JP2010133480A - Diaphragm valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a diaphragm valve which can reduce a water hammer in a simple and compact structure. <P>SOLUTION: The diaphragm valve V includes flow passages 18, 19, a primary-side valve hole 11, a valve seat 13, a secondary-side valve hole 12, an annular groove 14, and a valve body 2. The valve body 2 includes a thin-thick part 22 which expands in a truncated cone shape from the bottom face of a central part 21 toward a periphery 23, and a disc-shaped protrusion 24 formed on the bottom face of the central part 21 and inserted into the primary valve hole 11, and is fitted into the primary valve bole 11 in a state that a clearance is formed between the side face of the disc-shaped protrusion 24 and the internal face of the primary valve hole 11. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a diaphragm valve used in various industrial fields such as a semiconductor manufacturing field, a liquid crystal manufacturing field, a chemical substance manufacturing field or a food field.

  2. Description of the Related Art Conventionally, in a semiconductor manufacturing field, a liquid crystal manufacturing field, and the like, in order to control the flow of a fluid such as pure water, it is common to use a diaphragm valve provided with a valve body that seals the fluid.

  As such a diaphragm valve, for example, in Patent Document 1, an annular fitting portion of a diaphragm valve is provided in the main body in a valve having a structure in which the peripheral portion of the diaphragm is sandwiched between the main body and the housing to seal the fluid inside the main body. A configuration is disclosed that is fitted into the annular groove and fixed in a state of being pressed by an O-ring.

  According to this configuration, even if the seal portion undergoes creep deformation due to fluid pressure fluctuation or temperature change, liquid leakage does not occur.

  Moreover, in patent document 2, the movement of a valve body is started by providing the inner peripheral taper surface which inclines inward from the contact edge of the valve seat upper end of a main body, and the convex part which opposes an inner peripheral taper surface. Discloses a configuration in which the minimum flow passage cross-sectional area is gradually reduced to close the valve.

Therefore, with a relatively simple configuration, it is possible to prevent water hammer caused by sudden changes in flow velocity and pressure when the valve is closed.
JP 2004-169886 A JP 2004-316679 A

  However, in the above-mentioned Patent Document 1, since the flow rate adjustment control structure with respect to the change in the degree of opening and closing of the valve is not provided to the valve body, the water hammer is large, and there is a possibility that the piping system and the apparatus system are damaged by the vibration. .

  Further, in Patent Document 2 described above, although the water hammer can be reduced, the structure of the valve body is complicated, and therefore, there is a problem that it is not compact when an opening / closing stroke equivalent to that of the conventional product is provided.

  Accordingly, an object of the present invention is to provide a diaphragm valve that can reduce the water hammer with a simple and compact structure.

  In order to achieve the above object, a diaphragm valve of the present invention includes a flow path formed in a valve body, a primary valve hole opened in the middle of the flow path, and a valve provided around the primary valve hole. A seat, a secondary valve hole that is annularly opened around the valve seat, an annular groove that is provided around the secondary valve hole, and a peripheral edge that is hooked on the annular groove, And a valve body that seals the flow path by contacting a bottom surface of the valve seat, wherein the valve body extends in a truncated cone shape from the bottom surface of the central portion to the peripheral edge portion. And a disc-shaped projection provided on the bottom surface of the central portion and inserted into the primary valve hole, and a gap between the side surface of the disc-shaped projection and the inner surface of the primary valve hole It is characterized by being fitted into the primary side valve hole in a state where the above has occurred.

  An air supply / exhaust port that slides a piston connected to the valve body in the housing to seal the flow path so that the valve body contacts the valve seat over a predetermined time. The diameter is preferably reduced.

  Furthermore, the top surface of the valve seat is provided with a taper-shaped projecting portion having a trapezoidal cross section along the circumferential direction, and the bottom surface of the central portion of the valve body is a flat surface that abuts the taper-shaped projecting portion. Can be formed.

  The top surface of the valve seat is formed flat, and a flat surface in contact with the top surface is formed at the base of the thin portion of the valve body with respect to the bottom surface. .

  Further, the top surface of the valve seat is formed flat, and a taper surface that is in line contact with the inner corner of the top surface is formed at the base of the thin portion of the valve body with respect to the bottom surface. It can be.

  Thus, in the diaphragm valve of the present invention, the valve body is provided on the bottom part of the central part with a thin wall part that spreads in the shape of a truncated cone from the bottom part of the central part to the peripheral part, and the disc-shaped protrusion that is inserted into the primary valve hole. And is fitted to the primary valve hole in a state where a gap is formed between the side surface of the disk-shaped protrusion and the inner surface of the primary valve hole.

