Fluid control valve

Abstract

To provide a fluid control valve capable of improving replaceability of fluid by suppressing retention of the fluid while maintaining durability of a valve seat of a valve body.SOLUTION: A flow control valve 1 includes: a valve body 2 in which a first valve chamber 11 communicating with an inlet flow passage 8, a second valve chamber 12 communicating with an outlet flow passage 9 and a connection flow passage 13 connecting the first valve chamber and the second valve chamber are formed; a first diaphragm 3 mounted to the valve body to face the first valve chest; and a second diaphragm 4 mounted to the valve body to face the second valve chamber. In the valve body, a valve seat 15 is provided in a communication part of the first valve chamber and the connection flow passage. A valve element 3a coming into contact with / separating from the valve seat in a movement axis C direction is provided in the first diaphragm. The valve body includes an annular valve chamber formation surface 18 that forms the second valve chamber. A recessed part 20 is formed at a position separating outwards from the valve seat on the side opposite to the outlet flow passage sandwiching the movement axis of the valve chamber formation surface.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a fluid control valve used in devices for transferring various fluids in various industrial fields such as semiconductor manufacturing, chemical plants, and food processing. [Background technology]

[0002] As shown in FIG. 10 , for example, a known conventional fluid control valve is a fluid control valve 101 comprising a valve body 102 in which a first valve chamber 111 communicating with an inlet flow path 108, a second valve chamber 112 communicating with an outlet flow path 109, and a connecting flow path 113 connecting the first valve chamber 111 and the second valve chamber 112 are formed, a first diaphragm 103 attached to the valve body 102 so as to face the first valve chamber 111, and a second diaphragm 104 attached to the valve body 102 so as to face the second valve chamber 112, a valve seat 115 is provided in the valve body 102 at a communicating portion between the first valve chamber 111 and the connecting flow path 113, and a valve element 103 a is provided in the first diaphragm 103 which moves toward and away from the valve seat 115 in the direction of a moving axis C. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-107606 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional fluid control valve 101, because the second valve chamber 112 is a uniform space along the circumferential direction, the fluid is likely to take a shortcut from the inlet flow path 108 to the outlet flow path 109 (see arrow A in FIG. 10 ), and an insufficient flow path is formed on the side of the second valve chamber 112 opposite the outlet flow path 109 (the back side), which can become a stagnation area for the fluid. If the proportion of this stagnation area increases, it takes longer to replace the fluid when switching the working fluid and starting up the device, resulting in a long start-up time for the device. Furthermore, dirt is likely to accumulate in the stagnation area, which can easily cause problems due to dirt at the destination of the fluid supply.

[0005] Patent Document 1 (see FIGS. 1 and 2) discloses a technique for suppressing fluid stagnation by providing a communication groove 27 on the side of the body 11 opposite the discharge passage 21, and by using the communication groove 27 to preferentially direct the fluid to the portion of the third fluid chamber R3 that is farthest from the discharge passage 21. However, with the technique disclosed in Patent Document 1, the communication groove 27 is located directly above the valve seat portion 25c, which reduces the thickness of the portion of the body 11 that includes the valve seat portion 25c, making it difficult to maintain the durability of the valve seat portion 25c.

[0006] The present invention has been made in consideration of the above-mentioned current situation, and aims to provide a fluid control valve that can suppress fluid retention and improve fluid replacement while maintaining the durability of the valve seat of the valve body. [Means for solving the problem]

[0007] The present invention is as follows. 1. A valve body having a first valve chamber communicating with an inlet flow path, a second valve chamber communicating with an outlet flow path, and a connecting flow path connecting the first valve chamber and the second valve chamber; a first diaphragm attached to the valve body so as to face the first valve chamber; a second diaphragm attached to the valve body so as to face the second valve chamber; Equipped with a valve seat is provided in the valve body at a communicating portion between the first valve chamber and the connecting flow path, The first diaphragm is provided with a valve body that moves toward and away from the valve seat in a moving axial direction, the valve body has an annular valve chamber forming surface that forms the second valve chamber, a recessed portion formed on the valve chamber forming surface at a position spaced outward from the valve seat on the opposite side of the movement axis from the outlet flow path; 2. A fluid control valve according to claim 1, wherein the recessed portion is disposed on the outer periphery side of the valve chamber forming surface. 3. The fluid control valve according to 1 above, wherein the recessed portion is formed such that the angular range (θ2) in the circumferential direction around the movement axis is 25 to 75 degrees. 4. A fluid control valve as described in 1 above, wherein the distance (L1) between the recess and the valve seat in a direction perpendicular to the axis of movement is in the range of (radius of first valve chamber - radius of connecting flow path) + 3 mm to radius of second valve chamber - 3 mm. 5. A fluid control valve according to claim 1, wherein the recess has a flat bottom surface. [Effects of the Invention]

[0008] According to the present invention, a recess is formed at a position away from the valve seat on the opposite side of the valve chamber surface from the outlet flow path across the movement axis, thereby suppressing fluid retention and improving fluid replacement while maintaining the durability of the valve seat of the valve body. [Brief explanation of the drawings]

[0009] The present invention will be further described in the following detailed description by way of non-limiting examples of exemplary embodiments according to the present invention and with reference to the mentioned drawings, in which like reference numerals refer to like parts throughout the several views of the drawings.

