Fluid control valve

Abstract

A diaphragm member 34 is formed in a spherical crown shape the center of which is positioned on an extension line of an axial center CL of an operation rod 9 and that bulges out to the side of the operation rod 9. At the apex, the diaphragm member 34 is held, from both sides thereof in a direction parallel to the axial center CL, by a first holding piece 93 that is in contact with the diaphragm member 34 from the side of the operation rod 9 and a second holding piece 323 that is in contact with the diaphragm member 34 from the side of a valve body 32. The first holding piece 93 and the second holding piece 323 are formed in circular shapes positioned coaxially with the operation rod 9, and the diameter D11 of the first holding piece 93 is larger than the diameter D of the second holding piece 323. A surface of the first holding piece 93 facing the diaphragm member 34 is a convex spherical surface 94 that is formed so as to bulge out to the side of the diaphragm member 34 and that has the center thereof on the axial center CL of the operation rod 9.

Description

Fluid Control Valve

[0001] The present invention relates to a fluid control valve comprising an operating rod, a valve body connected to the operating rod, a valve seat against which the valve body comes into contact and separates, and a diaphragm located between the operating rod and the valve body, in which the valve body, driven by the operating rod, comes into contact and separates along the axis of the operating rod, thereby controlling a control fluid.

[0002] In semiconductor manufacturing processes, multiple types of process gases are used in film formation processes. Fluid control valves are used to control the flow rates of these process gases. Examples of fluid control valves include those disclosed in Patent Documents 1 and 2. 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 moving a diaphragm member toward and away from a valve seat.

[0003] More specifically, a stem (diaphragm retainer) abuts against the apex of a diaphragm member formed in a spherical crown shape, and the operation of the actuator causes the stem to press and deform the diaphragm member, causing it to abut against the valve seat. The state in which the diaphragm member abuts against the valve seat is the closed state of the fluid control valve. When the pressure on the diaphragm member by the stem is released, the self-restoring force of the diaphragm member causes it to return to its original spherical crown shape, and the diaphragm member moves away from the valve seat. The state in which the diaphragm member moves away from the valve seat is the open state of the fluid control valve.

[0004] JP 2016-180490 A JP 2017-223318 A

[0005] However, because the process gas used in atomic layer deposition (ALD), a film formation technology that has become widespread in recent years, is heated to a high temperature (approximately 200°C), the self-returning force of the diaphragm member is reduced at such high temperatures, and there is a risk that the diaphragm member may not be able to fully return to its original spherical crown shape when the fluid control valve is switched from a closed state to an open state. If the diaphragm member is unable to fully return to its original spherical crown shape, the distance between the diaphragm member and the valve seat in the open state becomes smaller, raising concerns about a decrease in the Cv value. While increasing the Cv value of fluid control valves (i.e., increasing the amount of gas that can be flowed at one time) is desirable in order to shorten the semiconductor film formation process as much as possible and improve productivity, a decrease in the Cv value due to a decrease in the self-returning force of the diaphragm member as described above is undesirable.

[0006] Therefore, the inventors of the present invention have conceived of using a fluid control valve 100 as shown in FIG. 5, for example, 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 unit 4, which includes a pneumatically driven air cylinder 6. A piston (not shown) is mounted inside the air cylinder 6 so as to be slidable in the vertical direction in FIG. 5 . The up and down movement of the piston causes the operating rod 11 to move up and down. Furthermore, a valve element 32 is connected to the tip of the operating rod 11, and the valve element 32 moves toward and away from a valve seat 33 as the operating rod 11 moves up and down. The diaphragm member 34 is formed in a disk shape, and its outer periphery is clamped and fixed within the fluid control valve 100, while its center is clamped from the vertical direction in FIG. 5 between the clamping portion 111 of the operating rod 11 and the valve element 32.

[0008] In the fluid control valve 100 described above, when the valve element 32 moves toward and away from the valve seat 33, deformation occurs in the diaphragm member 34 as shown in Figures 6A to 6C. Figure 6A is a diagram showing the state of the diaphragm member 34 when the fluid control valve 100 shown in Figure 5 is in the valve open state. Figure 6B is a diagram showing the state of deformation of the diaphragm member 34 immediately after the valve element 32 of the fluid control valve 100 shown in Figure 5 starts to move in the abutting direction. Figure 6C is a diagram showing the state of deformation of the diaphragm member 34 when the fluid control valve 100 shown in Figure 5 is in the valve closed state.

