Fluid control valve

Abstract

To provide a fluid control valve capable of increasing the stroke amount.SOLUTION: A diaphragm member 34 has a center located on the extension line of an axial center CL of an operation rod 9 and is spherically crown-shaped swollen to the side of the operation rod 9. At the peak, it is held from both sides in the direction parallel to the axial center CL by a first holding piece 93 contacting the diaphragm member 34 from the side of the operation rod 9 and a second holding piece 323 contacting the diaphragm member 34 from the side of a valve element 32. The first holding piece 93 and the second holding piece 323 are formed in a circle-shape located coaxially with the operation rod 9, and a diameter D11 of the first holding piece 93 is longer than a diameter D of the second holding piece 323. The face of the first holding piece 93, opposed to the diaphragm member 34, is formed to be swollen to the side of the diaphragm member 34, as a convex face 94 having a center on the axial center CL of the operation rod 9.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a fluid control valve that includes an operating rod, a valve body connected to the operating rod, a valve seat against which the valve body makes contact and separates, and a diaphragm positioned between the operating rod and the valve body, and controls the flow of a control fluid by causing the valve body driven by the operating rod to make contact and separate along the axial direction of the operating rod.

Background Art

[0002] In the film formation process in the semiconductor manufacturing process, a plurality of types of process gases are used. In order to control the flow rate of this process gas, a fluid control valve is used. As the fluid control valve, for example, the fluid control valves disclosed in Patent Document 1 and Patent Document 2 are known. The fluid control valve disclosed in Patent Document 1 is an air-operated on-off valve that controls the flow rate of the process gas by causing a diaphragm member to make contact and separate from the valve seat.

[0003] More specifically, a stem (diaphragm presser) is in contact with the apex of a diaphragm member formed in a spherical crown shape, and the diaphragm member is pressed and deformed by the stem by the operation of an actuator to be made to contact the valve seat. The state in which the diaphragm member is in contact with the valve seat is the valve closed state of the fluid control valve. Then, when the pressing of the diaphragm member by the stem is released, the diaphragm member returns to its original spherical crown shape by its own restoring force, and the diaphragm member separates from the valve seat. The state in which the diaphragm member is separated from the valve seat is the valve open state of the fluid control valve.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the process gas used in atomic layer deposition (ALD), a thin-film deposition technology that has become widespread in recent years, is at a high temperature (around 200 degrees Celsius). At such high temperatures, the self-recovering force of the diaphragm component decreases, which may make it difficult for the fluid control valve to return to its original spherical shape when moving from the closed state to the open state. If the diaphragm component does not return to its original spherical shape, the distance between the diaphragm component and the valve seat in the open state decreases, raising concerns about a decrease in the Cv value. In order to shorten the semiconductor thin-film deposition process as much as possible and improve productivity, it is desirable to increase the Cv value of fluid control valves (i.e., increase the amount of gas that can flow at once), and the decrease in the Cv value due to the reduced self-recovering force of the diaphragm component as described above is undesirable.

[0006] Therefore, the inventors of the present invention considered using a fluid control valve 100, such as the one shown in Figure 5, as a countermeasure to the problem of the self-restoring force of the diaphragm member decreasing at high temperatures.

[0007] The fluid control valve 100 includes an actuator section 4, which is equipped with a pneumatically driven air cylinder 6. Inside the air cylinder 6, a piston (not shown) is mounted so as to be slidable in the vertical direction in Figure 5. The up-and-down movement of the piston causes the operating rod 11 to move up and down. Furthermore, a valve body 32 is connected to the tip of the operating rod 11, which contacts and separates from the valve seat 33 as the operating rod 11 moves up and down. The diaphragm member 34 is formed in a disc shape, with its outer circumference clamped and fixed within the fluid control valve 100, and its central portion clamped from the vertical direction in Figure 5 by the clamping portion 111 of the operating rod 11 and the valve body 32.