[0010] [Figure 1] 1 is a vertical cross-sectional view of a fluid control valve according to a first embodiment. [Figure 2] FIG. 2 is an enlarged view of the portion indicated by the arrow II in FIG. [Figure 3] 1A and 1B are explanatory views of a valve body according to the first embodiment, in which (a) is a perspective view and (b) is a plan view. [Figure 4] 1A and 1B are diagrams showing the results of fluid simulation of a fluid control valve, where FIG. 1A shows the results for the fluid control valve of the first embodiment, and FIG. 1B shows the results for a conventional fluid control valve. [Figure 5] FIG. 10 is a vertical cross-sectional view of a fluid control valve according to a second embodiment. [Figure 6] FIG. 6 is an enlarged view of the portion indicated by the arrow VI in FIG. 5. [Figure 7] 10A and 10B are perspective views of a valve body according to a second embodiment, where (a) shows a state seen from the first valve chamber side, and (b) shows a state seen from the second valve chamber side. [Figure 8] 10A and 10B are explanatory diagrams of a valve body according to other embodiments, in which (a) shows an embodiment having a plurality of recesses, (b) shows an embodiment having a recess located in the radial middle of the valve chamber forming surface, and (c) shows an embodiment having a recess that is approximately rectangular in plan view. [Figure 9] 10A and 10B are explanatory views of a recessed portion according to another embodiment. [Figure 10] FIG. 1 is a longitudinal sectional view of a conventional fluid control valve. DETAILED DESCRIPTION OF THE INVENTION

[0011] The matters set forth herein are for illustrative purposes only and are intended to provide an illustrative description of the embodiments of the present invention, with the aim of providing what is believed to be the most effective and easily understandable explanation of the principles and conceptual features of the present invention. In this regard, it is not intended to show structural details of the present invention beyond the extent necessary for a fundamental understanding of the present invention, and the description, taken together with the drawings, will make clear to those skilled in the art how some forms of the present invention may be actually embodied.

[0012] Hereinafter, the present invention will be specifically described by way of embodiments with reference to the drawings.

[0013] <Embodiment 1> 1, the fluid control valve 1 according to this embodiment includes a valve body 2, and a first diaphragm 3 and a second diaphragm 4 that are provided in the valve body 2 and move a valve element 3a toward and away from a valve seat 15 in the direction of a movement axis C. The fluid control valve 1 also includes a plate 5 attached to the upper part of the valve body 2, and a pressurizing unit 6 attached to the lower part of the valve body 2. The fluid control valve 1 functions as a constant pressure valve, as will be explained later in the description of its operation.

[0014] The valve body 2 is formed with a first valve chest 11 that communicates with the inlet flow path 8, a second valve chest 12 that communicates with the outlet flow path 9, and a connecting flow path 13 that connects the first valve chest 11 and the second valve chest 12. The first valve chest 11 is provided as a flat circular recess (specifically, a substantially cylindrical recess) in the center of the lower part of the valve body 2. The second valve chest 12 is provided as a flat circular recess (specifically, a substantially cylindrical recess) with a larger diameter than the first valve chest 11 in the center of the upper part of the valve body 2. The connecting flow path 13 is provided in the center of the valve body 2 as a flat circular hole (specifically, a substantially cylindrical hole) with a smaller diameter than the first valve chest 11 and the second valve chest 12.

[0015] The inlet flow path 8 extends linearly in a direction perpendicular to the movement axis C, with one end opening to the inner circumferential surface 11a of the first valve chamber 11. The outlet flow path 9 includes a vertical flow path 9a that extends linearly along the movement axis C and has an upper end that opens to the bottom surface 12b of the second valve chamber 12, and a horizontal flow path 9b that is connected to the lower end of the vertical flow path 9a and extends linearly in a direction perpendicular to the movement axis C. The inlet flow path 8 and the outlet flow path 9 are arranged such that the axis of the inlet flow path 8 and the axis of the horizontal flow path 9b substantially coincide with each other when viewed from the direction of the movement axis C (see FIG. 3(b)). However, the arrangement of the inlet flow path 8 and the outlet flow path 9 is not particularly limited. For example, when viewed from the direction of the movement axis C, the axis of the inlet flow path 8 and the axis of the horizontal flow path 9b may be substantially parallel, or the axis of the inlet flow path 8 and the axis of the horizontal flow path 9b may intersect.

