diaphragm valve

Abstract

To suppress the generation of particles by making it hard to generate a clearance on a joint surface between a separating membrane part and a valve body in a diaphragm in which the separating membrane part and the valve body part are joined.SOLUTION: A diaphragm valve is equipped with a valve body 13 formed with a valve chamber 19, a diaphragm 15 that includes a separating membrane part 15b having a base part 15a at a center and a valve body part 15c joined to the base part 15a, and a drive part 17 that has a stem 35. The stem 35 includes a base end part 35a connected to the drive part 17, a coupling part 35b provided at a tip end part, and an intermediate part 35c that extends between the base end part 35a and the coupling part 35b and is thinner than the base end part 35a. The coupling part 35b is united in the valve body part 15c. Between the base end part 35b and the base part 15a of the diaphragm, an energizing member 51 energizing the base part 15a toward the coupling part 35b is disposed.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a diaphragm valve having a diaphragm in which a valve body portion that moves toward and away from a valve seat and a diaphragm portion are joined together. [Background technology]

[0002] For example, when controlling the flow rate of chemicals used in semiconductor manufacturing equipment, diaphragm valves are often used. These valve valves have a diaphragm with a diaphragm that separates the flow path or valve chamber through which the chemical flows from the actuator and a valve body supported at the center of the diaphragm. In diaphragm valves, the diaphragm repeatedly elastically deforms to move the valve body toward and away from the valve seat, thereby controlling the flow rate. Since such diaphragms come into contact with the chemicals, they require chemical resistance and flexural durability due to the repeated elastic deformation. For this reason, diaphragms are typically made from polytetrafluoroethylene (PTFE), which has high flexural durability. Because PTFE cannot be injection molded, diaphragms are manufactured by cutting a block that is compression-molded and then sintered from powdered PTFE. However, PTFE tends to generate dust, which can generate particles from the diaphragm's valve body, which repeatedly contacts and separates from the valve seat. In semiconductor manufacturing, the inclusion of particles in the chemicals significantly impacts the yield of semiconductor manufacturing. Therefore, it is preferable to suppress dust generation from the valve body portion of the diaphragm that comes into contact with the chemical solution.

[0003] One way to prevent dust generation from the valve body is to form the valve body from perfluoroalkoxyalkane (PFA), a fluorine-based resin material that is less likely to generate dust. However, PFA has low flexural durability, making it unsuitable for use in diaphragms that undergo repeated elastic deformation. Therefore, it has been proposed to bond a valve body made of PFA to a diaphragm made of PTFE.

[0004] For example, Patent Document 1 discloses a fluid control valve in which a diaphragm member (i.e., diaphragm portion) is formed from PTFE, a first fluororesin material, and is provided with a diaphragm membrane and a rod-shaped portion provided in the center of the diaphragm membrane, and has an outer circumferential uneven surface on the outer periphery of part of the rod-shaped portion; this diaphragm member is formed from PTFE, the first fluororesin material, and a valve seat abutment member (i.e., valve portion) is formed from PFA, a second fluororesin material that can be injection molded, and has a valve seat abutment surface and a recessed portion provided on the opposite side thereof; the rod-shaped portion is fitted into the recessed portion so that the outer circumferential uneven surface formed on the outer periphery of the rod-shaped portion of the diaphragm member and the inner circumferential uneven surface formed on the inner periphery of the recessed portion of the valve seat abutment member are tightly engaged with each other, thereby joining the diaphragm member and the valve seat abutment member. Furthermore, Patent Document 1 discloses a method for manufacturing a fluid control valve, which includes an insert molding step of injection-molding a second round rod from a second fluororesin material with a first round rod formed from a first fluororesin material inserted therein, followed by cutting the first round rod into the shape of the above-mentioned diaphragm member and the second round rod into the shape of the above-mentioned valve seat abutment member. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6873991 Summary of the Invention [Problem to be solved by the invention]

[0006] In the technology disclosed in Patent Document 1, when a diaphragm member and a valve seat abutment member made of different fluororesin materials are joined by engaging their concave and convex surfaces (mechanical bonding), differences in the hardness of the materials can cause minute gaps between the concave and convex surfaces when the resin bonded structure is subjected to an impact, such as when the valve body and valve seat abut when the valve is closed. Furthermore, changes in the temperature of the fluid can cause the bonded structure to expand and contract, resulting in minute gaps between the concave and convex surfaces due to differences in the expansion and contraction rates. In particular, in fluid devices such as valves, if liquid penetrates and accumulates in these gaps, it can cause deterioration of the valve body and increase particle generation over time. Furthermore, even when the bonded structure is formed by insert molding, as in the technology disclosed in Patent Document 1, differences in the hardness of the materials can cause minute gaps between the concave and convex surfaces when the resin bonded structure is subjected to an impact, such as when the valve body and valve seat abut when the valve is closed. This can also cause particle generation over time due to liquid penetrating the gaps.

