JP7507028B2 - Diaphragm Valve - Google Patents

Description

The present invention relates to a diaphragm valve, and in particular to a diaphragm valve that is used primarily in semiconductor and liquid crystal manufacturing equipment and is suitable for situations where heat resistance and chemical resistance are required.

For example, in semiconductor and liquid crystal manufacturing facilities, highly corrosive high-temperature, high-purity chemicals are sometimes used, and to accommodate this, diaphragm valves made of resins with excellent heat and chemical resistance, such as fluororesin, are often used. These valves usually have a valve box with a flow path and a diaphragm valve body, both made of resins such as fluororesin, and a drive unit with a resin body is provided on top of these. The valve box, diaphragm valve body, and drive unit are fixed together with other parts installed inside by tightening assembly bolts.

In this type of resin valve, the resin parts repeatedly expand and contract due to changes in fluid temperature and ambient temperature, causing creep, and the dimensional changes caused by this creep can make it impossible to ensure external sealing performance. Countermeasures against this problem are generally known.

For example, in the chemical liquid control valve of Patent Document 1, the peripheral protrusion formed on the diaphragm valve body is fitted into a seal groove in the fluororesin body, and an O-ring is sandwiched between the peripheral protrusion of the diaphragm valve body and the clamping surface of the cylinder. As a result, when the body or diaphragm valve body shrinks when the fluid temperature or ambient temperature changes, and the clamping force of the diaphragm valve body between the body and cylinder weakens, the elastic force of the O-ring compensates.

Meanwhile, the diaphragm valve in Patent Document 2 is constructed in such a way that a resin diaphragm valve body, valve main body (body), cylinder tube, cover, and plate are stacked one on top of the other with parts assembled inside, and these are joined together with assembly bolts, and a diaphragm retainer is placed on the top of the diaphragm valve body, and a disc spring made of a heat-resistant and chemical-resistant material is interposed between the diaphragm retainer and the bottom of the cylinder tube. When creep occurs in the diaphragm valve body or body due to changes in fluid temperature or atmospheric temperature, this valve uses the elastic force of the disc spring to constantly press the diaphragm valve body towards the body, bringing them into close contact with each other, preventing gaps between the parts due to creep and ensuring sealing.

On the other hand, in the resin valve in Patent Document 3, the clamping portion of the outer periphery of the diaphragm is sandwiched between a resin valve chamber side valve body and an actuation side valve body, and is integrated by screwing in an assembly bolt and nut that penetrate the joint surface between the valve chamber side valve body and the actuation side valve body. In this valve, the assembly bolt and nut are screwed in near the joint surface between the valve chamber side valve body and the actuation side valve body, in order to prevent a decrease in the sealing ability of the diaphragm due to thermal expansion and contraction of the body.

Patent No. 3867995 Japanese Patent Application Laid-Open No. 1-93674 Patent No. 3527303

In the case of a diaphragm valve in which the resin valve box, diaphragm valve body, and drive unit are integrated by the above-mentioned assembly bolts, if the assembly bolts are made of a metal material, the linear expansion coefficient (linear expansion coefficient) of the metal assembly bolts and the resin parts such as the diaphragm valve body and valve box will differ, and the resin parts will deform more when exposed to high heat. When there is such a difference in thermal expansion, the resin parts will be prone to repeated thermal expansion and contraction due to changes in fluid temperature and atmospheric temperature when the fixed parts are positioned with the assembly bolts.

As a result, excessive thrust is repeatedly applied to the plastic parts, making them susceptible to creep deformation. In particular, if the diaphragm valve body and valve box, which are the liquid-contacting parts, undergo plastic deformation, the clamping pressure at the parts sealing them decreases, which can result in fluid leaking to the outside. Furthermore, the liquid-contacting parts are often made of fluororesins such as PFA and PTFE, and these resins are susceptible to plastic deformation due to temperature changes.

