Diaphragm valve

Abstract

This diaphragm valve comprises: a valve body (13) that has a valve chamber (19) and a valve seat (21) which is formed around an opening from an inlet flow path (25) to the valve chamber (19); a diaphragm (15); and a driving part that has a diaphragm holding part (57). The diaphragm (15) includes a valve body part (51) that moves toward and away from the valve seat (21), a membrane part (53), an outer peripheral edge part (55), and an annular bridge part (59) that is more rigid than the membrane part (53) and that connects the outer peripheral edge part (55) and the membrane part (53). The outer peripheral edge part (55) includes a flange part (55a) and a cylindrical collar part (55b), and the diaphragm holding part (57) has a protruding part (57a) that protrudes toward the valve seat (21). The protruding part (57a) sandwiches at least a part of the collar part (55b) of the diaphragm between the outer peripheral surface of the protruding part (57a) and the inner peripheral surface of the valve chamber (19).

Description

Diaphragm valve

[0001] The present invention relates to a diaphragm valve comprising a valve body portion that moves toward and away from a valve seat, a membrane portion that extends outward from the outer circumferential surface of the valve body portion and is deformable in the direction of the movement axis, and an outer peripheral edge portion provided on the outside of the membrane portion.

[0002] For example, when controlling the flow rate of chemicals used in semiconductor manufacturing equipment, a diaphragm valve is often used, which has a diaphragm with a membrane that separates the valve chamber through which the chemical flows from the drive unit and a valve body supported in the center of the membrane. A diaphragm valve generally comprises a valve body having an inlet passage, an outlet passage and a valve chamber communicating with them, a diaphragm positioned to close the opening above the valve chamber, and a drive unit attached to the top of the valve body to drive the diaphragm. In such a diaphragm valve, the diaphragm is supported by the valve body, and the valve body, which is supported by the valve body via the membrane of the diaphragm, is reciprocated along the axis of movement by the drive unit, causing the valve body to move toward and away from the valve seat formed around the opening from the passage to the valve chamber, thereby opening and closing the diaphragm valve.

[0003] In the diaphragm valve as described above, in order to prevent the outer peripheral edge of the diaphragm in contact with the valve body from deforming during reciprocation of the valve body along the movement axis direction, the outer peripheral edge is pressed against and fixed to the valve body by the bottom of the drive unit, or by the drive unit via a diaphragm retainer configured as a separate member, and in many cases has a structure in which it is directly or indirectly clamped between the valve body and the drive unit. In addition, in order to improve the sealing performance between the diaphragm and the valve body, as described in Patent Document 1, a structure has been proposed in which a horizontally extending horizontal support portion and a vertically extending vertical support portion are provided on the outer peripheral edge of the diaphragm, and the horizontal support portion and the vertical support portion are clamped between the drive unit or the diaphragm retainer and the valve body. Specifically, a horizontally extending horizontal support portion and a vertically extending vertical support portion are provided on the outer peripheral edge of the diaphragm, and a cylindrical protruding portion protruding from the bottom of the drive unit or the diaphragm retainer is provided on the bottom of the drive unit or the diaphragm retainer, the horizontal support portion of the outer peripheral edge of the diaphragm is placed on the periphery of the upper opening of the valve chamber of the valve body, and the horizontal support portion is inserted into the valve chamber, the horizontal support portion is clamped between the peripheral surface of the upper opening of the valve chamber of the valve body and the bottom of the drive unit or the diaphragm retainer, and the vertical support portion is clamped between the inner peripheral surface of the valve chamber and the outer peripheral surface of the protruding portion.

[0004] When a diaphragm valve is used in a line for circulating a chemical solution, the diaphragm is in contact with the chemical solution, so chemical resistance is also required. In addition, in a diaphragm valve, the valve body is moved in the movement axis direction to bring it into contact with and separate from the valve seat, so flexibility and bending durability are required for the membrane portion that supports the valve body so that the membrane portion can follow the movement of the valve body. For this reason, the diaphragm is generally formed of polytetrafluoroethylene (PTFE) which has excellent chemical resistance, high flexibility and bending durability, and the membrane portion is generally thinned.