[0009] When the fluid control valve 100 is in the open state, the diaphragm member 34 is in a state close to its natural, undeformed state ( FIG. 6A ). When the operating rod 11 is driven in the abutment direction to bring the valve element 32 into abutment against the valve seat 33, the diaphragm member 34 is deformed by being pushed downward from the center portion sandwiched between the operating rod 11 (sandwiching portion 111) and the valve element 32 toward the valve seat 33 (see FIG. 5 ) ( FIG. 6B ). When the valve element 32 abuts against the valve seat 33, i.e., when the fluid control valve 100 is in the closed state, the diaphragm member 34 is in its most deformed state ( FIG. 6C ).

[0010] To change the valve state from a closed state to an open state, the operating rod 11 is driven upward in the figure. This causes the operating rod 11 and the valve element 32 to move in the same direction, so that the valve element 32 moves away from the valve seat 33, and the fluid control valve 100 enters the open state. At this time, the diaphragm member 34 is sandwiched between the operating rod 11 (sandwiching portion 111) and the valve element 32, and therefore the central portion is pulled up in the direction away from the valve seat 33, ensuring that the diaphragm member 34 can be reliably restored to its original shape as shown in FIG. 6A . Therefore, even in a high-temperature environment, such as when a high-temperature process gas is used as the control fluid, the diaphragm member 34 can be prevented from failing to return to its original shape.

[0011] However, the above-described fluid control valve 100 has the following problem. The inventors of the present application discovered that, when the diaphragm member 34 is deformed, as shown in Figures 6A-6C, stress is concentrated at the clamped portion P21 of the diaphragm member 34. If the portion where stress is concentrated on the diaphragm member 34 is always the same in this way, when the valve body 32 of the fluid control valve 100 repeatedly comes into and out of contact with the valve seat 33, there is a risk that the diaphragm member 34 will be damaged at the portion P21 where the stress is concentrated.

[0012] Furthermore, in recent years, there has been a demand for a higher Cv value for fluid control valves, and therefore a desire to increase the distance (stroke amount) between the valve open position and the valve closed position of the valve disc compared to conventional valves. However, increasing the stroke amount increases the amount of deformation of the diaphragm valve disc. As the deformation amount increases, stress concentration at the portion P21 described above increases the likelihood of damage to the diaphragm member 34. In other words, the stress concentration occurring in the diaphragm member 34 is a factor that prevents an increase in the stroke amount from being achieved.

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

[0014] In order to solve the above problems, a fluid control valve according to one aspect of the present invention has the following configuration.

[0015] (1) A fluid control valve comprising an operating rod, a valve element connected to the operating rod, a valve seat against which the valve element contacts and separates, and a diaphragm member located between the operating rod and the valve element, wherein the valve element is driven by the operating rod and contacts and separates along the direction of the axis of the operating rod, thereby controlling a control fluid. The diaphragm member has a center located on an extension of the axis and is formed in a spherical crown shape that bulges out toward the operating rod, and its apex is such that the diaphragm can be seen from the operating rod side. The valve is characterized in that it is clamped from both sides in a direction parallel to the axis by a first clamping piece that contacts the ram member 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 that is positioned coaxially with the operating rod, the diameter of the first clamping piece is larger than the diameter of the second clamping piece; and the surface of the first clamping piece that faces the diaphragm member is formed to bulge toward the diaphragm member and is a convex spherical surface with its center on the axis.

[0016] (2) In the fluid control valve described in (1), it is preferable that a first radius, which is the radius of the convex spherical surface, is smaller than a second radius, which is the radius of the spherical surface of the diaphragm member that faces the convex spherical surface.

[0017] (3) In the fluid control valve described in (2), it is preferable that the first radius is 50% or more and 65% or less of the second radius.

[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] According to the above-described fluid control valve, when the valve disc attempts to contact the valve seat, the diaphragm member deforms by being pushed downward toward the valve seat from the apex portion sandwiched between the first and second clamping pieces. During this deformation, the diaphragm member conforms to 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 periphery as the valve disc approaches the valve seat. The inventors of the present application have confirmed through finite element analysis that the area where stress concentrates on the diaphragm member is the outermost periphery of the contact area. In other words, when switching from an open state to a closed state, the area where stress concentrates on the diaphragm member moves in accordance with the change in the contact area and is not constant. This makes the diaphragm member less susceptible to damage, even when the valve disc is repeatedly engaged and disengaged. By making the diaphragm member less susceptible to damage, the distance (stroke) between the open and closed states of the valve disc can be increased compared to conventional valves. If the stroke amount can be increased, the distance between the valve body and the valve seat increases when the valve is open, and the Cv value of the fluid control valve increases.