[0008] In the fluid control valve 100 described above, deformation occurs in the diaphragm member 34 as the valve body 32 contacts and separates from the valve seat 33, as shown in Figure 6. Figure 6 shows the deformation of the diaphragm member 34 when the fluid control valve 100 shown in Figure 5 moves from an open state to a closed state, where (a) represents the open state, (b) represents the moment immediately after the valve body begins to move in the contact direction, and (c) represents the closed state.

[0009] When the fluid control valve 100 is in the open position, the diaphragm member 34 is in a state close to its natural, undeformed state (Figure 6(a)). When the operating rod 11 is driven in the contact direction to bring the valve body 32 into contact with the valve seat 33, the diaphragm member 34 deforms as it is pushed downwards from the central part, which is held between the operating rod 11 (clamping portion 111) and the valve body 32, toward the valve seat 33 (see Figure 5) (Figure 6(b)). The diaphragm member 34 is in its most deformed state when the valve body 32 comes into contact with the valve seat 33, that is, when the fluid control valve 100 is in the closed position (Figure 6(c)).

[0010] Furthermore, to change the valve from a closed state to an open state, the operating rod 11 is driven upward in the figure. As a result, the operating rod 11 and the valve body 32 move in the same direction, causing the valve body 32 to separate from the valve seat 33, and the fluid control valve 100 becomes open. At this time, since the diaphragm member 34 is held between the operating rod 11 (clamping portion 111) and the valve body 32, the central part is pulled upward in the direction away from the valve seat 33, and it can be reliably returned to its original shape as shown in Figure 6(a). Therefore, even in high-temperature environments, such as when a high-temperature process gas is used as the control fluid, it is possible to prevent the diaphragm member 34 from failing to return to its original shape.

[0011] However, the fluid control valve 100 described above had the following problem. The inventors of this application discovered that when the diaphragm member 34 is deformed, stress concentrates at the clamped portion P21 of the diaphragm member 34, as shown in Figure 6. If the location where the stress of the diaphragm member 34 is concentrated remains constant, there is a risk that the diaphragm member 34 may break at the stress-concentrated portion P21 when the valve body 32 of the fluid control valve 100 repeatedly comes into contact with and separates from the valve seat 33.

[0012] Furthermore, in recent years, there has been a demand for higher Cv values ​​in fluid control valves, which requires increasing the distance (stroke amount) between the valve body's open and closed positions. However, increasing the stroke amount leads to greater deformation of the diaphragm valve body. This increased deformation makes the diaphragm member 34 more susceptible to damage due to stress concentration in the aforementioned P21. The stress concentration in the diaphragm member 34 is a factor preventing the achievement of increased stroke amount.

[0013] The present invention has been made in view of the above problems, and aims to provide a fluid control valve capable of increasing the stroke amount. [Means for solving the problem]

[0014] To solve the above problems, a fluid control valve in one aspect of the present invention has the following configuration.

[0015] (1) A fluid control valve comprising an operating rod, a valve body connected to the operating rod, a valve seat on which the valve body abuts and separates, and a diaphragm member located between the operating rod and the valve body, wherein the valve body driven by the operating rod controls the controlled fluid by abutting and separating along the direction of the axis of the operating rod, wherein the diaphragm member is formed in the shape of a spherical crown with its center located on the extension of the axis and bulging toward the side of the operating rod, and at its apex, the diaphragm member is formed in the shape of a spherical crown that bulges toward the side of the operating rod. The valve body is clamped from both sides in a direction parallel to the axis by a first clamping piece that contacts the diaphragm member and a second clamping piece that contacts the diaphragm member from the side of the valve body; the first and second clamping pieces are formed in a circular shape and are coaxial with the operating rod, the diameter of the first clamping piece is larger than the diameter of the second clamping piece; the surface of the first clamping piece facing the diaphragm member is formed to bulge outwards toward the diaphragm member and is a convex spherical surface with its center on the axis. The first radius, which is the radius of the convex spherical surface, is smaller than the second radius, which is the radius of the spherical surface of the diaphragm member opposite to the convex spherical surface; the first radius is 50-65% of the second radius; and the location of stress concentration in the diaphragm member moves in accordance with the variation in the contact range between the convex spherical surface and the spherical surface due to the contact and separation intervals. It is characterized by the following.