[0016] The valve body 2 is provided with an annular valve seat 15 at the communicating portion between the first valve chamber 11 and the connecting flow path 13 (see FIG. 2). The valve seat 15 is located on the upper surface 11b of the first valve chamber 11, adjacent to the opening of the connecting flow path 13. However, the valve seat 15 may also be located on the upper surface 11b of the first valve chamber 11, away from the opening of the connecting flow path 13, outward (i.e., in the centrifugal direction about the movement axis C). The valve seat 15 is also formed by an annular rib that protrudes into the first valve chamber 11. However, if a rib is provided on the valve disc 3a side, the valve seat 15 may also be formed by an annular surface with which the rib comes into contact and separates.

[0017] The first diaphragm 3 is attached to the valve body 2 so as to face the first valve chamber 11 and separate the first valve chamber 11 from the outside. The first diaphragm 3 is provided with a valve element 3a that moves toward and away from the valve seat 15 in the direction of the movement axis C. Specifically, the first diaphragm 3 has the valve element 3a that moves in the direction of the movement axis C, an annular membrane portion 3b that movably supports the valve element 3a, and an outer peripheral edge portion 3c that is provided on the outer periphery of the membrane portion 3b.

[0018] The second diaphragm 4 is attached to the valve body 2 so as to face the second valve chamber 12 and separate the second valve chamber 12 from the outside. The second diaphragm 4 has a base 4a that moves in the direction of the movement axis C, an annular membrane portion 4b that movably supports the base 4a, and an outer peripheral edge portion 4c provided on the outer periphery of the membrane portion 4b. At least a portion of the base 4a is sized to be able to be inserted into the connecting flow path 13.

[0019] The valve element 3a of the first diaphragm 3 and the base 4a of the second diaphragm 4 are not connected to each other and can be moved toward or away from each other. However, the valve element 3a and the base 4a may be connected by screwing, fitting, or other means. The first diaphragm 3 and the second diaphragm 4, particularly the membrane portions 3b and 4b, are preferably made of polytetrafluoroethylene (PTFE), which has flexibility and high bending resistance, since they are subjected to repeated bending. However, the valve element 3a is preferably made of perfluoroalkoxyalkane (PFA), which has low dust-generating properties, since it is prone to generating particles when it contacts the valve seat 15. Therefore, the first diaphragm 3 may be configured such that only the valve seat contact surface of the valve element 3a is made of PFA, and the remaining portions are made of PTFE. The valve body 2 may be made of an appropriate material, such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), perfluoroalkoxyalkane (PFA), or polychlorotrifluoroethylene (PCTFE).

[0020] The plate 5 is attached to the top of the valve body 2 with fasteners (not shown), such as bolts, so that the outer peripheral edge 4c of the second diaphragm 4 is sandwiched between the plate 5 and the valve body 2. A working fluid supply port 5a is formed in the bottom surface of the plate 5. A pressurized chamber 5b, which is separated from the second valve chamber 12, is formed between the plate 5 and the upper surface of the second diaphragm 4. By supplying working fluid to the pressurized chamber 5b through the working fluid supply port 5a and varying the pressure within the pressurized chamber 5b, the valve element 3a of the first diaphragm 3 together with the base 4a of the second diaphragm 4 can be moved up and down to approach or move away from the valve seat 15.

[0021] The pressurizing unit 6 is attached to the bottom of the valve body 2 with fasteners (not shown) such as bolts so as to sandwich the outer peripheral edge 3c of the first diaphragm 3 between the valve body 2. The pressurizing unit 6 has a movable body 6b that moves in the direction of the movement axis C within a pressurizing chamber 6a formed between the assembled housings 22a and 22b, a biasing spring 6c that biases the movable body 6b in a direction toward the first valve chamber 11, and a stem 6d extending from the top of the movable body 6b. The valve body 3a of the first diaphragm 3 is connected to the tip of the stem 6d by screwing, fitting, or the like.

[0022] 2 and 3, the valve body 2 has an annular valve chamber forming surface 18 that forms the second valve chamber 12. The valve chamber forming surface 18 is made up of the bottom surface 12b of the second valve chamber 12. The valve chamber forming surface 18 is a conical surface centered on the movement axis C, and in a cross section along the movement axis C of the valve body 2, it is inclined at a predetermined inclination angle θ1 (for example, 5 degrees) with respect to a direction perpendicular to the movement axis C. However, the magnitude of this inclination angle θ1 is not particularly limited, and from the viewpoint of the formability of the second valve chamber 12 as a constant pressure valve, it is preferably 3 to 13 degrees (more preferably 3 to 6 degrees, and even more preferably 4 to 5 degrees).

[0023] A recess 20 is formed on the valve chamber forming surface 18 on the opposite side of the outlet flow path 9 from the outlet flow path 9 (the back side) of the second valve chamber 12 (see FIG. 1 ). The recess 20 is located in the valve body 2, away from the valve seat 15 (i.e., in the centrifugal direction centered on the movement axis C). Specifically, the recess 20 is located closer to the outer periphery of the valve chamber forming surface 18. The distance L1 between the recess 20 and the valve seat 15 in the direction perpendicular to the movement axis C is 6 mm. However, the size of this distance L1 is not particularly limited, and is preferably 5 to 10 mm (more preferably 5 to 8 mm, and even more preferably 5 to 7 mm) from the viewpoints of ensuring the thickness of the portion of the valve body 2 including the valve seat 15 and preventing the valve body 2 from becoming too large in the radial direction. The vertical width L2 of the recess 20 is 5 mm. However, the size of this vertical width L2 is not particularly limited, and from the viewpoint of suppressing pressure rise on the opposite side of the outlet flow path 9 of the second valve chamber 12, it is preferably 3 to 7 mm (more preferably 4 to 6 mm, and even more preferably 4 to 5 mm).

