Diaphragm valve

Abstract

To provide a diaphragm valve capable of enhancing alignment performance of a diaphragm piece, retaining seal performance of a valve seat, and improving seal performance of the valve seat even when a thrust for sealing the valve seat is suppressed small in a structure having an assembly tolerance making disassemble / assemble free.SOLUTION: A diaphragm valve 1 has a diaphragm piece 70 arranged at a tip of a stem 50 in a contactable manner, and is put in a valve closed state where a diaphragm 60 is brought into contact with a valve seat 44 via the diaphragm piece 70 pushed in a valve closing direction by the stem 50. A tip surface 53a of the stem 50 has a spherical shape. The diaphragm piece 70 is provided with a recess 71 at which the tip of the stem 50 is interposed, and an inner bottom 71a of the recess 71 is in a spherical shape having a curvature radius larger than a curvature radius of the tip surface 53a of the stem 50, and forming a central part as the lowest surface.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a diaphragm valve, and more particularly to a diaphragm valve in which a valve using a diaphragm is opened and closed by movement of a stem. [Background technology]

[0002] Conventionally, valves used in semiconductor manufacturing equipment, solar cell manufacturing equipment, liquid crystal manufacturing equipment, etc. are required to have little dead space and suppress particle generation, and diaphragm valves are often used to meet these requirements.

[0003] In a diaphragm valve, the diaphragm and the valve seat are repeatedly brought into contact with and separated from each other, which causes wear, and therefore it is necessary to periodically replace the diaphragm, valve seat, and other wear parts. In particular, when used in processes that open and close valves at high temperatures and high speeds, such as ALD (Atomic Layer Deposition), the valve seats and other components are more susceptible to wear, and wear parts such as the valve seats must be replaced more frequently. Diaphragm valves, which are prone to component wear, require particularly high durability, and to achieve this, it is necessary to reduce the thrust force that seals the valve seat to prevent damage to the valve seat. On the other hand, it is also necessary to improve the ease of disassembly and assembly to facilitate part replacement during maintenance. For example, Patent Document 1 describes a diaphragm valve that is easy to disassemble and assemble.

[0004] This patent proposes a diaphragm valve having an assembly or cartridge that facilitates replacement of the diaphragm, the valve seat, or both. The diaphragm valve described in Patent Document 1 is configured such that, when the valve is closed, the diaphragm is brought into contact with the valve seat via a button (diaphragm piece) disposed on the tip side of the actuator stem. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2016-505125 Summary of the Invention [Problem to be solved by the invention]

[0006] However, with the diaphragm valve described in Patent Document 1, if the thrust force that seals the valve seat is reduced, for example, the stem will rattle due to the influence of gaps as play between the stem and diaphragm piece inside the valve caused by assembly tolerances that allow for free disassembly and assembly, and the way the stem pushes against the diaphragm piece will become uneven. This will make the valve more susceptible to the influence of tilting of the valve seat caused by uneven parallelism of the valve seat and valve body due to assembly tolerances, resulting in unstable sealing. To solve this problem, it is necessary to stabilize the axial movement of the diaphragm piece and improve the centering performance of the diaphragm piece.

[0007] The present invention was developed to solve the problems of the past, and its purpose is to provide a diaphragm valve that has an assembly tolerance that allows for free disassembly and assembly, and that improves the alignment performance of the diaphragm piece and maintains the sealing performance of the valve seat, even when the thrust force that seals the valve seat is kept small, thereby further improving the sealing performance of the valve seat. [Means for solving the problem]

[0008] In order to achieve the above object, the invention of claim 1 is a diaphragm valve having a diaphragm piece arranged so as to be able to abut freely against the tip of a stem, the diaphragm being brought into a valve closed state by the diaphragm piece being pushed in the valve closing direction by the stem, the tip surface of the stem being spherical, the diaphragm piece being provided with a recess into which the tip of the stem is inserted, the inner bottom surface of the recess being spherical with a radius of curvature larger than the radius of curvature of the tip surface of the stem and with the center being the lowest surface.

[0009] The invention according to claim 2 is a diaphragm valve in which the inner bottom surface of the recess is formed at as deep a position as possible while ensuring a predetermined strength.