[0018] (4) In the fluid control valve described in any one of (1) to (3), it is preferable that the diameter of the first clamping piece is greater than 35% of the diameter when projected onto a plane perpendicular to the axis of the diaphragm member.

[0019] In the fluid control valve described above, when the valve body attempts to contact the valve seat, the diaphragm member deforms by being pushed downwards toward the valve seat from the apex where it is clamped by the first and second clamping pieces. As this deformation occurs, the diaphragm member deforms along the shape of the convex spherical surface of the first clamping piece, so the contact area between the convex spherical surface and the diaphragm member expands from the center of the diaphragm member toward the outer circumference as the valve body approaches the valve seat. The inventors of this application have confirmed through finite element analysis that the point where stress is concentrated in the diaphragm member is the outermost part of the contact area. In other words, when moving from the valve open state to the valve closed state, the point where stress is concentrated in the diaphragm member moves in accordance with the fluctuation of the contact area and is not constant, so the diaphragm member is less likely to be damaged even if the valve body repeatedly moves between contact and separation. By making the diaphragm member less likely to be damaged in this way, it becomes possible to increase the distance (stroke amount) between the valve body's open state and valve closed state compared to conventional designs. If the stroke length can be increased, the distance between the valve body and the valve seat will increase when the valve is open, thus increasing the Cv value of the fluid control valve. [Effects of the Invention]

[0020] According to the fluid control valve of the present invention, it is possible to increase the stroke amount. [Brief explanation of the drawing]

[0021] [Figure 1] This is a cross-sectional view of a fluid control valve according to this embodiment. [Figure 2] This is a magnified view of part A in Figure 1. [Figure 3] This is a perspective view of the diaphragm component. [Figure 4] This figure shows the deformation of the diaphragm member when the fluid control valve according to this embodiment moves from an open state to a closed state, where (a) represents the open state, (b) represents the moment immediately after the valve body begins to move in the contact direction, and (c) represents the closed state. [Figure 5]The figure is a cross-sectional view of a fluid control valve invented by the inventor of the present application as a countermeasure against the problem that the self-return force of the diaphragm member decreases at high temperatures. [Figure 6] The figure shows how the diaphragm member of the fluid control valve shown in FIG. 5 is deformed when the valve changes from the valve-open state to the valve-closed state. (a) represents the valve-open state, (b) represents immediately after the valve body starts to move in the contact direction, and (c) represents the valve-closed state. [Figure 7] It is a graph showing the relationship between the amount of movement of the valve body from its position in the valve-open state in the contact direction and the stress generated in the diaphragm member. [Figure 8] It is a graph showing the relationship between the stroke amount of the valve body at high temperatures and the Cv value.

Embodiments for Carrying Out the Invention

[0022] An embodiment of the fluid control valve according to the present invention will be described in detail with reference to the drawings. Note that the drawings used in the description are simplified for the purpose of explanation and do not accurately represent the shape, dimensions, etc.

[0023] (Regarding the configuration of the fluid control valve) The configuration of the fluid control valve 1 according to the present embodiment will be described using the drawings. FIG. 1 is a cross-sectional view of the fluid control valve 1 according to the present embodiment. FIG. 2 is a partial enlarged view of part A of FIG. 1. FIG. 3 is a perspective view of the diaphragm member 34.

[0024] The fluid control valve 1 is a pneumatically driven gas valve disposed in the gas supply system of a semiconductor manufacturing apparatus. As shown in FIG. 1, it comprises a drive unit 2 and a valve unit 3. Further, the drive unit 2 comprises an actuator unit 4 and a spring unit 5.

[0025] First, the actuator unit 4 will be described. The actuator unit 4 comprises a pneumatically driven air cylinder 6 and a connection bracket 7 for connecting the air cylinder 6 and the spring unit 5.

[0026] The air cylinder 6 comprises a cylindrical case 61, a piston (not shown) loaded inside the case 61, and a cylindrical drive shaft (not shown) coupled to the piston. The piston is slidable in the vertical direction in Figure 1 within the case 61, and the drive shaft moves back and forth along its axial direction in accordance with the vertical movement of the piston. The axial direction of the drive shaft is parallel to the vertical direction in Figure 1 and coincides with the direction in which the valve body 32, described later, contacts and separates from the valve seat 33. Note that the upper side in the figure is the separation direction, and the lower side is the contact direction.