[0005] Japanese Patent No. 6681723

[0006] As described above, in a configuration where horizontal and vertical support portions of the outer edge are sandwiched between the drive unit and the valve body, if the membrane portion is thinned, it becomes more prone to deformation. Therefore, as the valve body reciprocates along the direction of the movement axis, the membrane portion deforms to conform to the shape of the valve chamber side surface of the bottom of the drive unit and the protrusion of the diaphragm retainer. At this time, the connection portion between the membrane portion and the outer edge portion that is in contact with the valve body slides against the valve body, and particles may be generated due to frictional wear. Since the contact point between the membrane portion and the valve body near the outer edge portion faces the wetted area inside the valve chamber, if particles are generated at the sliding point, the particles will be mixed into the fluid flowing inside the diaphragm valve. PTFE is prone to generating dust, and in particular, when the diaphragm is formed from PTFE, the above-mentioned problem of particle generation near the outer edge portion is more likely to occur, from the viewpoint of ensuring the flexibility of the membrane portion and having excellent chemical resistance.

[0007] In fields requiring high levels of cleanliness, particles generated within diaphragm valves can pose a problem. For example, in the semiconductor wafer manufacturing process, particles, various metals, polymer compounds, and other contaminants can remain on or adhere to the semiconductor wafer, significantly impacting its quality. Therefore, semiconductor wafers are cleaned using cleaning solutions during the manufacturing process. However, if particles are generated in the diaphragm valves used in the semiconductor wafer manufacturing process, and the cleaning solution containing these particles is discharged from the diaphragm valve and used to clean the semiconductor wafer, it can lead to insufficient cleaning and a decrease in the cleanliness of the semiconductor wafer.

[0008] Therefore, the object of the present invention is to suppress the generation of particles from the diaphragm due to sliding between the diaphragm and the valve body caused by the deformation of the diaphragm, in order to solve the problems present in the prior art.

[0009] In view of the above objectives, the present invention provides a valve body having a first passage, a second passage, a valve chamber through which the first and second passages communicate, and a valve seat formed around an opening from the first passage to the valve chamber; a diaphragm; and a drive unit having a diaphragm retaining portion at its bottom and driving the diaphragm, wherein the diaphragm includes a valve body portion that moves toward and away from the valve seat, an annular membrane portion extending outward from the outer circumferential surface of the valve body portion and deformable in the direction of the movement axis, and an annular outer peripheral edge portion provided on the outside of the membrane portion, and the outer peripheral edge portion of the diaphragm is sandwiched between the valve body and the diaphragm retaining portion. The present invention provides a diaphragm valve in which the diaphragm has higher rigidity than the membrane portion and further includes an annular bridge portion that extends inward from the outer peripheral edge portion and connects the outer peripheral edge portion and the membrane portion, the outer peripheral edge portion includes an annular flange portion and a cylindrical collar portion whose one end in the direction of the central axis is connected to the inner peripheral edge end of the flange portion, the diaphragm retaining portion has a cylindrical projection portion that protrudes from the bottom surface of the drive portion toward the valve seat, and when the projection portion is inserted into the valve chamber, at least a part of the collar portion of the diaphragm is sandwiched between the outer peripheral surface of the projection portion and the inner peripheral surface of the valve chamber.

[0010] In the diaphragm valve described above, an annular bridge portion is provided between the outer peripheral edge of the diaphragm and the membrane portion. The annular bridge portion extends inward from the outer peripheral edge, which is sandwiched between the valve body and the diaphragm retaining portion, and has higher rigidity than the membrane portion. The membrane portion is not directly connected to the collar portion of the outer peripheral edge, but is connected to the annular bridge portion, which has higher rigidity than the membrane portion. Furthermore, the collar portion of the outer peripheral edge is sandwiched between the inner circumferential surface of the valve chamber of the valve body and the outer circumferential surface of the protrusion of the diaphragm retaining portion. Therefore, deformation due to deformation of the membrane portion is less likely to occur at the outer peripheral edge and at the connection portion between the outer peripheral edge and the annular bridge portion. In addition, since the membrane portion is not in contact with the valve body, it does not come into contact with the valve body due to deformation of the membrane portion. As a result, sliding between the diaphragm and the valve body due to deformation of the membrane portion is reduced, making it possible to suppress the generation of particles.