[0007] Therefore, an object of the present invention is to solve the problems present in the prior art by making it less likely for gaps to occur at the joint surface between the diaphragm portion and the valve body portion in a diaphragm in which the diaphragm portion and the valve body portion are joined, thereby suppressing the generation of particles. [Means for solving the problem]

[0008] In view of the above object, the present invention provides a diaphragm valve comprising: a valve body formed with a first flow path, a second flow path, and a valve chamber through which the first flow path and the second flow path communicate; a diaphragm including a diaphragm portion having a base portion in the center and a valve element portion joined to the base portion and supported by the diaphragm portion; and a drive portion having a stem, wherein the valve element portion is connected to the stem and driven by the drive portion to move the valve element portion toward and away from an annular valve seat formed around an opening from the first flow path to the valve chamber, and the stem includes a base end connected to the drive portion, a connecting portion, and an intermediate portion extending between the base end and the connecting portion and being thinner than the base end, the connecting portion is connected to the valve element portion, and a biasing member that biases the base portion toward the connecting portion is disposed between the base end and the base portion of the diaphragm.

[0009] In the above-described diaphragm valve, the connecting portion of the stem extending from the drive portion is connected to the valve body portion, and a biasing member disposed between the base end of the stem and the base portion of the membrane portion of the diaphragm biases the base portion toward the connecting portion. As a result, the biasing member presses the base portion against the valve body portion connected to the connecting portion at the tip end of the stem. Therefore, even if an impact is applied to the valve body when the valve body abuts against the valve seat during valve closing, causing the valve body to deform, or even if the valve body and base portion expand and contract due to temperature changes of the liquid in the valve chamber, a gap is unlikely to form between the valve body portion and the base portion.

[0010] In the above-mentioned diaphragm valve, it is preferable that the connecting hole penetrates the base portion and extends to the inside of the valve body portion, that an enlarged recess is provided on the inner surface of the end portion of the connecting hole located within the valve body portion, that the connecting portion of the stem is thicker than the middle portion, and that the connecting portion of the stem pressed into the connecting hole engages with the enlarged recess and is connected to the valve body portion.

[0011] It is also preferable that the biasing member is made of a ring-shaped elastic member and is attached around the middle portion, and it is even more preferable that the elastic member is an O-ring.

[0012] The diaphragm portion may be made of polytetrafluoroethylene (PTFE), and the valve body portion may be made of perfluoroalkoxyalkane (PFA). [Effects of the Invention]

[0013] According to the present invention, even if an impact is applied to the valve disc when it contacts the valve seat while the valve is closed, causing the valve disc to deform, or even if the valve disc or base expands or contracts due to temperature changes in the liquid in the valve chamber, a gap is unlikely to form between the valve disc and the base. This prevents liquid in the valve chamber from entering the gap and causing deterioration of the material due to the infiltrated liquid, which can lead to particle generation from the valve disc or base. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a cross-sectional view showing the overall configuration of one embodiment of a diaphragm valve according to the present invention. [Figure 2] 2 is an enlarged view showing a diaphragm and a valve chamber in the diaphragm valve shown in FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a diaphragm valve according to the present invention will be described with reference to the drawings.

[0016] First, the overall configuration of one embodiment of a diaphragm valve according to the present invention will be described with reference to Figure 1. Diaphragm valve 11 comprises a valve body 13, a diaphragm 15, and a drive unit 17 that drives diaphragm 15, with drive unit 17 attached to the top of valve body 13.

[0017] The valve body 13 has a valve chamber 19 formed in the center of the upper part, and first and second flow paths communicating with the valve chamber 19. The valve chamber 19 has an annular valve seat 21, to which the diaphragm 15 moves in contact, formed around the opening from the first flow path to the valve chamber 19. In the illustrated embodiment, the first flow path is an inlet flow path 25 that extends from an inlet port 23 formed on one of the opposing side surfaces of the valve body 13 and opens at 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 port 27 formed on the other of the opposing side surfaces of the valve body 13 and opens at a side surface 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.