[0027] The tip of the drive shaft of the air cylinder 6 on the valve section 3 side protrudes from the case 61 and is connected to a cylindrical operating rod 9 that is located coaxially with the drive shaft. Therefore, as the drive shaft of the air cylinder 6 moves forward and backward, the operating rod 9 also moves forward and backward along its axis CL (see Figure 2).

[0028] The operating rod 9 is inserted through the spring portion 5 and extends from inside the connecting bracket 7 to the valve portion 3. As shown in Figure 2, the operating rod 9 has an enlarged diameter portion 91 in the portion inserted into the valve portion 3, which is larger in diameter than the portion inserted through the connecting bracket 7 and the portion inserted inside the spring portion 5, thereby forming a stepped portion 92. Furthermore, the operating rod 9 has a first clamping piece 93 at the end of the enlarged diameter portion 91 opposite to the stepped portion 92. The first clamping piece 93, together with the second clamping piece 323 described later, is used to clamp the diaphragm member 34 described later. The first clamping piece 93 is circular in shape with the radial direction being perpendicular to the axis CL of the operating rod 9, and is located coaxially with the axis CL. The diameter D11 of the first clamping piece 93 is larger than the diameter of the enlarged diameter portion 91. Furthermore, the surface of the first clamping piece 93 facing the diaphragm member 34 is a convex spherical surface 94 that bulges out toward the diaphragm member 34. The center of the convex spherical surface 94 is located on the axis CL of the operating rod 9, and its radius (first radius) is set to, for example, approximately 70 mm. In addition, the outer edge of the convex spherical surface 94 is chamfered with an R-chamfer.

[0029] Furthermore, a female threaded portion 95 is provided on the end face of the operating rod 9 on the valve portion 3 side, allowing the valve body 32, which will be described later, to be screwed into it.

[0030] Next, the spring section 5 will be described. The spring section 5 includes a compression coil spring 52 located coaxially with the operating rod 9 in the internal space 51. The compression coil spring 52 is compressed between the end face 53 on the actuator section 4 side of the internal space 51 and the stepped portion 92 of the operating rod 9. As a result, the compression coil spring 52 constantly biases the operating rod 9 in the contact direction (downward in the figure).

[0031] Next, the valve section 3 will be described. The valve section 3 comprises a body 31, a valve element 32, a valve seat 33, and a diaphragm member 34. The body 31 has a cylindrical portion 315 that connects to the spring section 5. In addition, a valve chamber 311 is formed inside the cylindrical portion 315 of the body 31.

[0032] The valve chamber 311 communicates with the input channel 313 at the center of its bottom via a valve port 312. This input channel 313 is used to input process gas into the valve chamber 311. An annular valve seat 33 is fixed to the bottom surface of the valve chamber 311, on the outer circumference of the valve port 312 and coaxial with the valve port 312. This valve seat 33 is made of, for example, heat-resistant PI (polyimide) or PFA (tetrafluoroethylene perfluoroalkyl vinyl ether copolymer). Furthermore, the valve chamber 311 communicates with the output channel 314 radially outside the valve seat 33. This output channel 314 is used to output process gas from the valve chamber 311.

[0033] The valve body 32 is made of, for example, stainless steel. The valve body 32 has a cylindrical main body 321, and further has a male threaded portion 322 on the operating rod 9 side of the main body 321. The valve body 32 is connected to the operating rod 9 by screwing the male threaded portion 322 into the female threaded portion 95 of the operating rod 9.

[0034] Furthermore, the valve body 32 is provided with a second clamping piece 323 on the side opposite to the male threaded portion 322 of the main body 321. The second clamping piece 323 is circular in shape, with its radial direction being perpendicular to the axis CL of the operating rod 9, and is located coaxially with the axis CL. The diameter D12 of the second clamping piece 323 is smaller than the diameter D11 of the first clamping piece 93. When the valve body 32 is connected to the operating rod 9, the second clamping piece 323, together with the first clamping piece 93, clamps the diaphragm member 34 from the top and bottom directions in Figure 2. The surface of the second clamping piece 323 facing the diaphragm member 34 is flat, and the outer edge of this flat surface is rounded off.