[0011] In the diaphragm valve described above, it is preferable that the projection is configured such that when the projection is inserted into the valve chamber, at least a portion of the projection and the annular bridge portion abut in the direction of the movement axis. In this case, it is even more preferable that the annular bridge portion extends inward from the other end of the collar portion in a tapered manner toward the side away from the valve seat, and that the projection has an inclined surface that abuts against the annular bridge portion. With this configuration, even if a force acts from the membrane portion toward the annular bridge portion toward the valve seat when the membrane portion moves toward the valve seat, the deformation of the annular bridge portion toward the valve seat is prevented by the diaphragm retaining portion. As a result, sliding between the diaphragm and the valve body due to the deformation of the membrane portion is further reduced, and the generation of particles can be further suppressed.

[0012] In one embodiment, an annular projection is provided on the outer circumferential surface of the collar portion, and the collar portion of the diaphragm can be sandwiched between the outer circumferential surface of the projection and the inner circumferential surface of the valve chamber while the annular projection is fitted into an annular groove provided on the inner circumferential surface of the valve chamber.

[0013] It is preferable that the annular bridge portion is formed to be thicker than the film portion.

[0014] In one embodiment, the first flow path and the second flow path may be configured to open to the bottom of the valve chamber.

[0015] In the diaphragm valve of the present invention, the membrane portion is connected to an annular bridge portion which has higher rigidity than the membrane portion. Therefore, deformation due to deformation of the membrane portion is less likely to occur at the outer edge and the connection portion between the outer edge and the annular bridge portion. Furthermore, the membrane portion of the diaphragm does not come into contact with the valve body. Because the membrane portion of the diaphragm does not come into contact with the valve body in this way, sliding between the diaphragm and the valve body due to deformation of the membrane portion is reduced, making it possible to suppress the generation of particles.

[0016] This is a longitudinal cross-sectional view showing a diaphragm valve according to one embodiment of the present invention. This is an enlarged cross-sectional view of a key part showing the diaphragm valve shown in Figure 1 with the valve body seated on the valve seat. This is an enlarged cross-sectional view of a key part showing the diaphragm and diaphragm retainer of a diaphragm valve according to another embodiment.

[0017] Hereinafter, an embodiment of a diaphragm valve equipped with a diaphragm according to the present invention will be described with reference to the drawings.

[0018] First, with reference to Figures 1 and 2, the overall configuration of a diaphragm valve 11 equipped with a diaphragm according to one embodiment of the present invention will be described. The diaphragm valve 11 comprises a valve body 13, a diaphragm 15, and a drive unit 17 for driving the diaphragm 15, the drive unit 17 being mounted on the upper part of the valve body 13.

[0019] The valve body 13 has a valve chamber 19 formed in the upper center, and a first flow path and a second flow path that communicate with the valve chamber 19. The valve chamber 19 has an annular valve seat 21 formed around the opening from the first flow path to the valve chamber 19, to which the valve body portion 51 of the diaphragm 15 (described later) moves toward and toward. In the illustrated embodiment, the first flow path is an inlet flow path 25 that extends from an inlet 23 formed on one side of the valve body 13 and opens in the center of the bottom of the valve chamber 19, and the second flow path is an outlet flow path 29 that extends from an outlet 27 formed on the other side of the valve body 13 and opens on the side of the valve chamber 19, and the annular valve seat 21 is formed around the opening from the inlet flow path 25 to the valve chamber 19.

[0020] The drive unit 17 comprises a drive unit housing 31 attached to the upper part of the valve body 13 and having a mechanism housing space formed inside, a cover member 33 attached to the upper part of the drive unit housing 31, a stem 35 connected to the diaphragm 15, and a drive mechanism housed in the mechanism housing space and driving the stem 35. The drive mechanism may be operated by fluid pressure such as air or working fluid, or it may be operated manually. In the illustrated embodiment, a cylinder section is formed as a mechanism housing space within the drive unit housing 31, and the drive mechanism consists of a piston 37 housed in the cylinder section and a coil spring 39 as a biasing member.

