JP2012017830A - Fluid control valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly durable flow control valve relating to a valve seat seal structure of a flow control valve controlling the flow of fluid.SOLUTION: In the flow control valve 1 controlling the flow of the fluid by contacting or spacing apart the valve body 20 to or from the valve seat 10 of the body 2 having the valve seat 10, at least the valve seat contacting part 23 contacting to or spacing apart from the valve seat 10 of the valve body 20 is made of rubber, the lower face 23a of the valve seat contacting part 23 is formed in a planar shape, the valve seat 10 has an upward convex shape and has a top part of a curved face shape at the uppermost end. A surface inside the valve seat, lowering downward, is formed radially inside relative to the direction along the radial direction HX of the valve seat 10; and a surface outside the valve seat, lowering downside, is formed radially outside sandwiching the top part in the valve seat 10.

Description

  The present invention relates to a valve seat seal structure for a fluid control valve that controls the flow of fluid.

Conventionally, as a fluid control valve for controlling the flow of fluid, for example, a poppet valve disclosed in Patent Document 1 can be cited. FIG. 14 is a cross-sectional view illustrating the valve seat seal structure of the poppet valve of Patent Document 1.
In Patent Document 1, as shown in FIG. 14, the valve seat forming portion 110 is convex upward, and has a seating portion 110 a at the innermost position relative to the axis CL of the valve seat forming portion 110. The outer tapered surface 110b descends radially outward from the seating portion 110a. The diaphragm valve body 120 has a flat lower surface 120a that comes into contact with or is separated from the seating portion 110a.

As in the poppet valve of Patent Document 1, in a fluid control valve in which a valve body formed of an elastic material such as rubber is in contact with or away from the valve seat to control the flow of fluid, the valve seat is It is formed at the upper end of the valve seat forming portion formed in a convex shape on the upper side, and is located on the inner side in the diameter with respect to the axis of the valve seat.
The valve seat of the valve seat forming portion is formed with an outer tapered surface that descends from the curved top portion toward the outside of the diameter, and the flat valve seat abutting portion that is the lower surface of the valve body is formed on the top portion of the valve seat. In addition, a seal structure that abuts or separates from the upper end portion of the outer tapered surface is common.
With such a seal structure, when the valve is closed, the valve seat contact portion of the valve body is elastically deformed, so that the top portion of the valve seat and the upper end portion of the outer tapered surface are in contact with the valve seat contact of the valve body. A large repulsive force is generated around the top of the valve seat by biting into the contact portion, and a fluid control valve having a high sealing force is obtained.

As another embodiment of the fluid control valve, FIG. 15 shows an example of a seal structure of a valve seat that has been conventionally implemented in a fluid control valve for high temperature fluid that controls a high temperature fluid such as steam.
A small-diameter portion 151a is formed at the lower end of a valve shaft 151 that is connected to a pilot mechanism (not shown) and is slidable in the vertical direction, and a screw portion 151b is formed at the tip. A support disc 152 is fitted into the small diameter portion 151a. A fluororesin valve member 153 having a flat bottom surface is fitted into the groove of the support disk 152, and is sandwiched between the pressing plates 157 and fixed by screwing the nut 156 to the screw portion 151b. The reason why the fluorine-based resin is used for the valve member 153 is that, since the fluid is high temperature, the heat resistance of the rubber is insufficient, and the rubber cannot be used for the valve body.
Such a fluid control valve is closed when a flat valve seat abutting portion 153a, which is the lower surface of the valve member 153, abuts the valve seat 154 of the valve seat forming portion 155, and this valve seat abutting When the part 153a is separated from the valve seat 154, the valve is opened.
However, when the valve is closed, a pressing force is applied to the valve member in a state where a high-temperature fluid is flowing. Therefore, there is a problem that the valve member made of a fluororesin is deformed by creep. In the fluid control valve disclosed in No. 2, each shape of the valve seat and the valve body is devised.

FIG. 16 is a cross-sectional view showing the fluid control valve described in Patent Document 2. FIG. 17 is an explanatory diagram schematically showing an X portion in FIG. 16 in an enlarged manner.
Patent Document 2 is a fluid control valve 200 that controls the flow of fluid by bringing a resin valve body abutting portion 221 out of the valve body 220 into contact with or away from the valve seat 210. As shown in FIGS. 16 and 17, the valve seat 210 is formed in a convex shape on the upper side, and extends from the inner peripheral surface 210 a along the axis CL on the inner side of the diameter with respect to the axis CL of the fluid control valve 200. It has an outer tapered surface 210c that descends radially outward across the valve seat curved surface 210b. Further, the valve body 220 has an inclined surface 221a that expands from the lower side to the upper side at the valve body contact portion 221 that contacts the valve seat curved surface 210b.
In Patent Document 2, when the seal portion gradually moves to the upper side of the inclined surface 221a due to the progress of creep, the diameter of the seal portion increases from the position P to the position Q along with this. Therefore, the moving distance as a diameter can be reduced. Thereby, patent document 2 can extend a contact part for the time until a contact part exceeds a design limit, and is a highly durable flow control valve.
Even in a fluid control valve in which a fluororesin is used instead of rubber for the valve body (valve body abutting portion) as in Patent Document 2, the shape of the valve seat is from the curved top to the diameter of the valve seat. It has a shape that descends on the outer tapered surface toward the outside.

JP-A-9-229213 JP 2007-170583 A

However, in a fluid control valve that controls the flow of fluid by abutting or separating a flat valve body having a valve seat abutting portion made of rubber, the user of the fluid control valve has a high pressure. In some cases, the flow of the low-pressure fluid is controlled as a fluid that is actually flow-controlled using a fluid control valve configured for the above-mentioned specifications. In this case, when the flow of the low-pressure fluid is controlled using the high-pressure fluid control valve, the progress of the damage to the valve body that occurs with time is accelerated, the sealing performance is reduced, and after the use of the fluid control valve, There was a problem that fluid leakage occurred in a short usage time.
This problem occurs for the following reason.

For example, a fluid control valve is used in a solar cell manufacturing apparatus or the like. The fluid control valve controls the flow of fluid from the input port to the output port by contacting or separating the valve body from the valve seat between the input port and the output port.
In a solar cell manufacturing apparatus or the like, the fluid that is flow controlled by the fluid control valve is, for example, an inert gas such as nitrogen or pure water, and the fluid temperature when flowing through the fluid control valve is The temperature is such that rubber can be used. The valve body of the fluid control valve is formed of rubber in order to enhance the sealing performance with the valve seat.

Such fluid control valves are generally classified into a normally closed (NC) type and a normally open type (NO). The pressing force when the valve body is brought into contact with the valve seat is the urging force by the urging member. (NC) or the pressing force (NO) due to the operating air pressure is the only difference, so here, the structure of the part that controls the fluid will be briefly described on behalf of the NC type fluid control valve.
The fluid control valve has an urging member such as a spring that generates a large pressing force that overcomes the pressure of the circulating fluid. The urging member urges the valve body through a piston to provide a valve seat. To close the valve and shut off the flow of fluid from the input port to the output port. At this time, since the flat valve seat abutting portion which is the lower surface of the valve body is made of rubber, the valve seat abutting portion is formed by elastic deformation of the valve seat abutting portion. High sealing force can be obtained.
On the other hand, the fluid control valve is opened by separating the valve body that is in contact with the valve seat from the valve seat with the reaction force against the pressing force of the biasing member via the piston by the operating air pressure, Flow fluid from input port to output port.