[0010] The invention of claim 3 is a diaphragm valve having a holding member that holds the diaphragm piece so that it can move freely in the axial direction of the diaphragm piece, and the diaphragm piece has an axial height that allows it to be guided in the axial direction by the holding member using the side outer peripheral surface of the diaphragm piece as a sliding surface. [Effects of the Invention]

[0011] According to the invention of claim 1, the tip surface of the stem is spherical, the diaphragm piece is provided with a recess into which the tip of the stem is inserted, and the inner bottom surface of the recess has a radius of curvature larger than the radius of curvature of the tip surface of the stem and is spherical with the center as the lowest surface. As a result, when the tip surface of the stem presses against the inner bottom surface of the recess in the diaphragm piece to close the valve, the stem moves toward the bottommost surface of the inner bottom surface while abutting its spherical tip surface against the spherical inner bottom surface of the recess. As a result, the position at which the stem presses against the diaphragm piece is closer to the valve seat, and when the stem tilts and presses against the internal bottom surface of the diaphragm piece, which is separate from the stem, the moment that rotates the diaphragm piece is kept small, preventing the diaphragm piece from tilting so much that alignment performance is reduced due to play in assembly tolerances. Therefore, in a configuration with assembly tolerances that allow for free disassembly and assembly, even if the thrust force that seals the valve seat is kept small, the alignment performance of the diaphragm piece can be improved and the sealing performance of the valve seat can be maintained, thereby further improving the sealing performance of the valve seat.

[0012] According to the invention of claim 2, the inner bottom surface of the recess in the diaphragm piece is formed at a position as deep as possible while ensuring the specified strength, so that the tip surface of the stem can press against the inner bottom surface at a deeper position in the recess, and the stem presses against the inner bottom surface at a position closer to the valve seat.Therefore, the moment acting on the diaphragm piece when the stem tilts and presses against the inner bottom surface of the recess can be kept small while ensuring the strength of the diaphragm piece. Furthermore, the tip of the stem can be inserted deeper into the recess of the diaphragm piece, which results in a more compact device size in the axial direction of the stem. Furthermore, even if the valve seat is tilted due to assembly tolerances, the position at which the stem presses against the inner bottom surface can be made close to the axis of the diaphragm piece, thereby further improving alignment performance.

[0013] According to the invention of claim 3, a holding member is provided that holds the diaphragm piece so that it can move freely in the axial direction of the diaphragm piece, and the diaphragm piece has a height that allows it to be guided in the axial direction by the holding member, with the outer peripheral surface of the side of the diaphragm piece serving as a sliding surface. This ensures a stable height of the sliding surface for guiding the diaphragm piece and the retaining member in the axial direction of the diaphragm piece, while by inserting the tip of the stem deeper into the recess of the diaphragm piece, the position at which the stem presses the diaphragm piece becomes closer to the valve seat. Therefore, the diaphragm piece can be stably guided so as to be movable in the axial direction, while the moment acting on the diaphragm piece can be kept small. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 2 is a cross-sectional view showing a schematic configuration of the diaphragm valve according to the embodiment in an open state. [Figure 2] 1 is a cross-sectional view showing a schematic configuration of a diaphragm valve according to an embodiment in a valve closed state. [Figure 3] FIG. 2 is a perspective cross-sectional view of the diaphragm and its surroundings shown in FIG. 1. [Figure 4] FIG. 4 is an enlarged view of a portion A shown in FIG. 3. [Figure 5] FIG. 4 is an enlarged view of part B shown in FIG. 3. [Figure 6] FIG. [Figure 7] FIG. 2 is a front cross-sectional view of the diaphragm piece. [Figure 8] 10A and 10B are diagrams for explaining a moment acting on the diaphragm piece when the stem presses the diaphragm piece in a tilted state. [Figure 9] 10 is a diagram illustrating the difference in alignment performance due to differences in the depth of the inner bottom surface of the recess when the diaphragm piece is tilted in response to a valve seat that is slightly tilted due to assembly tolerances. [Figure 10] 10 is a diagram illustrating the difference in alignment performance due to differences in the depth of the inner bottom surface of the recess when the diaphragm piece is tilted in response to a valve seat that is slightly tilted due to assembly tolerances. DETAILED DESCRIPTION OF THE INVENTION