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

[0021] 5 is a cross-sectional view of the fluid control valve according to the present embodiment; FIG. 6 is a partially enlarged view of portion A in FIG. 1; FIG. 7 is a perspective view of the diaphragm member; FIG. 8 is a view showing the state of the diaphragm member when the fluid control valve according to the present embodiment is in a valve open state; FIG. 9 is a view showing the state of deformation of the diaphragm member immediately after the valve element of the fluid control valve according to the present embodiment starts to move in the abutting direction; FIG. 10 is a view showing the state of deformation of the diaphragm member when the fluid control valve according to the present embodiment is in a valve closed state; FIG. 11 is a cross-sectional view of a fluid control valve invented by the inventor of the present application as a solution to the problem of a decrease in the self-returning force of the diaphragm member at high temperatures; FIG. 12 is a view showing the state of the diaphragm member when the fluid control valve shown in FIG. 1 is in a valve open state; FIG. 13 is a view showing the state of deformation of the diaphragm member immediately after the valve element of the fluid control valve shown in FIG. 1 starts to move in the abutting direction; FIG. 14 is a view showing the state of deformation of the diaphragm member when the fluid control valve shown in FIG. 1 is in a valve closed state; FIG. 15 is a graph showing the relationship between the amount of movement of the valve element in the abutting direction from a position in the valve open state and the stress generated in the diaphragm member; FIG. 16 is a graph showing the relationship between the stroke amount of the valve element at high temperatures and the Cv value.

[0022] An embodiment of a 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] (Configuration of the Fluid Control Valve) The configuration of the fluid control valve 1 according to this embodiment will be described with reference to the drawings. Fig. 1 is a cross-sectional view of the fluid control valve 1 according to this embodiment. Fig. 2 is a partially enlarged view of portion A in 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 a gas supply system of a semiconductor manufacturing device, and as shown in Figure 1, it comprises a drive unit 2 and a valve unit 3. The drive unit 2 further comprises an actuator unit 4 and a spring unit 5.

[0025] First, a description will be given of the actuator unit 4. The actuator unit 4 includes a pneumatically driven air cylinder 6 and a connecting bracket 7 for connecting the air cylinder 6 and the spring unit 5.

[0026] The air cylinder 6 includes a cylindrical case 61, a piston (not shown) installed inside the case 61, and a columnar drive shaft (not shown) connected to the piston. The piston is slidable in the vertical direction in FIG. 1 within the case 61, and the drive shaft advances and retreats along its axial direction as the piston moves up and down. The axial direction of the drive shaft is parallel to the vertical direction in FIG. 1 and coincides with the direction in which a valve element 32 (described later) moves toward and away from a valve seat 33. The upper side in the figure indicates the moving away direction, and the lower side indicates the moving toward and away from the valve seat 33.

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

[0028] The operating rod 9 is inserted through the spring portion 5 and extends from inside the connection bracket 7 to the valve portion 3. As shown in FIG. 2 , the operating rod 9 has an enlarged-diameter portion 91 at the portion inserted into the valve portion 3. The enlarged-diameter portion 91 has a larger diameter than the portions inserted into the connection bracket 7 and the spring portion 5, thereby forming a stepped portion 92. Furthermore, the operating rod 9 has a first clamping piece 93 at the end opposite the stepped portion 92 of the enlarged-diameter portion 91. The first clamping piece 93, together with a second clamping piece 323 (described later), is used to clamp a diaphragm member 34 (described later). The first clamping piece 93 has a circular shape whose radial direction is perpendicular to the axis CL of the operating rod 9 and is positioned 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. The surface of the first clamping piece 93 facing the diaphragm member 34 is a convex spherical surface 94 formed to bulge 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 the radius (first radius) is set to, for example, approximately 70 mm. The outer periphery of the convex spherical surface 94 is rounded and chamfered.

[0029] A female screw portion 95 is drilled on the end surface of the operating rod 9 on the valve portion 3 side, and a valve body 32 (described later) can be screwed onto the female screw portion 95.