The manufacturer of the fluid control valve prepares multiple specifications of the set pressure when opening and closing the valve body with respect to the valve seat, so that the pressure of the fluid flowing through the fluid control valve corresponds to the size actually used by the user. The fluid control valve is manufactured in various variations.
That is, when the fluid to be controlled is high pressure, a fluid control valve for high pressure is used, and a biasing member that generates a considerably large pressing force is used for the fluid control valve for high pressure. On the other hand, when the fluid to be controlled is at a low pressure, a fluid control valve for low pressure is used, and this fluid control valve has a biasing member that biases the valve body toward the valve seat with a relatively small pressing force. Is used.

By the way, when the pressure of the fluid to be controlled by the fluid control valve is different in, for example, 0.3 MPa, 0.5 MPa, and 1 MPa at three locations A, B, and C where the fluid control valve is disposed. Originally, it is desirable to select and arrange a fluid control valve having a specification that matches the pressure of the fluid to be controlled.
However, depending on the user of the fluid control valve, in the above example, the fluid control valve for 1 MPa may be used even when the pressure of the fluid to be flow controlled is 0.3 MPa or 0.5 MPa.
In this way, when the flow control of the low pressure fluid is performed with the fluid control valve for high pressure, the flowing fluid is low pressure. A large pressing force is applied to the valve seat.
In other words, the relative difference between the pressing force and the drag force becomes large, and the valve body abuts against the valve seat by applying an excessively large pressing force toward the valve seat to close the valve. It is a situation.

Here, FIG. 18 is an explanatory diagram for explaining how the valve seat contact portion of the valve body is damaged by the flow control of the low pressure fluid by the fluid control valve for high pressure.
As described above, in the conventional seal structure for a fluid control valve, the valve seat is formed at the upper end of the valve seat forming portion that is formed in a convex shape on the upper side, and is positioned radially inward with respect to the axis of the valve seat. The valve seat forming portion is formed with an outer tapered surface that descends from the top of the valve seat toward the outside of its diameter.
If a conventional high-pressure fluid control valve configured with a seal structure is used to control the flow of low-pressure fluid, the pressing force toward the valve seat acts on the valve close more than necessary. Of the valve seat abutting portion of the valve body, a portion where the top of the valve seat and the upper end portion of the outer tapered surface abut is elastically deformed larger than usual, and the amount of deformation is also large.
In particular, if excessive elastic deformation occurs locally near the top 311 of the valve seat 310, considerable strain (shear strain) is concentrated near the top 311 of the valve seat 310, so that the valve body 320 is easily damaged. As shown in FIG. 18, in the valve seat abutting portion 323 of the valve body 320, a crack occurs with time at a portion where the innermost diameter Y of the valve seat located on the inner side of the top portion 311 bites. As a result, the sealing performance between the valve body 320 and the valve seat 310 deteriorates in a short usage time after using the fluid control valve, and even if the fluid control valve is closed, the input port and the output port Fluid leakage occurred between the two, which was a problem.

  The present invention has been made to solve the above problems, and an object thereof is to provide a highly durable fluid control valve.

In order to solve the above problems, the fluid control valve of the present invention has the following configuration.
(1) In a body having a valve seat and a fluid control valve that controls the flow of fluid by bringing a valve body into contact with or separating from the valve seat, a valve seat that comes into contact with or separates from at least the valve seat. The contact portion is made of a material having elasticity, and the lower surface of the valve seat abutting portion is formed in a flat shape. The valve seat has a convex shape on the upper side and has a curved top at the uppermost end. A valve seat inner surface that descends downward is formed on the inner side in the radial direction of the valve seat, and descends downward on the radially outer side across the top. A valve seat outer surface is formed.
(2) In the fluid control valve described in (1), the inner surface of the valve seat is an inner tapered surface with an inclination angle θi and the outer surface of the valve seat is an inclination angle θo with respect to a horizontal plane along the radial direction of the valve seat. The inclination angle θi is smaller than the inclination angle θo.
(3) In the fluid control valve described in (1), both the inner surface of the valve seat and the outer surface of the valve seat are curved surfaces.
(4) In the fluid control valve described in (2) or (3), when the magnitude of the strain at the time of tensile break, which is the strain when the valve seat contact portion is pulled and broken, is 1, the valve seat is closed by closing the valve. The valve closing strain generated in the contact portion is set to 1/6 or less of the tensile breaking strain.
(5) In the fluid control valve according to any one of (1) to (4), when the valve is in a closed state, the valve seat contact portion of the valve body is elastically deformed by contact with the valve seat. The height of the inner surface of the valve seat is set to be greater than the amount of crushing with respect to the direction along the axial direction of the fluid control valve.
(6) The fluid control valve described in (5) is characterized in that the valve member is a diaphragm valve formed of a diaphragm valve body having expansion / contraction flexibility.

The operation and effect of the fluid control valve having the above configuration will be described.
In the fluid control valve of the present invention,
(1) Among the valve bodies, at least a valve seat abutting portion that abuts or separates from the valve seat is made of an elastic material, and a lower surface of the valve seat abutting portion is formed in a flat shape. The valve seat has a curved top at the uppermost end, and the valve seat has a valve seat inner side surface that descends downward in the radial direction with respect to the direction along the radial direction of the valve seat. Since the valve seat outer surface that is formed and is formed on the outer side of the diameter across the top portion and descending downward is formed, using the fluid control valve configured with high-pressure specifications, Even when the flow of the low-pressure fluid is controlled as the fluid for flow control, it is possible to suppress the occurrence of excessive distortion that has been locally generated in the vicinity of the top of the valve seat.

That is, in a general fluid control valve, in order to close the valve, a pressing force is applied directly or indirectly to the valve body to bring the valve body into contact with the valve seat. By elastically deforming, the vicinity of the top portion of the valve seat bites into the valve seat abutting portion of the valve body, and a large repulsive force can be generated.
Like the conventional fluid control valve, the fluid control valve of the present invention also applies a pressing force directly or indirectly to the valve body, closes the valve body against the valve seat, and acts on the valve body. The pressing force is set based on a design value corresponding to the magnitude of the pressure of the fluid that actually flows through the fluid control valve.
However, depending on the user who uses the fluid control valve, there is a case in which the flow of the low-pressure fluid is controlled as the fluid that is actually flow-controlled using the fluid control valve configured with the high-pressure specification.
In such a usage, the fluid control valve has a low pressure of the fluid flowing, so that the drag from the fluid to the valve body is small, and the valve with a considerably large pressing force set by the design value for high pressure. It will cause the body to act toward the valve seat.
Therefore, in the conventional fluid control valve, excessive elastic deformation locally occurs near the top of the valve seat, and a considerable strain (shear strain) concentrates near the top of the valve seat. As a result, after use, The sealing performance between the valve body and the valve seat deteriorates in a short usage time, and even if the fluid control valve is closed, fluid leakage occurs between the input port and the output port.

On the other hand, in the fluid control valve of the present invention, the valve seat has a convex shape on the upper side and has a curved top at the uppermost end, and the valve seat has a direction along the radial direction of the valve seat, An inner side surface of the valve seat that descends downward is formed on the inner side of the diameter, and an outer surface of the valve seat that descends downward is formed on the outer side of the diameter across the top.
As a result, when the valve is closed, the valve seat contact portion is elastically deformed by the pressing force acting on the valve body, and in addition to the top of the valve seat and the outer surface of the valve seat, the inside of the valve seat that was not in the conventional valve seat structure The side surface comes into contact with the valve seat contact portion of the valve body. At this time, similar to the conventional fluid control valve, the fluid control valve according to the present invention also causes shear strain at the valve seat contact portion.
The shear strain refers to a first reference cross section per predetermined area at an arbitrary position when the valve seat contact portion is viewed from a radial direction perpendicular to the vertical direction in which the valve body contacts or separates from the valve seat. The pressing force to the valve body acts in the vertical direction on the first reference cross section and the second reference cross section having the same shape and the same area as the first reference cross section and separated by the length L0 parallel to the radial direction. The second reference cross section is a change amount obtained by dividing the relative displacement L1 in the vertical direction from the first reference cross section by the length L0.