[0015] An embodiment of a diaphragm valve 1 according to the present invention will be described in detail below with reference to FIGS. It should be noted that the present disclosure is not limited to the embodiments shown below. It should be noted that the drawings are schematic, and the dimensional relationships and ratios of elements may differ from reality. Furthermore, the drawings may include portions in which the dimensional relationships and ratios differ from one another. FIG. 1 is a cross-sectional view showing a schematic configuration of a diaphragm valve 1 according to an embodiment in an open state. FIG. 2 is a cross-sectional view showing a schematic configuration of a diaphragm valve 1 according to an embodiment in a closed state. FIG. 3 is a perspective cross-sectional view of the vicinity of the diaphragm 60 shown in FIG. 1. FIG. 4 is an enlarged view of portion A shown in FIG. 3. FIG. 5 is an enlarged view of portion B shown in FIG. 3. FIG. 6 is a front view of the stem 50. FIG. 7 is a front cross-sectional view of the diaphragm piece 70. FIG. 8 is a diagram for explaining the moment acting on the diaphragm piece 70 when the stem 50 presses the diaphragm piece 70 in an inclined state. FIGS. 9 and 10 are diagrams for explaining the difference in alignment performance due to differences in the depth of the inner bottom surface 71a of the recess 71 when the diaphragm piece 70 is inclined in response to a valve seat 44 that is slightly inclined due to assembly tolerances. For the purpose of explaining the configuration, the up and down directions are defined based on the drawings, but this direction is an example and is not limiting.

[0016] The diaphragm valve 1 according to the embodiment of the present invention includes an actuator 10, a valve body 30, and a connecting member 90 that connects the actuator 10 and the valve body 30 together. <About the actuator 10> The actuator 10 functions as a drive source for a stem 50 that drives the valve to open and close, and in this embodiment, an air actuator is used.

[0017] The actuator 10 has a case 11 in which a drive mechanism 20 including a piston 21 is housed. The drive mechanism 20 has a piston 21 that presses the stem 50 in the valve closing direction, a spring 24 that urges the piston 21 in the valve closing direction, and an air connection part 25 that serves as a connection part to an air supply source.

[0018] <Regarding the Piston 21 of the Actuator 10> The piston 21 has a first piston 22 and a second piston 23 that separate the air chambers 26 and 27 into two with a partition wall 12 provided in the case 11 in between.

[0019] The first piston 22 has a flange portion 22a that forms a flange-shaped wall that separates the inside of the case 11 above the partition wall 12, and a protruding shaft portion 22b that protrudes from the center of the upper surface of the flange portion 22a.

[0020] The second piston 23 has a flange portion 23a that forms a flange-shaped wall that separates the inside of the case 11 below the partition wall 12, a piston-side protruding shaft portion 23b that protrudes from the central upper surface of the flange portion 23a, and a stem-side protruding shaft portion 23c that protrudes from the central lower surface of the flange portion 23a.

[0021] The piston-side protruding shaft portion 23b protrudes into the air chamber 26 on the first piston 22 side through a through-hole 12a formed in the center of the partition wall 12, and is adapted to come into contact with the flange portion 22a of the first piston 22.

[0022] The stem-side protruding shaft portion 23c is in sliding contact with the inner surface of the guide hole 91 of the connecting member 90, which has a reduced diameter compared to the inner surface of the case 11 against which the flange portion 23a of the second piston 23 is in sliding contact, and its tip surface 23d is in contact with the stem 50.

[0023] In the first piston 22 and the second piston 23, O-rings 22c and 23e are fitted onto the outer peripheral surfaces of the flange portions 22a and 23a, the protruding shaft portion 22b, the piston-side protruding shaft portion 23b, and the stem-side protruding shaft portion 23c. The first piston 22 and the second piston 23 are capable of moving in the axial direction while maintaining an airtight seal between them and the inner peripheral surface of the case 11 via the O-rings 22c and 23e.

[0024] The first piston 22 and the second piston 23 have flow paths 28 formed therein that are connected to each other, forming a continuous flow path 28 that connects the air connection portion 25 to each of the air chambers 26 and 27. When the supply of air to the air chambers 26, 27 is stopped, the piston 21 is moved downward in the valve closing direction via the flange portion 22a of the first piston 22, which is pressed by the elastic force of the spring 24.

[0025] On the other hand, when air is supplied from the air supply source via air connection part 25, air fills each of air chambers 26, 27 through flow passages 28 formed in piston 21. As a result, piston 21 is moved upward in the valve opening direction against the elastic force of spring 24 by the pressure of the air filling air chambers 26, 27.