[0021] The piston 37 has a piston body 37a that is slidably housed within the cylinder portion of the drive unit housing 31, and a guide shaft 37b that extends upward from the upper surface of the piston body 37a. A stem 35 is connected to the piston body 37a so as to extend downward from the piston body 37a. The outer circumferential surface of the piston body 37a is in vertically slidable contact with the inner circumferential surface of the cylinder portion, dividing the internal space of the cylinder portion into an upper space 41 enclosed by the upper surface of the piston body 37a, the inner circumferential wall of the cylinder portion, and the ceiling surface of the cylinder portion (i.e., the lower surface of the cover member 33), and a lower space 43 enclosed by the lower surface of the piston body 37a, the inner circumferential wall of the cylinder portion, and the bottom surface of the cylinder portion (i.e., the bottom of the drive unit housing 31). The guide shaft 37b is inserted into a through hole 33a provided through the cover member 33 and is designed to guide the vertical movement of the piston 37. The stem 35, which is connected to the piston body 37a, is slidably inserted into a through hole 31a that penetrates the bottom of the drive unit housing 31, and extends to the valve chamber 19, with its tip connected to the diaphragm (more specifically, the valve body 51, which will be described later).

[0022] In this embodiment, a vent 33b is formed in the lid member 33 that communicates with the cylinder section that partitions the upper space 41, allowing ventilation between the upper space 41 and the outside through the vent 33b. In addition, a working fluid supply port 45 is formed on the side of the drive unit housing 31 that communicates with the bottom of the cylinder section that partitions the lower space 43, allowing working fluid to be supplied into the lower space 43 from the working fluid supply port 45. Furthermore, a coil spring 39 is positioned in a compressed state between the lower surface of the lid member 33 (the ceiling surface of the cylinder section) and the upper surface of the piston body 37a.

[0023] The drive unit 17 is attached to the valve body 13 such that the guide shafts 37b of the stem 35 and piston 37 are perpendicular to the surface of the valve seat 21. O-rings 47 and 49 are fitted to the outer circumferential surface of the piston body 37a and the outer circumferential surface of the stem 35, which is inserted into the through hole 31a at the bottom of the drive unit housing 31. This configuration prevents the working fluid supplied to the lower space 43 from leaking out from between the outer circumferential surface of the piston body 37a and the inner circumferential surface of the cylinder portion of the drive unit housing 31, and between the outer circumferential surface of the stem 35 and the inner circumferential surface of the through hole 31a at the bottom of the drive unit housing 31 (i.e., the bottom surface of the cylinder portion).

[0024] The diaphragm 15 is positioned to close the upper opening of the valve chamber 19 (hereinafter referred to as the upper opening). As shown in detail in Figure 2, the diaphragm 15 includes a valve body portion 51 located in the center and moving toward and toward the valve seat 21, an annular membrane portion 53 formed to be thin in thickness to facilitate bending and supporting the central valve body portion 51, and an annular outer peripheral edge portion 55 provided on the outer periphery of the membrane portion 53. The valve body portion 51 has a bottom surface 51a provided at the end on the valve seat 21 side in the direction of the movement axis, and an annular raised portion 51b that protrudes from the bottom surface 51a and has a valve seat contact surface at its apex that moves toward and toward the valve seat 21. The membrane portion 53 is formed to extend radially outward from the outer periphery of the upper end of the valve body portion 51, and the outer periphery of the membrane portion 53 has a generally circular shape. The diaphragm 15 is fixed to the valve body 13 by sandwiching its outer peripheral edge 55 between the valve body 13 and the diaphragm retaining portion 57 provided at the bottom of the drive unit 17 (specifically, its drive unit housing 31), allowing the valve body 51 to move in the direction of the movement axis via the membrane portion 53 to move toward and away from the valve seat 21. The movement axis extends in a direction perpendicular to the surface of the valve seat 21 (i.e., the vertical direction in Figure 1).

