The present invention relates to a diaphragm valve and a method of adjusting a Cv value of the diaphragm valve.
Valves such as ball valves are used in a number of product fields such as manufacturing apparatuses, plant apparatuses, and inspection devices as a device for controlling fluid flow.
A valve includes a valve body having a communicating part which communicates an inlet flow path and an outlet flow path, and a valve element disposed at the communicating part. The valve element is driven by a handle provided at an upper part thereof in a case of a manually operating valve and by a motor or the like in the case of an automatic valve, and a joint member referred to as a stem is interposed between the handle or the motor or the like and the valve element.
For example, an automatic diaphragm valve (see
In order to move the stem 58 upward, the operation air is caused to act on the respective pistons 59 and 60. For this purpose, an upper operation air introduction chamber 79 and a lower operation air introduction chamber 80 are formed below the pistons 59, 60 respectively. The upper and lower pistons 59, 60 are formed with an axial passage 59a and radial passages 59b, 60b for sending the introduced operation air to the respective operation air introduction chambers 79, 80. The operation air is introduced into the respective operation air introduction chambers 79, 80, thereby applying an upward force to the respective pistons 59, 60. A counter plate 76 is interposed between the pistons 59 and 60.
PTL 1: JP-A-2016-161022
When the diaphragm holder 57 moves to an uppermost position and thus does not press the diaphragm 56, a fully opened state is achieved. An amount of fluid flowing in this state relates to a capacitive coefficient of the valve, which is referred to as a Cv value. According to JIS standard, the Cv value is a flow rate value indicating a flow rate of freshwater at a temperature of 60 degrees F. flowing through the valve with a pressure difference of 1 Psi within a specific operation range, which is expressed by US gallon/min. The Cv value is proportional to an opening area where the fluid flows with the valve fully opened, and thus an adequate combination of components is required in order to minimize variation of the Cv value among the same products.
Components which may affect the opening area where the fluid flows with the valve fully opened in the diaphragm valve 50 of the related art illustrated in
It is an object of the present invention to provide a diaphragm valve configured to allow for adjustment of a Cv value during assembly of the diaphragm valve, and a method of adjusting the Cv value.
The present invention (1) provides a diaphragm valve including: a valve body provided with a fluid flow path; a diaphragm configured to open and close the fluid flow path; an actuator configured to press the diaphragm; a bonnet interposed between the valve body and a casing of the actuator; a stem moved by the actuator; and a diaphragm holder disposed between the stem and the diaphragm and including an outer edge having a diameter larger than an outer diameter of the stem, in which the bonnet includes a through hole coaxial with the stem and formed with a female thread, the through hole accommodates a cylindrical body screwed therein, the cylindrical body having a male thread formed on an outer surface thereof for engaging the female thread, the stem is inserted into the cylindrical body, the cylindrical body has a diaphragm-side end surface protruding from a diagram-side opening surface of the through hole toward the diaphragm, a stem-side end surface of the diaphragm holder at an outer edge thereof and the diaphragm-side end surface of the cylindrical body are in abutment with each other, the position of the abutted surfaces in a direction of a stem axis are allowed to be adjusted by a degree of engagement between the male thread and the female thread.
In the present invention (1), the cylindrical body is provided as a Cv value adjustment member which is not provided on the diaphragm valve in the related art. The cylindrical body is formed with the male thread, which is to be engaged with the female thread formed in an interior of the bonnet, on an outer peripheral surface. The stem is inserted into the cylindrical body, and the diaphragm holder is disposed between the stem and the diaphragm. Once the bonnet is secured to the valve body, even when a fluid is flowed therethrough, the fluid is prevented from leaking out. Since the diaphragm-side end surface of the cylindrical body and the stem-side end surface of the diaphragm holder at the outer edge thereof are brought into abutment with each other, and the position of a plane of abutment may be adjusted by adjusting the degree of engagement between the male thread and the female thread, precise adjustment of the Cv value is achieved by assembling the diaphragm valve in association with such adjustment.