In a fluid control valve configured with a conventional valve seat structure, the top portion of the valve seat that is convex upward and formed in an annular shape is located inside the radial direction of the valve seat, and the inside diameter of the top portion is the valve It was an inner peripheral surface in the vertical direction of the seat. Therefore, when the conventional fluid control valve is in the closed state, the elastic deformation in the vertical direction is locally localized at the valve seat abutting portion of the valve body from the vicinity of the inner peripheral surface of the valve seat to the top of the valve seat. Caused excessive shear strain.
However, in the fluid control valve of the present invention, unlike the conventional fluid control valve, the inner surface of the valve seat is directed from the top to the lower side inside the diameter as a portion that contacts the valve seat contact portion when the valve is closed. Since the valve seat abuts, the elastic deformation in the vertical direction is suppressed to a small level compared to the conventional valve seat structure at the portion where the valve seat abuts from the inner surface of the valve seat to the top. Can be suppressed smaller.
Therefore, in the valve seat abutting portion of the valve body, the elastic deformation in the vertical direction does not occur excessively in the portion where the vicinity of the top of the valve seat abuts, and the occurrence of local distortion can be suppressed. Cracks due to the biting of the valve become difficult to occur over time in the valve seat abutting portion.
Therefore, even when using the fluid control valve of the present invention configured for high pressure to control the flow of low pressure fluid, local distortion is caused in the valve seat contact portion of the valve body. Since the occurrence of spillage can be suppressed, the valve seat abutment part is not easily damaged, and the highly durable fluid control valve that can maintain the sealing performance between the valve body and the valve seat for a long period of time after using the fluid control valve It is possible to provide an excellent effect.

(2) Further, with respect to a horizontal plane along the radial direction of the valve seat, the inner surface of the valve seat is an inner tapered surface with an inclination angle θi, and the outer surface of the valve seat is an outer tapered surface with an inclination angle θo. Since θi is smaller than the inclination angle θo, the durability of the valve seat abutting portion is made to be a conventional valve seat structure formed by an outer tapered surface that descends from the top convex to the outer diameter side of the valve seat. Compared to, it can be improved.
That is, in the conventional valve seat structure, the inner diameter of the top portion is the inner peripheral surface of the valve seat in the vertical direction. Therefore, in the valve-closed state, the valve seat contact portion is mainly localized at the portion that contacts the vicinity of the top portion. However, in the fluid control valve of the present invention, the valve seat abutting portion is a portion that abuts not only the top portion but also the inner tapered surface having an inclination angle θi that is gentler than the inclination angle θo of the valve seat outer surface. Is elastically deformed over a wide range. For this reason, in the valve seat abutting portion, the elastic deformation in the vertical direction is suppressed to a smaller extent than the conventional valve seat structure at the portion that bites in from the valve seat inner surface to the top, so that the occurrence of shear strain is more reliable. Can be suppressed.
Therefore, the durability of the valve seat abutting portion can be improved as compared with the conventional valve seat structure formed by the outer tapered surface that descends from the top convex to the radially outer side of the valve seat.

By the way, the valve seat contact portion of the valve body is made of an elastic material having elasticity, such as rubber, and has ductility. When a tensile load is applied to the elastic material, the strain of the elastic material increases as the tensile load increases.
Even when the valve is closed, the top of the valve seat and the upper end of the inner tapered surface and the upper end of the outer tapered surface adjacent to the top bite into the valve seat abutting portion of the valve body. Is elastically deformed, and distortion occurs in the valve seat contact portion. That is, the valve body is repeatedly opened and closed, and a constant load (distortion) is repeatedly applied to the valve seat contact portion, and fatigue occurs in the valve seat contact portion over time.
In the fluid control valve of the present invention, the inner surface of the valve seat is an inner tapered surface having an inclination angle θi, and the outer surface of the valve seat is an outer tapered surface having an inclination angle θo, and the inclination angle θi is smaller than the inclination angle θo. It has become.
Thereby, the distortion generated in the valve seat abutting portion when the valve is closed can be suppressed to be smaller than the strain at the time of tensile rupture, which is a distortion when the valve seat abutting portion is pulled and broken.
Therefore, in the fluid control valve of the present invention, even when the valve body is repeatedly opened and closed, distortion at the valve seat contact portion can be suppressed, and the number of times the valve body is repeatedly opened and closed until the valve seat contact portion breaks. Therefore, the valve seat abutting portion of the valve body is hardly damaged over a long period of time.

(3) Further, since both the valve seat inner side surface and the valve seat outer side surface are curved surfaces, the flow control is actually performed using the fluid control valve configured with the high pressure specification as in (1). Even when the flow of the low-pressure fluid is controlled as the fluid, it is possible to suppress the occurrence of excessive distortion that has conventionally been locally generated near the top of the valve seat.
(4) Further, when the magnitude of the strain at the time of tensile break, which is the strain when the valve seat abutting portion is pulled and fractured, is 1, the strain at the time of closing that occurs in the valve seat abutting portion due to valve closing is the tensile fracture. Since it is set to 1/6 or less of the time strain, the number of breaks until the valve seat contact part breaks can be set to, for example, 1 million times or more.

(5) When the valve is closed, the valve seat contact portion of the valve body is elastically deformed by contact with the valve seat and is crushed by a predetermined amount of squeezing, in the axial direction of the fluid control valve. Since the height of the inner surface of the valve seat is set to be larger than the amount of crushing with respect to the direction along the direction, the flow of the low pressure fluid is controlled using the fluid control valve of the present invention configured with the specifications for high pressure. Thus, even when the valve body is closed by applying a pressing force toward the valve seat more than necessary and the valve body is brought into contact with the valve seat, conventionally, the valve body has been locally generated near the top of the valve seat. It is possible to reliably suppress the occurrence of excessive distortion.

(6) Further, since the valve member is a diaphragm valve formed by a diaphragm valve body having expansion / contraction flexibility, the pressure of the control fluid on the secondary side is large, and the pressure received from the control fluid to the diaphragm valve body is large. Therefore, the valve closing requires a large closing force to overcome the pressure received by the diaphragm valve body. As described above, even if the valve seat abutting portion of the diaphragm valve body is brought into contact with the valve seat with a large closing force, the fluid control valve of the present invention has a valve body near the top of the valve seat. Generation of excessive distortion can be suppressed.

It is sectional drawing which shows the structure of the fluid control valve which concerns on embodiment, and is a figure which shows a valve closing state. It is sectional drawing which shows the valve opening state of the fluid control valve shown in FIG. It is explanatory drawing explaining the shape of the valve seat of the fluid control valve which concerns on Example 1. FIG. It is a table | surface which shows the relationship between the control factor of the L9 orthogonal table | surface used by investigation, and its level about the shape of the valve seat of the fluid control valve which concerns on Example 1. FIG. FIG. 5 is a pie chart showing the results of control factor contribution ratios shown in FIG. 4. FIG. It is explanatory drawing explaining the shape of the valve seat of the fluid control valve which concerns on Example 2. FIG. It is a figure which shows an analysis result about the shape of the valve seat of the fluid control valve which concerns on Example 1. FIG. It is a figure which shows an analysis result about the shape of the valve seat of the fluid control valve which concerns on Example 2. FIG. It is a figure which shows an analysis result about the shape of the valve seat of the conventional fluid control valve which concerns on the comparative example 1. FIG. It is a figure which shows an analysis result about the shape of the valve seat of the conventional fluid control valve which concerns on the comparative example 2. FIG. It is explanatory drawing explaining the positional relationship of the valve seat in a valve closing state, and a valve body about the fluid control valve which concerns on Example 1. FIG. It is explanatory drawing explaining the shape of the valve seat inner surface about the valve seat of the fluid control valve which concerns on Example 1. FIG. It is a fatigue diagram of the material which concerns on a rubber-made test piece. It is sectional drawing which shows the valve-seat seal structure of the poppet valve disclosed by patent document 1. FIG. It is a figure which shows an example of the seal structure of the valve seat of the fluid control valve for fluids which concerns on a prior art. 10 is a cross-sectional view showing a fluid control valve disclosed in Patent Document 2. FIG. FIG. 17 is an explanatory diagram schematically showing an X portion enlarged in FIG. 16. It is explanatory drawing explaining a mode that damage arises in the valve-seat contact part of a valve body.