[0025] In the illustrated embodiment, the membrane portion 53 is formed to extend radially outward from the outer circumference of the upper end of the valve body portion 51. At least a portion of the outer peripheral edge portion 55 provided on the outer circumference of the membrane portion 53 is sandwiched between the upper surface of the area surrounding the upper opening of the valve chamber 19 of the valve body 13 and the diaphragm retaining portion 57 of the drive unit 17, and the diaphragm 15 partitions the space between the valve chamber 19 and the drive unit 17 while supporting the valve body portion 51 above the valve chamber 19 via the membrane portion 53. Furthermore, the valve body portion 51 has a shape in which a frustoconical portion is continuously formed at the upper end of a cylindrical portion, that is, a weight shape with a tapered upper end, and its bottom surface 51a (valve seat contact surface) is positioned to face the valve seat 21, and moves in the direction of the movement axis to approach and move away from the valve seat 21. However, the diaphragm 15 is not limited in shape as long as its outer peripheral edge 55 is fixed to the valve body 13 by being sandwiched between the valve body 13 and the diaphragm retaining portion 57, and the valve body portion 51 moves toward and away from the valve seat 21 via the membrane portion 53 to open and close the opening from the inlet passage 25 to the valve chamber 19.

[0026] The diaphragm retaining portion 57 does not need to be integrally formed with the valve body 13, as long as its outer peripheral edge 55 can be sandwiched between the valve body 13 and the diaphragm retaining portion 57. For example, the diaphragm retaining portion 57 may be formed as a separate component from the valve body 13, and sandwiched between the drive unit housing 31 and the valve body 13 with its outer peripheral edge 55 positioned between the valve body 13 and the diaphragm retaining portion 57. In this case, the diaphragm retaining portion 57 may be formed from a synthetic resin material or from an elastic material.

[0027] As shown in detail in Figure 2, the outer peripheral edge portion 55 includes an annular flange portion (horizontal support portion) 55a located at the outermost edge of the diaphragm 15 and extending horizontally, and a cylindrical collar portion (vertical support portion) 55b extending from the inner peripheral edge end of the flange portion 55a along a central axis parallel to the moving axis (an axis extending vertically in Figure 1). The diaphragm retaining portion 57 is configured to include a cylindrical projection portion 57a ​​that protrudes from the bottom surface of the drive unit housing 31 (more specifically, the center of the bottom of the diaphragm retaining portion 57) toward the valve seat 21. When the drive unit 17 is attached to the valve body 13 and the protruding portion 57a ​​of the diaphragm retaining portion 57 is inserted into the upper opening of the valve chamber 19 of the valve body 13, the flange portion 55a is sandwiched between the bottom surface portion of the diaphragm retaining portion 57 located outside the protruding portion 57a ​​and the upper surface of the surrounding area of ​​the upper opening of the valve chamber 19 of the valve body 13, and the collar portion 55b is sandwiched between the outer circumferential surface of the protruding portion 57a ​​of the diaphragm retaining portion 57 and the inner circumferential surface of the upper opening of the valve chamber 19 of the valve body 13, thereby fixing the diaphragm 15 to the valve body 13.

[0028] Furthermore, the outer surface of the collar portion 55b may be provided with an annular projection 55c having a semicircular cross-section, and the inner circumferential surface of the upper opening of the valve chamber 19 of the valve body 13 may be provided with an annular groove 13a having a trapezoidal cross-section. It is preferable that the annular projection 55c be formed to be slightly larger than the annular groove 13a. With this configuration, when the annular projection 55c on the outer surface of the collar portion 55b is engaged with the annular groove 13a on the inner circumferential surface of the valve chamber 19, and the protruding portion 57a ​​of the diaphragm retaining portion 57 of the drive unit 17 is inserted into the valve chamber 19 of the valve body 13 to attach the drive unit 17 to the upper part of the valve body 13, the annular projection 55c deforms and tightly fits into the annular groove 13a, thereby improving the sealing performance between the diaphragm 15 and the valve body 13.

[0029] In this embodiment, as shown in Figures 1 and 2, an annular projection 55c is provided on the collar portion 55b of the outer peripheral edge 55 of the diaphragm 15, and the annular projection 55c is engaged with an annular groove 13a provided on the inner circumferential surface of the valve chamber 19 of the valve body 13. However, an annular groove may also be provided on the collar portion 55b of the diaphragm 15, and an annular projection may be provided on the inner circumferential surface of the valve chamber 19, and the annular projection provided on the inner circumferential surface of the valve chamber 19 may be engaged with the annular groove provided on the collar portion 55b.