[0026] <About the valve body 30> The valve body 30 has a body 40, a stem 50, a diaphragm 60 that is movable toward and away from the valve seat 44 inside the body 40, a diaphragm piece 70, and a retaining member 80 that holds the diaphragm piece 70 so that it can move freely in the axial direction of the diaphragm piece 70.

[0027] <About Body 40> The body 40 is made of, for example, stainless steel and has a generally rectangular parallelepiped appearance. This body 40 is formed with a primary side flow path 41 on the upstream side through which the control fluid flows in, and a secondary side flow path 42 on the downstream side through which the control fluid flows out, and an annular valve seat 44 is provided on the opening edge surface that penetrates the primary side flow path 41 upward and opens toward the valve chamber 43.

[0028] <About Stem 50> The stem 50 has a generally cylindrical appearance, one end of which abuts against the stem-side protruding shaft portion 23c of the second piston 23, and the other end of which abuts against the diaphragm piece . The stem 50 is provided with two enlarged diameter portions 51 and 52 between one end and the other end thereof. The stem 50 is guided in the vertical direction by the outer peripheral surfaces of two upper and lower enlarged diameter portions 51, 52 spaced apart in the axial direction being in sliding contact with the inner peripheral surface of a guide hole 91 of the connecting member 90. In addition, in consideration of ease of disassembly and assembly, the stem 50 is arranged in the guide hole 91 with a clearance T1 so that the outer diameter of the enlarged diameter portions 51, 52 is slightly smaller than the diameter of the guide hole 91 and the stem 50 can be inserted and removed freely from the guide hole 91 (see Figures 4 and 5). The stem 50 also has an abutment portion 53 which has an outer diameter smaller than the enlarged diameter portions 51 and 52 and which protrudes further downward than the lower enlarged diameter portion 52 . This abutment portion 53 forms the tip of the stem 50 that is inserted into the recess 71 of the diaphragm piece 70. The tip of the stem 50 only needs to have an outer diameter and an axial length that allow it to be inserted into at least the recess 71 of the diaphragm piece 70. The contact portion 53 has a spherical tip surface 53 a that contacts the inner bottom surface 71 a of the recess 71 of the diaphragm piece 70 .

[0029] <About Diaphragm 60> The diaphragm 60 is made of a metal such as a nickel-cobalt alloy and has an approximately disk-like shape, and its outer peripheral edge 60a is clamped and fixed between a step 45 formed on the inner surface of the body 40 and the lower outer peripheral edge 80a of the retaining member 80. In this embodiment, when assembling the diaphragm 60 inside the body 40, the outer peripheral edge 60a of the diaphragm 60 is placed on the step 45 of the body 40, and then the lower end outer peripheral edge 80a of the retaining member 80 is placed on top of the diaphragm 60 so that it overlaps the outer peripheral edge 60a of the diaphragm 60. Then, with the outer peripheral edge 60a of the diaphragm 60 sandwiched between the step 45 and the retaining member 80, the connecting member 90 and the body 40 are screwed together, whereby the diaphragm 60 is sandwiched and fixed inside the body 40. The diaphragm 60, with its outer peripheral edge 60a fixed in this manner, is capable of elastically deforming such that the region inside the outer peripheral edge 60a can move toward and away from the valve seat 44.

[0030] <About Diaphragm Piece 70> As shown in FIGS. 3 and 7, the diaphragm piece 70 is, for example, a cylindrical metal member having one end surface countersunk to form a recess 71 having a circular outer shape. The recess 71 may be formed by a processing method other than the countersinking. For example, the recess 71 may be formed by die molding.

[0031] The inner bottom surface 71a of the recess 71 has a radius of curvature R2 greater than the radius of curvature R1 (see FIG. 6) of the tip surface 53a of the stem 50, and is spherical with the center portion as the lowest surface. Therefore, the stem 50 can move in an aligning manner along the inner bottom surface 71a of the recess 71 while maintaining the tip surface 53a in contact with the inner bottom surface 71a. As shown in FIG. 5, the recess 71 has a dimension set so as to form a gap S that allows the abutting portion 53 of the stem 50 to move in a centered manner within the recess 71.

[0032] Furthermore, the inner bottom surface 71a of the recess 71 is formed at a position as deep as possible while still ensuring a predetermined strength. In this embodiment, "as deep as possible while still ensuring a predetermined strength" refers to a strength determined by the relationship between the axial height H of the diaphragm piece 70 and the depth D of the inner bottom surface 71a, which is provided at a predetermined depth relative to the height H; for example, the depth D is set to have as large a ratio as possible to the height H as long as the durability required of the valve is met.