In response to this, in the chemical liquid control valve of Patent Document 1, an O-ring is attached between the diaphragm and the cylinder, while in Patent Document 2, a disc spring is provided between the diaphragm retainer and the cylinder tube to accommodate plastic deformation of the resin parts, but these methods have the problem of increasing the number of parts, assembly man-hours, and weight.

Furthermore, none of these valves take into account the difference in the amount of plastic deformation due to the difference in the linear expansion coefficient between the resin parts and the metal assembly bolts described above. If there is a large difference in the linear expansion coefficient between the resin parts and the assembly bolts, the displacement caused by creep near the clamped portion of the diaphragm cannot be absorbed, which may result in external leakage.
That is, in the case of Patent Document 1, since the elastic force of the O-ring is used to absorb the displacement, when the shrinkage of the resin part becomes large, the elastic deformation of the O-ring becomes insufficient, and a gap occurs between the diaphragm valve body and the valve body, which may cause external leakage. In addition, in Patent Document 2, if the resilient force of the disc spring is weak, it may not be possible to absorb the deformation near the pinched part of the diaphragm valve body. Furthermore, in the case of Patent Document 1, the O-ring may be damaged or deteriorated due to an excessive load, which may cause external leakage.

In the case of Patent Document 3, the length of the metal assembly bolt is shortened to reduce its amount of thermal expansion, and an attempt is made to suppress the displacement of the plastic valve bodies due to the difference in the linear expansion coefficient between the assembly bolt and the plastic valve body. However, the effect of the difference in the amount of thermal contraction between the assembly bolt and the plastic valve body remains, so there is a possibility that the gap that occurs between the plastic valve bodies cannot be fully absorbed. As a countermeasure, an elastic absorbing member made of rubber or the like is provided on the back side of the diaphragm clamping part. However, as in the case of the O-ring in Patent Document 1, this configuration utilizes the elastic force of a separate elastic body, so there is a risk of the same problem as in Patent Document 1 occurring and leakage to the outside.

The present invention was developed to solve the problems of the past, and its purpose is to provide a diaphragm valve with excellent heat and chemical resistance, which absorbs the displacement near the clamping part of the diaphragm caused by the difference in thermal expansion due to changes in fluid temperature and atmospheric temperature, and maintains the adhesion near the external seal part of the diaphragm to prevent external leakage of fluid.

In order to achieve the above object, the invention of claim 1 is a diaphragm valve comprising: a body having a valve chamber communicating an inflow passage and an outflow passage; a diaphragm that opens and closes by moving toward and away from a valve seat provided in the valve chamber; a clamping portion provided on the body for clamping the outer periphery of the diaphragm; a pressing body made of a resin material provided on the operating mechanism side for clamping the outer periphery of the diaphragm in the clamping portion; a fastening member for fastening the body side and the operating mechanism side; and an external seal portion constituted by the clamping portion and the outer periphery of the diaphragm with the body side and the operating mechanism side fastened by the fastening member, wherein an annular slit portion for generating thrust is formed in the clamping portion of the pressing body in a direction intersecting the axial direction of the diaphragm.

The invention according to claim 2 is a diaphragm valve in which the pressing body is assembled in a state in which the groove width of the gap width of the slit portion of the pressing body is narrowed to apply a reaction force when the body side and the operating mechanism side are assembled.

The invention according to claim 3 is a diaphragm valve in which the pressing body is a resin bonnet.

The invention according to claim 4 is a diaphragm valve in which the pressing body is a resin cylinder case provided on the operating mechanism side.

The invention according to claim 5 is a diaphragm valve in which the fastening member is a metal set screw or a bolt and nut.

The invention according to claim 6 is a diaphragm valve in which an annular protrusion is formed on the clamping portion of the external seal portion.

The invention of claim 7 is a diaphragm valve in which the gap width and depth of the slit portion are designed to generate thrust based on the strength of the resin material, the required thrust for adhesion, and the operating temperature range.