[0018] The drive unit 17 includes a drive unit housing 31 attached to the top of the valve body 13 and having a mechanism accommodating space formed therein, a cover member 33 attached to the top of the drive unit housing 31, a stem 35 connected to the diaphragm 15, and a drive mechanism housed in the mechanism accommodating space and driving the stem 35. In this embodiment, a cylinder portion is formed as the mechanism accommodating space inside the drive unit housing 31, and the drive mechanism is composed of a piston 37 housed in the cylinder portion and a coil spring 39 as a biasing member.

[0019] The piston 37 has a piston body 37a slidably housed in the cylinder portion of the drive unit housing 31 and a guide shaft 37b extending upward from the piston body 37a, and a stem 35 is connected to the piston body 37a so as to extend downward from the piston body 37a. The stem 35 is slidably inserted into a through-hole that penetrates the bottom of the drive unit housing 31, and its tip is connected to the diaphragm 15 (more specifically, the valve body 15c, described later). The outer peripheral surface of the piston body 37a is in vertical slidable contact with the inner peripheral surface of the cylinder portion, dividing the internal space of the cylinder portion into an upper space 41 surrounded by the top surface of the piston body 37a, the inner peripheral wall of the cylinder portion, and the ceiling surface of the cylinder portion (i.e., the lower surface of the lid member 33), and a lower space 43 surrounded by the bottom surface of the piston body 37a, the inner peripheral 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 slidably inserted into a through hole provided through the cover member 33, and guides the piston 37 in its up and down movement.

[0020] A vent hole 45 communicating with the cylinder section that defines the upper space 41 is formed in the cover member 33, and ventilation is possible between the upper space 41 and the outside through the vent hole 45. A working fluid supply port 47 communicating with the bottom of the cylinder section that defines the lower space 43 is formed in the side of the drive unit housing 31, and working fluid can be supplied from the working fluid supply port 47 into the lower space 43. Furthermore, a coil spring 39 is arranged in a compressed state between the lower surface of the cover member 33 (the ceiling surface of the cylinder section) and the upper surface of the piston body 37a.

[0021] The stem 35 includes a base end 35a connected to the piston body 37a, a connecting portion 35b provided at the tip end, and an intermediate portion 35c extending between the base end 35a and the connecting portion 35b and narrower than the base end 35a and the connecting portion 35b. The connecting portion 35b is preferably cone-shaped, tapering toward the tip. This cone-shaped configuration makes it easier to press-fit the connecting portion 35b of the stem 35 into a connecting hole 49, which will be described later.

[0022] The diaphragm 15 includes a diaphragm portion 15b having a base portion 15a protruding downward at its center, a diaphragm portion 15b, and a valve element portion 15c joined to the base portion 15a. The diaphragm portion 15b is formed to extend radially outward from the outer periphery of the upper end of the base portion 15a, and the outer periphery of the diaphragm portion 15b has a generally circular shape. The outer periphery of the diaphragm portion 15b is sandwiched between the upper surface of the surrounding area of ​​the upper opening of the valve chamber 19 of the valve body 13 and the bottom surface of the actuator housing 31. In this manner, the diaphragm 15 supports the valve element portion 15c above the valve chamber 19 via the diaphragm portion 15b, thereby separating the valve chamber 19 from the actuator 17. In the illustrated embodiment, the valve element portion 15c has a shape resembling a truncated cone connected to a cylinder, and its bottom surface (valve seat contact surface) is positioned facing the valve seat 21. The base portion 15a is joined to the valve body portion 15c so that its peripheral surface is smoothly connected to the side surface of the truncated cone portion of the valve body portion 15c. However, the shape of the valve body portion 15c is not limited as long as it can be supported within the valve chamber 19 by the diaphragm portion 15b and can move toward and away from the valve seat 21 to open and close the opening from the inlet flow path 25 to the valve chamber 19.

