JP2022111615A - diaphragm valve - Google Patents

Abstract

To prevent increase of stress in a film part of a diaphragm to achieve long life in a diaphragm valve in which an outer periphery part of the diaphragm is compressed.SOLUTION: A diaphragm valve includes: a valve body 2 having a valve seat 22; and a diaphragm 23 having a film part 41, which has a valve body 24, and an annular attachment part 32, which encloses the film part 41, and formed of a plastic material. The diaphragm valve includes a cylinder 31 (a holding member) which cooperates with the valve body 2 to sandwich and hold the attachment part 32 of the diaphragm 23. An annular groove 43 is formed between the film part 41 and the attachment part 32.SELECTED DRAWING: Figure 2

Description

The present invention relates to a diaphragm valve with a diaphragm made of plastic material.

As a conventional diaphragm valve of this type, there is one described in Patent Document 1, for example. A diaphragm valve disclosed in US Pat. No. 5,900,000 comprises a diaphragm made of plastic material and having a valve body. The diaphragm has a disk-shaped membrane and a valve body located in the center of the membrane, and the outer periphery of the membrane is attached to the valve body.

In this type of diaphragm valve, in order to prevent fluid from leaking from the outer peripheral portion of the diaphragm, it is necessary to sandwich the outer peripheral portion between the valve body and the pressing member so that the outer peripheral portion is compressed in the thickness direction. There is

Japanese Patent Application Laid-Open No. 2007-24090

When the outer peripheral part of the diaphragm made of plastic material is compressed, the deformation of the outer peripheral part caused by the compressive force is transmitted to the membrane part, and the sealing surface pressure (compressive stress) is also generated in the membrane part, causing the membrane part to be deformed. load increases. When the diaphragm valve is used, this membrane section is repeatedly driven and fatigued, and is also subjected to a load such as creep stress generated by receiving internal pressure from the fluid. Therefore, in a diaphragm valve in which the outer peripheral portion of the diaphragm is compressed, there is a problem that the film portion of the diaphragm is easily damaged.

When the diaphragm is made of fluorine resin, as can be seen from the graph shown in FIG. 7, when a stress of 17 MPa is applied as a load, it breaks after 100,000 hours (11 years), and when a stress of 25 MPa is applied, it breaks after 50 hours. do.
If the membrane of the diaphragm is damaged, the internal process fluid leaks to the outside, causing equipment failure.

SUMMARY OF THE INVENTION It is an object of the present invention to prevent an increase in stress in a membrane portion of a diaphragm and extend its life in a diaphragm valve in which the outer peripheral portion of the diaphragm is compressed.

In order to achieve this object, a diaphragm valve according to the present invention has a valve body having a valve seat, a membrane portion having a valve body seated on the valve seat, and an annular mounting portion surrounding the membrane portion, a diaphragm made of a plastic material; and a cylindrical holding member that sandwiches and holds the mounting portion of the diaphragm in cooperation with the valve body; A groove is formed.

In the diaphragm valve according to the present invention, the film portion is formed such that one end face in the thickness direction is positioned on the same plane as one end face in the axial direction of the mounting portion, and the mounting portion The groove is formed to be thicker and extends radially inward from the holding member, and the groove extends radially inward from the holding member in the inner peripheral side end of the mounting portion. It may be formed so as to be open at one end surface and have a depth corresponding to the thickness of the film portion.

In the diaphragm valve of the present invention, a ring made of a material having higher rigidity than that of the diaphragm may be fitted in the groove.

In the present invention, the groove blocks the transmission path of the compressive force from the attachment portion of the diaphragm to the membrane portion. Therefore, in a diaphragm valve in which the outer peripheral portion of the diaphragm is compressed, it is possible to prevent an increase in stress in the film portion of the diaphragm and extend the life of the valve.

1 is a side view of a diaphragm valve according to the present invention; FIG. FIG. 2 is a cross-sectional view showing an enlarged main part. FIG. 3 is a perspective cross-sectional view of a main part viewed obliquely. FIG. 4 is a schematic diagram showing an analysis result when adopting the configuration of the present invention. FIG. 5 is a schematic diagram showing the analysis results when the configuration of the present invention is not adopted. FIG. 6 is a cross-sectional view showing an enlarged main part of the second embodiment. FIG. 7 is a graph showing stress rupture properties of fluororesin.