  Therefore, when sealing the flow path, by flowing fluid through the gap between the side surface of the disk-shaped protrusion and the inner surface of the primary valve hole, the flow rate immediately before sealing is reduced, and water hammer is reduced. can do.

  In addition, the air supply / exhaust port for sliding the piston connected to the valve body within the housing is reduced in diameter so that the valve body contacts the valve seat over a predetermined time, so that the moving speed of the valve body It becomes late and water hammer can be reduced.

  Furthermore, a tapered protrusion is provided on the top surface of the valve seat, and a flat surface is formed on the bottom surface of the central portion of the valve body, so that the water hammer can be reduced with a simple and compact structure.

  And while the top surface of a valve seat is formed flat, the water hammer can be reduced by a simple and compact structure by forming the flat surface which contact | abuts a top surface in the base of the thin part of a valve body.

  In addition, the top surface of the valve seat is formed flat, and the base of the thin part of the valve body is formed with a tapered surface that makes line contact with the inner corner of the top surface. Hammer can be reduced.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  First, the whole structure of the diaphragm valve V of this Embodiment is demonstrated using FIG.

  The diaphragm valve V according to the present embodiment is inserted between the pipes 85 and 86 as shown in FIG. Then, the air is sent through the air pipes 88 and 89 attached to the inserts 58 and 59 provided in the housing 5, thereby moving the piston 4 (see FIGS. 1 and 3) to move the valve body 2 inside the valve body 1. (See FIGS. 1 and 3) is opened and closed to control the flow of a fluid such as a chemical solution or pure water flowing through the pipes 85 and 86.

  Next, the configuration of the diaphragm valve V of the present embodiment will be described using the exploded perspective view of FIG. FIG. 3 shows a case where the inner spring 61 and the outer spring 62 are used for reverse operation.

  As shown in FIGS. 1 and 3, the diaphragm valve V according to the present embodiment includes a valve body 1 provided with a flow path, a valve body 2 that seals the flow path, and presses the valve body 2 against the valve body 1. And a piston 4 having a cylindrical sliding portion 41 for opening and closing the valve body 2 and a housing 5 in which the piston 4 is slidably incorporated.

  The valve body 1 is formed in a container shape from a resin such as polyvinyl chloride, impact-resistant hard vinyl chloride, heat-resistant hard vinyl chloride, polypropylene, or polyvinylidene fluoride. As shown in FIG. An upstream channel 18 formed as an extension of the pipeline, a downstream channel 19 formed as an extension of the downstream channel, and a primary that is bent and opened on the side surface of the upstream channel 18 The side valve hole 11 and the secondary side valve hole 12 formed in an annular shape around the primary side valve hole 11 and connected to the downstream side flow path 19 are integrally provided.

  The primary-side valve hole 11 is provided so as to open in a circular shape on the side surface near the center of the valve body 1 by bending the upstream-side flow path 18 having a circular cross section near the center inside the valve body 1 at a substantially right angle. It is done.

  The secondary valve hole 12 is provided around the primary valve hole 11 so as to open in an annular shape concentric with the primary valve hole 11, and is connected to the upstream side of the downstream flow path 19. Has been.

  A cylindrical partition for separating from the secondary side valve hole 12 is provided around the primary side valve hole 11, and this partition has a trapezoidal shape with the inner peripheral side of the top surface 13b facing upward. A valve seat 13 having a tapered protrusion 13a protruding in a cross-sectional shape is formed (see FIG. 5).

  In addition, the inner surface 13c in the vicinity of the tip of the cylindrical partition wall is thinly cut along the circumferential direction so as to be a perfect circle, and the inner surface 13c has two steps formed by a cutting surface and a non-cutting surface. A cylindrical inner surface is formed (see FIGS. 1, 4 and 5).

  Furthermore, an annular groove 14 is formed around the secondary side valve hole 12 via an inclined surface so that the peripheral part 23 of the valve body 2 described later can be fitted and the valve body 2 can be hooked. It has become.

  The valve body 2 according to the present embodiment is formed of a synthetic resin such as polytetrafluoroethylene or a synthetic rubber such as ethylene propylene rubber. As shown in FIGS. A central portion 21, a thin-walled portion 22 that spreads outward in a truncated cone shape so as to be connected to the bottom surface of the central portion 21, and a peripheral portion that is formed so as to bend the peripheral edge of the thin-walled portion 22 downward in an L-shape 23 and a disc-like protrusion 24 that protrudes from the bottom surface of the short cylindrical central portion 21 into a short cylindrical shape (disc shape) with a slightly smaller outer diameter.