[0023] The diaphragm 15 is constructed of different components, with the base portion 15a and the diaphragm portion 15b made of PTFE, which has high bending durability, especially since the diaphragm portion 15b is subject to repeated bending. Meanwhile, the valve body portion 15c is made of PFA, which has low dust-generating properties, because it is prone to generating particles when it comes into contact with the valve seat 21. The PTFE or PFA used to form the diaphragm 15 may be chemically modified or crosslinked by ionizing radiation. Chemically modified PTFE is particularly preferred. The actuator housing 31, cover member 33, stem 35, and piston 37 of the actuator 17 may be made of an appropriate material, such as polyvinylidene fluoride (PVDF), PTFE, PFA, or polychlorotrifluoroethylene (PCTFE).

[0024] The base portion 15a and the valve body portion 15c may be joined by mechanical bonding, such as by engaging concave and convex surfaces, screwing, or insert molding, or by welding or bonding with an adhesive. However, when used in semiconductor manufacturing, for example, mechanical bonding may cause particles to be released into the liquid in the valve chamber 19 due to sliding at the joint, contaminating the liquid, while bonding with an adhesive may cause adhesive components to leach into the liquid in the valve chamber, contaminating the liquid. Therefore, it is preferable to join the base portion 15a and the valve body portion 15c by welding. Welding can be performed by, for example, laser welding, heat welding, hot air welding, induction welding, or baking.

[0025] The diaphragm 15 is provided with a connecting hole 49 that penetrates the base portion 15a and extends into the valve body portion 15c. The stem 35 is slidably inserted into the connecting hole 49, and the connecting portion 35b is coupled to the valve body portion 15c. In the illustrated embodiment, an annular enlarged recess 49a is provided on the inner circumferential surface of the end portion of the connecting hole 49 located within the valve body portion 15c, forming a locking hole portion at the end portion. That is, the locking hole portion is thicker than the intermediate hole portion that extends from the base portion 15a to the inside of the valve body portion 15c, forming a step at the boundary between them. Furthermore, the connecting portion 35b of the stem 35 is thicker than the intermediate portion 35c. The connecting portion 35b at the tip of the stem 35 is press-fitted into the connecting hole 49, and the connecting portion 35b engages with the enlarged recess 49a, thereby joining the connecting portion 35b of the stem 35 to the valve body portion 15c, and connecting the valve body portion 15c of the diaphragm 15 to the stem 35. By connecting the valve body portion 15c of the diaphragm 15 to the stem 35 in this manner, the diaphragm 15 (more specifically, its valve body portion 15c) can move toward and away from the valve seat 21 via the stem 35 as the piston 37 moves up and down. Furthermore, if the stem 35 is connected to the valve body portion 15c as described above, it is possible to prevent the valve body portion 15c from falling off the base portion 15a, even if the base portion 15a and the valve body portion 15c should separate.

[0026] The connection between the connecting portion 35b at the tip of the stem 35 and the valve body 15c can also be achieved by other methods, such as screwing a male thread on the outer circumferential surface of the connecting portion 35b into a female thread on the inner circumferential surface of the connecting hole 49, or by bonding with an adhesive. However, when the connecting portion 35b at the tip of the stem 35 and the valve body 15c of the diaphragm 15 are connected by screwing, if a gap occurs at the joint surface between the base portion 15a of the diaphragm 15 and the valve body 15c, particles generated in the connecting hole 49 during screwing may pass through the gap and be released into the liquid in the valve chamber 19, potentially contaminating the liquid. Therefore, it is preferable to connect the connecting portion 35b at the tip of the stem 35 to the valve body 15c by a method other than screwing.

[0027] In the diaphragm valve 11, a biasing member 51 is sandwiched between the base end 35a of the stem 35 (more specifically, the step between the base end 35a and the intermediate portion 35c) and the base portion 15a of the diaphragm portion 15b of the diaphragm 15, and the biasing member 51 biases the base portion 15a toward the connecting portion 35b at the tip of the stem 35. As a result, the biasing member 51 presses the base portion 15a against the valve body portion 15c connected to the connecting portion 35b, and even if the valve body portion 15c is deformed by the impact of the valve body portion 15c abutting on the valve seat 21 when the valve is closed (if the base portion 15a and the valve body portion 15c are joined, even if the joint between the base portion 15a and the valve body portion 15c is destroyed by the deformation), a gap is unlikely to occur between the base portion 15a and the valve body portion 15c. Similarly, even if a difference in the amount of expansion and contraction occurs due to a temperature change of the liquid in the valve chamber 19 caused by a difference in the expansion and contraction rates of the base portion 15a and the valve body portion 15c, a gap is unlikely to form between the base portion 15a and the valve body portion 15c. Therefore, it is possible to suppress an increase in particles over time due to deterioration of the material constituting the base portion 15a or the valve body portion 15c caused by the liquid in the valve chamber 19 that has entered the gap between the base portion 15a and the valve body portion 15c.