[0033] <Regarding the holding member 80> The holding member 80 holds the diaphragm piece 70 so that it can move freely in the axial direction of the diaphragm piece 70 . As described above, the holding member 80 also clamps and fixes the outer peripheral edge portion 60a of the diaphragm 60 from above the step portion 45 of the body 40. The holding member 80 has a generally cylindrical appearance, and is formed with a guide hole 81 in the central portion, which serves as the axis, for holding the diaphragm piece 70 movably in the axial direction. This diaphragm piece 70 is arranged in the guide hole 81 with a gap T2 that provides a slight radial play relative to the guide hole 81, taking into consideration the ease of disassembly and assembly, allowing it to be freely inserted and removed from the guide hole 81, and the amount of movement required for alignment (see Figure 5).

[0034] Here, the diaphragm piece 70 has a height H in the axial direction that allows it to be guided in the axial direction by the holding member 80 with the outer peripheral surface 70a of the side portion of the diaphragm piece 70 as a sliding surface. In other words, the diaphragm piece 70 has a height H required for being stably guided in the axial direction by the holding member 80 . The guide hole 81 of the holding member 80 is set to a dimension required to stably guide the outer peripheral side surface 70a of the diaphragm piece 70 having such height H in the axial direction. More specifically, the guide hole 81 is set at a height substantially equal to that of the diaphragm piece 70 in the axial direction.

[0035] <Regarding the connecting member 90> The connecting member 90 connects the actuator 10 and the valve body 30. The upper end of the connecting member 90 is screwed into the lower end of the case 11 of the actuator 10 and connected to the case 11. The lower end of the connecting member 90 is screwed into the upper end of the valve body 30 and connected to the body 40 . The lower end surface of the connecting member 90 is adapted to abut against the upper end surface of the retaining member 80, and as the fastening operation by screwing the connecting member 90 and the body 40 proceeds, the connecting member 90 pushes the retaining member 80 downward, thereby clamping and fixing the outer peripheral edge portion 60a of the diaphragm 60 between the step portion 45 of the body 40 and the lower end outer peripheral edge portion 80a of the retaining member 80.

[0036] <Moment acting on the diaphragm piece 70 when the stem 50 presses the diaphragm piece 70 in a tilted state> Next, with reference to FIG. 8, a description will be given of the moment acting on the diaphragm pieces 70, 170 when the stem 50 presses the diaphragm pieces 70, 170 in an inclined state. FIG. 8(a) shows a diaphragm piece 70 having a spherical inner bottom surface 71a, and FIG. 8(b) shows a diaphragm piece 170 having a flat inner bottom surface 171a. The diaphragm piece 70 shown in Figure 8(a) has a spherical inner bottom surface 71a whose outer periphery is equal in depth to the flat inner bottom surface 171a of Figure 8(b), and whose depth increases from the outer periphery to the center in a spherical shape with the lowest point. In addition, in order to simplify the explanation, the diaphragm 60 arranged between the diaphragm pieces 70, 170 and the valve seat 44 is omitted from Figures 8(a) and (b), and the force acting on the diaphragm 60 is not explained.

[0037] As shown in FIG. 8, when the stem 50 is tilted and presses against the inner bottom surfaces 71a, 171a of the diaphragm pieces 70, 170, a downward force F tilted relative to the vertical direction acts on the inner bottom surface 71a. The force F acting in this tilted direction is resolved into a horizontal force F1 and a vertical force F2. Therefore, for example, a moment acts on the diaphragm pieces 70, 170 to rotate them counterclockwise with the left side of the valve seat 44 in FIG. 8 as a fulcrum. When such a moment acts on the diaphragm pieces 70, 170, the diaphragm pieces 70, 170 move away from the fulcrum on the right side of the valve seat 44 in the figure, and the force with which the diaphragm pieces 70, 170 press against the valve seat 44 becomes uneven.

[0038] Here, if the vertical distance from the valve seat 44 serving as the fulcrum to the position where the stem 50 abuts against the inner bottom surfaces 71a and 171a is r, the moment M is expressed by the formula M=F1×r.