  The central portion 21 is formed in a short cylindrical shape having an outer diameter larger than the inner diameter of the valve seat 13, and a mounting hole 27 in which the tip of the shaft portion 42 of the piston 4 is attached to the center of one end surface of the cylinder. And a disk-shaped protrusion 24 is formed on the other end face.

  In addition, a flat surface 25 is formed in an annular shape outside the disc-shaped protrusion 24 on the bottom surface of the central portion 21 and is in contact with the upper surface of a tapered protrusion 13a described later.

  Moreover, the thin part 22 is formed in the thin disk shape which spreads continuously around the flat surface 25 of the bottom face of the center part 21, and becomes a truncated cone shape by inclining toward the periphery from the center. .

  Further, when the diaphragm valve V is operated, as shown in FIGS. 4 (a) and 4 (b), the peripheral edge and the root of the thin wall portion 22 are deformed by the flexibility of the resin. The annular flat surface 25 around the disc-shaped protrusion 24 on the bottom surface of the central portion 21 of the valve body 2 is brought into contact with the valve seat 13 to close the valve, or the bottom surface of the central portion 21 of the valve body 2 is disc-shaped. The annular flat surface 25 around the protrusion 24 can be opened away from the valve seat 13.

  In addition, the diaphragm valve V of the present embodiment has a narrow movement range (short stroke) in addition to a small thickness in the moving direction of the valve body 2 and a simple structure, as shown in FIG. Furthermore, the overall structure is a compact structure in which the height H, width W, and inter-surface Z are suppressed.

  The disc-shaped protrusion 24 is provided to form a gap through which a fluid passes between the valve body 2 and the valve seat 13 immediately before closing the valve, and the outer diameter of the central portion 21 is reduced. By doing so, it is formed in a thin (low height) disk shape protruding from the bottom surface of the central portion 21.

  Therefore, as shown in FIG. 5, there is a small gap B between the side surface 24a of the disc-shaped protrusion 24 and the inner surface 13c of the valve seat 13 so that a small amount of fluid can pass just before the valve is closed. It is formed.

  In addition, the disk-like protrusion 24 is formed so as to have a height h that is several times the width B of the gap so as not to protrude too much so as not to disturb the flow of fluid when the valve is opened. .

  In addition, as shown in the experiment of the Example mentioned later, when the pipe diameter is 25 mm, if this disk-like protrusion 24 is formed with an outer diameter of 24 mm and a height of about 1 mm, the width B on one side B = 0.5 mm ( It has been confirmed that a cylindrical minute gap having a height h = 1 mm (1/25 of the pipe diameter) is formed at 1/50 of the pipe diameter and the water hammer can be efficiently suppressed.

  Further, as shown in FIGS. 1 and 3, the valve body presser 3 is formed in a cylindrical shape having a circular hole 31 by resin, and O-rings 73 and 74 are fitted to the side surface and one end surface of the column. ing. As will be described later, the valve body presser 3 is provided with a communication hole that communicates the sliding space of the inner valve body 2 with the outer side at a position corresponding to the air vent hole of the housing 5.

  The piston 4 is formed of a resin, and has a large-diameter columnar sliding portion 41 and a small-diameter columnar shaft portion 42 protruding from the center of one surface of the sliding portion 41. Are provided as a unit.

  As shown in FIG. 1, the sliding portion 41 is formed in a columnar shape having a predetermined height, and an O-ring 71 is fitted on the side surface, and a column is concentrically overlapped on the top surface. The protrusion 43 is provided.

  An inner spring 61 as a coil spring and an outer spring 62 as a coil spring are disposed in the protruding portion 43 in a nested manner.

  When the housing 5 is fixed to the valve body 1, the inner spring 61 and the outer spring 62 are sandwiched between the top of the housing 5 and the piston 4 and are compressed in the axial direction.

  Therefore, when air is not sent through the air supply / exhaust port 59a of the insert 59, the valve body 2 connected to the piston 4 is pressed against the valve seat 13 by the elastic reaction force of the inner spring 61 and the outer spring 62, and the primary side. The valve hole 11 is closed.

  Furthermore, the housing 5 of the present embodiment is formed of resin, and inserts 58 and 59 for mounting air pipes 88 and 89 (see FIG. 2) are provided on the side surfaces, and further, a valve body presser is provided. An air vent hole is provided corresponding to the three communication holes, and a sliding surface 51 of the piston 4 is provided inside.

