening member 80, causing it to elastically bend so that the contact surface 54aa with the lower surface 61c of the diaphragm 61 expands from the tip 54e towards the base. For this reason, the diaphragm 61 is placed on the tip 54e of the body-side annular clamping portion 54 such that its outer peripheral end extends radially outward from the contact portion with the tip 54e of the body-side annular clamping portion 54. As a result, the outer peripheral edge 61a of the diaphragm 61, which is clamped and fixed between the body-side annular clamping portion 54 and the bonnet-side annular clamping portion 74, can ensure a contact surface with the body-side annular clamping portion 54, which increases when the bonnet 70 is tightened and fixed by the tightening member 80.

[0054] Next, using Figures 6 and 7, the elastic bending of the body-side annular clamping portion 54 when the bonnet 70 is tightened and fixed to the body 50 will be explained in conjunction with the procedure for assembling the bonnet 70 to the body 50. Please note that the assembly procedure is just one example and is not limited to the explanation below. Figure 6 is a diagram illustrating the bending of the body-side annular clamping portion 54 when the bonnet 70 is tightened and fixed to the body 50. Figure 7 shows, in the upper figure, the vicinity of the outer peripheral edge 61a of the diaphragm 61 before the bonnet 70 is pushed downward by the clamping member 80, and in the lower figure, the vicinity of the outer peripheral edge 61a of the diaphragm 61 after the bonnet 70 has been pushed downward by the clamping member 80 and is clamped and fixed between the body-side annular clamping portion 54 and the bonnet-side annular clamping portion 74.

[0055] When assembling the diaphragm 61 into the body 50, first the outer peripheral edge 61a of the diaphragm 61 is placed on the body-side annular clamping portion 54 of the body 50. Then, the bonnet 70, which is connected to the actuator 20 and positioned inside the fastening member 80, is placed on top of the diaphragm 61 so that the bonnet-side annular clamping portion 74 overlaps the upper surface 61b of the outer peripheral edge 61a of the diaphragm 61. In this case, as described above, the diaphragm 61 is placed on the tip 54e of the body-side annular clamping portion 54 such that its outer peripheral end extends radially outward from the contact portion with the tip 54e of the body-side annular clamping portion 54.

[0056] Then, with the outer peripheral edge 61a of the diaphragm 61 sandwiched between the body-side annular clamping portion 54 and the bonnet-side annular clamping portion 74, the fastening member 80 and the body 50 are screwed together and tightened. When the fastening member 80 is rotated to screw it onto the body 50, the fastening member 80 moves downward along the axis A as it rotates, and the tip 80a of the fastening member 80 comes into contact with the stepped outer surface 72a of the hood 70, pushing the hood 70 downward.

[0057] When the bonnet 70 is pushed downward by the clamping member 80, the annular clamping portion 74 on the bonnet side presses against the outer peripheral edge 61a of the diaphragm 61. When the bonnet-side annular clamping portion 74 presses against the outer peripheral edge 61a of the diaphragm 61, the body-side annular clamping portion 54, as shown in Figure 6, receives the tightening load from the bonnet-side annular clamping portion 74 via the diaphragm 61 when clamping and fixing the outer peripheral edge 61a of the diaphragm 61, and thus elastically bends and deforms. The body-side annular clamping portion 54 elastically flexes and deforms in such a way that it increases the contact surface 54aa of the body-side annular clamping portion 54 that is in close contact with the diaphragm 61. The body-side annular clamping portion 54, while receiving a clamping load applied downward in Figure 6, tilts toward the recessed portion 54d on the side surface 54b, allowing a portion of the clamping load to escape. In this way, as the body-side annular clamping portion 54 inclines toward the dug-in portion 54d, the angle formed by the contact side surface 54a and the inner peripheral surface 53a of the cylindrical portion 53 is enlarged, and the contact surface 54aa with the outer peripheral edge portion 61a of the diaphragm 61 is increased.

[0058] More specifically, before the bonnet 70 is pushed downward by the clamping member 80, as shown in the upper diagram of FIG. 7, the body-side annular clamping portion 54 supports the outer peripheral edge portion 61a of the diaphragm 61 with only the tip portion 54e in contact with the lower surface 61c of the diaphragm 61. In addition, in order to show the size of the contact surface between the lower surface 61c of the diaphragm 61 and the body-side annular clamping portion 54, the width T1 of the contact surface 54aa is shown in the figure.