According to the invention of claim 1, the valve has excellent heat resistance and chemical resistance, and can be assembled in a state where a thrust in the sealing direction is generated on the external seal part by the reaction force of the annular slit part for generating thrust formed at the clamping part of the resin pressing body. As a result, when the body side and the operating mechanism side are made of resin material and the fastening member is made of metal material, even if the fluid temperature and the ambient temperature change, the slit part absorbs the displacement near the clamping part of the diaphragm caused by the thermal expansion difference, while the thrust in the sealing direction by the slit part maintains the adhesion force near the external seal part of the diaphragm, reliably preventing the fluid from leaking to the outside. By absorbing the displacement due to the thermal expansion difference in this way, it is possible to suppress plastic deformation on the body side and the operating mechanism side.

According to the invention of claim 2, by incorporating the pressing body in a state in which the groove width of the gap width of the slit part of the pressing body is reduced and a reaction force is applied during assembly, a thrust is constantly generated at the clamping part of the pressing body, and by maintaining this thrust, it is possible to prevent the fluid from leaking to the outside from the external seal part regardless of the presence or absence of plastic deformation of the resin part.

According to the invention of claim 3 or 4, the pressing body can be a resin bonnet or a resin cylinder case, and in either case, a slit can be provided at the clamping portion to generate thrust and suppress external leakage.

According to the invention of claim 5, the entire unit can be integrated by using ordinary metal set screws or bolts and nuts as fastening members, and even when the body side and the operating mechanism side are made of resin, they can be firmly integrated by fastening with fastening members while absorbing the thermal contraction difference, improving adhesion, and reliably preventing external leakage of fluid from the external seal portion.

According to the invention of claim 6, the annular protrusion presses against the outer periphery of the diaphragm, and the thrust from the pressing body is concentrated on the external seal portion, increasing the pressing force between the clamping portion of the body and the outer periphery of the diaphragm and preventing external leakage from the valve chamber. Furthermore, the annular protrusion can position and hold the diaphragm in a centered state, improving the valve sealing performance of the diaphragm.

According to the invention of claim 7, the gap width and depth of the slit section can be set arbitrarily according to the strength of the resin material, the required thrust for adhesion, and the operating temperature range to generate a predetermined thrust, so that even if the type of resin material, the valve diameter, the fluid temperature, or the ambient temperature differs, external leakage can be reliably suppressed.

FIG. 1 is a longitudinal sectional view showing an embodiment of a diaphragm valve of the present invention. FIG. 2 is a partially cutaway left side view of FIG. 1 . FIG. 2 is an enlarged cross-sectional view of a main portion of FIG. 1 . 1A is a partially cutaway front view of a diaphragm valve, and FIG. FIG. 4 is an enlarged cross-sectional view showing a main portion of another embodiment of the diaphragm valve of the present invention. FIG. 2 is a schematic diagram showing the vicinity of an external seal portion.

The following describes an embodiment of the diaphragm valve of the present invention with reference to the drawings. Figure 1 shows a vertical cross-sectional view of an embodiment of the diaphragm valve of the present invention, Figure 2 shows a partially cutaway left side view of Figure 1, and Figure 4(a) shows a partially cutaway front view of the diaphragm valve.

In the figure, the diaphragm valve of the present invention comprises a body 1, an operating mechanism 2, and a fastening member 7. The operating mechanism 2 comprises a diaphragm 3, an operating body 4, a cylinder case 5, a pressing body 6, and a spring 22, and is used mainly in semiconductor and liquid crystal related manufacturing equipment where heat resistance and chemical resistance are required. In this example, the pressing body 6 consists of a bonnet.

The body 1 is made of a fluororesin such as PTFE, and has an inlet 10 and an outlet 11 formed on its bottom side. Inside the body 1, a valve chamber 12 is formed that connects the inlet 10 and the outlet 11. An annular step 13 is formed on the inner periphery of the valve chamber 12, and a clamping portion 14 is provided on the upper surface of the annular step 13 to clamp the outer periphery 3a of the diaphragm 3.

A ring-shaped protrusion 15 of appropriate height and width is formed on the clamping portion 14, and this ring-shaped protrusion 15 is provided with a predetermined diameter dimension within the range of the depth D of the slit portion 16 in FIG. 3 in the vertical direction (axial direction) so as to correspond to the position of the slit portion 16 of the diaphragm 3 described later. An annular valve seat 17 is formed near the boundary with the inlet 10 of the valve chamber 12.