The present invention (2) is the valve of the present invention (1) characterized in that the bonnet is provided with a recess on an upper part thereof; the cylindrical body is provided at an upper part thereof with a cylindrical body flange having a diameter larger than the male thread and smaller than an inner diameter of the recess, and the cylindrical body flange is secured to a bottom surface of the recess by screw means.
As the Cv value is determined by the degree of engagement between the male thread and the female thread, if the cylindrical body rotates with respect to the bonnet, the Cv value changes correspondingly. In order to avoid such an event, the cylindrical body flange is secured to the bottom surface of the recess by the screw means to prevent an occurrence of changes in the Cv value after assembly.
The present invention (3) is the diaphragm valve according to the present invention (1), characterized in that the actuator is secured to the bonnet or the valve body with a diaphragm-side end surface of the actuator pressing an actuator-side end surface of the cylindrical body.
In the same manner as the present invention (2), the present invention (3) is devised to prevent changes in the Cv value after assembly of the diaphragm valve. With the configuration in which the diaphragm-side end surface of the actuator presses the actuator-side end surface of the cylindrical body to cause the actuator to be secured to the bonnet or the valve body, the occurrence of changes in the Cv value after assembly may be prevented.
The present invention (4) is a method of adjusting a Cv value of a diaphragm valve including: a step of placing a diaphragm configured to open and close a fluid flow path on a valve body provided with the fluid flow path, placing a holding adapter configured to press and hold an outer peripheral edge of the diaphragm on a valve body side on the diaphragm, and placing a stem configured to deform the diaphragm in an opening or closing direction on the diaphragm, the stem including, at a lower end portion thereof, a diaphragm holder having an outer edge with a diameter larger than an outer diameter of the stem; a step of screwing a male thread formed on an outer peripheral surface of a cylindrical-shaped cylindrical body into engagement with a female thread formed on an inner peripheral surface of the cylindrical-shaped bonnet to accommodate the cylindrical body in the interior of the bonnet; a step of inserting the stem in the cylindrical body, attaching the bonnet in which the cylindrical body is accommodated to the valve body, and pressing the holding adapter with a diaphragm-side end surface of the bonnet to secure the diaphragm to the valve body; a step of flowing a fluid into the fluid flow path and measure a Cv value; a step of bringing the diaphragm-side end surface of the cylindrical body into abutment with the stem side end surface of the diaphragm holder at the outer edge thereof; a step of repeating changing a degree of engagement between the male thread and the female thread, flowing a fluid through the fluid flow path, and measuring the Cv value until a target Cv value is achieved; and a step of securing the cylindrical body to the bonnet after the Cv value is adjusted to the target Cv value of the diaphragm valve.
A lower end surface of the bonnet presses an upper end surface of the holding adapter, so that the diaphragm is secured to the valve body. Accordingly, even when a fluid is flowed through the fluid flow path, the fluid is prevented from leaking out.
Before the diaphragm is secured to the valve body, the stem having the diaphragm holder at the lower end portion thereof is placed on the diaphragm without pressing the diaphragm, the stem is inserted through the interior of the cylindrical body, and the cylindrical body is accommodated in the interior of the bonnet by means of engagement or the like.
In a state in which hermeticity in the flow path is maintained, a fluid is flowed in a fully opened state, which corresponds to a state in which no pressing force is applied to the diaphragm, and the Cv value is measured. The Cv value at the initial measurement is preferably set to be slightly larger than the target Cv value. After the diaphragm-side end surface of the cylindrical body is brought into abutment with a stem-side end surface of the holding adapter, the degree of engagement between the female thread formed on the inner peripheral surface of the bonnet and the male thread formed on the outer peripheral surface of the cylindrical-shaped cylindrical body is adjusted in view of the result of measurement of the Cv value. When the position of a plane of abutment between the diaphragm-side end surface of the cylindrical body and the stem-side end surface of the diaphragm holder is moved toward the diaphragm, the position of the contact surface of the diaphragm holder with the diaphragm is lowered and thus the diaphragm is deflected, so that the Cv value is reduced. Repeating these procedures may results in the Cv value closer to the target value.