[0059] When starting to push the bonnet 70 downward by the clamping member 80, as shown in the lower diagram of FIG. 7, the body-side annular clamping portion 54 deflects so as to enlarge the angle formed with the inner peripheral surface 53a of the cylindrical portion 53 from the angle B1b to the angle B1a (B1b < B1a, B2b < B2a). Then, the body-side annular clamping portion 54 further increases the surface facing the lower surface 61c of the diaphragm 61, that is, the surface that can contact the lower surface 61c of the diaphragm 61 from the tip portion 54e toward the base side. In this way, the diaphragm fixing structure 10 of the valve according to the first embodiment of the present invention increases the surface facing the lower surface 61c of the diaphragm 61, so that the body-side annular clamping portion 54 increases the contact surface 54aa with the outer peripheral edge portion 61a of the diaphragm 61 and clamps and fixes the diaphragm 61 between the bonnet 70.

[0060] When the outer peripheral edge portion 61a of the diaphragm 61 is clamped and fixed between the body-side annular clamping portion 54 and the bonnet-side annular clamping portion 74 of the bonnet 70, due to the increase in the contact surface 54aa, the width of the contact surface 54aa becomes a width T2 larger than the width T1 when only the tip portion 54e was in contact.

[0061] Furthermore, the torque used when tightening the fastening member 80 should be controlled, for example, by using a torque wrench to achieve a predetermined torque. The predetermined torque for tightening the fastening member 80 can be determined to a value that passes the leak test, based on the evaluation of the tightening torque and leakage amount using a leak detection device, as shown in the evaluation results using Table 1 described later.

[0062] Once the tightening operation by the tightening member 80 is completed, the body-side annular clamping portion 54 flexes by a predetermined amount, thereby releasing the tightening load from the tightening member 80, and in close contact with the diaphragm 61, clamps and fixes the outer peripheral edge 61a of the diaphragm 61 between itself and the bonnet-side annular clamping portion 74.

[0063] Next, using Table 1, we will explain the results of a comparative evaluation of the tightening torque of the tightening member 80 required to pass the leak test between the diaphragm valve 1 (product of this embodiment) according to this embodiment 1 and a conventional product. The conventional product used in this comparative evaluation differs from the diaphragm valve according to this embodiment 1 in that the annular clamping portion 54 on the body side does not bend or deform, but otherwise has substantially the same configuration as the diaphragm valve. In this comparative evaluation, a helium leak detector was used as the leak detection device. Furthermore, the passing criterion is that the amount of He gas detected by the helium leak detector is 1.0E-10 (Pa·m3 / s) or less.

[0064] [Table 1]

[0065] <Results of comparative evaluation> As shown in Table 1, the diaphragm valve 1 according to this embodiment 1 makes it possible to obtain a satisfactory product with a smaller tightening torque compared to conventional products. In other words, the diaphragm valve 1 according to this embodiment 1 is capable of ensuring a predetermined sealing performance with a smaller tightening torque than conventional products.

[0066] Next, using Table 2, we will explain the results of a comparative evaluation of the Cv values ​​of the diaphragm valve 1 according to this embodiment (product of this embodiment) and the conventional product at room temperature (26°C) and high temperature (100°C). The conventional product used in this comparative evaluation differs from the diaphragm valve according to this embodiment 1 in that the annular clamping portion 54 on the body side does not bend or deform, but otherwise has substantially the same configuration as the diaphragm valve. In this evaluation, the conventional product and the diaphragm valve 1 according to this embodiment 1 use a body 50 made of a material with a higher coefficient of linear expansion than the diaphragm 61. Body 50 is made of stainless steel. The diaphragm 61 is made of a cobalt alloy.

[0067] [Table 2]

[0068] As shown in Table 2, the comparative evaluation results indicate that the conventional product shows a lower Cv value at high temperatures compared to the Cv value at room temperature. On the other hand, in the diaphragm valve 1 according to this embodiment 1, no change in the Cv value is observed when comparing the Cv value at room temperature and high temperature. Thus, the decrease in the Cv value at high temperatures compared to room temperature in conventional products is thought to be due to the difference in the coefficients of linear expansion between the diaphragm and the body. In other words, because the body has a larger coefficient of linear expansion than the diaphragm, as shown in Figure 8A, in the conventional diaphragm valve 5 (conventional product), when the temperature rises from room temperature to high temperature, thermal expansion causes the inner circumferential surface 553a of the cylindrical portion 553 of the body 550 to deform, expanding its inner diameter. This deformation causes the diaphragm 61 to be pulled radially outward by the body 550. Thus, in the conventional diaphragm valve 5, when the temperature rises from room temperature to high temperature, the diaphragm 61 is pulled radially outward by the body 550 (in the direction of arrow D1), causing the central part to move downward (in the direction of arrow D2), and as a result, the Cv value decreases.