(Embodiment)
Hereinafter, embodiments of a fluid control valve according to the present invention will be described in detail with reference to the drawings. Drawing 1 is a sectional view showing the composition of the fluid control valve concerning an embodiment, and is a figure showing a valve closing state. FIG. 2 is a cross-sectional view showing the open state of the fluid control valve shown in FIG.
The fluid control valve 1 according to the embodiment is, for example, a diaphragm valve used in a solar cell manufacturing apparatus or the like, and controls the flow of fluid by bringing the valve body 20 into contact with or away from the valve seat 10. In the fluid control valve 1, one end of the biasing spring 50 is supported by the piston 40 and the other end is supported by the cover 60, and the valve body 20 is controlled by the biasing force of the biasing spring 50 when the pressing force by the pilot air does not act. It is a normally closed type fluid control valve that closes in contact with the seat 10.
The fluid that is flow controlled by the fluid control valve 1 is, for example, an inert gas such as nitrogen or a fluid such as pure water, and the temperature of the fluid when flowing through the fluid control valve can be rubber. The temperature is about.

  An input port 18 and an output port 19 are formed in the body 2. The input port 18 and the output port 19 communicate with each other through a valve hole in which the valve seat 10 is formed. The valve seat 10 is formed in an annular shape having a certain curvature, has a convex shape on the upper side, and has a curved top 11 on the uppermost end. The valve seat 10 is formed with a valve seat inner side surface 12 that descends downward on the inner side in the radial direction HX along the radial direction of the valve seat 10 (left and right direction in FIGS. 1 and 2). In addition, a valve seat outer surface 13 that descends downward is formed on the outer diameter side across the top 11. The specific shape of the valve seat 10 will be described in detail later.

A hollow cylinder 30 is attached to the body 2. Of the hollow portion of the cylinder 30, the lower hollow portion 35 divided by the piston 40 communicates with the operation port 32. Of the hollow portion of the cylinder 30, the upper hollow portion 36 divided by the piston 40 communicates with the air vent port 31 of the cover 60 that closes the hollow portion of the cylinder 30. Further, an urging spring 50 for urging the piston 40 downward is disposed between the cover 60 and the piston 40 in the upper hollow portion 36.
A piston 40 is slidably held in the hollow portion of the cylinder 30 in the vertical direction. A valve shaft 41 is formed at the center of the piston 40 toward the lower side. The valve shaft 41 is held by the valve shaft bracket 33 of the cylinder 30 so as to be slidable in the vertical direction via a seal member.
As shown in FIG. 1, a small-diameter portion 41a is formed at the lower end of the valve shaft 41, and a screw portion 41b is formed around the small-diameter portion 41a.

Next, the valve body 20 will be described. The valve body 20 includes a valve support member 21 and a valve member 22. The metal valve support member 21 is screwed into the screw portion 41b. The valve member 22 is attached to the flange 21 a of the valve support member 21, and the flange 21 a is fixed by being fitted in the groove of the valve member 22.
The valve member 22 of the valve body 20 is a diaphragm valve body having expansion / contraction flexibility, and isolates the flow path of the body 2 from the surrounding atmosphere. The valve member 22 has a valve seat abutting portion 23 that abuts or separates from the valve seat 10, and a lower surface 23 a of the valve seat abutting portion 23 is formed in a planar shape.
The valve member 22 including the valve seat abutting portion 23 is made of a material having elasticity such as rubber such as nitrile rubber (NBR), fluorine rubber (FKM, FFKM), ethylene propylene rubber (EPM, EPDM). Yes.
Note that, as described above, the target of the fluid whose flow is controlled by the fluid control valve 1 is, for example, a fluid such as pure water in addition to an inert gas such as nitrogen. Therefore, the valve seat contact portion 23 is made of rubber.

Next, the operation of the fluid control valve 1 having the above configuration will be described.
When the flow from the input port 18 toward the output port 19 is interrupted with respect to the fluid to be controlled, pilot air is not supplied to the operation port 32. At this time, the piston 40 is urged downward by the urging spring 50, and the valve seat abutting portion 23 of the valve member 22 is pressed through the valve shaft 41 and the valve support member 21 by the pressing force of the urging spring 50. Is pressed by the valve seat 10.
On the other hand, when flowing the fluid to be controlled to the output port 19, pilot air is supplied to the operation port 32 by an electromagnetic valve (not shown). The piston 40 moves upward by the force of the pilot air, and the state shown in FIG. 2 is obtained. The valve member 22 moves upward via the valve shaft 41 and the valve support member 21, the valve seat contact portion 23 of the valve member 22 is separated from the valve seat 10, and fluid flows from the input port 18 to the output port 19. And flow.

Next, as a specific shape of the valve seat 10, the shape of the valve seat 10 according to the first embodiment will be described with reference to FIGS. 3, 11, and 12. FIG. 3 is an enlarged schematic diagram of the F part in FIG. 1 and is an explanatory diagram for explaining the shape of the valve seat of the fluid control valve according to the first embodiment.
Example 1
In the present embodiment, as shown in FIG. 3, the valve seat outer side surface 13 is an outer tapered surface having an inclination angle θo with respect to the horizontal plane HS along the radial direction HX of the valve seat 10, and the valve seat inner side surface 12 is inclined. This is a case where the inner tapered surface is formed with an inclination angle θi smaller than the angle θo.
In this embodiment, as the shape of the valve seat 10 of the fluid control valve 1, the inner tapered surface 12 is formed with an inclination angle θi of 15 °, and the outer tapered surface 13 is formed with an inclination angle θo of 25 °. . Moreover, the curvature R in the top part 11 is formed in the circular arc shape of 0.5 mm, for example, and the surface of the top part 11, the inner side taper surface 12, and the outer side taper surface 13 are surfaces along a curve which has no inflection point geometrically. It is connected.

FIG. 11 is an explanatory diagram for explaining the positional relationship between the valve seat and the valve body in the closed state of the fluid control valve according to the first embodiment. FIG. 12 is an explanatory diagram illustrating the shape of the inner surface of the valve seat with respect to the valve seat of the fluid control valve according to the first embodiment.
In the fluid control valve 1 according to the present embodiment, the valve seat abutting portion 23 of the valve body 20 is the surface of the top portion 11, the inner tapered surface 12, and the outer tapered surface 13 of the valve seat 10 when in the closed state. Is crushed with a predetermined crushing amount s. Further, the height t from the intersection point where the valve seat inner side surface 10a and the inner tapered surface 12 of the valve seat 10 are connected to the apex of the top portion 11 with respect to the direction along the axial center CL direction of the fluid control valve 1 is the amount of collapse. It is set larger than s.
In addition, as shown in FIG. 12, when the part which the valve seat inner side surface 10a and the inner side taper surface 12 connect is formed in curved surface shape, the intersection of this curved surface and valve seat inner side surface 10a, and top part The height to the top of 11 is the height t.