(First embodiment)
An embodiment of a diaphragm valve according to the present invention will be described in detail below with reference to FIGS. 1 to 5. FIG. A diaphragm valve 1 shown in FIG. 1 includes a valve body 2 drawn at the bottom in FIG. and an actuator 5 . The valve body 2 is made of a plastic material such as fluororesin, and the bonnet 4 is made of a metal material such as stainless steel.

The valve body 2 includes a main body 11 to which the bonnet 4 is attached, an upstream joint 12 protruding from the main body 11 toward one side (leftward in FIG. 1), and a protruding side from the main body 11 toward the other side. and a downstream joint 13 . A circular recess 14 opening toward the bonnet 4 is formed at one end of the main body 11 to which the bonnet 4 is attached. The circular recess 14 is formed so that the opening shape is circular. The opening of circular recess 14 is closed by bonnet 4 and actuator 5 .

The upstream joint 12 and the downstream joint 13 are for connecting pipes (not shown). A fluid made of liquid or gas flows through the piping. A corrosive fluid can be used as this fluid.
The upstream joint 12 and the downstream joint 13 are each formed in a columnar shape, and external threads 15 and 16 are formed on the outer peripheral portions thereof for attaching pipes. An upstream passage hole 21 is formed in the central portion of the upstream joint 12 . The upstream passage hole 21 extends from the upstream joint 12 through the main body 11 of the valve body 2 toward the circular recess 14 and opens at the center of the bottom of the circular recess 14 . The direction in which the upstream passage hole 21 opens at the bottom of the circular recess 14 is the direction from the bottom of the circular recess 14 toward the opening.

As shown in FIG. 2 , a valve seat 22 is formed at the bottom of the circular recess 14 and around the opening of the upstream passage hole 21 . An upstream passage hole 21 opens at the center of the valve seat 22 . A valve body 24 of a diaphragm 23 to be described later is seated on the valve seat 22 . The diaphragm 23 is housed in the bottom of the circular recess 14 and is driven by an actuator 5 to be described later in the opening/closing direction (vertical direction in FIG. 2) in which the valve element 24 contacts and separates from the valve seat 22 . A detailed description of the diaphragm 23 will be given later.

A downstream passage hole 25 is formed in the central portion of the downstream joint 13 as shown in FIG. The downstream passage hole 25 extends from the downstream joint 13 through the main body 11 of the valve body 2 toward the circular recess 14 , and opens radially outward from the valve seat 22 at the bottom of the circular recess 14 . ing.

The bonnet 4 has a cylinder 31 that fits into the circular recess 14 of the valve body 2, as shown in FIG. A seal member (not shown) is provided at a joint portion between the valve body 2 and the bonnet 4 . The cylinder 31 cooperates with the bonnet 4 to sandwich and hold an annular mounting portion 32 formed on the outer peripheral portion of the diaphragm 23, which will be described later. A fluid chamber 33 is formed between the diaphragm 23 and the bottom of the circular recess 14 by sandwiching the mounting portion 32 between the bonnet 4 and the cylinder 31 . The fluid chamber 33 communicates between the upstream passage hole 21 and the downstream passage hole 25 when the valve element 24 is separated from the valve seat 22 . In this embodiment, the cylinder 31 corresponds to the "holding member" according to the invention.

The actuator 5 has a drive shaft 34 inserted into the cylinder 31 of the bonnet 4 and is attached to the bonnet 4 so that the drive shaft 34 is coaxial with the circular recess 14 and the cylinder 31 . A seal member (not shown) is provided between the inner peripheral surface of the cylinder 31 and the drive shaft 34 .
The actuator 5 also includes an electric drive source (not shown) that drives the drive shaft 34 in the above-described opening and closing directions.
A diaphragm 23 is attached to the tip of the drive shaft 34 near the bottom of the circular recess 14 .