[0069] On the other hand, in the diaphragm valve 1 according to this embodiment 1, when the temperature rises from room temperature to high temperature, as shown in Figure 8B, the inner circumferential surface 53a of the cylindrical portion 53 of the body 50 deforms due to thermal expansion, increasing its inner diameter. However, the annular clamping portion 54 on the body side flexes to relieve the load caused by the deformation, so that the diaphragm 61 is not pulled radially outward by the body 50. Therefore, in the diaphragm valve 1 according to this embodiment 1, even if the temperature rises from room temperature to high temperature, the diaphragm 61 is not pulled radially outward by the body 50, preventing the central part from sinking downward, and as a result, the Cv value does not decrease.

[0070] <Effects of Embodiment 1> As described above, according to the valve diaphragm fixing structure 10 of Embodiment 1, when the outer peripheral edge 61a of the diaphragm 61 is clamped and fixed between the body-side annular clamping portion 54 provided inside the cylindrical portion 53 and the bonnet-side annular clamping portion 74 provided at the lower end of the bonnet 70, the body-side annular clamping portion 54 receives the tightening load when clamping and fixing the outer peripheral edge 61a of the diaphragm 61 via the diaphragm 61, and is elastically deformed to increase the contact surface 54aa of the body-side annular clamping portion 54 that is in close contact with the diaphragm 61. Therefore, according to the valve diaphragm fixing structure 10 of Embodiment 1, by adjusting the amount of deflection of the body-side annular clamping portion 54, the clamping load is appropriately released, deformation of the diaphragm 61 is suppressed, and the contact surface 54aa is prevented from being crushed. The outer peripheral edge 61a of the diaphragm 61 can be held in close contact with the body-side annular clamping portion 54 at a predetermined position between the body-side annular clamping portion 54 and the bonnet-side annular clamping portion 74. As a result, the durability of the diaphragm 61 and the sealing performance of the outer peripheral edge 61a of the diaphragm 61 held in place by the body 50 are improved, and the Cv value can be stabilized.

[0071] Furthermore, according to the valve diaphragm fixing structure 10 of Embodiment 1, the body-side annular clamping portion 54 is provided projecting upward at acute angles B1b and B2b with respect to the inner circumferential surface 53a of the cylindrical portion 53 of the body 50, and is designed to be elastically flexible so as to increase the angle with respect to the inner circumferential surface 53a under clamping load. This makes it easy to insert a processing tool through the opening 53c at the top of the cylindrical portion 53 of the body 50 and perform processing to adjust the wall thickness so that the body-side annular clamping portion 54 inside the cylindrical portion 53 can be elastically flexible and deformable.

[0072] Furthermore, according to the valve diaphragm fixing structure 10 of Embodiment 1, the body-side annular clamping portion 54 is provided to be elastically flexible and deformable so as to increase the contact surface 54aa with the diaphragm 61 by receiving the tightening load when clamping and fixing the outer peripheral edge portion 61a of the diaphragm 61 via the diaphragm 61, and the coefficient of linear expansion of the body 50 is greater than that of the diaphragm 61. As a result, even if the outer peripheral edge 61a of the diaphragm 61 is pulled radially outward by the body 50 due to the difference in the coefficients of linear expansion between the body 50 and the diaphragm 61 in a high-temperature environment, the annular clamping portion 54 on the body side bends and acts to release the radially outward pulling force, thereby keeping the outer peripheral edge 61a of the diaphragm 61 in its original clamping and fixing position. This prevents the central part of the diaphragm 61 from sinking due to the outer peripheral edge 61a being pulled radially outward by the body 50, and consequently prevents a decrease in the Cv value even when used in a high-temperature environment.

[0073] Furthermore, according to the valve diaphragm fixing structure 10 of Embodiment 1, by having a tightening member 80 that tightens and fixes the bonnet 70 by screwing into the cylindrical portion 53 between the bonnet 70 and the cylindrical portion 53, when tightening and fixing the bonnet 70 to the body 50 while rotating the tightening member 80, if the bonnet 70 rotates in the direction of rotation of the tightening member 80 and is pressed unevenly against the outer peripheral edge 61a of the diaphragm 61, there is a risk that the diaphragm 61 may twist. However, the body-side annular clamping portion 54 elastically flexes, releasing a portion of the tightening load, thereby preventing the diaphragm 61 from twisting, and consequently preventing malfunctions caused by the twisting of the diaphragm 61.