[0030] Next, the spring unit 5 will be described. The spring unit 5 includes a compression coil spring 52 located coaxially with the operating rod 9 in an internal space 51. The compression coil spring 52 is compressed by an end surface 53 of the internal space 51 on the actuator unit 4 side and a step portion 92 of the operating rod 9. Therefore, the compression coil spring 52 always biases the operating rod 9 in the abutment direction (downward in the figure).

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

[0032] The valve chamber 311 communicates with an input flow path 313 at the center of its bottom via a valve port 312. This input flow path 313 is used to input process gas into the valve chamber 311. A circular valve seat 33 is fixed to the bottom of the valve chamber 311, on the outer circumferential side of the valve port 312 and coaxially with the valve port 312. The valve seat 33 is made of, for example, a heat-resistant material such as PI (polyimide) or PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer). The valve chamber 311 communicates with an output flow path 314 radially outward of the valve seat 33. The output flow path 314 is used to output the process gas from the valve chamber 311.

[0033] The valve element 32 is made of, for example, stainless steel. The valve element 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 element 32 is connected to the operating rod 9 by threading the male threaded portion 322 into the female threaded portion 95 of the operating rod 9.

[0034] The valve element 32 also includes a second clamping piece 323 on the side of the main body 321 opposite the side of the male thread portion 322. The second clamping piece 323 has a circular shape with a radial direction perpendicular to the axis CL of the operating rod 9 and is positioned coaxially with the axis CL. A diameter D12 of the second clamping piece 323 is smaller than a diameter D11 of the first clamping piece 93. When the valve element 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 above and below in FIG. 2 . The surface of the second clamping piece 323 facing the diaphragm member 34 is flat, and the outer periphery of the flat surface is rounded and chamfered.

[0035] The valve body 32 also has a contact portion 324 that contacts and moves away from the valve seat 33 on the side opposite the main body portion 321 of the second clamping piece 323. This contact portion 324 also has a circular shape that is located coaxially with the axis CL of the operating rod 9. Because the valve body 32 is connected to the operating rod 9, the contact portion 324 contacts and moves away from the valve seat 33 along the direction of the axis CL as the operating rod 9 moves back and forth.

[0036] The diaphragm member 34 is made of, for example, a Ni alloy. The center of the diaphragm member 34 is located on an extension of the axis CL and is formed in a spherical crown shape that bulges toward the operating rod 9. Therefore, an opposing surface 341 that faces the convex spherical surface 94 of the diaphragm member 34 is spherical. The radius (second radius) of the sphere of the opposing surface 341 is set to, for example, approximately 140 mm. The surface behind the opposing surface 341 is referred to as a back surface 342. A cut 343 is provided at the apex of the diaphragm member 34 (opposing surface 341). This cut 343 has a circular shape with its radial direction perpendicular to the axis CL and is positioned coaxially with the axis CL. The outer periphery of the opposing surface 341 has a flat edge 344 that is perpendicular to the axis CL. This edge 344 has a circular shape with its 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 into the cutout 343 of the diaphragm member 34 from the side opposite 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. The male threaded portion 322 is then threaded onto 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 (the up-down direction in the figure) by the first clamping piece 93 and the second clamping piece 323 at the edge of the cutout 343, as shown in FIG. 1 or 2 . In other words, the operating rod 9 and the diaphragm member 34 are coupled together. 1 or 2, the edge portion 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 an upper portion thereof, and is adapted to repeatedly undergo elastic deformation as the valve element 32 moves in the contact and separation directions.

[0038] (Operation of the Fluid Control Valve) The operation of changing the fluid control valve 1 from the valve open state to the valve closed state will be described. When operating air is supplied to the air cylinder 6, the fluid control valve 1 is in the valve open state, as shown in FIG. 1 . As described above, the operating rod 9 is always biased in the abutting direction by the compression coil spring 52. Therefore, the valve open state is a 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 from this state to the valve closed state, the supply of operating air to the air cylinder 6 is stopped. Then, the biasing force of the compression coil spring 52 presses the operating rod 9 and the valve element 32 down toward the valve seat 33, and the abutment portion 324 of the valve element 32 abuts against the valve seat 33.