[0024] The recess 20 is formed in a plane fan shape. The angular range θ2 of the recess 20 in the circumferential direction centered on the movement axis C is 50 degrees. However, this angular range θ2 is not particularly limited, and from the viewpoint of suppressing pressure increases on the side of the second valve chamber 12 opposite the outlet flow path 9, it is preferable that the angular range θ2 be 25 to 75 degrees (more preferably 30 to 70 degrees, and even more preferably 35 to 65 degrees). The recess 20 has a bottom surface 20a and upright wall surfaces 20b rising from the left and right side edges of the bottom surface 20a. The bottom surface 20a is formed by a plane perpendicular to the movement axis C. The inner peripheral edge of the bottom surface 20a intersects with and is directly connected to the valve chamber forming surface 18. The outer peripheral edge of the bottom surface 20a is connected to the inner peripheral surface 12a of the second valve chamber 12 via a connecting surface 20c having an arc-shaped longitudinal cross section.

[0025] Next, the operation and effect of the fluid control valve (constant pressure valve) 1 configured as described above will be explained. In the fluid control valve 1, the valve element 3a of the first diaphragm 3 is pushed upward by the biasing force of the biasing spring 6c and pressed against the valve seat 15. When working fluid is supplied from this state into the pressurized chamber 5b through the working fluid supply port 5a, the base 4a of the second diaphragm 4 is pushed downward and abuts against the valve element 3a. When the valve element 3a is further pressed downward by the base 4a against the biasing force of the biasing spring 6c, the valve element 3a separates from the valve seat 15, allowing fluid to pass from the first valve chamber 11 to the second valve chamber 12 (see FIG. 1). The flow rate can be set to any value by adjusting the working fluid supplied into the pressurized chamber 5b to change the gap between the valve element 3a and the valve seat 15.

[0026] When the fluid is at a set value, the valve element 3a comes to rest in a position where three forces are balanced: the biasing force of the biasing spring 6c, the force pushing up the lower surface of the second diaphragm 4 due to the pressure of the fluid, and the force pushing down the upper surface of the second diaphragm 4 due to the pressure of the working fluid. Strictly speaking, the lower surface of the valve element 3a and the membrane portion 3b of the first diaphragm 3 are subjected to pressure from the fluid in the first valve chamber 11, but their pressure-receiving areas are nearly equal, so the forces are nearly canceled out.

[0027] In this state, if the upstream fluid pressure increases, the pressure in the second valve chamber 12 also increases instantaneously. As a result, the force acting on the bottom surface of the second diaphragm 4 from the working fluid becomes greater than the force acting on the top surface of the second diaphragm 4 from the fluid, causing the second diaphragm 4 to move upward. As a result, the valve disc 3a also moves upward together with the base 4a, reducing the opening area between the valve seat 15 and the valve disc 3a and decreasing the pressure in the second valve chamber 12. Eventually, the valve disc 3a comes to rest at a position where the three forces mentioned above are balanced, and the fluid pressure in the second valve chamber 12 returns to approximately the same pressure as before the upstream fluid pressure increased.

[0028] On the other hand, when the pressure on the upstream side decreases, the pressure in the second valve chamber 12 also decreases instantaneously. As a result, the force acting on the bottom surface of the second diaphragm 4 from the working fluid becomes smaller than the force acting on the top surface of the second diaphragm 4 from the fluid, and the second diaphragm 4 moves downward. As a result, the valve disc 3a also moves downward together with the base 4a, increasing the opening area between the valve seat 15 and the valve disc 3a and increasing the pressure in the second valve chamber 12. Eventually, the valve disc 3a comes to rest at a position where the above three forces are balanced, and the fluid pressure in the second valve chamber 12 returns to approximately the same pressure as before the upstream fluid pressure decreased.

[0029] As described above, even if the fluid pressure upstream of the fluid control valve 1 fluctuates, the fluid pressure in the second valve chamber 12 changes very little. Therefore, if there is no change in the pressure loss in the piping downstream of the fluid control valve 1, the flow rate can be maintained constant. Furthermore, since the fluid pressure in the second valve chamber 12 can be adjusted by the pressure of the working fluid in the pressurizing chamber 5b, the flow rate can also be adjusted by the working fluid. Furthermore, if no working fluid is supplied to the pressurizing chamber 5b, the movable body 6b is pushed up by the biasing force of the biasing spring 6c, and the valve element 3a, which is linked to the movable body 6b via the stem 6d, is also pushed up. Therefore, the valve element 3a comes into contact with the valve seat 15, blocking the flow of fluid.