[0035] Furthermore, the valve body 32 is provided with a contact portion 324 on the side opposite to the main body portion 321 of the second clamping piece 323, which contacts and separates from the valve seat 33. This contact portion 324 is also circular in shape and is located coaxially with the axis CL of the operating rod 9. Since the valve body 32 is connected to the operating rod 9, as the operating rod 9 moves forward and backward, the contact portion 324 moves in a manner that contacts and separates from the valve seat 33 along the direction of the axis CL.

[0036] The diaphragm member 34 is made of, for example, a Ni alloy. The diaphragm member 34 is formed in a spherical shape with its center located on the extension of the axis CL and bulging out toward the operating rod 9. Therefore, the opposing surface 341 of the diaphragm member 34 that faces the convex spherical surface 94 is spherical. The radius (second radius) of the sphere of the opposing surface 341 is set to, for example, approximately 140 mm. The back surface of the opposing surface 341 is referred to as the back surface 342. A cut 343 is provided at the apex of the diaphragm member 34 (opposing surface 341). This cut 343 is circular in shape with the radial direction perpendicular to the axis CL and is located coaxially with the axis CL. The outer circumference of the opposing surface 341 is also provided with a planar edge 344 perpendicular to the axis CL. This edge 344 is circular in shape with the radial direction perpendicular to the axis CL.

[0037] The diaphragm member 34 described above is fixed inside the fluid control valve 1 as follows. The male threaded portion 322 of the valve body 32 is inserted through the cut end 343 of the diaphragm member 34 from the opposite side of the opposing surface 341, and the diaphragm member 34 and the valve body 32 are positioned coaxially with the back surface 342 of the diaphragm member 34 in contact with the second clamping piece 323 of the valve body 32. Then, the male threaded portion 322 is screwed into the female threaded portion 95 of the operating rod 9 until the convex spherical surface 94 of the first clamping piece 93 contacts the spherical surface 341 of the diaphragm member 34. As a result, the diaphragm member 34 is clamped from both sides in the direction of the axis CL (up and down direction in the figure) by the first clamping piece 93 and the second clamping piece 323 at the edge of the cut end 343, as shown in Figure 1 or Figure 2. In other words, the operating rod 9 and the diaphragm member 34 are connected. Furthermore, as shown in Figure 1 or Figure 2, the edge 344 of the diaphragm member 34 is clamped and fixed from above and below within the valve portion 3. By being fixed inside the fluid control valve 1 as described above, the diaphragm member 34 divides the inside of the cylindrical portion 315 of the body 31 into the valve chamber 311 and its upper part, and repeatedly undergoes elastic deformation as the valve body 32 moves in the direction of contact and separation.

[0038] (Regarding the operation of fluid control valves) The operation of changing the fluid control valve 1 from the open state to the closed state will now be described. When operating air is supplied to the air cylinder 6, the fluid control valve 1 enters the open state, as shown in Figure 1. As described above, the operating rod 9 is always biased in the direction of contact with the compression coil spring 52, so the open state is the state in which the actuator unit 4 pulls the operating rod 9 upward in the figure against the biasing force of the compression coil spring 52. To change the valve from this state to the closed state, the supply of operating air to the air cylinder 6 is stopped. Then, due to the biasing force of the compression coil spring 52, the operating rod 9 and the valve body 32 are pushed down toward the valve seat 33, and the contact portion 324 of the valve body 32 comes into contact with the valve seat 33.

[0039] Next, the deformation that occurs in the diaphragm member 34 when changing from the valve open state to the valve closed state as described above will be explained using Figure 4. Figure 4 is a diagram showing the deformation of the diaphragm member 34 when the fluid control valve 1 according to this embodiment changes from the valve open state to the valve closed state, where (a) represents the valve open state, (b) represents the moment immediately after the valve body 32 begins to move in the contact direction, and (c) represents the valve closed state.