[0039] Next, the deformation that occurs in the diaphragm member 34 when the valve is changed from the open state to the closed state as described above will be described with reference to Figures 4A to 4C. Figure 4A is a diagram showing the state of the diaphragm member 34 when the fluid control valve 1 according to this embodiment is in the open state. Figure 4B is a diagram showing the state of deformation of the diaphragm member 34 immediately after the valve element 32 of the fluid control valve 1 according to this embodiment starts to move in the abutting direction. Figure 4C is a diagram showing the state of deformation of the diaphragm member 34 when the fluid control valve 1 according to this embodiment is in the closed state.

[0040] When the fluid control valve 1 is in the open state, the diaphragm member 34 is in a state close to its natural, undeformed state (FIG. 4A). When the operating rod 9 is driven in the abutment direction and the valve element 32 attempts to abut against the valve seat 33, the diaphragm member 34 is deformed by being pushed downward from the center portion sandwiched between the first sandwiching piece 93 and the second sandwiching piece 323 toward the valve seat 33 (see FIG. 2) (FIG. 4B). When the valve element 32 abuts against the valve seat 33, i.e., when the fluid control valve 1 is in the closed state, the diaphragm member 34 is in its most deformed state (FIG. 4C). During this deformation, 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 toward the outer periphery as the valve body 32 approaches the valve seat 33 (Figures 4B and 4C).

[0041] The inventors of the present application confirmed through finite element analysis that, as described above, when the diaphragm member 34 deforms, the location where stress concentrates is the outermost peripheral portion P11 of the contact area A11. In other words, when switching from the valve open state to the valve closed state, the location where stress concentrates on the diaphragm member 34 moves in accordance with the fluctuations in the contact area A11 and is not constant. Therefore, the diaphragm member 34 is less likely to be damaged even when the valve element 32 repeatedly moves between contact and separation. By making the diaphragm member 34 less likely to be damaged in this way, it is possible to increase the distance (stroke amount) between the valve open state and the valve closed state of the valve element 32 compared to conventional devices. Increasing the stroke amount increases the distance between the valve element 32 and the valve seat 33 in the valve open state, thereby increasing the Cv value of the fluid control valve 1.

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

[0043] Furthermore, a larger stroke amount can be ensured by making the diameter D11 of the first clamping piece 93 as large as possible. Specifically, it is desirable that the diameter D11 (see FIG. 2) of the first clamping piece 93 be a value exceeding 35% of the diameter D21 (see FIG. 3) of the diaphragm member 34. 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, i.e., the diameter of the edge portion 344 in this embodiment.

[0044] This will be described in detail with reference to Figures 7 and 8. Figure 7 is a graph showing the relationship between the stroke of the valve element 32 in the abutment direction from its position in the valve open state (hereinafter referred to as the valve open position) and the stress generated in the diaphragm member, comparing the cases where the diameter D11 of the first clamping piece 93 is 35%, 65%, and 85% of the diameter D21 of the diaphragm member 34. The waveform indicated by the dashed dotted 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 indicated 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 is the waveform when the diameter D11 is 85% of the diameter D21. The rising portions of each waveform indicate the occurrence of stress concentration to the extent that it may cause damage to the diaphragm member 34. Figure 8 is a graph showing the relationship between the stroke amount and the Cv value when the valve element 32 is at a high temperature. 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 movement amount of the valve element 32 reaches S1 (see FIG. 7). In other words, when the movement amount of the valve element 32 reaches S1, a stress concentration occurs that is strong enough to cause the diaphragm member 34 to break. Therefore, a stroke amount of S1 can be ensured at most. When the stroke amount S1 is ensured, the Cv value of the fluid control valve 1 (fluid control valve 100) is C1 (see FIG. 8).

[0046] For example, when the diameter D11 of the first clamping piece 93 is approximately 65% ​​of the diameter D21 of the diaphragm member 34, a rising edge of the waveform is observed when the valve element 32 reaches the travel distance S2 (see FIG. 7). In other words, when the valve element 32 reaches the travel distance S2, a stress concentration occurs strong enough to cause the diaphragm member 34 to break. Therefore, a maximum stroke amount of S2 can be ensured. 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 FIG. 8). This is approximately 1.5 times the Cv value when the diameter D11 is 35% of the diameter D21.

