Adjustment valve

Abstract

Provided is an adjustment valve with which an internal component such as a seat ring can be easily attached and detached, an automatic aligning function of a seat ring via a plug is exhibited with high accuracy to incorporated the plug and the seat ring in a centering state, and even when the valve is driven using a low-output actuator among pneumatic actuators, flow rate can be accurately controlled when the valve is opened and a high degree of sealing is exhibited when the valve is closed.　A seat ring 11 arranged in a body 10 is fixed via a seat retainer 13, fluid control is made possible by the seat ring and a valve body part 40, a plug 16 is inserted into a plug insertion hole 25, a plug guide 15 and the plug are adjusted to a clearance in a fixed range, and the seat ring is arranged while having a clearance so as to satisfy the relationship A > C > B, where A is the swing width of the plug on the actuator side, B is the clearance between the plug and the plug guide, and C is the clearance between the seat ring and a valve seat holding part.

Description

Control valve

[0001] The present invention relates to a regulator valve for regulating and controlling the flow rate of a fluid.

[0002] This type of control valve is designed to adjust the flow rate of a fluid by moving a plug (stem) back and forth relative to a seat ring installed inside the body to change the flow path area formed in the opening between the seat ring and the plug head. In this case, a pneumatic actuator is generally installed to precisely adjust the fluid flow rate, and this actuator controls the advancement and retreat of the plug.

[0003] Among these control valves, globe valve-type control valves in particular are known to be capable of precise flow rate adjustment by adjusting the position of a plug relative to a seat ring, and to be capable of flowing large flow rates of fluid while finely controlling the fluid flow rate, pressure, etc. In recent years, as with other types of valves, control valves including globe valve-type control valves are also desired to be usable over a long period of time by replacing internal parts from the perspective of MRO (Maintenance, Repair, and Operations), and for example, when the seat ring on the valve seat side deteriorates due to repeated flow rate control, there is a demand for this seat ring to be easily detachable for replacement or maintenance.

[0004] Therefore, in this type of globe valve-type control valve, the seat ring is sometimes removably attached to the body by screwing it in, and the screw can be loosened to remove the seat ring from the body so that it can be replaced or maintained.

[0005] In contrast, in the globe valve of Patent Document 1, the outer periphery of a valve seat (seat ring) is fitted into an opening in the valve body that opens and closes the flow path, and a cylindrical guide is provided within the valve body to guide the movement of the valve disc, and the tip of this guide presses the upper part of the valve seat, fixing the valve seat to the periphery of the opening. In this valve, the valve seat is fixed between the valve body and the cylindrical guide, so that if the valve seat wears out and needs repair, it can be replaced without loosening the screws as with the above-mentioned screw-in type seat ring.

[0006] In the control valve of Patent Document 2, the seat ring is removably sandwiched between the opening on the plug (stem) mounting side of the body and the cage, which serves as a seat retainer. This mounting structure allows the seat ring to be detached for replacement or maintenance. A bonnet is provided above the plug, and the upper and lower parts of the cage are held between the bonnet and the body. The cage is mounted within the body while being held concentric with the valve disc. The seat ring is fitted into the body opening while being positioned, and is fixed from above the seat ring by the bonnet via the cage.

[0007] In this valve, the plug is supported by plug guides provided at multiple locations in the axial direction and is journaled to the bonnet (body) through these plug guides to suppress runout of the tip seal portion. Furthermore, the plug seal portion is tapered, while the seal surface of the seat ring is also tapered to allow surface contact with the plug seal portion. With this configuration, when the valve is closed, the plug seal portion, centered by the plug guide, makes surface contact with the seal surface of the seat ring to seal them.

[0008] Japanese Patent Application Laid-Open No. 6-281021 U.S. Patent Registration No. 3,504,888

[0009] In globe valve-type control valves, if the seat ring is attached to the body by threads as described above, replacement or maintenance requires loosening and removal of the screws, which is time-consuming. Furthermore, if corrosion occurs in the threaded portion due to aging or other factors, making the seat ring impossible to remove, the entire body may need to be replaced. Another problem is that the seat ring needs to be threaded, and high machining precision is required to install the seat ring in the correct position.

[0010] Generally, in the case of a control valve with a lift valve structure, such as a globe valve, in order to precisely adjust minute flow rates, the plug tip is gradually tapered toward the tip so that the clearance between the plug tip (plug head side) and the seat ring that occurs when the valve is open is constantly increased or decreased. In contrast, the plug tip of the globe valve disclosed in Patent Document 1 is not gradually tapered, making this globe valve unsuitable for use as a control valve. As such, it is difficult to precisely adjust flow rates in the minute flow rate range with this globe valve.

[0011] In the control valve of Patent Document 2, the seat ring is mounted in a positioned state between the body and a cage that is centered relative to the valve disc, and the plug, which is journaled in the bonnet (body) through a plug guide section, is moved back and forth relative to the seat ring, and the flow rate is adjusted by the head section, which has a gradually tapering diameter on the tip side of the plug.