  When air is introduced from the air supply / exhaust port 59a in the insert 59 close to the valve body 2, the piston 4 guides the sliding surface 51 against the elastic reaction force of the inner spring 61 and the outer spring 62. Then, the valve body 2 is moved in the opening direction.

  On the other hand, when air is introduced from the air supply / exhaust port 58a in the insert 58 far from the valve body 2, the piston 4 is guided to the sliding surface 51 by the elastic reaction force of the inner spring 61 and the outer spring 62, and the valve The body 2 is moved in the closing direction, and the bottom surface of the disc-shaped protrusion 24 provided at the central portion 21 of the valve body 2 comes into contact with the upper surface of the tapered protrusion 13a of the valve seat 13 to achieve water stoppage.

  Further, of the air supply / exhaust ports 58a, 59a of the present embodiment, the supply / exhaust port 59a on the side that is exhausted when the valve body 2 descends (closes) closes the valve body 2 over a predetermined time. The diameter of the hole is reduced more than usual so as to contact the seat 13. Specifically, the supply / exhaust port 58a on the air supply side when being lowered is 1.0 mm, while the supply / exhaust port 59a on the exhaust side is formed to be 0.4 mm.

  That is, in the case of a pipe diameter of 25 mm, as shown in an experiment of an embodiment described later, the valve body 2 is set so that the time required for closing the valve body 2 is increased from 0.186 seconds to 1.30 seconds. The hole diameter of only the air supply / exhaust port 59a that is exhausted when the valve is lowered (closed) is formed small.

  Next, the operation of the diaphragm valve V of the present embodiment will be described with reference to FIGS. 4 (a), 4 (b), and 5. FIG.

  When used for reverse operation as in the present embodiment, the valve body 2 is closed in a normal state in which no air is supplied.

  In the case of opening the valve, as shown in FIGS. 1 and 4B, air is sent to the airtight space near the valve body 2 through the air supply / exhaust port 59a in the insert 59, so that the inner spring 61 and The piston 4 is moved away from the valve seat 13 against the elastic reaction force of the outer spring 62.

  Then, with the movement of the piston 4, the valve body 2 also moves away from the valve seat 13, and a gap is formed between the lower surface of the valve body 2 and the valve seat 13, and this gap The fluid flows from the upstream channel 18 to the downstream channel 19.

  On the contrary, when closing the valve, if the air supply to the airtight space near the valve body 2 through the air supply / exhaust port 59a of the insert 59 is shut off, the elastic reaction force of the inner spring 61 and the outer spring 62 is released. Then, the valve body 2 connected to the piston 4 is pressed against the valve seat 13 to return to the original state.

  At this time, a gap having a width B is formed between the side surface 24 a of the disc-like protrusion 24 of the valve body 2 and the inner surface 13 c of the valve seat 13, and a small amount of fluid flows from the upstream flow path 18 to the downstream side through this gap. It flows to the road 19.

  Then, after the fluid flows from the upstream flow path 18 to the downstream flow path 19 for the time required to pass the length of the gap in the flow path direction (corresponding to the height h of the disk-shaped protrusion 24), the valve body The two flat surfaces 25 are brought into contact with the upper surface of the tapered protrusion 13a of the valve seat 13 so that the flow path is completely sealed.

  Next, the operation of the diaphragm valve V of the present embodiment will be described.

  As described above, in the diaphragm valve V of the present embodiment, the valve body 2 is provided on the bottom surface of the central portion 21 with the thin-walled portion 22 extending in the shape of a truncated cone from the bottom surface of the central portion 21 to the peripheral portion 23. 11 and a disc-like projection 24 inserted into the disc 11, and the primary side with a gap formed between the side surface 24a of the disc-like projection 24 and the inner surface 13c of the valve seat 13 forming the primary valve hole 11. It is characterized by being fitted into the valve hole 11.

  Therefore, when sealing the flow path, the fluid is allowed to pass while reducing the flow rate by flowing the fluid through the gap between the side surface 24a of the disc-shaped protrusion 24 and the inner surface 13c of the primary side valve hole 11. Water hammer can be reduced.

  In other words, as shown in the graph of FIG. 6, in the case of the conventional type, since the gap is not provided, the minimum opening area decreases linearly when sealing, so the flow rate immediately before and after sealing The difference increases.

  Here, the opening minimum area means an area obtained by integrating the shortest distance between the valve body 2 and the valve seat 13 by one round along the annular gap.

  On the other hand, when the protrusion height is 1 mm (the same type as the embodiment and the first and second modifications), the gap is provided so that the minimum opening area is kept constant for a predetermined time when sealing. By gradually decreasing in a curved line, a certain amount of fluid flows during that time, so the flow rate difference immediately before and after sealing does not become so large.