[0028] In the illustrated embodiment, the biasing member 51 is an O-ring attached to the outer periphery of the intermediate portion 35c of the stem 35. However, the biasing member 51 is not limited to an O-ring as long as it can apply a biasing force to the base portion 15a. For example, the biasing member 51 can be a resin or metal coil spring or spring washer, or an annular rubber packing member, arranged to surround the intermediate portion 35c of the stem 35. The metal coil spring or spring washer, rubber O-ring, or annular packing member may be coated with PFA or PTFE. Peroxide vulcanization is preferred as a rubber vulcanization method. Fluorine rubber is preferred as the rubber material for the O-ring or annular packing member. Using an O-ring as the biasing member 51 can effectively prevent lubricating oil used in the drive unit 17 from leaking into the valve chamber 19, even if a gap occurs between the base portion 15a and the valve body portion 15c.

[0029] Next, the operation of the diaphragm valve 11 will be described with reference to Figures 1 and 2. As shown in Figure 1, under normal circumstances when no working fluid is supplied from the working fluid supply port 47 to the drive unit 17, the piston 37 of the drive unit 17 is urged downward by the coil spring 39 and pushed down. As a result, the valve body portion 15c moves in a direction approaching the valve seat 21 via the stem 35 and is pressed against the valve seat 21, and the diaphragm valve 11 is in a closed state as shown in Figure 1. Accordingly, the diaphragm portion 15b, which supports the valve body portion 15c via the base portion 15a, also deforms in a direction away from the drive unit 17.

[0030] When working fluid is supplied to the working fluid supply port 47 of the actuator 17 from the valve closed state, the fluid pressure of the working fluid that has flowed into the lower space 43 of the cylinder acts upward on the piston body 37a, pushing the piston 37 up against the biasing force of the coil spring 39. At this time, air in the upper space 41 is released to the outside through the vent hole 45. As a result, the valve body 15c is moved away from the valve seat 21 via the stem 35, and the diaphragm valve 11 enters the open state. Accordingly, the diaphragm portion 15b also deforms in a direction approaching the actuator 17. When the supply of working fluid to the working fluid supply port 47 is stopped, the piston 37 is again biased downward by the coil spring 39 and pushed down, and the valve body 15c presses against the valve seat 21, returning to the closed state.

[0031] In the diaphragm valve 11, the valve body portion 15c repeatedly moves toward and away from the valve seat 21, and particularly when the valve body portion 15c abuts against the valve seat 21, impacts tend to generate particles. For this reason, in the diaphragm valve 11, it is desirable that the diaphragm portion 15b (including the base portion 15a) of the diaphragm 15, which repeatedly deforms (bends), be made of PTFE, which has high bending durability, while the valve body portion 15c, which repeatedly moves toward and away from the valve seat 21 and tends to generate particles, be made of PFA, which has low dust-generating properties. In such a case, it is necessary to mold the base portion 15a and the valve body portion 15c of the diaphragm 15 separately, and then join the valve body portion 15c, which is made of PFA, to the base portion 15a, which is made of PTFE. The joining is performed by mechanical bonding, welding, bonding with an adhesive, or the like.