[0039] In this case, in the configuration of FIG. 8(a) in which the inner bottom surface 71a of the diaphragm piece 70 is formed in a spherical shape, the moment M1 acting on the diaphragm piece 70 is M1=F1×r1. In the configuration of FIG. 8(b) in which the inner bottom surface 171a of the diaphragm piece 170 is formed flat, the moment M2 acting on the diaphragm piece 170 is M2=F1×r2. Here, due to the relationship r2>r1, M2>M1. In other words, compared to diaphragm piece 170 having a flat inner bottom surface 171a, diaphragm piece 170 having a spherical inner bottom surface 71a can reduce the moment acting on diaphragm pieces 70, 170 and reduce the variation in the force pressing diaphragm pieces 70, 170 against valve seat 44, thereby improving the alignment performance of diaphragm pieces 70, 170 relative to valve seat 44.

[0040] From this, the inventors of the present application have discovered that the smaller the moment acting on diaphragm piece 70, the better the alignment performance, and that in order to reduce this moment, the vertical distance r from valve seat 44, which serves as the fulcrum, to the position where stem 50 presses against inner bottom surface 71a must be reduced. In other words, they discovered that the depth of inner bottom surface 71a of diaphragm piece 70 can be increased, and that the alignment performance can be further improved by making inner bottom surface 71a spherical so that the area near the axis of inner bottom surface 71a of diaphragm piece 70 is the lowest surface. The inventors of the present application also discovered that by making the inner bottom surface 71a of the diaphragm piece 70 spherical, it becomes possible to insert the tip of the stem 50 deeper into the recess 71 of the diaphragm piece 70, thereby making it possible to make the device dimensions in the axial direction of the stem 50 more compact.

[0041] Next, using Figures 9 and 10, we will explain the difference in alignment performance due to differences in the depth of the inner bottom surface 71a of the recess 71 when the diaphragm piece 70 is tilted in response to the valve seat 44 being slightly tilted due to assembly tolerances.

[0042] First, with reference to FIG. 9, it will be explained that when the diaphragm piece 70 is tilted, the tilt of the inner bottom surface 71a pressed by the stem 50 changes depending on the depth of the inner bottom surface 71a. FIG. 9 shows the diaphragm piece 70 tilted in response to the valve seat 44 being slightly tilted due to assembly tolerances. The broken lines L1 to L4 shown in the drawing indicate a plurality of inner bottom surfaces 71a that are changed to different depths with respect to the diaphragm piece 70 having a predetermined height. Further, dashed line C2 indicates the intersections with dashed lines L1 to L4 as positions where the stem 50 presses against the inner bottom surfaces 71a having different depths. Moreover, solid lines S1 to S4 indicate the inclination of the inner bottom surface 71a at the position where the stem 50 presses. Positions P1 to P4 indicate the lowest positions of the inner bottom surfaces 71a having different depths in the state shown in the drawing. Moreover, the solid line C1 indicates the axis of the diaphragm piece 70.

[0043] As shown in Figure 9, when the diaphragm piece 70 is slightly tilted, forming the inner bottom surface 71a of the diaphragm piece 70 at a deeper position reduces the inclination of the inner bottom surface 71a at the pressing position of the stem 50 relative to the inner bottom surface 71a. It can also be seen that the deeper the inner bottom surface 71a is formed, the closer the bottommost positions P1 to P4 of the inner bottom surface 71a are to the axis C1 of the diaphragm piece .

[0044] Such a change in the inclination of the inner bottom surface 71a at the pressing position of the stem 50 and a change in the bottommost position of the inner bottom surface 71a due to a difference in the depth of the inner bottom surface 71a brings about the following differences in alignment performance. That is, as shown in Figure 10(a), for a diaphragm piece 70 in which the inner bottom surface 71a is formed at a shallow position, the inclination of the inner bottom surface 71a that contacts the stem 50 is greater than in the others, and the lowest position P1 of the inner bottom surface 71a of the diaphragm piece 70 is located farther from the axis C1 than in the others. As a result, the stem 50 becomes more likely to slide along the inner bottom surface 71a toward the lowest position P1, and is more likely to be moved along the inner bottom surface 71a toward the lowest position P1, which is farther away from the axis C1 of the diaphragm piece 70.As a result, the pressing position of the stem 50 against the inner bottom surface 71a moves to a position farther away from the axis C1 of the diaphragm piece 70.