Next, the grounds for setting the inclination angle θi to 15 ° and the inclination angle θo to 25 ° in the first embodiment will be described.
The inclination angle θi of the inner taper surface 12 and the inclination angle θo of the outer taper surface 13 are set through simulation. Before explaining the contents of the simulation, first, the background of the simulation will be briefly described. .
A user of a fluid control valve, such as the fluid control valve 1, that controls the flow of fluid by contacting or separating a flat valve body having a valve seat abutting portion made of rubber and contacting the valve seat. When using a fluid control valve configured with specifications for controlling the flow of low-pressure fluid that actually flows, the damage to the valve body that occurs over time is accelerated, sealing performance decreases, and the fluid control valve After using the valve, there was a problem that fluid leaked in a short usage time.

In order to solve this problem, the applicant avoids the occurrence of local distortion in the vicinity of the top portion 311, as shown in FIG. 18 to be referred to, and sets the innermost diameter inside Y of the valve seat abutting portion 323 of the valve body 320. In order to prevent cracks from occurring, the factors causing excessive elastic deformation near the top 311 of the valve seat 310 were examined from various angles.
The following are four factors that may be affected.
A. The outer diameter Φ of the valve support member 21
B. Radius R of the top 11 of the valve seat 10
C. Inclination angle θi of inner tapered surface 12 of valve seat 10
D. Inclination angle θo of the outer tapered surface 13 of the valve seat 10

Therefore, in order to investigate how much these four factors affect each other and cause excessive elastic deformation, the applicant conducted a simulation based on an experimental design which is one of the quality control methods. went. FIG. 4 shows a table showing the relationship between the control factor of the L9 orthogonal table used in the simulation and its level.
Specifically, the simulation is performed based on the L9 orthogonal table in the experimental design, and as shown in FIG. 4, the above factors A to D are set as the control factors as shown in FIG. Three levels from the first level to the third level listed are listed.
As the manufacturer of the fluid control valve 1, the level of each factor is greatly increased based on the applicant's abundant know-how and experience, and the design values according to the required specifications of the fluid control valve 1. It is set.

FIG. 5 is a pie chart showing the result of the contribution ratio of the control factor shown in FIG. As can be seen from FIG. 5, the control factor having the highest contribution ratio among the four control factors is “C. Inclination angle θi of the inner tapered surface 12 of the valve seat 10” occupying 82%. Next, “B. Radius R of the top portion 11 of the valve seat 10”, which was 9%, followed by “D. The outer tapered surface 13 of the valve seat 10 is only 1%. It can be seen that the inclination angle θo ”.
According to the simulation, the applicant has the lowest contribution rate, “C. Inclination angle θi = 15 °”, which is the first level of “C. Inclination angle θi of inner tapered surface 12 of valve seat 10”, which has the highest contribution rate. The optimum combination of level values was found with “Dlant angle θo = 25 °” which is the first level of “D. Inclination angle θo of outer tapered surface 13 of valve seat 10”.
Example 1 is a case of “inclination angle θi = 15 °” and “inclination angle θo = 25 °” obtained as a combination of optimum level values.

  The contribution ratios of both the control factors “A. Outer diameter Φ of valve support member 21” and “B. Radius R of top 11 of valve seat 10” are “D. Inclination of outer tapered surface 13 of valve seat 10”. Although it is somewhat larger than the control factor of “angle θo”, the ratio of the total contribution ratio is relatively low. In addition, it is also necessary to make it possible for the user of the fluid control valve 1 to deal with the specifications of the fluid control valve 1 according to needs. Therefore, in actually manufacturing the fluid control valve 1, the level values relating to both the control factors of “A. Outer diameter Φ of the valve support member 21” and “B. Radius R of the top 11 of the valve seat 10” are obtained. The fluid control valve 1 is configured with a degree of freedom.

(Example 2)
Next, the shape of the valve seat 10 according to the second embodiment will be described with reference to FIG. FIG. 6 is a schematic diagram similar to FIG. 3, and is an explanatory diagram for explaining the shape of the valve seat of the fluid control valve according to the second embodiment.
In this embodiment, in the upper end portion of the valve seat 10, the top portion 11, the valve seat inner side surface 12, and the valve seat outer side surface 13 all have the same curvature r and are formed by arcuate curved surfaces.
In this embodiment, as the shape of the valve seat 10 of the fluid control valve 1, the valve seat inner surface 10 a and the valve seat outer peripheral surface 10 b of the valve seat 10 are connected by, for example, an arc having a curvature r of 1.25 mm. , The valve seat inner side surface 12 and the valve seat outer side surface 13 are connected by a surface along a curved line having no inflection point geometrically.

In addition to Example 1 described above, as examples in which the shape of the valve seat is different from each other, Example 2 and Comparative Example 1 and Comparative Example 2 for the fluid control valve according to the related art are also included in the experimental design method. Based on the simulation. For the fluid control valves according to Examples 1 and 2 and Comparative Examples 1 and 2, the shear strain generated in the valve seat contact portion of the valve body when the valve is closed is analyzed by FEM, The strain distribution was examined.
Among the simulation conditions according to Examples 1 and 2 and Comparative Examples 1 and 2, the conditions common to Examples 1 and 2 and Comparative Examples 1 and 2 are the outer diameter Φ of the valve support member 21 according to Examples 1 and 2. In Comparative Examples 1 and 2, the outer diameter Φ of the portion corresponding to the valve support member 21 is Φ = 25 mm.

The simulation conditions of parts different in each of Examples 1 and 2 and Comparative Examples 1 and 2 are shown.
Example 1
Example 1 above, and reprinting the simulation conditions,
Inclination angle θi = 15 ° of the inner tapered surface 12
Inclination angle θo of outer tapered surface 13 = 25 °
Radius R of top 11 = 0.5mm
(Example 2)
Example 2 above, and reprinting the simulation conditions,
Curved surface in which the top portion 11, the inner tapered surface 12 and the outer tapered surface 13 are formed in a semicircular arc shape having a curvature r = 1.25 mm (Comparative Example 1)
The upper end surface of the valve seat is a flat surface with a radius R of the top portion being infinite (Comparative Example 2)
It is a conventional valve seat shape like patent documents 1 and 2, and each of the following conditions is a portion corresponding to fluid control valve 1 concerning an embodiment, respectively.
Inclined angle of inner tapered surface θi = 90 °
Inclined angle of outer tapered surface θo = 15 °
Top radius R = 0.5mm

The analysis result of Example 1 is shown in FIG. 7, the analysis result of Example 2 is shown in FIG. 8, the analysis result of Comparative Example 1 is shown in FIG. 9, and the analysis result of Comparative Example 2 is shown in FIG. In FIGS. 7 to 10, the display is changed in accordance with the magnitude of the shear strain in the vertical direction. The distribution in which the shear strain is the largest is painted black, and the magnitude of the stress is set to level 1 for convenience. On the other hand, the dot pitch was roughened as the shear strain became relatively small, and the distribution where the shear strain was the smallest was expressed as level 9.
The shear strain refers to a first reference cross section per predetermined area at an arbitrary position when the valve seat contact portion 23 is viewed from a radial direction perpendicular to the vertical direction in which the valve body 20 contacts or separates from the valve seat 10. And the pressing force to the valve body 20 in the vertical direction with respect to the second reference cross section having the same shape and the same area as the first reference cross section and separated from the first reference cross section by a length L0 parallel to the radial direction. As a result of the action, the second reference cross section is a change amount obtained by dividing the relative displacement L1 that is displaced in the vertical direction from the first reference cross section by the length L0.
7 to 10, the level corresponding to the magnitude of the shear strain is an absolute magnitude, and the magnitude of the shear strain corresponding to level 1 is 90%, which is level 9. The magnitude of the corresponding shear strain is 10%, and there is a difference of 9 times between the level 1 and the level 9 in the ratio of the magnitude of the strain.