The diaphragm 23 is made of a plastic material such as fluorine resin and has a predetermined shape. As shown in FIGS. 2 and 3, the diaphragm 23 according to this embodiment includes a disk-shaped membrane portion 41 having the valve body 24 seated on the valve seat 22 described above, and a valve body extending from the center portion of the membrane portion 41 . It has a plug 42 protruding in the opposite direction to 24 and an annular mounting portion 32 surrounding the membrane portion 41 . The valve body 24 is formed in a columnar shape and protrudes toward the bottom of the circular recess 14 from the central portion of the membrane portion 41 . When the valve body 24 is seated on the valve seat 22 , the upstream passage hole 21 opening to the valve seat 22 is closed.

One end face 41 a in the thickness direction of the film portion 41 (the upper end face in FIGS. 2 and 3 and located on the side opposite to the valve body 24 ) is one end face 32 a in the axial direction of the mounting portion 32 . It is formed so as to be positioned on the same plane as the An annular groove 43 , which will be described later, is formed between the film portion 41 and the mounting portion 32 .

The plug 42 is formed to protrude by a predetermined length from the central portion of the membrane portion 41 in the direction opposite to the valve body 24. and a threaded portion 42b that is screwed into and connected to . The diaphragm 23 is attached to the drive shaft 34 by screwing the threaded portion 42 b onto the drive shaft 34 . Therefore, when the actuator 5 operates and the drive shaft 34 advances and retreats with respect to the valve body 2, the valve body 24 of the diaphragm 23, the plug 42, and the central portion of the membrane portion 41 move integrally with the drive shaft 34. The upstream passage hole 21 opening to the valve seat 22 is opened and closed.

The mounting portion 32 is formed to be thicker than the membrane portion 41 , extends radially inward from the cylinder 31 , and fits into an annular groove 44 formed in the outer peripheral portion of the bottom of the circular recess 14 . When the cylinder 31 of the bonnet 4 is pushed from the opposite direction to the valve body 2 while being fitted in the annular groove 44 , the mounting portion 32 is compressed in the axial direction and adheres tightly to the wall surface of the circular recess 14 . , substantially function as a sealing member that seals the fluid chamber 33 . 2 and 3 are drawn in a state in which the mounting portion 32 is not compressed.

A groove 43 provided between the mounting portion 32 and the film portion 41 is formed at the inner peripheral side end portion of the mounting portion 32 and on the side opposite to the bottom of the circular recess 14 . is opened at one end face 32a in the axial direction of the . Moreover, the groove 43 is formed to have a depth corresponding to the thickness of the film portion 41 . The bottom of the groove 43 is formed to have a U-shaped cross section so that stress concentration does not occur when the film portion 41 is displaced in the thickness direction with respect to the mounting portion 32 .

When the mounting portion 32 of the diaphragm 23 is pressed by the cylinder 31 of the bonnet 4 in a state where it is fitted in the annular groove 44 of the valve body 2, the mounting portion 32 is compressed and deformed radially inward. . When the state of stress generated in the diaphragm 23 at this time was analyzed, the results shown in FIG. 4 were obtained. As a comparative example, FIG. 5 shows the analysis results when a diaphragm in which the grooves 43 are not formed is used. In FIG. 5, the same reference numerals are given to the same or equivalent members as those explained with reference to FIGS.

In FIGS. 4 and 5, the magnitude of the stress is represented by the shade of color, and the color is drawn so that the greater the stress, the darker the color, and the smaller the stress, the lighter the color.
As can be seen from FIG. 5, when the groove 43 is not formed, the stress generated in the film portion 41 increases due to the compression of the outer peripheral portion (mounting portion 32) of the diaphragm 23. As shown in FIG. In this case, the maximum stress generated in the film portion 41 was 5.1 MPa.
On the other hand, when grooves 43 are formed as shown in FIG. The stress generated at 41 is smaller than in the case shown in FIG. In this case, the maximum stress generated in the film portion 41 was 3.3 MPa.

Therefore, by forming the groove 43 between the film portion 41 and the mounting portion 32 of the diaphragm 23 as shown in this embodiment, the diaphragm 23 is moved to the diaphragm valve 1 so that the stress generated in the film portion 41 is reduced. Since it can be incorporated inside, it is possible to extend the life of the film portion 41 of the diaphragm 23 .