[0045] In this way, when the pressing position of the stem 50 moves to a position farther away from the axis C1 of the diaphragm piece 70, the stem 50 presses the diaphragm piece 70 at a position farther away from the axis C1 of the diaphragm piece 70 than at other positions. Therefore, for a diaphragm piece 70 in which the inner bottom surface 71a is formed at a shallow or deep position, the load pressing against the valve seat 44 through the diaphragm piece 70 becomes uneven compared to one in which the inner bottom surface 71a is formed at a deeper position, resulting in inferior alignment performance.

[0046] On the other hand, as shown in Figure 10(b), for diaphragm pieces 70 in which the inner bottom surface 71a is formed at a deeper position, the inclination of the inner bottom surface 71a that contacts the stem 50 is smaller than in the others, and the lowest position P4 of the inner bottom surface 71a of the diaphragm piece 70 is closer to the axis C1 than in the others. Therefore, when the stem 50 is moved on the inner bottom surface 71a toward the lowest position P4, the pressing position of the stem 50 against the inner bottom surface 71a is more likely to move to a position closer to the axis C1 of the diaphragm piece 70, making it possible to make the load pressing against the valve seat 44 via the diaphragm piece 70 more uniform than in other cases. Therefore, the alignment performance is superior to that of a valve having an inner bottom surface 71a formed at a shallower position.

[0047] <Diaphragm valve 1 opening and closing operation> Next, the valve opening and closing operation of the diaphragm valve 1 will be described. In the diaphragm valve 1 in the valve open state shown in FIG. 1, the piston 21 has moved upward against the downward resilient force of the spring 24 by the driving force of the air filled in the air chambers 26 and 27 . In this valve open state, the diaphragm 60 is released from the pressing force of the stem 50 via the diaphragm piece 70 and is in a neutral elastic state, and bulges upward to separate from the valve seat.

[0048] When the air supply to the diaphragm valve 1 in this open state is stopped, the air is discharged from each of the air chambers 26, 27, and the force lifting the piston 21 against the elastic force of the spring 24 weakens, and the piston 21 is pushed downward by the elastic force of the spring 24. Then, the stem 50, which is in contact with the stem-side protruding shaft portion 23c of the second piston 23, is pushed downward as the piston 21 descends. As the stem 50 moves downward while being guided by the guide hole 91 of the connecting member 90, the spherical tip surface 23d presses against the inner bottom surface 71a of the diaphragm piece 70, forcing the diaphragm piece 70 downward. At this time, the diaphragm piece 70 moves downward while being guided in the axial direction by the holding member 80 . Here, the diaphragm piece 70 is set at a height that allows it to be stably guided in the axial direction by the holding member 80, and therefore moves downward while being stably guided by the holding member 80. When the diaphragm piece 70 is pushed downward in this manner, the diaphragm 60 is pressed downward and the central portion is elastically deformed to be recessed, thereby being tightly fitted to the valve seat 44, and the diaphragm valve 1 is in the valve closed state shown in Figure 2.

[0049] Here, when the stem 50 presses the diaphragm piece 70 downward while tilted, a moment acts on the diaphragm piece 70 as described above. However, because the inner bottom surface 71a of the diaphragm piece 70 is spherical, the position at which the stem 50 presses the inner bottom surface 71a can be located deeper in the diaphragm piece 70, and the vertical distance to the valve seat 44 can be kept smaller. As a result, the moment acting on the diaphragm piece 70 can be kept small, thereby improving alignment performance.

[0050] Furthermore, if the valve seat 44 is tilted due to assembly tolerances or the like, the diaphragm piece 70 presses against the valve seat 44 in a tilted state in accordance with the tilt of the valve seat 44 . In this case, as described above, by forming the inner bottom surface 71a of the diaphragm piece 70 at a deeper position, the pressing position of the stem 50 against the inner bottom surface 71a can be positioned closer to the axis C1 of the diaphragm piece 70, thereby further improving the alignment performance.