According to the diaphragm valve of the present invention, the Cv value closer to the target Cv value is achieved without selecting members during assembly, and manufacture of diaphragm valve with less variation in the Cv value is achieved. In addition, even when the actuator encounters a failure, for example, removal of the bonnet from the valve body is not necessary, and thus the fluid in the flow path is not exposed to the outside air.
Referring now to the drawings, a detailed description of preferable examples of the present invention will be given below illustratively. Note that shapes, relative layouts, and the like of components described in these examples are illustrative only without limiting the scope of the invention unless otherwise specifically noted. Likewise, directions of the members may be referred to as up(per), low(er), left and right depending on the directions on the drawings for the sake of convenience, these terms are not intended to limit the scope of the present invention.
The diaphragm valve 1 includes a valve body 2 including a fluid inflow passage 2a and a fluid outflow passage 2b; an actuator 4 mounted above the valve body 2 via a bonnet 3; an annular valve seat 2e provided on a peripheral edge of a fluid inflow passage 2a; a metallic diaphragm 2f configured to open and close the fluid flow path by being pushed against, or retracted away from, the annular valve seat 2e; a diaphragm holder 7 configured to press the diaphragm 2f downward; a compression coil spring (biasing member) 11; and a stem 8 configured to be moved downward by a pressing force of the compression coil spring 11 and moved upward by supplying a working fluid (hereinafter simply referred to as “operation air”) to the actuator 4 to move the diaphragm 2f in opening or closing direction; upper and lower pistons 9, 10; and drive means 13 configured to drive the upper and lower pistons 9,10. Note that the fluid inflow passage 2a and the fluid outflow passage 2b may work in an opposite way in terms of inflow and outflow.
The diaphragm 2f has an upwardly protruding arcuate shape which is formed into a spherical shell shape in a natural state. The diaphragm 2f is formed of, for example, a nickel alloy sheet and is formed into a spherical shell shape by cutting out the plate into a circular shape and making a center portion swelled upward. The diaphragm 2f may be formed of a stainless steel sheet or of a laminated body made of a stainless steel sheet and nickel-cobalt alloy sheet.
A holding adapter 15 is disposed between a lower end surface of the bonnet 3 and a bottom surface of the valve body recess 2c of the valve body 2, and an outer peripheral edge of the diaphragm 2f is retained between the holding adapter 15 and the bottom surface of the valve body recess 2c of the valve body 2 and is secured by screwing the bonnet 3 inward.
The upper piston 9 includes a disc-shaped piston body 21 and a protruding shaft portion 22 extending upward from an upper surface of a center portion of the piston body 21. The lower piston 10 includes a disc-shaped piston body 23, an upper protruding shaft portion 24 extending upward from an upper surface of a center portion of the piston body 23, and a lower protruding shaft portion 25 extending downward from a lower surface of the center portion of the piston body 23.
A counter plate 26 is fixed so as to be positioned between the upper piston 9 and the lower piston 10, whereby spaces of movement of the pistons 9, 10 are defined above and below the counter plate 26, respectively.
An upper end portion of the upper protruding shaft portion 24 of the lower piston 10 is fitted into a recess provided on a lower surface of the piston body 21 of the upper piston 9. A compression coil spring 11 is provided so as to urge the upper piston 9 downward, whereby the upper and lower pistons 9, 10 are moved integrally upward and downward.
The actuator 4 is principally accommodated in an interior of a casing 4a and is connected to the drive means 13 via a one-touch joint 31. The drive means 13 is configured to cause the operation air to act on the respective pistons 9, 10 for moving the stem 8 upward, and the upper operation air introduction chamber 29 and a lower operation air introduction chamber 30 therefor are formed below the respective pistons 9, 10. The upper and lower pistons 9, 10 are formed with axial passages 9a, 10b and radial passages 9b, 10b for sending operation air introduced via the one-touch joint 31 to the respective operation air introduction chambers 29, 30. The operation air is introduced into the respective operation air introduction chambers 29, 30, thereby applying an upward force to the respective pistons 9, 10. In addition, exhaust ports 4b, 4c for releasing air in the respective operation air introduction chambers 29, 30 are provided in the casing 4a.