The diaphragm 3 is made of fluororesin such as PTFE, like the body 1, and has a shape with a central cylindrical portion 20 and an annular portion 21 provided on the outer periphery of the cylindrical portion 20. The outer periphery 3a described above is formed thickly on the outermost diameter side of the annular portion 21. The diaphragm outer periphery 3a is provided with a width size in the radial direction that is approximately the same as that of the clamping portion 14. The diaphragm 3 is attached to the valve chamber 12 with the actuator 4 connected to the upper part of the cylindrical portion 20 and the outer periphery 3a placed on the clamping portion 14. A valve body seal surface 20a is formed on the bottom side of the cylindrical portion 20, and when the cylindrical portion 20 moves up and down due to the lifting and lowering of the actuator 4, the valve body seal surface 20a comes into contact with and separates from the valve seat 17 to open and close the flow path.

The actuator 4 is a piston, made of a resin material such as polyamide, and is housed in the cylinder case 5 in a centered state so that it can freely reciprocate. A spring 22 made of a coil spring is attached between the actuator 4 and the cylinder case 5 in a resilient state, and the actuator 4 is resiliently urged by this spring 22 in a direction that presses against the diaphragm 3.

The cylinder case 5 is made of a resin material such as polyamide and is formed in a rectangular parallelepiped shape, with a piston housing section 23 provided inside. In the piston housing section 23, an air supply port 24 is formed between the actuator 4 and the pressing body 6, and compressed air for driving can be supplied from this air supply port 24 between the actuator 4 and the pressing body 6. Meanwhile, an exhaust port 25 is formed on the rear side of the actuator 4 of the piston housing section 23.

When compressed air is supplied from the air inlet 24, the pressure causes the actuator 4 to rise against the resilient force of the spring 22, opening the valve, and the air on the spring 22 side of the piston housing 23 is exhausted from the exhaust port 25. On the other hand, when the supply of compressed air from the air inlet 24 is stopped, the actuator 4 is lowered by the spring 22, closing the valve. Figures 1 to 3 show the diaphragm valve in the closed state.

In FIG. 3, the pressing body 6 is made of a bonnet as described above, and this bonnet 6 is formed into a cylindrical shape from a resin material such as PEEK, and is provided on the operating mechanism 2 side from the body 1, sandwiching the diaphragm 3. A rectangular flange 30 having approximately the same shape as the outer shape of the body 1 and the cylinder case 5 is formed on the outer periphery of the bonnet 6, and the bonnet 6 is assembled with the flange 30 sandwiched between the body 1 and the cylinder case 5. O-rings 31 and 32 are attached to the contact surfaces between the diaphragm cylindrical portion 20 of the bonnet 6 and the cylinder case 5, respectively, and these O-rings 31 and 32 seal the respective contact surfaces.

In this embodiment, the bonnet 6 clamps the outer periphery 3a of the diaphragm 3 in the clamping portion 14, and a clamping portion 33 is provided below the clamping portion 14 to clamp the outer periphery 3a of the diaphragm. A ring-shaped slit portion 16 for generating thrust is formed in the clamping portion 33 in a direction intersecting the axial direction of the diaphragm 3, and the slit portion 16 generates thrust in the clamping portion 33 to press the external seal portion 35 (described later) toward the body 1.

The slit portion 16 is formed with a predetermined gap width W and depth D on the outer periphery of the lower part of the bonnet 6, and these predetermined width W and depth D are set to a size that generates an appropriate thrust based on the resin material strength of the resin part, the required thrust for adhesion, and the operating temperature range, and the thrust by the clamping part 33 is set by the size of this slit portion 16. In the vertical direction of the figure, the slit portion 16 is formed in a range that overlaps at least with the annular protrusion 15 of the clamping portion 14 in the axial direction.