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

[0048] As described above, if the diameter D11 of the first clamping piece 93 is a value that exceeds 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 element 32 more greatly, that is, it is possible to increase the stroke amount. Note that it is desirable that the diameter D11 of the first clamping piece 93 be as large as possible within the structure of the fluid control valve 1, 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 includes (1) an operating rod 9, a valve element 32 connected to the operating rod 9, a valve seat 33 against which the valve element 32 comes into contact and separates, and a diaphragm member 34 located between the operating rod 9 and the valve element 32, and the valve element 32 is driven by the operating rod 9 to come into contact with and separate from the valve seat 33 along the direction of the axis CL of the operating rod 9, thereby controlling the control fluid. In this fluid control valve 1, the center of the diaphragm member 34 is located on an extension of the axis CL, and the diaphragm member 34 is formed in a spherical crown shape that bulges out toward the operating rod 9, and its apex (cutout 343) is in contact with the side of the operating rod 9. the first clamping piece 93 and the second clamping piece 323 are formed in a circular shape positioned coaxially 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 so as to bulge 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) facing the convex spherical surface 94 of the diaphragm member 34.

[0051] (3) In the fluid control valve 1 described in (2), it is preferable that the first radius is 50% or more and 65% or less 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 above-described fluid control valve 1, when the valve element 32 is brought into contact with the valve seat 33, the diaphragm member 34 is deformed by being pressed downward from the apex portion thereof sandwiched between the first sandwiching piece 93 and the second sandwiching piece 323 toward the valve seat 33. During this deformation, the diaphragm member 34 deforms along the shape of the convex spherical surface 94 of the first sandwiching piece 93, so that 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 periphery as the valve element 32 approaches the valve seat 33. The inventors of the present application have confirmed through finite element analysis that the location where stress concentrates on the diaphragm member 34 is the outermost periphery P11 of the contact area A11. In other words, when switching from the valve open state to the valve closed state, the point on the diaphragm member 34 where stress is concentrated moves in accordance with fluctuations in the contact range A11 and is not constant, so the diaphragm member 34 is less likely to be damaged even when the valve element 32 repeatedly moves between contact and separation. By making the diaphragm member 34 less likely to be damaged in this way, it is possible to increase the distance (stroke amount) between the position of the valve element 32 in the valve open state and the position of the valve closed state compared to conventional cases. If the stroke amount can be increased, the distance between the valve element 32 and the valve seat 33 becomes larger in the valve open state, and the Cv value of the fluid control valve 1 increases.

[0054] The above-described embodiment is merely illustrative and does not limit the present invention in any way. Therefore, various improvements and modifications are possible within the spirit and scope of the present invention. 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. However, other drive sources, such as an electric direct-acting motor, may also be used. Furthermore, in this embodiment, the first clamping piece 93 and the operating rod 9 are integrally formed as the same member. However, the first clamping piece 323 and the operating rod 9 may be separate members. Similarly, the second clamping piece 323 and the valve body 32 are integrally formed as the same member. However, the second clamping piece 323 and the valve body 32 may be separate members.

[0055] REFERENCE SIGNS LIST 1 fluid control valve 9 operating rod 32 valve body 33 valve seat 34 diaphragm member 93 first 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 against which the valve body comes into contact and separates, and a diaphragm member located between the operating rod and the valve body, wherein the valve body, driven by the operating rod, comes into contact and separates along the direction of the axis of the operating rod, thereby controlling a controlled fluid; the diaphragm member has a center located on an extension of the axis, and is formed in a spherical crown shape that bulges toward the operating rod, and is clamped at its apex from both sides in a direction parallel to the axis by a first clamping piece that comes into contact with the diaphragm member from the operating rod side, and a second clamping piece that comes into contact with the diaphragm member from the valve body side; the first clamping piece and the second clamping piece are formed in a circular shape that is located coaxially with the operating rod, and the diameter of the first clamping piece is greater than the diameter of the second clamping piece; a surface of the first clamping piece facing the diaphragm member is formed to bulge toward the diaphragm member and is a convex spherical surface having a center on the axis.

2. A fluid control valve as claimed in claim 1, characterized in that a first radius, which is the radius of the convex spherical surface, is smaller than a second radius, which is the radius of the spherical surface facing the convex spherical surface of the diaphragm member.

3. A fluid control valve according to claim 2, wherein the first radius is 50% or more and 65% or less of the second radius.

4. A fluid control valve as claimed in any one of claims 1 to 3, characterized in that the diameter of the first clamping piece is greater than 35% of the diameter of the diaphragm member when projected onto a plane perpendicular to the axis of the diaphragm member.

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