[0040] When the fluid control valve 1 is in the open position, the diaphragm member 34 is in a state close to its natural, undeformed state (Figure 4(a)). Then, when the operating rod 9 is driven in the contact direction and the valve body 32 approaches the valve seat 33, the diaphragm member 34 deforms as it is pushed downwards from the central part, which is held between the first clamping piece 93 and the second clamping piece 323, toward the valve seat 33 (see Figure 2) (Figure 4(b)). The diaphragm member 34 is in the most deformed state when the valve body 32 comes into contact with the valve seat 33, that is, when the fluid control valve 1 is in the closed position (Figure 4(c)). As this deformation occurs, the diaphragm member 34 deforms along the shape of the convex spherical surface 94, so that the contact area A11 between the convex spherical surface 94 of the first clamping piece 93 and the opposing surface 341 of the diaphragm member 34 expands from the center to the outer circumference as the valve body 32 approaches the valve seat 33 (Figures 4(b), (c)).

[0041] The inventors of this application have confirmed through finite element analysis that the point where stress concentrates when the diaphragm member 34 deforms is the outermost part P11 of the contact range A11. In other words, when moving from the valve open state to the valve closed state, the point where stress concentrates in the diaphragm member 34 moves in accordance with the fluctuation of the contact range A11 and is not constant. Therefore, even if the valve body 32 repeatedly moves between contact and separation, the diaphragm member 34 is less likely to be damaged. By making the diaphragm member 34 less likely to be damaged in this way, it becomes possible to increase the distance (stroke amount) between the valve body 32 in the valve open state and the valve closed state compared to conventional designs. If the stroke amount can be increased, the distance between the valve body 32 and the valve seat 33 will be larger in the valve open state, and the Cv value of the fluid control valve 1 will be larger.

[0042] Here, as shown in Figures 4(b) and 4(c), in order to deform the diaphragm member 34 along the shape of the convex spherical surface 94, it is desirable that the radius of the convex spherical surface 94 be 50-65% of the radius of the spherical surface 341. In this embodiment, the radius of the convex spherical surface 94 (first radius) is approximately 70 mm, while the radius of the opposing surface 341 of the diaphragm member 34 (second radius) is approximately 140 mm.

[0043] Furthermore, by making the diameter D11 of the first clamping piece 93 as large as possible, a larger stroke amount can be secured. Specifically, it is desirable that the diameter D11 of the first clamping piece 93 (see Figure 2) is greater than 35% of the diameter D21 of the diaphragm member 34 (see Figure 3). Note that the diameter D21 of the diaphragm member 34 is the diameter when the diaphragm member 34 is projected onto a plane perpendicular to the axis CL of the operating rod 9, that is, in this embodiment, the diameter of the edge portion 344.

[0044] Specifically, this will be explained using Figures 7 and 8. Figure 7 is a graph showing the relationship between the amount of movement (stroke) of the valve body 32 in the contact direction from the valve open position (hereinafter referred to as the valve open position) and the stress generated in the diaphragm member. It compares the cases where the diameter D11 of the first clamping piece 93 is 35% of the diameter D21 of the diaphragm member 34, 65% of the diameter D21, and 85% of the diameter D21. The waveform shown by the dashed line in Figure 7 is the waveform when the diameter D11 is 35% of the diameter D21. Note that setting the diameter D11 to 35% of the diameter D21 is the same as the relationship between the diameter of the clamping portion 111 and the diameter of the diaphragm member 34 in the fluid control valve 100 shown in Figure 5. The waveform shown by the solid line in Figure 7 is the waveform when the diameter D11 is 65% of the diameter D21. The dashed waveform in Figure 7 represents the waveform when the diameter D11 is 85% of the diameter D21. The rising parts of each waveform indicate stress concentration that is strong enough to cause fracture in the diaphragm member 34. Figure 8 is a graph showing the relationship between the stroke amount and the Cv value of the valve body 32 at high temperatures. It shows that the Cv value increases as the stroke amount increases.