[0030] This fluid control valve 1 is used in devices that transfer various fluids in various industrial fields, such as semiconductor manufacturing, chemical plants, and food processing. When switching the fluid used and starting up the device, the presence of the recess 20 in the fluid control valve 1 makes the space on the side opposite the outlet flow path 9 of the second valve chamber 12 larger than the other spaces, thereby suppressing an increase in fluid pressure on the side opposite the outlet flow path 9 of the second valve chamber 12. This makes it difficult for the fluid to take a shortcut from the inlet flow path 8 side to the outlet flow path 9 side, and ensures a sufficient flow rate of fluid on the side opposite the outlet flow path 9 of the second valve chamber 12.

[0031] Here, when the results of the fluid simulation of the present fluid control valve 1 (see FIG. 4(a)) are compared with the results of the fluid simulation of the conventional fluid control valve 101 (see FIG. 11) (see FIG. 4(b)), it is found that the present fluid control valve 1 has an increased fluid flow at the back part P of the outlet flow path 9 of the second valve chamber 12 compared to the conventional fluid control valve 101, and the fluid replacement time is reduced by approximately 11%.

[0032] As described above, according to the fluid control valve 1 of this embodiment, a recess (groove) 20 is formed at a position away from the valve seat (seal portion) 15 on the opposite side of the valve chamber forming surface 18 from the outlet flow path 9 across the movement axis C. This prevents a rise in fluid pressure on the side of the second valve chamber 12 opposite the outlet flow path 9 (the back side), allowing a sufficient flow rate of fluid to flow and facilitating fluid replacement when switching the working fluid and starting up the device. Furthermore, fluid stagnation is less likely to occur on the side of the second valve chamber 12 opposite the outlet flow path 9, preventing problems caused by dirt that is likely to be trapped in stagnation at the fluid supply destination. Furthermore, the thickness of the portion of the valve body 2 including the valve seat 15 can be ensured, maintaining the durability of the valve seat 15.

[0033] Furthermore, in this embodiment, the recessed portion 20 is disposed closer to the outer periphery of the valve chamber forming surface 18. This makes it possible to more effectively suppress the increase in fluid pressure on the side opposite the outlet flow path 9 of the second valve chamber 12.

[0034] In this embodiment, the distance L1 between the recess 20 and the valve seat 15 in the direction perpendicular to the movement axis C is 6 mm. This ensures a sufficient thickness for the portion of the valve body 2 including the valve seat 15, and also prevents the valve body 2 from becoming too large in the radial direction.

[0035] In this embodiment, the recess 20 is formed so that the angular range θ2 in the circumferential direction about the movement axis C is 50 degrees. This makes it possible to more effectively suppress the increase in fluid pressure on the side of the second valve chamber 12 opposite the outlet flow path 9.

[0036] In this embodiment, the bottom surface 20a of the recessed portion 20 is formed as a flat surface, which makes it possible to more effectively prevent the occurrence of a stagnant portion of the fluid on the side of the second valve chamber 12 opposite the outlet flow path 9.

[0037] Furthermore, in this embodiment, the inner peripheral edge of the bottom surface 20a of the recessed portion 20 intersects with and is directly connected to the valve chamber forming surface 18. This makes it possible to more effectively prevent the occurrence of stagnation of fluid on the side of the second valve chamber 12 opposite the outlet flow path 9.

[0038] Furthermore, in this embodiment, the outer peripheral edge of the bottom surface 20a of the recessed portion 20 is connected to the inner peripheral surface of the second valve chamber 12 via a connecting surface 20c that has an arc-shaped longitudinal cross section. This makes it possible to more effectively prevent the occurrence of stagnation of fluid on the side of the second valve chamber 12 opposite the outlet flow path 9.

[0039] <Embodiment 2> Next, a fluid control valve 31 according to a second embodiment will be described with reference to FIGS. 5 to 7, but components that are substantially the same as those in the above-described fluid control valve 1 will be assigned the same reference numerals and detailed description thereof will be omitted.

[0040] 5, the fluid control valve 31 according to this embodiment includes a valve body 32, and a first diaphragm 33 and a second diaphragm 34 that are provided in the valve body 32 and move a valve element 46 toward and away from a valve seat 45 in the direction of a movement axis C. The fluid control valve 31 also includes a plate 35 attached to the bottom of the valve body 32, and a pressurizing unit 36 ​​attached to the top of the valve body 32. The fluid control valve 31 functions as a back pressure valve, as will be explained later in the description of its operation.