  In Example 1, as shown in FIG. 7, in the valve seat abutting portion 23, the shear strain generated in the apex vicinity abutting portion Ma in the vicinity of the apex 11 is larger than that in the vicinity thereof. The size stays at the maximum level of about 3 at the apex contact portion Ma, and the surrounding Mb and Mc of the apex contact portion Ma are also level 4 and level 5, and the distribution of shear strain is generally dispersed. It turns out that it is. Specifically, the shear strain generated in the vicinity of the top portion 11 in the valve seat contact portion 23 was 44%.

Next, in Example 2, as shown in FIG. 8, in the valve seat contact part 23, as shown in FIG. 8, the shear strain applied to the top vicinity contact part M in the vicinity of the top part 11 is compared with the periphery thereof. Although it is larger, its size remains at level 3 at the maximum. Specifically, the shear strain generated in the vicinity of the top portion 11 in the valve seat contact portion 23 was 51%.
On the other hand, in Example 2, the distribution of the overall shear strain tended to be slightly denser than that in Example 1, but the surroundings Mb and Mc around the apex vicinity contact portion Ma were observed. Are considered to be level 4 and level 5 and error ranges that do not affect the actual use of the fluid control valve 1.

On the other hand, in Comparative Example 1, as shown in FIG. 9, in the valve seat abutting portion 423, the shear strain is locally present in the vicinity of the top portion near the abutting portion Na that abuts on the radially inner corner portion 411 of the valve seat 410. The size has reached the maximum level 1. As described above, when the shear strain is locally concentrated near the top contact portion Na due to excessive elastic deformation generated in the valve seat contact portion 423, the shear elasticity in the vertical direction is particularly near the top contact portion Na. Distortion reached a maximum value of nearly 85%.
In addition, it can also be seen that, in the surroundings Nb and Nc in the vicinity of the apex contact portion Na, the level 2 and the level 3 and the portion having large shear strain are densely distributed after the level 1.

Similar to Comparative Example 1, in Comparative Example 2, as shown in FIG. 10, in the valve seat abutting portion 323, shear strain is locally present in the vicinity of the apex vicinity abutting portion Na in contact with the apex 311 of the valve seat 310. It is concentrated and its size has reached level 2 next to maximum level 1. As described above, when excessive shear deformation occurs in the valve seat abutting portion 323 and shear strain is locally concentrated near the apex contact portion Na, the shear elastic strain is maximized particularly near the apex contact portion Na. It can be seen that it reaches 75% or more.
Further, it can be seen that also in the surroundings Nb and Nc near the apex contact portion Na, the portions where the shear strain is large, such as level 3 and level 4 after level 2, are densely distributed.

Next, an endurance test was actually performed on the fluid control valve 1 according to Examples 1 and 2 and the fluid control valve according to Comparative Example 2 in order to verify the analysis results by the above simulation. In addition, about the fluid control valve which concerns on the comparative example 1, the durability test is not performed.
In the durability test, the fluid control valve 1 according to Examples 1 and 2 and the fluid control valve according to Comparative Example 2 were not allowed to flow, and the operating air at a pressure of 0.5 MPa was used as a pressing force from the valve body 20 or the like The load is applied to the valve seat abutting portions 23, 321 and 421 for 3 sec. This load is applied for 1 sec. The process of canceling the interval (OFF state) was performed as one cycle, and this process was repeated a plurality of cycles.
In the durability test, the outer diameter Φ of the valve support member 21 and the outer diameter of the corresponding portion in Comparative Examples 1 and 2 were both Φ = 25 mm. In addition, the material of the valve seat abutting portion is made of fluorine rubber.

The test results will be described.
In the case of the fluid control valve according to Comparative Example 2, the valve seat abutting portion 323 was broken at a repetition count of 300,000 times. As for the state of fracture, as shown in FIG. 18 to be referred to, cracks with time occurred in the innermost diameter Y.
In the case of Comparative Example 2, when the valve is closed, in the valve seat abutting portion 323, the shear strain is locally concentrated in the vicinity of the abutting portion N near the apex 311 of the valve seat 310, This is considered to be caused because the shear elastic strain in the vertical direction reached 75% or more.
On the other hand, in Examples 1 and 2, any of the valve seat contact portions 23 was able to withstand the number of repetitions of 3 million times or more, which is 10 times or more that of Comparative Example 2.
By closing the valve, there is no occurrence of local shear strain in the vicinity of the abutting portion that abuts on the top portion 11 of the valve seat 10 in the valve seat abutting portion 23, and the vertical shear elastic strain is 50. This is thought to be due to staying at around%.

Here, the relationship between the shear strain generated in the valve seat contact portion and the durability of the valve seat contact portion will be described with reference to FIG.
In the rubber material constituting the valve seat abutting portion 23, as with the mechanical properties of metal, the rubber material is pulled by using a load cell or the like, and a constant load (strain) is repeatedly applied to the rubber material to cause fatigue of the rubber material. When tested, the rubber material breaks due to fatigue due to repeated strain.
As a test condition of the fatigue test, a fixed stress (load) was applied to the test piece for 3 sec. Using the dumbbell test piece No. 3 shape defined in JIS K6251. This load is applied for 1 sec. The process of canceling the interval (OFF state) is performed as one cycle, and this process is repeated in a plurality of cycles.

Thus, when a fatigue test is performed on a test piece made of NBR which is a kind of rubber material, a fatigue diagram as shown in FIG. 13 is obtained. The fatigue diagram is power data obtained from NBR test pieces having a plurality of hardnesses.
FIG. 13 is a fatigue diagram of a material related to a rubber test piece. The vertical axis represents the ratio of load strain to the strain at the time of tensile fracture of the test piece (%), and the horizontal axis represents the test piece fractured. It is the graph which each described the frequency | count (number of times of a fracture | rupture) by (time). The strain at the time of tensile fracture of the test piece is “(breaking length−original length) / original length” in the test piece, and the load strain is “tensile length / original length in the test piece. That's it.
In the case of the fluid control valve according to Comparative Example 2, the manufacturer of the fluid control valve 1 has a short service life of 300,000 times for the valve seat abutting portion 323 so that at least one million times of breakage can be achieved. The fluid control valve 1 that improves the durability of the valve body 20 (the valve seat abutting portion 23) is designed and manufactured.
As can be seen from FIG. 13, in order to realize the number of breaks of 1 million, it is necessary to suppress the ratio of the load strain to the strain at the time of the tensile break of the test piece to 16% or less. That is, when the strain at the time of tensile fracture of the test piece is “1”, the amount of elastic deformation must be suppressed so that the load strain applied to the test piece falls within the range of about 1/6 or less.

As described above, in addition to the conventional fluid control valve, in the fluid control valve 1 according to the first and second embodiments, the valve seat contact portion 23 of the valve member 22 is, for example, nitrile rubber (NBR), fluorine rubber (FKM). , FFKM), ethylene propylene rubber (EPM, EPDM), etc., and is made of an elastic material.
Therefore, when the valve is closed, the top portion 11 of the valve seat 10 and the upper end portion of the inner tapered surface 12 and the upper end portion of the outer tapered surface 13 adjacent to the top portion 11 are in contact with the valve seat contact portion 23 of the valve body 20. Therefore, the valve seat abutting portion 23 is elastically deformed, and the valve seat abutting portion 23 is sheared.
However, the amount of elastic deformation in the valve seat abutting portion 23 as in the rubber test piece described above is such that the strain at the time of elastic deformation is within about 1/6 or less of the strain at the time of tensile fracture. If this is suppressed, the valve seat abutment portion 23 can be provided with a durability of 1 million breaks.