[0045] When the diameter D11 of the first clamping piece 93 is set to 35% of the diameter D21 of the diaphragm member 34, a rise in the waveform can be seen when the amount of movement of the valve body 32 reaches S1 (see Figure 7). In other words, when the amount of movement of the valve body 32 reaches S1, stress concentration occurs to the extent that it causes the diaphragm member 34 to break. Therefore, a maximum stroke amount of S1 can be secured. When a stroke amount of S1 is secured, the Cv value of the fluid control valve 1 (fluid control valve 100) is C1 (see Figure 8).

[0046] For example, if the diameter D11 of the first clamping piece 93 is set to approximately 65% ​​of the diameter D21 of the diaphragm member 34, a rise in the waveform can be seen when the amount of movement of the valve body 32 reaches S2 (see Figure 7). In other words, when the amount of movement of the valve body 32 reaches S2, stress concentration occurs to the extent that it causes the diaphragm member 34 to break. Therefore, a maximum stroke amount of S2 can be secured. This stroke amount is approximately 1.8 times the stroke amount when the diameter D11 is 35% of the diameter D21. The Cv value of the fluid control valve 1 when the stroke amount is S2 is C2 (see Figure 8). This is approximately 1.5 times the Cv value when the diameter D11 is 35% of the diameter D21.

[0047] For example, if the diameter D11 of the first clamping piece 93 is set to approximately 85% of the diameter D21 of the diaphragm member 34, the waveform rises when the amount of movement of the valve body 32 reaches S3 (see Figure 7). In other words, when the amount of movement of the valve body 32 reaches S3, stress sufficient to cause fracture occurs in the diaphragm member 34. Therefore, a maximum stroke of S3 can be secured. This stroke is approximately 2.5 times the stroke when the diameter D11 is 35% of the diameter D21. The Cv value of the fluid control valve 1 when the stroke is S3 is C3 (see Figure 8). This is approximately 1.65 times the Cv value when the diameter D11 is 35% of the diameter D21.

[0048] As described above, if the diameter D11 of the first clamping piece 93 is greater than 35% of the diameter D21 of the diaphragm member 34, it is possible to delay the rise of the waveform compared to when the diameter D11 is 35% of the diameter D21, as shown in Figure 7. In other words, it is possible to move the valve body 32 more, that is, to increase the stroke amount. It is desirable that the diameter D11 of the first clamping piece 93 be as large as the structure of the fluid control valve 1 allows, but in reality, it will be smaller than the diameter D21 of the diaphragm member 34.

[0049] As described above, the fluid control valve 1 according to this embodiment comprises (1) an operating rod 9, a valve body 32 connected to the operating rod 9, a valve seat 33 on which the valve body 32 comes into contact and separates, and a diaphragm member 34 located between the operating rod 9 and the valve body 32, and controls the controlled fluid by the valve body 32, which is driven by the operating rod 9 coming into contact and separating along the direction of the axis CL of the operating rod 9, wherein the diaphragm member 34 is formed in a spherical crown shape with its center located on the extension of the axis CL and bulging out toward the side of the operating rod 9, and at its apex (cut surface 343) toward the side of the operating rod 9 The valve body is characterized by being clamped from both sides in a direction parallel to the axis CL by a first clamping piece 93 that contacts the diaphragm member 34 from the side of the valve body 32 and a second clamping piece 323 that contacts the diaphragm member 34 from the side of the valve body 32; the first clamping piece 93 and the second clamping piece 323 are formed in a circular shape and are coaxial with the operating rod 9, the diameter D11 of the first clamping piece 93 is larger than the diameter D of the second clamping piece 323; and the surface of the first clamping piece 93 facing the diaphragm member 34 is formed to bulge out toward the diaphragm member 34 and is a convex spherical surface 94 having its center on the axis CL of the operating rod 9.

[0050] (2) In the fluid control valve 1 described in (1), it is preferable that the first radius, which is the radius of the convex spherical surface 94, is smaller than the second radius, which is the radius of the spherical surface (opposing surface 341) of the diaphragm member 34 that faces the convex spherical surface 94.