  As described above, since the flow rate difference immediately before and after the sealing does not increase, it is possible to prevent a water hammer that is propagated by impacting pressure fluctuation in a short time.

  That is, by reducing the flow rate and gradually reducing the energy of the fluid in the middle of the valve closing, the energy of the fluid when sealing is reduced, so the peak value of pressure fluctuation is reduced.

  In addition, when the primary side valve hole 11 is sealed, the thin part 22 moves so as to close the secondary side valve hole 12 at the same time, so that the fluid stays on the side of the central part 21 or the like. Can be prevented.

  Therefore, it is possible to prevent the time from the time that the fluid staying after the valve is closed from flowing into the downstream side from being attenuated and the vibration is attenuated.

  Further, the valve body 2 has a flat bottom surface of the disc-like protrusion 24 at the central portion 21, so that the flow rate when fully open is larger than in the conventional case.

  In addition, the valve body 2 takes a predetermined time for the supply / exhaust port 59a on the exhaust side when the valve body 2 that slides the piston 4 connected to the valve body 2 in the housing 5 descends (closes). By reducing the diameter so as to contact the valve seat 13, the moving speed of the valve body 2 is reduced, and the water hammer can be reduced.

  That is, as will be described in an experiment shown in Example 1 described later, conventionally, an air supply / exhaust port on the exhaust side when the valve body 2 descends (closes) in order to close quickly in consideration of responsiveness. The hole diameter of 59a was relatively large.

  On the other hand, in the present embodiment, considering the water hammer, the hole diameter of the air supply / exhaust port 59a on the exhaust side is made smaller than the conventional one so that the valve can be closed slowly over a predetermined time.

  By closing the valve over time in this way, the energy of the fluid decreases over time, so that the water hammer can be reduced.

  In addition, by causing the valve body 2 to contact the valve seat 13 over a predetermined time in this way, it is possible to mitigate the impact generated in the fluid by the valve body 2 itself moving in the direction opposite to the fluid.

  And since the stroke (movement range) of the valve body 2 of this Embodiment is small, when sealing, the volume change of the fluid which arises by the movement of the valve body 2 can be suppressed.

  In addition, by reducing the stroke of the valve body 2 as described above and narrowing the hole diameter of the air supply / exhaust port 59a as described above, it is possible to suppress the operation delay due to the narrowing of the air supply / exhaust port 59a.

  In other words, if the air supply / exhaust port 59a is throttled, the valve is closed over time and the operation is delayed. However, the time required for closing the valve body 2 can be shortened by shortening the stroke. In this case, such an operation delay can be suppressed.

  Furthermore, a tapered protrusion 13 a is provided on the top surface of the valve seat 13, and an annular flat surface 25 is formed around the disk-shaped protrusion 24 on the bottom surface of the central portion 21 of the valve body 2. Thus, the water hammer can be reduced by a simple and compact structure.

  That is, the tapered protrusion 13 a has a simple shape in which the inner surface is formed in a trapezoidal shape that is continuous from the inner surface 13 c of the valve seat 13, and the flat surface 25 of the valve body 2 has an annular shape around the disk-shaped protrusion 24. Since it is a simple shape formed in a planar shape, processing of the valve body 2 and the valve body 1 is facilitated.

  In addition, the top surface of the valve seat 13 comes into contact at a position slightly shifted inward from the vicinity of the root of the thin portion 22 provided on the outer peripheral edge of the annular flat surface 25, so that weakness in strength is obtained. The durability of the valve body 2 can be improved by avoiding the vicinity of the base of the thin-walled portion 22 that tends to become.

  Further, since the inner surface 13c in the vicinity of the tip of the cylindrical partition wall is thinly cut in the circumferential direction along the circumferential direction, the width B of the gap with the side surface 24a of the disk-shaped protrusion 24 is uniform over the entire circumference. The valve can be closed while maintaining the width B of the gap for a certain time (see FIGS. 1, 4 and 5).

  That is, in general, since the accuracy of the process of cutting a circular hole is high, a minute width B can be uniformly formed at a predetermined height h over the entire circumference between the valve body 2 processed with high accuracy. .

  Hereinafter, an experiment performed to determine the shape of the disc-like protrusion 24 of the valve body 2 of the diaphragm valve V described in the above embodiment will be described.

  First, experimental conditions will be described.

  In this experiment, as shown in FIG. 2, the diaphragm valve V is inserted in the middle of the pipes 85 and 86, and the valve body 2 is opened and closed by sending air through the air pipes 88 and 89. The pressure fluctuation of the pipe 86 on the side) was measured with a pressure gauge.