[0041] The valve body 32 is formed with a first valve chamber 41 that communicates with the inlet flow path 38, a second valve chamber 42 that communicates with the outlet flow path 39, and a connecting flow path 43 that connects the first valve chamber 41 and the second valve chamber 42. The first valve chamber 41 is provided as a flat circular recess (specifically, a substantially truncated conical recess) in the center of the upper part of the valve body 32. The second valve chamber 42 is provided as a flat circular recess (specifically, a substantially truncated conical recess) in the center of the lower part of the valve body 32. The connecting flow path 43 is provided in the center of the valve body 32 as a flat circular hole (specifically, a substantially cylindrical hole) with a diameter smaller than the first valve chamber 41 and the second valve chamber 42.

[0042] The inlet flow path 38 extends linearly in a direction perpendicular to the movement axis C, with one end opening to the inner circumferential surface 41 a of the first valve chamber 41. The outlet flow path 39 extends linearly in a direction perpendicular to the movement axis C, with one end opening to the inner circumferential surface 42 a of the second valve chamber 42. The inlet flow path 38 and the outlet flow path 39 are arranged so that their respective axes substantially coincide when viewed from the direction of the movement axis C. However, the arrangement of the inlet flow path 38 and the outlet flow path 39 is not particularly limited; for example, they may be arranged so that their respective axes are substantially parallel to each other when viewed from the direction of the movement axis C, or so that their respective axes intersect.

[0043] The valve body 32 is provided with an annular valve seat 45 at the communication portion between the first valve chamber 41 and the connecting flow path 43. The valve seat 45 is disposed at a position adjacent to the opening of the connecting flow path 43 on the inner circumferential surface 41a of the first valve chamber 41. However, the valve seat 45 may also be disposed at a position away from the opening of the connecting flow path 43 on the inner circumferential surface 41a of the first valve chamber 41 outward (i.e., in the centrifugal direction about the movement axis C). The valve seat 45 is formed by a corner where a pair of surfaces intersect.

[0044] The first diaphragm 33 is attached to the valve body 32 so as to face the first valve chamber 41 and separate the first valve chamber 41 from the outside. The first diaphragm 33 is provided with a valve element 46 that moves toward and away from a valve seat 45 in the direction of movement axis C. Specifically, the first diaphragm 33 has a base 33a that moves in the direction of movement axis C, an annular membrane portion 33b that movably supports the base 33a, and an outer peripheral edge portion 33c that is provided on the outer peripheral side of the membrane portion 33b. The upper part of the valve element 46 is connected to the base 33a by screwing, fitting, or the like. At least a portion of the valve element 46 is sized to be insertable into the connecting flow path 43.

[0045] The second diaphragm 34 is attached to the valve body 32 so as to face the second valve chamber 42 and separate the second valve chamber 42 from the outside. The second diaphragm 34 has a base 34a that moves in the direction of movement axis C, an annular membrane portion 34b that movably supports the base 34a, and an outer peripheral edge portion 34c provided on the outer peripheral side of the membrane portion 34b. The lower part of the valve element 46 is connected to the base 34a by screwing, fitting, or the like.

[0046] The first diaphragm 33 and the second diaphragm 34, particularly the membrane portions 33b and 34b, are preferably made of polytetrafluoroethylene (PTFE), which has flexibility and high bending resistance, since these portions are subjected to repeated bending. On the other hand, the valve element 46 is preferably made of perfluoroalkoxyalkane (PFA), which has low dust-generating properties, since it is likely to generate particles when it comes into contact with the valve seat 45. Furthermore, the valve body 32 can be made of an appropriate material such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), perfluoroalkoxyalkane (PFA), or polychlorotrifluoroethylene (PCTFE).

[0047] The plate 35 is attached to the lower part of the valve body 32 with fasteners (not shown), such as bolts, so as to sandwich the outer peripheral edge 34c of the second diaphragm 34 between the plate 35 and the valve body 32. The pressurizing unit 36 ​​is attached to the upper part of the valve body 32 with fasteners (not shown), such as bolts, so as to sandwich the outer peripheral edge 33c of the first diaphragm 33 between the plate 35 and the valve body 32 via a retaining member 36b. The pressurizing unit 36 ​​has a piston 36a arranged within its housing 52 so as to be movable along the movement axis C, a retaining member 36b that also functions as a spring receiver, and a biasing spring 36c arranged between the retaining member 36b and a flange provided on the piston 36a, so that the biasing spring 36c applies an upward biasing force to the piston 36a. The piston 36a is connected to the base 33a of the first diaphragm 33 by screwing, fitting, or the like. Furthermore, a working fluid supply port 53 is provided on the top of the housing 52, so that working fluid can be supplied to and discharged from the housing 52.

[0048] 6 and 7, the valve body 32 has an annular valve chamber forming surface 48 that forms the second valve chamber 42. The valve chamber forming surface 48 is made up of the inner circumferential surface 42a of the second valve chamber 42. The valve chamber forming surface 48 is a conical surface centered on the movement axis C, and in a cross section along the movement axis C of the valve body 32, it is inclined at a predetermined inclination angle θ1 (for example, 40 degrees) with respect to a direction perpendicular to the movement axis C. However, the magnitude of this inclination angle θ1 is not particularly limited, and from the viewpoint of the formability of the second valve chamber 42 as a back pressure valve, it is preferably 20 to 50 degrees (more preferably 30 to 50 degrees, and even more preferably 40 to 50 degrees).