[0030] The diaphragm 15 further includes an annular bridge portion 59 extending between the annular membrane portion 53 and the annular outer peripheral edge portion 55, so that the membrane portion 53 is connected to and supported by the outer peripheral edge portion 55 via the annular bridge portion 59. The annular bridge portion 59 extends inward from the inner peripheral edge end of the outer peripheral edge portion 55 and has higher rigidity than the membrane portion 53. That is, in the region between the valve body portion 51 and the outer peripheral edge portion 55, the annular bridge portion 59 is the portion with relatively high rigidity and is less prone to deformation, while the membrane portion 53 is the portion with relatively low rigidity and is easily deformable. The annular bridge portion 59 may be made from a material with higher rigidity than the membrane portion 53 to increase its rigidity, or the annular bridge portion 59 may be made thicker than the membrane portion 53 by forming the diaphragm 15 so that it is thicker than the membrane portion 53. The rigidity of the annular bridge portion 59 may be increased compared to the membrane portion 53 by providing ribs or the like on the surface of the annular bridge portion 59 that is farther from the valve seat 21.

[0031] Since the annular bridge portion 59 has higher rigidity than the membrane portion 53, when the valve body portion 51 is driven in the direction of the movement axis by the drive unit 17 to move toward and away from the valve seat 21 in order to open and close the diaphragm valve 11, and the membrane portion 53 deforms in the direction of the movement axis of the valve body portion 51, deformation of the annular bridge portion 59 accompanying the deformation of the membrane portion 53 is less likely to occur, and sliding of the connection portion between the annular bridge portion 59 and the outer peripheral edge portion 55 (specifically, the collar portion 55b) against the inner circumferential surface of the upper opening of the valve chamber 19 is suppressed. As a result, the generation of particles due to sliding is suppressed.

[0032] In the diaphragm valve 11, when the drive unit 17 is attached to the upper part of the valve body 13 and the protruding portion 57a ​​of the diaphragm retaining portion 57 is inserted into the upper opening of the valve chamber 19 of the valve body 13, it is preferable that the protruding portion 57a ​​contacts at least a part of the surface on the valve chamber side (opposite to the wetted surface) of the annular bridge portion 59 in the direction of the movement axis of the valve body portion 51 (up and down direction in the figure).

[0033] In conventional diaphragm valves, when the membrane portion 53 is directly connected to the outer peripheral edge portion 55, the membrane portion deforms along the shape of the valve chamber side surface of the bottom of the drive unit and the protrusion of the diaphragm retainer when the valve body portion 51 reciprocates along the direction of the movement axis. At this time, the connection portion of the membrane portion 53 with the outer peripheral edge portion 55 that is in contact with the inner circumferential surface of the valve chamber 19 slides against the inner circumferential surface of the valve chamber 19, and particles are generated due to frictional wear. In other words, when the membrane portion 53 deforms in the direction of the movement axis toward the drive unit 17 and returns toward the valve seat 21, the connection portion between the outer peripheral edge portion 55 and the membrane portion 53 slides against the inner circumferential surface of the valve chamber 19, and particles are generated. However, as described above, if the protruding portion 57a ​​of the diaphragm retaining portion 57 is in contact with a part of the surface of the annular bridge portion 59 on the valve chamber side in the direction of the movement axis of the valve body portion 51, the protruding portion 57a ​​prevents the annular bridge portion 59 from deforming toward the drive unit 17 in the direction of the movement axis of the valve body portion 51, thereby suppressing the deformation of the annular bridge portion 59 toward the drive unit 17 in the direction of the movement axis of the valve body portion 51. As a result, sliding of the connection portion between the annular bridge portion 59 and the outer peripheral edge portion 55 (specifically, the collar portion 55b) against the inner peripheral surface of the upper opening of the valve chamber 19 is further suppressed, and the generation of particles due to sliding is further suppressed.

[0034] The diaphragm 15 is preferably formed from polytetrafluoroethylene (PTFE), which has flexibility and high bending resistance, especially since the membrane portion 53 is subject to repeated bending. On the other hand, the valve body portion 51 is preferably formed from perfluoroalkoxyalkane (PFA), which has low dust generation properties, as it is prone to generating particles when it comes into contact with the valve seat 21. Therefore, the bottom surface portion (valve seat contact surface) of the valve body portion 51 may be formed from PFA, while the remaining portion of the diaphragm 15 is formed from PTFE, so that the bottom surface portion of the valve body portion 51 of the diaphragm 15 is made from a different material than the other parts. Furthermore, since the annular bridge portion 59 has higher rigidity than the membrane portion 53, it may be formed from PFA or the like, which has higher rigidity than the PTFE that forms the membrane portion 53. Furthermore, the valve body 13, the drive unit housing 31 of the drive unit 17, the cover member 33, the stem 35, and the piston 37 can be formed from suitable materials such as polyvinylidene fluoride (PVDF), PTFE, PFA, and polychlorotrifluoroethylene (PCTFE).