[0074] Furthermore, according to the diaphragm valve 1 of Embodiment 1, by having a valve diaphragm fixing structure 10, the same effects as the valve diaphragm fixing structure 10 can be achieved.

[0075] (Embodiment 2) Here, an embodiment 2 of the diaphragm valve according to the embodiment will be described with reference to Figures 9 and 10. Figure 9 is a cross-sectional view of a diaphragm valve 2 according to Embodiment 2 of the present invention. Figure 10 is an enlarged view of the area around the outer peripheral edge 61a of the diaphragm 61 of the diaphragm valve 2 shown in Figure 9. In Embodiment 2, the same reference numerals are used for the same parts as in Embodiment 1, thereby omitting redundant explanations. The diaphragm valve 2 of this embodiment 2 differs from the diaphragm valve 1 of embodiment 1 in that, instead of the body-side annular clamping portion 54, the bonnet-side annular clamping portion 174 is provided so as to be elastically flexible and deformable in order to increase the contact surface 154aa of the body-side annular clamping portion 154 that is in close contact with the diaphragm 61, by receiving the tightening load when clamping and fixing the outer peripheral edge portion 61a of the diaphragm 61 via the diaphragm 61. Furthermore, the valve diaphragm fixing structure 110 according to Embodiment 2 of the present invention comprises a body 150, a diaphragm 61, and a bonnet 170.

[0076] The bonnet-side annular clamping portion 174 is provided in a flexibly deformable manner on the annular groove 174b side formed on the outer peripheral surface of the lower end of the bonnet 170, thereby forming an annular contact surface 174a that abuts against the outer peripheral edge 61a of the diaphragm 61.

[0077] Next, the movement of the annular clamping portion 174 on the bonnet side when the bonnet 170 is tightened and fixed to the body 150 will be explained in conjunction with the procedure for assembling the bonnet 170 to the body 150. Please note that the assembly procedure is just one example and is not limited to the explanation below. Furthermore, the procedure similar to that in Embodiment 1 will not be described.

[0078] When the bonnet 170 is pushed downward by the clamping member 80, the bonnet-side annular clamping portion 174 of the bonnet 170 presses against the outer peripheral edge 61a of the diaphragm 61. When the bonnet-side annular clamping portion 174 presses against the outer peripheral edge 61a of the diaphragm 61, the bonnet-side annular clamping portion 174 receives the tightening load from the body-side annular clamping portion 154 via the diaphragm 61 when clamping and fixing the outer peripheral edge 61a of the diaphragm 61, causing it to elastically bend and deform. More specifically, the bonnet-side annular clamping portion 174, in Figure 10, receives the downward clamping load from the body-side annular clamping portion 154 as a reaction force via the diaphragm 61, while tilting toward the annular groove 174b so as to release a portion of the clamping load and to cause the outer peripheral edge 61a of the diaphragm 61 to follow the body-side annular clamping portion 154. In this way, the annular clamping portion 174 on the bonnet side is tilted toward the annular groove 174b, thereby increasing the contact surface area 154aa of the annular clamping portion 154 on the body side that is in close contact with the outer peripheral edge 61a of the diaphragm 61. Furthermore, the torque used when tightening the fastening member 80 should be controlled, for example, by using a torque wrench to ensure it reaches a predetermined value.

[0079] <Effects of Embodiment 2> According to the valve diaphragm fixing structure 110 of Embodiment 2, when the outer peripheral edge 61a of the diaphragm 61 is clamped and fixed between the body-side annular clamping portion 154 provided inside the cylindrical portion 53 and the bonnet-side annular clamping portion 174 provided at the lower end of the bonnet 170, the bonnet-side annular clamping portion 174 receives the tightening load when clamping and fixing the outer peripheral edge 61a of the diaphragm 61 via the diaphragm 61, and is elastically deformed to increase the contact surface 154aa of the body-side annular clamping portion 154 that is in close contact with the diaphragm 61. Therefore, according to the valve diaphragm fixing structure 110 of Embodiment 2, by adjusting the amount of deflection of the bonnet-side annular clamping portion 174, the clamping load can be appropriately released, suppressing deformation of the diaphragm 61 and preventing the contact surface 154aa from being crushed. This allows the outer peripheral edge 61a of the diaphragm 61 to be held in close contact with the body-side annular clamping portion 154 at a predetermined position between the body-side annular clamping portion 154 and the bonnet-side annular clamping portion 174. As a result, the durability of the diaphragm 61 and the sealing performance of the outer peripheral edge 61a of the diaphragm 61 held in place by the body 150 can be improved, and the Cv value can be stabilized.