[0049] A recess 50 is formed on the valve chamber forming surface 48 on the opposite side of the outlet flow path 39 from the outlet flow path 39 (the back side) of the second valve chamber 42, to suppress a rise in fluid pressure (see FIG. 5). The recess 50 is located in the valve body 32, away from the valve seat 45 (i.e., in the centrifugal direction about the movement axis C). Specifically, the recess 50 is located closer to the outer periphery of the valve chamber forming surface 48. The distance L1 between the recess 50 and the valve seat 45 in the direction perpendicular to the movement axis C is 4.5 mm. However, the size of this distance L1 is not particularly limited, and is preferably 3 to 7 mm (more preferably 4 to 6 mm, and even more preferably 4 to 5 mm) from the viewpoints of ensuring the thickness of the portion of the valve body 32 including the valve seat 45 and preventing the valve body 32 from becoming too large in the radial direction. The vertical width L2 of the recess 50 is 0.8 mm. However, the size of this vertical width L2 is not particularly limited, and from the viewpoint of suppressing pressure rise on the opposite side of the outlet flow path 39 of the second valve chamber 42, it is preferable that it be 0.5 to 1.5 mm (more preferably 0.7 to 1.3 mm, and even more preferably 0.8 to 1.0 mm).

[0050] The recess 50 is formed in a flat sector shape. The angular range θ2 of the recess 50 in the circumferential direction around the movement axis C is 50 degrees (see FIG. 7(b)). However, this angular range θ2 is not particularly limited, and from the viewpoint of suppressing a pressure increase on the side opposite the outlet flow path 9 of the second valve chamber 12, it is preferable that the angular range θ2 be 25 to 75 degrees (more preferably 30 to 70 degrees, and even more preferably 35 to 65 degrees). The recess 50 has a bottom surface 50a and an upright wall surface 50b rising from the periphery of the bottom surface 50a. The bottom surface 50a of the recess 50 is formed by a plane inclined with respect to a plane perpendicular to the movement axis C.

[0051] Next, the operation and effect of the fluid control valve 31 (back pressure valve) configured as described above will be explained. In the fluid control valve 31, the valve element 46 comes to rest at a position where three forces are balanced: the biasing force of the biasing spring 36c, the force pushing up the lower surface of the first diaphragm 33 due to the fluid pressure, and the force pushing down the upper surface of the first diaphragm 33 due to the pressure of the working fluid. Strictly speaking, the lower surface of the valve element 46 and the upper surface of the membrane portion 34b of the second diaphragm 34 are subjected to fluid pressure from the fluid in the second valve chamber 42, but because their pressure-receiving areas are set to be approximately equal, the two forces are approximately canceled out. When the pressure of the working fluid supplied to the pressurizing unit 36 ​​is increased, the force pushing down the first diaphragm 33 increases, bringing the valve element 46 and the valve seat 45 closer together and increasing the pressure in the first valve chamber 41. On the other hand, when the pressure of the working fluid supplied to the pressurizing unit 36 ​​is reduced, the force pressing down on the first diaphragm 33 decreases, the valve element 46 and the valve seat 45 move apart, and the pressure in the first valve chamber 41 decreases. Therefore, by adjusting the pressure of the working fluid, the pressure in the first valve chamber 41 can be set to a desired value.

[0052] When the fluid pressure on the inlet flow path 38 side increases while the three forces described above are balanced, the fluid pressure in the first valve chamber 41 momentarily increases, increasing the fluid pressure acting on the underside of the membrane portion 33b of the first diaphragm 33, so the first diaphragm 33 is pushed up, the valve element 46 and the valve seat 45 separate, the pressure in the first valve chamber 41 decreases, and finally the valve element 46 moves to a position where the three forces described above are balanced and comes to a rest. On the other hand, when the fluid pressure on the inlet flow path 38 side decreases, the fluid pressure in the first valve chamber 41 also momentarily decreases, decreasing the fluid pressure acting on the underside of the membrane portion 33b of the first diaphragm 33, so the first diaphragm 33 is pushed down, the valve element 46 and the valve seat 45 come closer, the pressure in the first valve chamber 41 increases, and finally the valve element 46 moves to a position where the three forces described above are balanced and comes to a rest.

[0053] This fluid control valve 31 is used in devices that transfer various fluids in various industrial fields, such as semiconductor manufacturing, chemical plants, and food processing. When switching the fluid used and starting up the device, the presence of the recess 50 in the fluid control valve 31 makes the space on the side opposite the outlet flow path 39 of the second valve chamber 42 larger than the other spaces, thereby suppressing a rise in fluid pressure on the side opposite the outlet flow path 39 of the second valve chamber 42. This makes it difficult for the fluid to take a shortcut from the inlet flow path 38 to the outlet flow path 39, ensuring that a sufficient flow rate of fluid flows on the side opposite the outlet flow path 39 of the second valve chamber 42. As described above, this fluid control valve 31 provides substantially the same functions and effects as the above-described fluid control valve 1.