[0012] When a cylinder-type pneumatic actuator is installed in such a control valve, the actuator is large and heavy relative to the valve body, which limits the installation locations of the control valve. In comparison, a diaphragm-type pneumatic actuator is known, which is smaller and lighter, and when this diaphragm-type actuator is installed, it can be installed in a narrow installation space, increasing the degree of freedom.

[0013] However, among actuators that use air pressure, a diaphragm-type actuator has a weaker driving force for moving the plug back and forth than, for example, a cylinder-type actuator mounted on a valve of the same diameter. Because this weak driving force also weakens the force transmitted to the tip of the plug, the amplitude of vibration at the tip of the plug is likely to increase.

[0014] For this reason, in the case of control valves equipped with actuators with weak driving force, such as diaphragm actuators, it is particularly necessary to assemble the seal portion of the plug tip and the seal surface of the seat ring in a state where they are accurately centered and aligned. If the centering is not performed accurately, when the valve is open, the width of the flow path area between the seat ring and the seal portion of the plug tip will not be uniform, or the plug tip will be tilted relative to the seat ring, making it impossible to maintain a constant change in the flow path area between the seat ring and the seal portion of the plug tip, and making it impossible to regulate the flow rate with high precision. Meanwhile, when the valve is closed, the seal between the seat ring and the plug tip will not be secured, which could result in leakage.

[0015] The present invention was developed to solve the above-mentioned problems, and its object is to provide a control valve in which internal parts such as a seat ring can be easily attached and detached, and the plug can be used to automatically align the seat ring with high precision, thereby assembling the plug and seat ring in a centered state, thereby enabling accurate flow control when the valve is open and exhibiting high sealing properties when the valve is closed, even when driven by a low-output pneumatic actuator.

[0016] In order to achieve the above object, the invention according to claim 1 provides a valve device in which an annular seat ring is disposed in a valve seat retaining portion formed in a groove shape within the body, and this seat ring is fixed by being pressed from above by the bonnet via a cylindrical seat retainer, and a plug having a valve body portion at its tip is provided so as to be able to advance and retreat relative to the seat ring, and fluid control is possible by adjusting the degree of contact and separation between the valve body portion and the seat ring, and an actuator is attached to the opposite side of the plug from the valve body portion to apply a driving force to operate the plug, and the plug is inserted into a plug insertion hole provided in the bonnet. a plug guide that guides the movement of the plug is provided on the inner peripheral surface of the plug insertion hole, and a clearance between the inner peripheral surface of the plug and the outer peripheral surface of the plug is adjusted to be within a certain range; the seat ring is disposed in the valve seat retaining portion with a clearance on the outer peripheral side that allows it to move circumferentially; and the relationship A > C > B is satisfied, where A is the overall amplitude of the plug that occurs on the actuator side, B is the clearance between the outer peripheral surface of the plug and the inner peripheral surface of the plug guide, and C is the clearance between the outer peripheral surface of the seat ring and the inner peripheral surface of the valve seat retaining portion.

[0017] The invention according to claim 2 is a control valve in which the plug guide is provided as a cylindrical member separate from the bonnet, and the plug guide is installed in the plug insertion hole.

[0018] The invention according to claim 3 is a control valve in which the plug includes a small diameter portion attached to the drive side of the actuator and a large diameter portion that is larger in diameter than the small diameter portion and is provided on the seat ring side, and the large diameter portion is inserted into and guided by the plug guide.

[0019] The invention according to claim 4 is a control valve in which a groove is provided on the outer periphery of the plug guide, which groove connects the small diameter side and large diameter side of the plug journaled within the body and bonnet.

[0020] The invention according to claim 5 is a control valve in which the actuator is a diaphragm actuator.

[0021] According to the invention of claim 1, a seat ring is disposed in an annular retaining portion within the body, and this seat ring is fixed by being pressed from above via a cylindrical seat retainer, allowing for easy installation and removal of internal components such as the seat ring. The relationship of plug runout A > clearance C between the outer surface of the seat ring and the inner periphery of the valve seat retainer > clearance B between the outer surface of the plug and the inner periphery of the plug guide is satisfied, allowing the plug to self-align the seat ring with high precision and allowing the plug and seat ring to be assembled in a centered state. Therefore, even when driven using a low-output pneumatic actuator, accurate flow control can be achieved by adjusting the flow rate while the seat ring and the disc portion at the tip of the plug are centered. Meanwhile, when the valve is closed, improved adhesion between the disc portion and the seat ring provides high sealing performance.

[0022] According to the invention of claim 2, by providing the plug guide separately from the bonnet, the plug guide can be formed using a material with a strength suitable for the plug, and even if the plug repeatedly slides back and forth against this plug guide, galling and damage to the plug guide can be reduced, and the plug guide can be replaced as needed.