  The experiment was conducted with the pipe 85 having a diameter of 25 (mm), a flow rate of 3 (m / s), a flow rate of 88 (liters / minute), and a pump pressure of 0.2 (MPa).

  Next, the results of experiments conducted by changing the shapes of the valve body 2 and the valve seat 13 and the closing speed of the valve body 2 will be described for each experimental example with reference to FIGS. 7 to 11 show the configurations of the valve body 2 and the valve seat 13 used in (a), and (b) shows the pressure fluctuation (upper side) and the downstream side (secondary) of the upstream (primary side) pipe line 85. The pressure fluctuation (lower side) of the secondary side pipe 86 is shown.

7 (b) to 11 (b), the vertical axis represents pressure, the horizontal axis represents time, one scale on the vertical axis represents 0.2 (MPa), and one scale on the horizontal axis represents 1 (s). Represents. In addition, the valve closing is started at the time indicated by the broken line on the second scale from the left of the horizontal axis.
(Conventional example)
First, as a conventional example, the bottom surface of the central portion 21 of the valve body 2 is formed in a truncated cone shape, the top surface of the valve seat 13 is formed flat, and the closing time of the valve body 2 is 0.186 (s). An experimental result is demonstrated using FIG.

  As shown in the experimental results of FIG. 7B, the maximum pressure on the primary side was 0.424 (MPa), and the maximum pressure on the secondary side was 0.469 (MPa).

  This is thought to be due to the large flow rate when fully closed and the large flow rate change per unit time.

  That is, the valve body 2 is not provided with a gap through which a fluid passes when closing, so that the flow rate immediately before the opening degree 0 (%) is large as shown in the conventional example of FIG. Become.

Further, since the diameter of the air supply / exhaust port 59a (see FIG. 1) on the exhaust side when the valve body 2 descends (closes) is not reduced, the moving speed at which the valve body 2 closes the flow path is reduced. And the flow rate change per unit time increases.
(Modification of the conventional example)
Next, as a modification of the conventional example shown in FIG. 7, the bottom surface of the central portion of the valve body 2 is formed in a truncated cone shape, the top surface of the valve seat 13 is formed flat, and the closing time 1. The experimental result in the case of 10 (s) will be described with reference to FIG.

  As shown in the experimental results of FIG. 8B, the maximum pressure on the primary side was 0.251 (MPa), and the maximum pressure on the secondary side was 0.189 (MPa).

  This is considered to be because the flow rate per unit time is small because the flow rate when fully closed is large, but the closing time is long.

  That is, the valve body 2 is not provided with a gap through which a fluid passes when closing, so that the flow rate immediately before the opening degree 0 (%) is large as shown in the conventional example of FIG. Become.

On the other hand, because the diameter of the air supply / exhaust port 59a (see FIG. 1) on the exhaust side when the valve body 2 is lowered (closed) is reduced, the valve body 2 moves when closing the flow path. The speed is reduced and the change in flow rate per unit time is reduced.
(Example)
Next, as an example corresponding to the above-described embodiment, a disc-shaped protrusion 24 is provided on the bottom surface of the central portion of the valve body 2, and a taper-shaped protrusion 13 a is provided on the top surface of the valve seat 13. The experimental result in the case of 2 closing time 1.30 (s) will be described with reference to FIG.

  As shown in the experimental results of FIG. 9B, the maximum pressure on the primary side was 0.257 (MPa), and the maximum pressure on the secondary side was 0.122 (MPa).

  This is considered to be because the flow rate per unit time is small because the flow rate at the time of full closure is small and the closure time is long.

  That is, the valve body 2 is provided with a gap through which a fluid passes when closed, between the side surface 24a of the disc-like protrusion 24 and the inner surface 13c of the valve seat 13, and therefore, the example shown in FIG. Thus, the flow rate immediately before the opening degree 0 (%) becomes small.

  Further, since the air supply / exhaust port 59a (see FIG. 1) on the exhaust side when the valve body 2 descends (closes) is reduced in diameter, the moving speed when the valve body 2 closes the flow path is reduced. Becomes smaller, and the change in flow rate per unit time becomes smaller.

In addition, when the valve is closed, the space on the side of the central portion 21 is blocked by the thin portion 22 so that the fluid does not stay in this portion, so that the time required for attenuation is shortened.
(Comparative example)
Next, as a comparative example, a curved thin portion 22 is provided on the upper side surface of the central portion 21 of the valve body 2, a conical protrusion is provided on the bottom surface of the central portion 21 of the valve body 2, and the top surface of the valve seat 13. FIG. 10 is used to explain the experimental results in the case where the taper-shaped projecting portion is provided in the valve body 2 and the valve body 2 has a closing time of 1.36 (s).