In a state in which the operation air is not introduced into the respective operation air introduction chambers 29, 30, the stem 8 is in the closed position (see
A joint member 6 is provided at a lower part of the actuator 4 as a part of the actuator 4 and is formed at an upper part thereof with a joint member recess 6c surrounded by a joint member upright wall 6d, and the piston body 23 is accommodated in the joint member recess 6c. The joint member 6 is formed with a joint member through hole 6a at a center thereof, and the lower protruding shaft portion 25 and the stem 8 are inserted into the joint member through hole 6a from above and from below, respectively, and a lower end of the lower protruding shaft portion 25 and an upper end of the stem 8 are capable of coming into and out of contact with each other in the joint member through hole 6a. The actuator 4 and the joint member 6 are secured by forming threads on an outer peripheral surface of the joint member upright wall 6d and an inner peripheral surface of a lower part of the actuator 4, screwing these threads into engagement with each other, and then fastening with fastening member such as a bolt from a side surface, or applying securing means such as welding.
The actuator 4 described above has a configuration of a so-called normally-closed type, which presses the diaphragm 2f to close the flow path when the operation air is not introduced. However, an actuator of a so-called normally-open type, which has the compression coil spring 11 on the diaphragm 2f side, presses the piston 23 away from the diaphragm to prevent the diaphragm 2f from being pressed when the operation air is not introduced, is also applicable.
A joint member male thread 6b is formed on a lower outer peripheral surface of the joint member 6, and the joint member male thread 6b is screwed into engagement with a bonnet upper female thread 3b formed on a side surface of a bonnet upper recess 3a on an upper part of the bonnet 3, so that the actuator 4 and the bonnet 3 are connected. By screwing a bonnet male thread 3c formed on the outer peripheral surface of the bonnet 3 and the valve body female thread 2d into engagement, the bonnet 3 is connected to the valve body 2.
The lower end of the stem 8 is provided with the diaphragm holder 7 having a diameter larger than the outer diameter of the stem 8, and an abutting part 7b is provided at a lower end portion of the diaphragm holder 7. The amount of upward movement of the stem 8 and the Cv value have a correlative relationship, and thus adjustment of the amount of upward movement of the stem is required for achieving a required Cv value.
The bonnet 3 is formed with a bonnet through hole 3e at a center thereof, and the cylindrical body 5 is inserted into the through hole 3e. The cylindrical body 5 is a Cv value adjusting member, which is the most important component of the present invention. A cylindrical body male thread 5a is formed on a lower outer periphery of the cylindrical body 5, and the cylindrical body male thread 5a is screwed into engagement with the bonnet lower female thread 3d.
The cylindrical body 5 is formed with a cylindrical through hole 5b, and the stem 8 is inserted into the interior of the cylindrical through hole 5b. The diaphragm holder 7 is attached to the lower end portion of the stem 8. The diaphragm holder 7 may be formed integrally with the stem 8. The diaphragm holder 7 is partly accommodated in a bonnet lower recess 3f. An outer edge portion 7a of the diaphragm holder 7 is in abutment with the lower end surface of the cylindrical body 5 at an upper surface 7c of the outer edge portion thereof. Accordingly, the Cv value can be adjusted by a vertical position of the abutted surfaces.
A cylindrical body flange 5c is formed on an upper part of the cylindrical body 5, and the cylindrical body flange 5c is secured to a bottom surface of the bonnet upper recess 3a by screw means (see
Next, the cylindrical body 5 is set as illustrated in
Next, the cylindrical body 5 is adjusted by screws as illustrated in
Number | Date | Country | Kind |
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2018-179889 | Sep 2018 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2019/036267 | 9/17/2019 | WO | 00 |