[0035] In the embodiments shown in Figures 1 and 2, the annular bridge portion 59 extends in a direction approximately perpendicular to the collar portion 55b (approximately horizontal in the figures), and the flat surface at the top of the projection 57a ​​of the diaphragm retaining portion 57 abuts against the annular bridge portion 59. However, if the annular bridge portion 59 is provided between the outer peripheral edge portion 55 and the membrane portion 53 and has higher rigidity than the membrane portion 53, it does not need to extend in a direction perpendicular to the collar portion 55b of the outer peripheral edge portion 55, and the annular bridge portion 59 may extend at an acute or obtuse angle with the collar portion 55b. Also, the projection 57a ​​may abut against the annular bridge portion 59 at locations other than the top.

[0036] Figure 3 shows the main parts of a diaphragm valve in another embodiment, including the diaphragm 15' and the diaphragm retaining portion 57. In the other embodiment shown in Figure 3, the annular bridge portion 59' of the diaphragm 15' extends at an acute angle with the collar portion 55b of the outer peripheral edge portion 55, and in the diaphragm retaining portion 57, the flat surface at the top does not abut the annular bridge portion 59', and the inclined surface 57b, which extends diagonally adjacent to the inside of the top of the projection portion 57a', is arranged to abut the annular bridge portion 59' in the direction of the movement axis of the valve body portion 51. Furthermore, in the embodiment shown in Figure 3, the annular bridge portion 59' is formed to be thicker than the membrane portion 53, thereby having higher rigidity than the membrane portion 53. Moreover, in the embodiment shown in Figure 3, the bottom surface 51a of the valve body portion 51, which is the valve seat contact surface, moves toward and away from the valve seat 21 formed at the top of the annular protrusion provided around the opening from the inlet passage 25 to the valve chamber 19. In the embodiment shown in Figure 3, the other components are the same as those in the embodiments shown in Figures 1 and 2. Therefore, a description of the common components is omitted here. In Figure 3, components that are common with the components of the embodiments shown in Figures 1 and 2 are given the same reference numerals.

[0037] Next, the operation of the diaphragm valve 11 shown in Figure 1 will be explained. The operation of the diaphragm valve in the embodiment shown in Figure 3 is similar.

[0038] Under normal conditions, when no working fluid is supplied to the drive unit 17 from the working fluid supply port 45, the piston 37 of the drive unit 17 is biased downward by the coil spring 39 and pushed down. As a result, the valve body 51 moves towards the valve seat 21 via the stem 35 and is pressed against the valve seat 21, causing the diaphragm valve 11 to close as shown in Figure 1. Consequently, the membrane 53 supporting the valve body 51 also deforms away from the drive unit 17.

[0039] When working fluid is supplied to the working fluid supply port 45 of the drive unit 17 from the valve closed state, the fluid pressure of the working fluid that has flowed into the lower space 43 of the cylinder section acts upward on the piston body 37a, pushing the piston 37 upward against the biasing force of the coil spring 39. At this time, the air in the upper space 41 is released to the outside through the vent 33b provided in the lid member 33. When the supply of working fluid to the working fluid supply port 45 is stopped, the coil spring 39 biases and pushes the piston 37 downward again, pressing the valve body 51 against the valve seat 21, and the valve returns to the closed state.