[0032] However, in a diaphragm in which the base portion 15a and the valve body portion 15c are joined, when the valve body portion 15c is pressed against the valve seat 21, the valve body portion 15c is deformed by the impact of the pressing, even if the joining between the base portion 15a and the valve body portion 15c is broken due to deformation of the valve body portion 15c in the case of a mechanical connection or welding or adhesive bonding, and a gap may be formed between the base portion 15a and the valve body portion 15c due to the deformation of the valve body portion 15c. Furthermore, due to the difference in the expansion and contraction rates of the base portion 15a and the valve body portion 15c, a gap may be formed between the base portion 15a and the valve body portion 15c as a result of expansion and contraction due to temperature changes of the liquid in the valve chamber 19. However, in the diaphragm 15, the valve body portion 15c is connected to the connecting portion 35b of the stem 35, and a biasing member 51 that biases the base portion 15a toward the connecting portion 35b of the stem 35 is disposed between the base end 35a of the stem 35 (more specifically, the step portion between the base end 35a and the intermediate portion 35c) and the base portion 15a of the separating membrane portion 15b of the diaphragm 15. Therefore, even if the valve body portion 15c is deformed, or even if the base portion 15a and the valve body portion 15c are joined by welding or the like and the joint is broken due to the deformation of the valve body portion 15c, or even if expansion and contraction occur due to temperature changes of the liquid in the valve chamber 19, the base portion 15a is pressed against the valve body portion 15c that is connected to the connecting portion 35b of the stem 35, and a gap is unlikely to form between the base portion 15a and the valve body portion 15c. As a result, it is possible to prevent the liquid in the valve chamber 19 from penetrating into the gap formed between the base portion 15a and the valve body portion 15c, which may be deteriorated by the penetrating liquid and cause particles to be released from the base portion 15a or the valve body portion 15c into the liquid in the valve chamber 19, thereby contaminating the liquid. This makes it easier to adopt the option of forming the base portion 15a and the valve body portion 15c of the diaphragm 15 separately from different materials and then joining them together.

[0033] Although the diaphragm valve 11 according to the present invention has been described above with reference to the illustrated embodiment, the present invention is not limited to the illustrated embodiment. For example, in the illustrated embodiment, the connecting portion 35b of the stem 35 engages with the enlarged recess 49a provided at the end of the connecting hole 49 located within the valve body portion 15c of the diaphragm 15, thereby connecting the connecting portion 35b of the stem 35 to the valve body portion 15c, thereby connecting the diaphragm 15 and the stem 35. However, as long as the valve body portion 15c of the diaphragm 15 and the connecting portion 35b of the stem 35 can be connected to each other, the connecting method is not limited. For example, the connecting portion 35b may be connected to the end of the connecting hole 49 located within the valve body portion 15c by adhesive or screwing. In this case, the connecting portion 35b of the stem 35 does not need to be thicker than the intermediate portion 35c. Furthermore, the present invention can be applied to constant pressure valves and flow control valves that have a diaphragm portion including a valve body portion and a base portion, in addition to on-off valves such as the diaphragm valve 11 shown in the figures, and can achieve the same effects as those of the illustrated embodiment. [Explanation of symbols]

[0034] 11 Diaphragm valve 13 Valve body 15 diaphragm 15a Base part 15b Diaphragm part 15c Valve body 19 Valve chamber 21 Valve seat 25 Inlet channel 29 Outlet flow path 35 stem 35a Proximal end 35b Connection part 35c middle part 49 Connection hole 49a Enlarged recess 51 biasing member

Claims

1. a valve body formed with a first flow path, a second flow path, and a valve chamber communicating with the first flow path and the second flow path; a diaphragm including a diaphragm portion having a base portion in the center and a valve body portion joined to the base portion and supported by the diaphragm portion; and a drive portion having a stem, wherein the valve body portion is connected to the stem and driven by the drive portion, and the valve body portion is moved toward and away from an annular valve seat formed around an opening from the first flow path to the valve chamber to perform an opening and closing operation, A diaphragm valve characterized in that the stem includes a base end connected to the drive portion, a connecting portion, and an intermediate portion extending between the base end and the connecting portion and thinner than the base end, the connecting portion is connected to the valve body portion, and a biasing member that biases the base portion toward the connecting portion is disposed between the base end and the base portion of the diaphragm.

2. 2. The diaphragm valve of claim 1, wherein a connecting hole penetrates the base portion and extends to the inside of the valve body portion, an enlarged recess is provided on the inner surface of the end portion of the connecting hole located within the valve body portion, the connecting portion of the stem is thicker than the intermediate portion, and the connecting portion of the stem press-fitted into the connecting hole engages with the enlarged recess to be connected to the valve body portion.

3. 3. The diaphragm valve according to claim 1, wherein the biasing member is a ring-shaped elastic member attached around the middle portion.

4. 4. The diaphragm valve of claim 3, wherein the elastic member is an O-ring.

5. 5. The diaphragm valve according to claim 1, wherein the diaphragm portion is formed from polytetrafluoroethylene (PTFE), and the valve body portion is formed from perfluoroalkoxyalkane (PFA).

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