[0054] The present invention is not limited to the above-described first and second embodiments, and various modifications can be made within the scope of the present invention based on the purpose and application. In other words, while the above-described first and second embodiments illustrate a configuration in which a single recess 20, 50 is provided in the valve-chamber-forming surface 18, 48 of the valve body 2, 32, the present invention is not limited to this. For example, as shown in Figure 8(a), a configuration in which a plurality of recesses 20, 50 (two in the figure) are provided in the valve-chamber-forming surface 18, 48 of the valve body 2, 32 may be employed. In this configuration, a plurality of recesses 20, 50 can be arranged in the circumferential direction around the movement axis C.

[0055] Furthermore, in the above-described first and second embodiments, the recessed portions 20, 50 are arranged on the outer periphery side of the valve chamber forming surface 18, 48, but this is not limitative. For example, as shown in FIG. 8(b), the recessed portions 20, 50 may be arranged in the radially middle portion of the valve chamber forming surface 18, 48.

[0056] Furthermore, in the above-described embodiments 1 and 2, the recessed portions 20, 50 formed in a plane fan shape are exemplified, but this is not limited to this, and for example, as shown in FIG. 8(c), the recessed portions 20, 50 may be formed in a plane shape that is a polygonal shape such as an approximately square or approximately triangular shape, an approximately elliptical shape, or an approximately circular shape.

[0057] In addition, in the above-described first and second embodiments, the recessed portions 20, 50 each having one bottom surface 20a, 50a are exemplified, but this is not limiting, and for example, recessed portions 20, 50 each having a plurality of bottom surfaces 20a, 50a in which adjacent bottom surfaces in the circumferential direction intersect with each other may be employed. In this embodiment, for example, recessed portions 20, 50 having a substantially V-shaped groove shape can be formed.

[0058] Furthermore, in the above-described embodiments 1 and 2, the recessed portions 20, 50 having bottom surfaces 20a, 50a made of flat surfaces are exemplified, but this is not limited thereto, and recessed portions 20, 50 having bottom surfaces 20a, 50a made of curved surfaces, hemispherical surfaces, etc. may also be used.

[0059] Furthermore, in the above-described first embodiment, the recessed portion 20 has a bottom surface 20a formed of a plane perpendicular to the movement axis C. However, the present invention is not limited to this. For example, as shown in Fig. 9, a recessed portion 20 may have a bottom surface 20a formed of a plane that is inclined with respect to the plane perpendicular to the movement axis C. In this embodiment, the inclination angle θ3 of the bottom surface 20a of the recessed portion 20 with respect to the horizontal is smaller than the inclination angle θ1 of the valve-chamber-forming surface 18 with respect to the horizontal. [Industrial Applicability]

[0060] The present invention is widely used as a technology relating to a fluid control valve that can be applied to, for example, a constant pressure valve, a back pressure valve, an on-off valve, a suck-back valve, etc. [Explanation of symbols]

[0061] 1,31; Fluid control valve 2,32; Valve body 3,33: First diaphragm 4,34: Second diaphragm 8,38; Inlet channel 9,39; Outlet channel 11,41;1st valve chamber 12,42;2nd valve chamber 13, 43; connecting passage 15, 45; valve seat 3a, 46; Valve body 18, 48; Valve chamber forming surface 20, 50; recessed portion 20a, 50a; bottom surface of recessed portion C: Axis of movement L1: Distance between recess and valve seat θ2: Circumferential angle range of the recess

Claims

1. a valve body having a first valve chamber communicating with an inlet flow path, a second valve chamber communicating with an outlet flow path, and a connecting flow path connecting the first valve chamber and the second valve chamber; a first diaphragm attached to the valve body so as to face the first valve chamber; a second diaphragm attached to the valve body so as to face the second valve chamber; Equipped with a valve seat is provided in the valve body at a communicating portion between the first valve chamber and the connecting flow path, The first diaphragm is provided with a valve body that moves toward and away from the valve seat in a moving axial direction, the valve body has an annular valve chamber forming surface that forms the second valve chamber, a recessed portion formed on the valve chamber forming surface at a position spaced outward from the valve seat on the opposite side of the movement axis from the outlet flow path;

2. 2. The fluid control valve according to claim 1, wherein the recessed portion is disposed on a side closer to an outer periphery of the valve chamber forming surface.

3. 2. The fluid control valve according to claim 1, wherein the recessed portion is formed so that an angular range (θ2) in the circumferential direction around the movement axis is 25 to 75 degrees.

4. 2. The fluid control valve according to claim 1, wherein a distance (L1) between the recessed portion and the valve seat in a direction perpendicular to the movement axis is in a range from (radius of first valve chest - radius of connecting flow path) + 3 mm to radius of second valve chest - 3 mm.

5. 2. The fluid control valve according to claim 1, wherein the recess has a flat bottom surface.

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