[0080] According to the valve diaphragm fixing structure 110 of Embodiment 2, the bonnet-side annular clamping portion 174 is provided so as to be able to flexibly deform toward the annular groove 174b, which is formed along the circumferential direction on the outer peripheral surface near the lower end surface of the bonnet 170. This makes it easy to process the bonnet-side annular clamping portion 174 so as to be able to flexibly deform toward the annular groove 174b, from the outer peripheral surface side of the bonnet 170.

[0081] Furthermore, according to the diaphragm valve 2 of Embodiment 2, by having a valve diaphragm fixing structure 110, the same effects as the valve diaphragm fixing structure 110 can be achieved.

[0082] 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.

[0083] In the embodiments 1 and 2 described above, the bodies 50 and 150 of the diaphragm valves 1 and 2 are shown as examples in which the inlet passage 51 and the outlet passage 52 are oriented perpendicular to the axis A of the stem 60. However, the invention is not limited to this, and any body that has a cylindrical section between the inlet passage and the outlet passage, within which a diaphragm with an outer circular shape that can open and close two passages is arranged. For example, as shown in the diaphragm valve 3 and valve diaphragm fixing structure 210 in Figure 11, the body 250 may have the inlet passage 251 and the outlet passage 252 oriented in the direction of axis A of the stem 60.

[0084] Furthermore, while embodiments 1 and 2 described above illustrate a method in which a single fastening member 80 is rotated to fasten and secure the bonnets 70 and 170 to the bodies 50 and 150, the invention is not limited to this, and other configurations are acceptable as long as the bonnet can be fastened and secured to the body. For example, multiple fastening members such as screws arranged circumferentially around the bonnet can be rotated to fasten and secure the bonnet to the body. [Explanation of symbols]

[0085] 1, 2, 3, 5 Diaphragm valves 10, 110, 210 valve diaphragm fixing structure 50, 150, 250, 550 Body 51, 251 Inlet side channel 52, 252 Outlet side flow path 53, 553 Cylindrical part 53a, 553a Inner surface 54, 154 Body-side annular clamping portion 54aa, 154aa contact surface 61 Diaphragm 61a Outer edge 70, 170 bonnet 74, 174 Bonnet-side annular clamping section 174b Ring groove 80 Fastening member

Claims

1. A diaphragm fixing structure comprising: a body having a cylindrical portion with a circular inner surface provided between an inlet-side flow path and an outlet-side flow path, within which two diaphragms with a circular outer shape that can open and close the aforementioned flow paths are arranged; and a substantially cylindrical bonnet that is tightened and fixed to the inside of the cylindrical portion in the axial direction of the cylindrical portion, wherein the outer peripheral edge of the diaphragm is clamped and fixed between a body-side annular clamping portion provided inside the cylindrical portion and a bonnet-side annular clamping portion provided at the lower end of the bonnet, A valve diaphragm fixing structure characterized in that at least one of the body-side annular clamping portion or the bonnet-side annular clamping portion receives a tightening load through the diaphragm when clamping and fixing the outer peripheral edge of the diaphragm, thereby elastically bending and deforming to increase the contact surface of the body-side annular clamping portion that is in close contact with the diaphragm.

2. The valve diaphragm fixing structure according to claim 1, wherein the body-side annular clamping portion is provided to protrude upward at an acute angle with respect to the inner circumferential surface of the cylindrical portion of the body, and is elastically flexible so as to increase the angle with respect to the inner circumferential surface due to the clamping load.

3. The valve diaphragm fixing structure according to claim 1, wherein the bonnet-side annular clamping portion is provided to be flexibly deformable toward the annular groove formed circumferentially on the outer circumferential surface near the lower end surface of the bonnet, by an annular groove formed along the circumferential direction.

4. The body-side annular clamping portion is provided to be elastically flexible and deformable so as to increase the contact surface with the diaphragm by receiving the clamping load when clamping and fixing the outer peripheral edge of the diaphragm via the diaphragm. The valve diaphragm fixing structure according to claim 1, wherein the coefficient of linear expansion of the body is greater than the coefficient of linear expansion of the diaphragm.

5. The valve diaphragm fixing structure according to claim 1, further comprising a fastening member that fastens and fixes the bonnet to the body by screwing into the cylindrical portion between the bonnet and the cylindrical portion.

6. A diaphragm valve having the diaphragm fixing structure of the valve according to claims 1 to 5.

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