  As shown in the experimental results in FIG. 10B, the maximum pressure on the primary side was 0.244 (MPa), and the maximum pressure on the secondary side was 0.115 (MPa).

However, the time required for attenuation is longer than that of the conventional example because the thin portion 22 is provided on the upper side surface of the central portion 21 of the valve body 2, and a space is generated on the side of the central portion 21. For this reason, it is considered that the fluid that has passed immediately before closing the valve stays in this space.
(Modification 1)
Hereinafter, the combination of the valve body 2 and the valve body 1 in a form different from the above embodiment will be described with reference to FIG. The description of the same or equivalent parts as those described in the above embodiment will be given the same reference numerals.

  In the first modification, unlike the above embodiment, a case where the valve seat 13 is formed flat will be described.

  First, when it demonstrates from a structure, the valve seat 13 of the modification 1 is provided with the flat top surface 13b, without providing the taper-shaped protrusion part 13a in the top surface 13b.

  The central portion 21 of the valve body 2 is formed in a short columnar shape, and has a mounting hole 27 to which the tip of the shaft portion 42 of the piston 4 is attached at the center of one end surface of the column. A disc-like protrusion 24 is formed on the end face of the.

  In addition, a flat surface 25 is formed in an annular surface outside the disc-like protrusion 24 on the bottom surface of the central portion 21 and is in contact with the upper surface of the flat top surface 13b.

  Next, the operation will be described.

  As described above, the top surface of the valve seat 13 of Modification 1 is formed flat, and a flat surface 25 that abuts the valve seat top surface 13b is formed at the base of the thin portion 22 of the valve body 2 with respect to the central portion 21. As a result, the water hammer can be reduced by a simple and compact structure.

  That is, the flat top surface 13b has a simple shape in which the upper end of the valve seat 13 is processed into a flat surface, and the flat surface 25 of the valve body 2 is simply formed in the shape of an annular surface around the disc-shaped protrusion 24. Since the shape is simple, the valve body 1 and the valve body 2 can be easily processed.

Other configurations and operational effects are substantially the same as those in the above-described embodiment, and thus the description thereof is omitted.
(Modification 2)
Hereinafter, the combination of the valve body 2 and the valve body 1 in a form different from the above-described embodiment and modification 1 will be described with reference to FIG. The description of the same or equivalent parts as those described in the above embodiment will be given the same reference numerals.

  In the second modification, unlike the above-described embodiment, the case where the valve seat 13 is formed flat and the tapered surface 26 is formed around the disk-shaped protrusion 24 will be described.

  First, when it demonstrates from a structure, the valve seat 13 of the modification 2 is provided with the flat top surface 13b, without providing the taper-shaped protrusion part 13a in the top surface 13b.

  The central portion 21 of the valve body 2 is formed in a short columnar shape, and has a mounting hole 27 to which the tip of the shaft portion 42 of the piston 4 is attached at the center of one end surface of the column. A disc-like protrusion 24 is formed on the end face of the.

  In addition, a frustoconical taper surface 26 that is inclined obliquely from the side surface 24a of the disc-like projection 24 to the root of the thin portion 22 is formed outside the disc-like projection 24 on the bottom surface of the central portion 21. Is formed.

  Therefore, the inner corner of the flat top surface 13b of the valve seat 13 and the truncated cone-shaped tapered surface 26 of the valve body 2 are in line contact with each other in a circular shape.

  Next, the operation will be described.

  As described above, the top surface 13b of the valve seat 13 of Modification 2 is formed flat, and the taper surface 26 that is in line contact with the inner corner of the top surface 13b is formed at the base of the thin portion 22 of the valve body 2. As a result, the water hammer can be reduced by a simple and compact structure.

  In other words, the flat top surface 13 b has a simple shape in which the upper end of the valve seat 13 is processed into a flat surface, and the tapered surface 26 of the valve body 2 is simply formed in the shape of a truncated cone around the disc-shaped protrusion 24. Due to the shape, the valve body 1 and the valve body 2 can be easily processed.

  In addition, when the valve is closed as in Modification 2, the flow path (gap) is formed obliquely so that the fluid passes diagonally immediately before sealing, so that the fluid passes without staying. Water hammer can be reduced.

  Other configurations and operational effects are substantially the same as those in the above-described embodiment, and thus the description thereof is omitted.