The body 1, cylinder case 5, and bonnet 6 described above are stacked one on top of the other and secured together with the fastening member 7, with the spring 22, actuator 4, diaphragm 3, and O-rings 31 and 32 assembled inside.

In FIG. 4, the fastening member 7 is a set screw made of metal such as SUS, and this set screw 7 is inserted into the insertion holes 5a and 6a formed in the cylinder case 5 and the bonnet 6, respectively, and then screwed into the female screw 1a formed in the body 1. This causes the cylinder case 5, the bonnet 6, and the body 1 to be fixed together.

When assembling the body 1 side and the operating mechanism 2 side, the groove width of the gap width W of the slit portion 16 in FIG. 3 is narrowed to apply a reaction force, and the bonnet 6 is inserted between the cylinder case 5 and the body 1, and in this state the body 1 side and the operating mechanism 2 side are fastened with the set screw 7. With this configuration, a thrust acts on the diaphragm outer periphery 3a side from the clamping portion 33 through the slit portion 16, and this thrust presses the diaphragm outer periphery 3a toward the clamping portion 14, reliably forming the external seal portion 35 by the clamping portion 14 and the diaphragm outer periphery 3a. At this time, the annular protrusion 15 described above is placed at the position of the external seal portion 35.

Specifically, the groove width of the gap width W of the slit portion 16 can be bent to, for example, about half to apply a reaction force to the bonnet 6. In this case, a reaction force is constantly generated from the clamping portion 33 in the direction of the diaphragm outer periphery 3a, and this reaction force constantly generates a thrust that presses the diaphragm outer periphery 3a in the direction of the clamping portion 14.

In the above embodiment, the pressing body is a resin bonnet 6, and the slit portion 16 is formed in the bonnet 6. However, the bonnet 6 may be omitted, and the resin cylinder case 5 may be used as the pressing body, and the slit portion 16 may be formed in the cylinder case 5. Furthermore, in either case, the slit portion 16 may be formed from the inner periphery side of the clamping portion, or the slit portion 16 may be provided in any position on the bonnet 6 or cylinder case 5 as long as a thrust can be applied to the external seal portion 35. In this case, it is desirable that the slit portion 16 is formed in the clamping portion 14, which is centered on the annular protrusion 15, at a position where a thrust acts from the vertical direction.

The fastening member 7 is not limited to a metal set screw, and may be, for example, a metal bolt and nut. In this case, although not shown, a base is attached to the bottom side of the body 1 as a base, and bolt insertion holes are formed in the base, the cylinder case 5, the bonnet 6, and the body 1. The base, the cylinder case 5, the bonnet 6, and the body 1 can be fixed together by fastening bolts and nuts through the bolt insertion holes. The fastening member does not necessarily have to be a separate body. For example, a screw-type portion formed by a combination of a male screw and a female screw may be provided on the cylinder case 5 side (bonnet 6 side) and the body 1 side, and the structure may be such that the parts are fastened together by screwing the screw-type portion.

The actuator 4 is operated automatically using a spring 22 and compressed air to open and close the valve, but a manual handle (not shown) can also be attached and used to manually raise and lower the actuator 4 to open and close the valve.

The body 1, diaphragm 3, cylinder case 5, and bonnet 6 can be made of various resin materials other than fluororesin. In this case, when chemical resistance is required for semiconductor manufacturing, etc., it is desirable to form at least the liquid-contacting parts, the body 1 and diaphragm 3, from a fluororesin such as PTFE.

Next, the operation of the diaphragm valve of the present invention in the above embodiment will be described.
When a diaphragm valve is used in semiconductor/liquid crystal manufacturing equipment, for example, the fluid temperature of ultra-high purity fluids such as chemicals may be 5°C to 100°C, and the surrounding atmospheric temperature may be about 0°C to 60°C. In this case, when the fluid temperature or the atmospheric temperature changes, the linear expansion coefficients of the resin parts, the body 1, the diaphragm 3, the cylinder case 5, and the bonnet 6, and the metal set screw 7, which is the fastening member, differ, and since the linear expansion coefficient of the resin parts is larger, excessive thrust is applied to the resin parts when the set screw 7 is tightened, which makes it easy for plastic deformation to occur. In particular, the body 1 and the diaphragm 3, which are the liquid-contacting parts, are easily affected by temperature changes because they are made of PTFE.