The film portion 41 according to this embodiment is formed so that one end face 41 a in the thickness direction is positioned on the same plane as one end face 32 a in the axial direction of the mounting portion 32 . The mounting portion 32 is formed to be thicker than the film portion 41 and is formed to extend radially inward from the cylinder 31 . The groove 43 is formed at the inner peripheral end portion of the mounting portion 32 positioned radially inward of the cylinder 31 so as to open to one axial end surface 32 a and have a depth corresponding to the thickness of the film portion 41 . It is Therefore, according to this embodiment, the compressive force is transmitted from the mounting portion 32 to the film portion 41 while bypassing the grooves 43, so that the compressive force is less likely to be transmitted from the mounting portion 32 to the grooves 43. , the stress generated in the film portion 41 due to the compression of the mounting portion 32 can be further reduced.

(Second embodiment)
A diaphragm used in a diaphragm valve according to the present invention can be configured as shown in FIG. In FIG. 6, the same or equivalent members as those explained with reference to FIGS. 1 to 4 are denoted by the same reference numerals, and detailed explanation thereof will be omitted as appropriate.
The diaphragm 51 shown in FIG. 6 is different from the diaphragm 23 shown in FIGS. 1 to 4 in that a ring 52 is attached to the groove 43 between the membrane portion 41 and the attachment portion 32, and is otherwise the same. be.

The ring 52 is formed so as to extend continuously in the circumferential direction of the groove 43 and is fitted into the groove 43 . The material forming ring 52 is a material that is stiffer than the plastic material forming diaphragm 23 . The material of the ring 52 according to this embodiment is metal.

When the ring 52 is fitted in the groove 43 , the space in the groove 43 is filled with the ring 52 . Therefore, when the cylinder 31 is pressed against the mounting portion 32 , the groove 43 is compressed by the compressive force acting on the mounting portion 32 . The radially outer wall of the is no longer displaced radially inward due to elastic deformation. As a result, the load that the mounting portion 32 receives from the cylinder 31 is not dispersed, so that the mounting portion 32 functions as a sealing member and the sealing surface pressure increases. In addition, since the metal ring 52 has much higher rigidity than fluororesin and is less likely to deform, by adopting this embodiment, the compressive force acting on the mounting portion 32 is transmitted through the ring 52 to the membrane portion 41 . can be prevented from being transmitted to
Therefore, by fitting the ring 52 into the groove 43, it is possible to improve the sealing performance and further reduce the stress generated in the membrane portion 41. FIG.

In the embodiment described above, an example in which the ring 52 is made of a metal material is shown, but the material of the ring 52 is not limited to the metal material. The material forming the ring 52 may be a hard plastic material having higher rigidity than the plastic material forming the diaphragm 23, or a ceramic material.

DESCRIPTION OF SYMBOLS 1... Diaphragm valve 2... Valve body 22... Valve seat 23, 51... Diaphragm 24... Valve body 31... Cylinder (holding member) 32... Mounting part 41... Membrane part 43... Groove 52... ring.

Claims (3)

a valve body having a valve seat;
a diaphragm formed of a plastic material, having a membrane portion having a valve body seated on the valve seat and an annular mounting portion surrounding the membrane portion;
a cylindrical holding member that sandwiches and holds the mounting portion of the diaphragm in cooperation with the valve body,
A diaphragm valve, wherein an annular groove is formed between the membrane portion and the mounting portion. A diaphragm valve according to claim 1, wherein
The film portion is formed so that one end surface in the thickness direction is located on the same plane as one end surface in the axial direction of the mounting portion,
the mounting portion is formed to be thicker than the film portion and extends radially inward from the holding member;
The groove is formed at an inner peripheral end portion of the mounting portion located radially inwardly of the holding member, and is open at one end face in the axial direction and has a depth corresponding to the thickness of the film portion. A diaphragm valve, characterized in that: In the diaphragm valve according to claim 1 or claim 2,
A diaphragm valve, wherein a ring made of a material having higher rigidity than said diaphragm is fitted in said groove.

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