  The preferred embodiments and examples of the present invention have been described in detail with reference to the drawings, but the specific configuration is not limited to the embodiments or examples, and does not depart from the gist of the present invention. A degree of design change is included in the present invention.

  For example, in the said embodiment and Example, it is about the case where a clearance gap is formed between the valve seat 13 by providing the disc-shaped protrusion 24 of a diameter smaller than the column-shaped center part 21 in the valve body 2. FIG. However, the present invention is not limited to this, and the inner diameter of the primary valve hole 11 near the top surface of the valve seat 13 may be increased to form a gap with the valve body 2.

  Moreover, although the said embodiment and Example demonstrated the case where the valve seat 13 and the valve body 2 of the diaphragm valve V of a reverse action produce a clearance gap, it is not limited to this, A normal action or a reset action is not limited to this. It can also be applied to a diaphragm valve.

It is sectional drawing explaining the structure of the diaphragm valve of the best embodiment of this invention. It is a perspective view explaining the structure of the pipe line provided with a diaphragm valve. It is a disassembled perspective view which decomposes | disassembles and demonstrates the structure of the diaphragm valve of the best embodiment of this invention. It is explanatory drawing explaining operation | movement of the diaphragm valve of an Example. (A) is an open state, (b) is a closed state. It is an expanded sectional view which expands and demonstrates the structure of a valve main body and a valve body. It is the graph which showed the relationship between the stroke of a valve body, and the opening minimum cross-sectional area of a primary side valve hole. It is explanatory drawing explaining experiment of a prior art example. (A) is sectional drawing, (b) is the graph which showed the pressure fluctuation. It is explanatory drawing explaining the experiment of the modification of a prior art example. (A) is sectional drawing, (b) is the graph which showed the pressure fluctuation. It is explanatory drawing explaining experiment of an Example. (A) is sectional drawing, (b) is the graph which showed the pressure fluctuation. It is explanatory drawing explaining experiment of a comparative example. (A) is sectional drawing, (b) is the graph which showed the pressure fluctuation. It is sectional drawing explaining the structure of the diaphragm valve of the modification 1. FIG. (A) is sectional drawing of a closed state, (b) is an expanded sectional view. It is sectional drawing explaining the structure of the diaphragm valve of the modification 2. FIG. (A) is sectional drawing of a closed state, (b) is an expanded sectional view.

Explanation of symbols

V Diaphragm valve 1 Valve body 11 Primary side valve hole 12 Secondary side valve hole 13 Valve seat 13a Tapered protrusion 14 Annular groove 18 Upstream flow path (flow path)
19 Downstream channel (channel)
2 Valve body 21 Central part 22 Thin part 23 Peripheral part 24 Disc-shaped protrusion 25 Flat surface 26 Tapered surface 4 Piston 5 Housing 58a, 59a Supply / exhaust port

Claims (5)

A flow path formed in the valve body, a primary valve hole opened in the middle of the flow path, a valve seat provided around the primary valve hole, and a secondary opened annularly around the valve seat A side valve hole, an annular groove provided around the secondary valve hole, a peripheral edge is hooked on the annular groove, and a bottom surface of a central portion contacts the valve seat to seal the flow path A diaphragm valve comprising:
The valve body includes a thin-walled portion that extends in a truncated cone shape from the bottom surface of the central portion to the peripheral edge portion, and a disk-shaped protrusion that is provided on the bottom surface of the central portion and is inserted into the primary valve hole. And
The diaphragm valve, wherein the diaphragm valve is fitted into the primary valve hole with a gap formed between a side surface of the disc-shaped protrusion and an inner surface of the primary valve hole.   An air supply / exhaust port for sliding a piston connected to the valve body in the housing to seal the flow path is contracted so that the valve body contacts the valve seat over a predetermined time. The diaphragm valve according to claim 1, wherein the diaphragm valve has a diameter. The top surface of the valve seat is provided with a tapered protrusion with a trapezoidal cross section along the circumferential direction,
3. The diaphragm valve according to claim 1, wherein a flat surface that abuts on the tapered protrusion is formed on a bottom surface of a central portion of the valve body. The top surface of the valve seat is formed flat,
The diaphragm valve according to claim 1 or 2, wherein a flat surface that contacts the top surface is formed at a base of the thin portion of the valve body with respect to the bottom surface. The top surface of the valve seat is formed flat,
The diaphragm valve according to claim 1 or 2, wherein a taper surface that is in line contact with an inner corner of the top surface is formed at a base of the thin portion of the valve body with respect to the bottom surface.

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