In the case of fluoro rubber (FKM), “strain at the time of tensile fracture” with respect to the material constituting the valve seat contact portion 23 is, for example, 310%, and “strain at the time of elastic deformation” falls within about 1/6 of the range. (Shear elastic strain) "is about 52% or less.
In the actual durability test, the number of breaks was 3 million times or more in both cases of Example 1 and Example 2.
This is clearly the result of the simulation analysis of “shear elastic strain 44%” (in the case of Example 1) and “shear elastic strain 51%” (in the case of Example 2). It is thought that it is because it is in the range of%, and in fact, the durability of the number of breaks exceeding 3 million, far exceeding the number of breaks of 1 million, has been proved through the durability test.

The operation and effect of the fluid control valve according to this embodiment having the above-described configuration will be described.
In the present embodiment, the valve seat contact portion 23 that contacts or separates from the valve seat 10 in the valve body 20 is made of rubber such as fluoro rubber (FKM, FFKM), ethylene propylene rubber (EPM, EPDM), or the like. The lower surface 23a of the valve seat abutting portion 23 is formed in a flat shape. The valve seat 10 has a convex shape on the upper side and a curved top portion 11 at the uppermost end. 10, a valve seat inner side surface 12 that descends downward is formed on the inner side in the radial direction HX of the valve seat 10, and on the outer diameter side with the top 11 interposed therebetween. Since the valve seat outer side surface 13 descending downward is formed, the flow of the low-pressure fluid is used as the fluid that is actually flow-controlled using the fluid control valve 1 configured with the high-pressure specification. Even when using the valve to control the In resulting have been excessive distortion occurs in will be able to inhibitory.

That is, in a general fluid control valve, in order to close the valve, a pressing force is applied directly or indirectly to the valve body to bring the valve body into contact with the valve seat. By elastically deforming, the vicinity of the top portion of the valve seat bites into the valve seat abutting portion of the valve body, and a large repulsive force can be generated.
Like the conventional fluid control valve, the fluid control valve 1 according to the present embodiment also causes the valve body 20 to contact the valve seat 10 by causing the pressing force to act indirectly on the valve body 20 via the piston 40. The pressing force applied to the valve body 20 is set based on the design value corresponding to the pressure of the fluid actually flowing from the input port 18 toward the output port 19 in the fluid control valve 1. Has been.
However, depending on the user who uses the fluid control valve, there is a case in which the flow of the low-pressure fluid is controlled as the fluid that is actually flow-controlled using the fluid control valve configured with the high-pressure specification.
In such a usage, the fluid control valve has a low pressure of the fluid flowing, so that the drag from the fluid to the valve body is small, and the valve with a considerably large pressing force set by the design value for high pressure. It will cause the body to act toward the valve seat. Therefore, in the conventional fluid control valve, excessive elastic deformation locally occurs near the top of the valve seat, and a considerable strain (shear strain) concentrates near the top of the valve seat. As a result, after use, The sealing performance between the valve body and the valve seat deteriorates in a short usage time, and even if the fluid control valve is closed, fluid leakage occurs between the input port and the output port.

On the other hand, in the fluid control valve 1 according to the present embodiment, the valve seat 10 has a convex shape on the upper side and a curved top portion 11 at the uppermost end, and the valve seat 10 has a diameter of the valve seat 10. A valve seat inner side surface 12 that is lowered toward the lower side is formed on the inner side in the direction along the direction HX, and the valve seat that is lowered toward the lower side on the outer diameter side across the top portion 11. An outer side surface 13 is formed.
As a result, the valve seat abutment portion 23 is elastically deformed by the pressing force acting on the valve body 20 when the valve is closed, and in addition to the top portion 11 of the valve seat 10 and the valve seat outer surface 13, the conventional valve seat structure is obtained. The valve seat inner side surface 12 that has not been in contact with the valve seat contact portion 23 of the valve body 20 bites into the valve seat 20. At this time, similarly to the conventional fluid control valve, in the fluid control valve 1 according to the present embodiment, shear strain is generated in the valve seat contact portion 23.

In a fluid control valve configured with a conventional valve seat structure, the top portion of the valve seat that is convex upward and formed in an annular shape is located inside the radial direction of the valve seat, and the inside diameter of the top portion is the valve It was an inner peripheral surface in the vertical direction of the seat. Therefore, when the conventional fluid control valve is in the closed state, the elastic deformation in the vertical direction is locally localized at the valve seat abutting portion of the valve body from the vicinity of the inner peripheral surface of the valve seat to the top of the valve seat. Caused excessive shear strain.
However, in the fluid control valve 1 according to the present embodiment, unlike the conventional fluid control valve, the valve seat inner side surface 12 is located on the inside of the diameter from the top portion 11 as a portion that contacts the valve seat contact portion 23 when the valve is closed. Therefore, in the valve seat abutting portion 23, the elastic deformation in the vertical direction is suppressed to be smaller than that of the conventional valve seat structure at the portion that bites in from the valve seat inner side surface 12 to the top portion 11. Therefore, the occurrence of shear strain can be suppressed to a smaller level.
Therefore, in the valve seat abutting portion 23 of the valve body 20, the elastic deformation in the vertical direction is not excessively generated in the portion where the vicinity of the top portion 11 of the valve seat 10 abuts, and the occurrence of local shear strain can be suppressed. Therefore, cracks due to the biting of the valve seat 10 are less likely to occur in the valve seat abutting portion 23 over time.
Therefore, even when the flow control valve 1 according to the present embodiment configured with high-pressure specifications is used to control the flow of low-pressure fluid, the valve seat contact portion of the valve body 20 23, since the occurrence of local distortion can be suppressed, the valve seat abutting portion 23 is difficult to be damaged, and the sealing performance between the valve body 20 and the valve seat 10 can be maintained for a long time after the fluid control valve 1 is used. The fluid control valve 1 having high durability that can be maintained over a long period of time can be provided.

Further, in the fluid control valve 1 according to the present embodiment, in Example 1, the valve seat inner side surface 12 is an inner tapered surface with an inclination angle θi with respect to the horizontal plane HS along the radial direction HX of the valve seat 10. The valve seat outer surface 13 is an outer tapered surface having an inclination angle θo, and the inclination angle θi is smaller than the inclination angle θo, so that the durability of the valve seat abutting portion 23 is increased from the top portion 11 convex upward. Compared to the conventional valve seat structure formed by the outer tapered surface that descends toward the outer diameter of 10, it can be improved.
That is, in the conventional valve seat structure, the inner diameter of the top portion is the inner peripheral surface of the valve seat in the vertical direction. Therefore, in the valve-closed state, the valve seat contact portion is mainly localized at the portion that contacts the vicinity of the top portion. In the fluid control valve 1 according to the first embodiment, in addition to the top portion 11, the fluid control valve 1 is in contact with the inner tapered surface 12 having an inclination angle θi that is gentler than the inclination angle θo of the valve seat outer surface 13. The valve seat contact portion 23 is elastically deformed over a wide range.
Therefore, in the valve seat abutting portion 23, the amount of elastic deformation in the vertical direction can be gradually changed at the portion that bites from the valve seat inner side surface 12 to the top portion 11, so that the occurrence of shear strain can be more reliably suppressed.
Therefore, the durability of the valve seat abutting portion 23 can be improved as compared with the conventional valve seat structure formed by the outer tapered surface that descends from the top convex to the radially outer side of the valve seat. .