[0051] <Effects of the embodiment> As described above, in the diaphragm valve 1 according to the embodiment, the tip surface 53a of the stem 50 is spherical, the diaphragm piece 70 is provided with a recess 71 into which the abutment portion 53, which is the tip of the stem 50, is interposed, and the inner bottom surface 71a of the recess 71 has a radius of curvature R2 that is larger than the radius of curvature R1 of the tip surface 53a of the stem 50, and is spherical with the center as the lowest surface. As a result, when the tip surface 53a of the stem 50 presses against the inner bottom surface 71a of the recess 71 of the diaphragm piece 70 to close the valve, the stem 50 moves toward the bottommost surface of the inner bottom surface 71a while abutting the spherical tip surface 53a against the spherical inner bottom surface 71a of the recess 71. As a result, the position at which the stem 50 presses against the diaphragm piece 70 is closer to the valve seat 44, and when the stem 50 tilts and presses against the internal bottom surface 71a of the diaphragm piece 70, which is separate from the stem 50, the moment that rotates the diaphragm piece 70 is kept small, preventing the diaphragm piece 70 from tilting so much that the alignment performance is reduced due to play in the assembly tolerances. Therefore, in a configuration with an assembly tolerance that allows for free disassembly and assembly, even if the thrust force that seals the valve seat 44 is kept small, the alignment performance of the diaphragm piece 70 can be improved and the sealing performance of the valve seat 44 can be maintained, thereby further improving the sealing performance of the valve seat 44.

[0052] Furthermore, in the diaphragm valve 1 according to the embodiment, the inner bottom surface 71a of the recess 71 of the diaphragm piece 70 is formed at a position as deep as possible while ensuring a predetermined strength, so that the tip surface 53a of the stem 50 can press against the inner bottom surface 71a at a deeper position in the recess 71, and the stem 50 presses against the inner bottom surface 71a at a position closer to the valve seat 44. Therefore, the moment acting on the diaphragm piece 70 when the stem 50 tilts and presses against the inner bottom surface 71a of the recess 71 can be kept small while ensuring the strength of the diaphragm piece 70. Furthermore, the abutment portion 53, which is the tip of the stem 50, can be inserted deeper into the recess 71 of the diaphragm piece 70, which results in a more compact device dimension in the axial direction of the stem 50. Furthermore, even if the valve seat 44 is tilted due to assembly tolerances, the pressing position of the stem 50 against the inner bottom surface 71a can be positioned close to the axis C1 of the diaphragm piece 70, thereby further improving alignment performance.

[0053] Furthermore, the diaphragm valve 1 according to the embodiment has a holding member 80 that holds the diaphragm piece 70 so that it can move freely in the axial direction, and the diaphragm piece 70 has an axial height H that allows it to be guided in the axial direction by the holding member 80, with the side outer peripheral surface 70a of the diaphragm piece 70 acting as a sliding surface. This ensures a stable height of the sliding surface for guiding the diaphragm piece 70 and the holding member 80 in the axial direction of the diaphragm piece 70, while also positioning the abutment portion 53, which is the tip of the stem 50, deeper into the recess 71 of the diaphragm piece 70, so that the position at which the stem 50 presses the diaphragm piece 70 is closer to the valve seat 44. Therefore, the diaphragm piece 70 can be stably guided so as to be movable in the axial direction, while the moment acting on the diaphragm piece 70 can be kept small.

[0054] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present disclosure.

[0055] For example, in the above embodiment, the diaphragm valve is of a normally closed type, but the diaphragm valve may be of a normally open type. The diaphragm valve may be an automatic type using an actuator, or a manual type using an operating handle.

[0056] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive, and the above embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims. [Explanation of symbols]

[0057] 1 diaphragm valve 44 Valve seat 50 stem 53a Tip surface 60 diaphragm 70 Diaphragm piece 70a Side outer surface 71 Recess 71a Internal bottom 80 Retaining member

Claims

1. A diaphragm valve has a diaphragm piece disposed so as to be able to abut against the tip of a stem, and the diaphragm is brought into a valve-closed state by abutting against a valve seat via the diaphragm piece being pushed in a valve-closing direction by the stem, The tip surface of the stem is spherical, the diaphragm piece is provided with a recess into which the tip end of the stem is inserted, A diaphragm valve characterized in that the inner bottom surface of the recess has a radius of curvature larger than the radius of curvature of the tip surface of the stem and is spherical with the center being the lowest surface.

2. 2. The diaphragm valve according to claim 1, wherein the inner bottom surface of the recess is formed at a position as deep as possible to ensure a predetermined strength.

3. a holding member that holds the diaphragm piece so as to be movable in the axial direction of the diaphragm piece; 3. The diaphragm valve according to claim 1, wherein the diaphragm piece has a height in the axial direction that allows the diaphragm piece to be guided in the axial direction by the holding member, with the outer peripheral surface of the side of the diaphragm piece acting as a sliding surface.

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