[0051] (3) In the fluid control valve 1 described in (2), it is preferable that the first radius is 50 to 65% of the second radius.

[0052] (4) In the fluid control valve 1 described in any one of (1) to (3), it is preferable that the diameter D11 of the first clamping piece 93 is greater than 35% of the diameter D21 when projected onto a plane perpendicular to the axis CL of the diaphragm member 34.

[0053] According to the fluid control valve 1 described above, when the valve body 32 attempts to contact the valve seat 33, the diaphragm member 34 deforms by being pushed downwards toward the valve seat 33 from the apex where it is clamped by the first clamping piece 93 and the second clamping piece 323. As this deformation occurs, the diaphragm member 34 deforms along the shape of the convex spherical surface 94 of the first clamping piece 93, so the contact area A11 between the convex spherical surface 94 and the diaphragm member 34 expands from the center of the diaphragm member 34 toward the outer circumference as the valve body 32 approaches the valve seat 33. The inventors of this application have confirmed by finite element analysis that the area where stress is concentrated in the diaphragm member 34 is the outermost part P11 of the contact area A11. In other words, when moving from the valve open state to the valve closed state, the point of stress concentration in the diaphragm member 34 moves in accordance with the fluctuation of the contact range A11 and is not constant. Therefore, even if the valve body 32 repeatedly moves between contact and separation, the diaphragm member 34 is less likely to be damaged. By making the diaphragm member 34 less likely to be damaged in this way, it becomes possible to increase the distance (stroke amount) between the valve body 32's open state and its closed state compared to conventional designs. If the stroke amount can be increased, the distance between the valve body 32 and the valve seat 33 becomes larger in the valve open state, and the Cv value of the fluid control valve 1 becomes larger.

[0054] The above embodiments are merely illustrative and do not limit the present invention in any way. Therefore, the present invention can naturally be improved and modified in various ways without departing from its essence. For example, the drive unit 2 of the fluid control valve 1 according to this embodiment uses a pneumatically driven air cylinder 6 as a drive source, but other drive sources such as an electric linear motor may be used. Also, in this embodiment, the first clamping piece 93 and the operating rod 9 are formed integrally as the same component, but the first clamping piece and the operating rod 9 may be made of separate components. Similarly, the second clamping piece 323 and the valve body 32 are formed integrally as the same component, but the second clamping piece 323 and the valve body 32 may be made of separate components. [Explanation of Symbols]

[0055] 1. Fluid control valve 9 Operating rod 32 valve body 33 valve seats 34 Diaphragm component 93 1st clamping piece 94 Convex spherical surface 323 Second clamping piece

Claims

1. A fluid control valve comprising an operating rod, a valve body connected to the operating rod, a valve seat on which the valve body abuts and separates, and a diaphragm member located between the operating rod and the valve body, wherein the valve body, driven by the operating rod, abuts and separates along the direction of the axis of the operating rod to control a controlled fluid, The diaphragm member is formed in a spherical shape with its center located on the extension of the axis and bulging out toward the operating rod, and at its apex, it is clamped from both sides in a direction parallel to the axis by a first clamping piece that contacts the diaphragm member from the operating rod side and a second clamping piece that contacts the diaphragm member from the valve body side. The first clamping piece and the second clamping piece are formed in a circular shape and are located coaxially with the operating rod, and the diameter of the first clamping piece is larger than the diameter of the second clamping piece. The surface of the first clamping piece facing the diaphragm member is formed to bulge outwards toward the diaphragm member and is a convex spherical surface having its center on the axis. The first radius, which is the radius of the convex spherical surface, is smaller than the second radius, which is the radius of the spherical surface of the diaphragm member opposite to the convex spherical surface. The first radius is 50-65% of the second radius. In accordance with the fluctuation in the contact range between the convex spherical surface and the spherical surface due to the aforementioned contact and separation interval, the location of stress concentration in the diaphragm member moves. A fluid control valve characterized by the following.

2. In the fluid control valve according to claim 1, The diameter of the first clamping piece is greater than 35% of the diameter when projected onto a plane perpendicular to the axis of the diaphragm member. A fluid control valve characterized by the following.

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