By the way, the valve seat contact part 23 of the valve body 20 is made of an elastic material having elasticity, such as rubber, and has ductility. When a tensile load is applied to an elastic material to a point where a tensile fracture occurs, the strain of the elastic material increases as the tensile load increases.
Even when the valve is closed, the top portion 11 of the valve seat 10 and the upper end portion of the inner tapered surface 12 and the upper end portion of the outer tapered surface 13 adjacent to the top portion 11 bite into the valve seat abutting portion 23 of the valve body 20. Therefore, the valve seat contact portion 23 is elastically deformed, and the valve seat contact portion 23 is distorted. That is, the valve body 20 is repeatedly opened and closed, and a constant load (distortion) is repeatedly applied to the valve seat contact portion 23, and fatigue occurs in the valve seat contact portion 23 over time.
In the fluid control valve 1 according to the first embodiment, the valve seat inner side surface 12 is an inner tapered surface having an inclination angle θi, and the valve seat outer surface 13 is an outer tapered surface having an inclination angle θo, and the inclination angle θi is It is smaller than the inclination angle θo.
Thereby, the distortion generated in the valve seat abutting portion 23 when the valve is closed can be suppressed to be lower than the strain at the time of tensile rupture, which is the strain when the valve seat abutting portion 23 is pulled and broken.
Therefore, in the fluid control valve 1 according to the present embodiment, even when the valve body 20 is repeatedly opened and closed, the distortion at the valve seat contact portion 23 can be suppressed, and the valve until the valve seat contact portion 23 breaks. Since the number of times of opening and closing the body 20 is dramatically increased, the valve seat abutting portion 23 of the valve body 20 is difficult to break for a long period of time.

In the fluid control valve 1 according to the present embodiment, in Example 2, the valve seat inner side surface 12 and the valve seat outer side surface 13 are both curved surfaces. Even when the fluid control valve 1 configured as described above is used to control the flow of a low-pressure fluid as a fluid that is actually flow-controlled, conventionally, excessive flow that has been locally generated near the top of the valve seat Generation of distortion can be suppressed.
Also, in Examples 1 and 2 of the fluid control valve 1 according to the present embodiment, when the magnitude of the strain at the time of the tensile break, which is a strain when the valve seat abutment portion 23 is pulled and broken, is 1, the valve is closed. Since the valve closing strain generated in the valve seat abutting portion 23 by the valve is set to 1/6 or less of the tensile breakage strain, the number of breaks until the valve seat abutting portion 23 breaks is set to 1,000,000. It can be more than 3 million times, far more than times.

  In the present embodiment, when the valve is closed, the valve seat contact portion 23 of the valve body 20 is elastically deformed by contact with the valve seat 10 and is crushed by a predetermined squeezing amount s. Since the height t of the valve seat inner side surface 12 is set to be larger than the crushing amount s with respect to the direction along the axial center CL direction of the valve 1, the fluid according to the present embodiment configured with high-pressure specifications. Even when the control valve 1 is used to control the flow of low-pressure fluid and the pressing force toward the valve seat is applied more than necessary and the valve body is brought into contact with the valve seat, the valve is closed. In the valve body, it is possible to reliably suppress the occurrence of excessive distortion locally generated near the top of the valve seat.

  In this embodiment, since the valve member 22 is a diaphragm valve 22 formed of a diaphragm valve body having expansion / contraction flexibility, the pressure of the control fluid on the secondary side is large, and the control fluid changes from the control fluid to the diaphragm valve body 22. Since the received pressure increases, the valve closing requires a large closing force to overcome the pressure received by the diaphragm valve body 22. Even when the diaphragm valve body 22 is brought into contact with the valve seat with such a large closing force, the fluid control valve 1 according to the present embodiment has the valve body 20 near the top 11 of the valve body 10. Excessive distortion can be reliably suppressed.

In the above, the present invention has been described with reference to the embodiments. However, the present invention is not limited to the above-described embodiments, and can be appropriately modified and applied without departing from the gist thereof.
(1) For example, in Example 2, the valve seat inner side surface 10a and the valve seat outer peripheral surface 10b of the valve seat 10 are both arcs having a curvature r of 1.25 mm, and the surface of the top portion 11 and the valve seat inner side surface 12 The valve seat outer surface 13 is connected by a surface along a curve having no inflection point geometrically.
However, as the shape of the valve seat, if the top surface, the inner surface of the valve seat and the outer peripheral surface of the valve seat are connected by a surface along a curved line having no inflection point, the inner surface of the valve seat and the valve seat The outer peripheral surface may be formed by curved surfaces having different curvatures.
(2) In the embodiment, when the fluid control valve 1 supports the biasing spring 50 at one end on the piston 40 and the other end on the cover 60, and the pressing force by the pilot air does not act, the biasing spring 501 The normally closed type fluid control valve in which the valve body 20 abuts against the valve seat 10 by the urging force is closed.
However, in the fluid control valve, a biasing member is disposed between one side of the piston corresponding to the pressure receiving side of the piston 40 of the present embodiment and the bottom side of the cylinder 30 so that the pressing force by the pilot air does not act. When the valve body is opened away from the valve seat by the urging force of the urging spring, the valve body comes into contact with the valve seat and closes when a pressing force is applied by pilot air. Also good.
In the normally open type fluid control valve, the operation port is disposed at the position of the air vent port 31 of the fluid control valve 1 of the present embodiment which is a normally closed type, and the air vent port is disposed at the position of the air port 32. Is done.

DESCRIPTION OF SYMBOLS 1 Fluid control valve 2 Body 10 Valve seat 20 Valve body 22 Valve member 23 Valve seat contact part 23a Lower surface 11 Top part 12 Inner taper surface (valve seat inner surface)
13 Outer taper surface (valve seat outer surface)
CL Center axis of fluid control valve HX Radial direction HS Horizontal plane θi, θo Inclination angle s Collapse amount t Height of inner surface of valve seat

Claims (6)

A body having a valve seat, and a fluid control valve that controls the flow of fluid by contacting or separating the valve body from the valve seat;
Among the valve bodies, at least the valve seat abutting portion that abuts or separates from the valve seat is made of an elastic material, and the lower surface of the valve seat abutting portion is formed in a planar shape,
The valve seat is convex on the upper side and has a curved top at the uppermost end,
The valve seat is formed with a valve seat inner side surface that descends downward on the inner side in the radial direction of the valve seat, and on the outer diameter side across the top portion. A fluid control valve characterized in that a valve seat outer surface that descends downward is formed. The fluid control valve according to claim 1,
The inner surface of the valve seat is an inner tapered surface with an inclination angle θi, and the outer surface of the valve seat is an outer tapered surface with an inclination angle θo with respect to a horizontal plane along the radial direction of the valve seat,
The fluid control valve, wherein the inclination angle θi is smaller than the inclination angle θo. The fluid control valve according to claim 1,
The valve seat inner side surface and the valve seat outer side surface are both curved surfaces. In the fluid control valve according to claim 2 or claim 3,
When the magnitude of the strain at the time of tensile break, which is the strain when the valve seat abutting portion is pulled and broken, is 1,
A fluid control valve characterized in that a valve closing strain generated in the valve seat contact portion by the valve closing is set to 1/6 or less of the strain at the time of tensile fracture. The fluid control valve according to any one of claims 1 to 4,
When in the valve-closed state, the valve seat contact portion of the valve body is elastically deformed by contact with the valve seat and is crushed by a predetermined squash amount,
The fluid control valve according to claim 1, wherein a height of the inner surface of the valve seat is set to be larger than the squeezing amount with respect to a direction along the axial direction of the fluid control valve. The fluid control valve according to claim 5,
A fluid control valve characterized in that the valve member is a diaphragm valve formed of a diaphragm valve body having expansion and contraction flexibility.

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