In response to this, the clamping portion 14 provided on the body 1 and the outer periphery of the diaphragm 3a form an external seal portion 35, and in this external seal portion 35, the bonnet 6 clamps the outer periphery of the diaphragm 3a to the clamping portion 14, and the clamping portion 33 of the bonnet 6 has an annular slit portion 16 for generating thrust. As a result, after the body 1 side and the operating mechanism 2 side are assembled, thrust is applied from the bonnet 6 to the outer periphery of the diaphragm 3a through the slit portion 16, and while the slit portion 16 absorbs the thermal expansion and contraction of the set screw 7 and the plastic parts (body 1, diaphragm 3, cylinder case 5, bonnet 6) due to temperature changes, the clamping portion 33 deforms to bend, suppressing plastic deformation of the plastic parts.

Therefore, even if fluids with temperature differences ranging from high (e.g. 100°C) to low (e.g. 5°C) repeatedly flow inside the valve and the plastic parts repeatedly thermally expand and contract relative to the set screw 7 due to changes in the fluid temperature and ambient temperature, the displacement of the plastic parts can be absorbed and creep deformation can be prevented.

In this way, by suppressing creep deformation of the resin parts, the thrust applied from the bonnet 6 to the external seal part 35 is maintained, and this thrust prevents a decrease in the adhesion of the external seal part 35, preventing fluid from leaking outside from the vicinity of the external seal part 35. In particular, even when the body 1 and diaphragm 3, which are the liquid-contacting parts, are formed from fluororesins such as PFA and PTFE to improve chemical resistance, the decrease in adhesion of the external seal part 35 caused by plastic deformation of these resins can be suppressed.

In addition, the annular protrusion 15 is formed on the clamping portion 14, and when this annular protrusion 15 comes into contact with the bottom surface of the diaphragm outer periphery 3a, the contact surface pressure is increased, improving the adhesion between them. At this time, since the annular protrusion 15 is provided within the gap width W of the slit portion 16 in the axial direction, the thrust from the bonnet 6 through the slit portion 16 acts to reliably bring the bottom surface side of the diaphragm outer periphery 3a and the clamping portion into close contact, and furthermore, the thrust is provided in a substantially vertical direction, improving the sealing performance.

When the body 1 side and the operating mechanism 2 side are assembled, the groove width of the gap width W of the slit portion 16 is narrowed and a reaction force is applied when the bonnet 6 is assembled, so that a thrust force is always generated that presses the diaphragm outer periphery 3a toward the clamping portion 14 side. As a result, even when there is no fluid flowing immediately after assembly, or when the plastic parts on the body 1 side and the operating mechanism 2 side expand or contract due to changes in fluid temperature or ambient temperature, the thrust force from the bonnet 6 is reliably maintained while reducing the stress generated in the external seal portion 35, ensuring the tight sealing of the external seal portion 35.

The gap width W and depth D of the slit portion 16 are set to generate thrust based on the strength of the resin material, the required thrust for adhesion, and the operating temperature range. By setting these gap width W and depth D to appropriate dimensions, it is possible to accommodate different diaphragm valve specifications and prevent external leakage without adding parts or increasing weight.

Figure 5 shows another embodiment of the diaphragm valve of the present invention. In this embodiment, the same parts as those in the above embodiment are designated by the same reference numerals, and their description will be omitted.

The operating mechanism 40 in the diaphragm valve of this embodiment includes a diaphragm 3, an operating body 4, and a cylinder case 41, with the cylinder case 41 serving as the pressing body. In this case, a slit portion 43 is formed in the clamping portion 42 of the cylinder case 41.