[0040] As the valve body 51 moves relative to the valve seat 21 in the direction of its movement axis during the opening and closing of the diaphragm valve 11, the membrane 53 deforms in the direction of its movement axis. The membrane 53 is connected to the collar portion 55b of the outer peripheral edge 55 via an annular bridge portion 59, which has higher rigidity than the membrane 53. Even if the membrane 53 deforms in the direction of its movement axis, the annular bridge portion 59, which has higher rigidity than the membrane 53, is less likely to deform in the direction of the movement axis of the valve body 51. Furthermore, if the protruding portion 57a ​​of the diaphragm retaining portion 57 is in contact with the annular bridge portion 59 in the direction of the movement axis of the valve body 51, the annular bridge portion 59 becomes even less likely to deform in the direction of the movement axis of the valve body 51. As a result, the connection portion between the annular bridge portion 59 and the collar portion 55b of the outer peripheral edge portion 55 is less likely to deform in a direction away from the inner circumferential surface of the upper opening of the valve chamber 19, and sliding between the connection portion between the annular bridge portion 59 and the collar portion 55b of the outer peripheral edge portion 55 and the inner circumferential surface of the valve chamber 19 is suppressed, thereby suppressing the generation of particles.

[0041] The diaphragms 15, 15' and the diaphragm valve 11 equipped therewith according to the present invention have been described above with reference to the illustrated embodiments, but the present invention is not limited to the illustrated embodiments. For example, in the embodiment shown in Figure 1, the annular bridge portion 59 is described as being formed from a material with higher rigidity than the membrane portion 53. However, the annular bridge portion 59 may be formed from the same material as the membrane portion 53, as long as it has higher rigidity than the membrane portion 53. In this case, for example, as in the embodiment shown in Figure 3, the annular bridge portion 59 may be made thicker than the membrane portion 53. Also, in the illustrated embodiments, the drive unit 17 is driven by a working fluid, but it may be driven manually.

[0042] 11 Diaphragm valve 13 Valve body 15 Diaphragm 15' Diaphragm 17 Actuator 19 Valve chamber 21 Valve seat 25 Inlet passage 29 Outlet passage 51 Valve body 51a Bottom surface 53 Membrane 55 Outer peripheral edge 57 Diaphragm retaining part 57a Protruding part 57a' Protruding part 57b Inclined surface 59 Annular bridge part 59' Annular bridge part

Claims

1. A diaphragm valve comprising: a valve body having a first passage, a second passage, a valve chamber through which the first and second passages communicate, and a valve seat formed around an opening from the first passage to the valve chamber; a diaphragm; and a drive unit having a diaphragm retaining portion at its bottom and driving the diaphragm, wherein the diaphragm includes a valve body portion that moves toward and away from the valve seat, an annular membrane portion extending outward from the outer circumferential surface of the valve body portion and deformable in the direction of the movement axis, and an annular outer peripheral edge portion provided on the outside of the membrane portion, and the outer peripheral edge portion of the diaphragm is sandwiched between the valve body and the diaphragm retaining portion, A diaphragm valve characterized in that the diaphragm further includes an annular bridge portion having higher rigidity than the membrane portion and extending inward from the outer peripheral edge portion to connect the outer peripheral edge portion and the membrane portion, the outer peripheral edge portion includes an annular flange portion and a cylindrical collar portion whose one end in the direction of the central axis is connected to the inner peripheral edge end of the flange portion, the diaphragm retaining portion has a cylindrical projection portion that protrudes from the bottom surface of the drive portion toward the valve seat, and when the projection portion is inserted into the valve chamber, at least a part of the collar portion of the diaphragm is sandwiched between the outer peripheral surface of the projection portion and the inner peripheral surface of the valve chamber.

2. The diaphragm valve according to claim 1, wherein the projection is configured such that when the projection is inserted into the valve chamber, the projection and at least a portion of the annular bridge portion come into contact in the direction of the moving axis.

3. The diaphragm valve according to claim 2, wherein the annular bridge portion extends in a tapered shape from the other end of the collar portion toward the side away from the valve seat, and the protruding portion has an inclined surface that abuts against the annular bridge portion.

4. The diaphragm valve according to claim 1, wherein an annular projection is provided on the outer circumferential surface of the collar portion, and the collar portion of the diaphragm is sandwiched between the outer circumferential surface of the projection and the inner circumferential surface of the valve chamber when the annular projection is fitted into an annular groove provided on the inner circumferential surface of the valve chamber.

5. The diaphragm valve according to claim 1, wherein the annular bridge portion is formed to be thicker than the membrane portion.

6. The diaphragm valve according to any one of claims 1 to 5, wherein the first flow path and the second flow path open to the bottom of the valve chamber.

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