In this way, even when the pressing body is the cylinder case 41, just as in the case of the bonnet 6 in the above embodiment, a thrust is generated by the slit portion 43, and this thrust absorbs the thermal expansion and contraction of the resin parts due to changes in fluid temperature and ambient temperature, and maintains the adhesion near the external seal portion 35, which is composed of the clamping portion 14 of the body 1 and the outer periphery 3a of the diaphragm, thereby reliably suppressing external leakage.

Next, to confirm the difference in performance of the external seal with or without the slit, we performed stress analysis on the bonnet at room temperature and after heating. Figure 6 shows a schematic diagram of the area near the external seal 35.

In FIG. 6(a), when the slit portion 16 is formed, at room temperature after assembly, the displacement near the external seal portion 35 is about 0.2 mm, and the stress generated in the external seal portion 35 is about 31 MPa. After the temperature is raised, the displacement near the external seal portion 35 is about 0.4 mm, and the stress generated in the external seal portion 35 is about 52 MPa.

On the other hand, for comparison, as shown in FIG. 6(b), when there is no slit portion, at room temperature after assembly, the displacement near the external seal portion 35 is about 0.2 mm, and the stress generated in the external seal portion 35 is about 47 MPa. Furthermore, after the temperature is raised, the displacement near the external seal portion 35 is about 0.4 mm, and the stress generated in the external seal portion 35 is about 82 MPa.

The above stress analysis results showed that the displacement near the external seal did not change whether the slit 16 was present or not at room temperature or after heating, but it was confirmed that the stress generated in the external seal 35 was significantly greater without the slit than with the slit, both at room temperature and after heating.

For this reason, when there is no slit, compared to when there is a slit, the stress generated increases both at room temperature and when the temperature is raised, even when there is no dimensional change in the external seal portion 35, making it particularly prone to distortion near the external seal portion 35 and making it more likely to cause external leakage.

On the other hand, when a slit portion 16 is provided as in the present invention, the stress generated in the external seal portion 35 can be kept low, so it can be said that it is possible to suppress the occurrence of distortion, maintain the tight seal between the diaphragm outer periphery 3a and the clamping portion 14, and suppress external leakage.

Although the embodiment of the present invention has been described in detail above, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention as described in the claims of the present invention.

REFERENCE SIGNS LIST 1 Body 2 Actuating mechanism 3 Diaphragm 3a Diaphragm outer periphery 4 Actuating body 5 Cylinder case 6 Bonnet (pressing body)
7 Set screw (fastening member)
REFERENCE SIGNS LIST 10 inlet passage 11 outlet passage 12 valve chamber 14 clamping portion 15 annular protrusion 16 slit portion 17 valve seat 33 clamping portion 35 external seal portion D depth of slit portion W gap width of slit portion

Claims (7)

a clamping portion provided on the body for clamping an outer periphery of the diaphragm; a pressing body made of a resin material provided on the operating mechanism side for clamping the outer periphery of the diaphragm between the clamping portion; a fastening member for fastening the body side and the operating mechanism side; and an external seal portion constituted by the clamping portion and the outer periphery of the diaphragm in a state in which the body side and the operating mechanism side are fastened by the fastening member, wherein a ring-shaped slit portion for generating thrust is formed in the clamping portion of the pressing body in a direction intersecting the axial direction of the diaphragm. The diaphragm valve according to claim 1, in which the pressing body is assembled in a state in which the groove width of the gap width of the slit portion of the pressing body is narrowed to apply a reaction force when the body side and the operating mechanism side are assembled. The diaphragm valve according to claim 1 or 2, wherein the pressing body is a resin bonnet. The diaphragm valve according to claim 1 or 2, wherein the pressing body is a resin cylinder case provided on the operating mechanism side. The diaphragm valve according to any one of claims 1 to 4, wherein the fastening member is a metal set screw or a bolt and nut. A diaphragm valve as claimed in any one of claims 1 to 5, in which an annular protrusion is formed on the clamping portion of the external seal portion. A diaphragm valve according to any one of claims 1 to 6, in which the gap width and depth of the slit portion are set to generate thrust based on the strength of the resin material, the required thrust for adhesion, and the operating temperature range.

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