[0023] According to the invention of claim 3, the plug has a small-diameter portion that is attached to the drive side of the actuator, thereby reducing the torque of the actuator for operating the plug and enabling the use of a smaller, lower-output actuator. A large-diameter portion, larger than the small-diameter portion, is provided on the seat ring side of the plug, and this large-diameter portion is inserted and guided by the plug guide. This reduces the amplitude of the plug's runout compared to when the small-diameter portion is guided. Because the plug is guided by the large-diameter portion on the seat ring side, which is closer to the disc portion, the magnitude of runout generated on the actuator side and transmitted to the disc portion can be reduced compared to when the small-diameter portion on the farther side from the disc portion is guided.

[0024] According to the invention of claim 4, a groove is provided on the outer periphery of the plug guide, which connects the small diameter side and large diameter side of the plug that is journaled within the body and bonnet. This allows fluids such as air that have accumulated on the bonnet side to escape to a flow path inside the body through the groove, preventing a rise in pressure due to the accumulation of fluids such as air on the bonnet side, allowing the plug to operate smoothly and enabling highly accurate flow rate adjustment.

[0025] According to the invention of claim 5, the actuator is a diaphragm-type actuator, which makes it possible to achieve a smaller and lighter actuator than other pneumatic actuators, and thus to achieve a compact automatic control valve capable of automatically controlling the flow rate, thereby achieving a compact overall size. In this case, even if the deflection of the plug on the actuator side increases, the deflection of the valve body portion on the tip side of the plug is kept small, and the automatic alignment function of the plug with respect to the seat ring is reliably demonstrated, thereby achieving highly accurate flow rate control when the valve is open, and at the same time, achieving high sealing performance when the valve is closed.

[0026] Fig. 2 is a schematic longitudinal sectional view showing an embodiment of a control valve according to the present invention. Fig. 3 is a partially enlarged sectional view showing the vicinity of the valve body of Fig. 1. Fig. 4 is an enlarged perspective sectional view of a main part of Fig. 1. Fig. 5 is a schematic exploded perspective view showing a plug, a plug guide, and a seat ring.

[0027]

[0023] An embodiment of a control valve according to the present invention will be described in detail below with reference to the drawings. Fig. 1 is a schematic longitudinal sectional view showing an embodiment of the control valve according to the present invention, Fig. 2 is a partially enlarged sectional view showing the vicinity of the valve body of Fig. 1, Fig. 3 is an enlarged perspective sectional view of a main portion of Fig. 1, and Fig. 4 is an enlarged sectional view of a main portion of Fig. 1.

[0028] 1 to 4, the control valve body 1 of the embodiment of the present invention has a globe valve type structure and is provided with a diameter size of, for example, ½ to 4 inches. Water, steam, air, and various other fluids are used as the fluids, and when the valve is open, these fluids can be allowed to flow while regulating the flow rate, while when the valve is closed, leakage of these fluids can be prevented.

[0029] The control valve main body 1 comprises a valve main body portion 2 and an actuator 3, of which the valve main body portion 2 has a body 10, a seat ring 11, a gasket 12, a seat retainer 13, a bonnet 14, a plug guide 15, and a plug (stem) 16.

[0030] The body 10 of the valve main body 2 is formed from a metal material such as carbon steel casting, and is provided with an inlet 10a and an outlet 10b on both sides. A substantially cylindrical mounting recess 10c is bored out in the substantially vertical direction between the inlet 10a and the outlet 10b, and the inlet 10a and the outlet 10b on both sides are connected through this mounting recess 10c. An opening 10d is formed on the upper side of the mounting recess 10c, and a valve seat holder 17 is formed in the shape of a recessed groove on the lower side of the mounting recess 10c, and an annular seat ring 11 is placed against this annular valve seat holder 17.

[0031] The seat ring 11 is formed in an annular shape from a metal material such as a stainless steel alloy, and has an annular plate portion 20 formed with an outer diameter that allows it to be inserted into the valve seat holder 17, and an annular protrusion portion 21 formed and protruding downward from the inner periphery of the annular plate portion 20. The annular protrusion portion 21 has an outer diameter that allows it to be inserted into the inner periphery of a communicating flow passage 22 formed in the lower part of the valve seat holder 17, while a tapered surface 23 is formed on the upper inner periphery of the annular plate portion 20, and when the valve is closed, the tip end side of the plug 16 abuts against this tapered surface 23, thereby enabling sealing.

[0032] The gasket 12 is made of a resin material such as PTFE (polytetrafluoroethylene) and is formed into an annular shape with dimensions approximately the same as the outer diameter of the annular plate portion 20 of the seat ring 11, and is fitted between the seat ring 11 and the valve seat retaining portion 17. As a result, the gap between the body 10 and the seat ring 11 is sealed by the gasket 12, preventing back leakage from this area.

[0033] The seat retainer 13 is formed in a cylindrical shape from a metal material such as a stainless steel alloy, and has openings 24 formed in multiple locations on the cylindrical portion, which connect the inner and outer peripheries, and when the valve is open, fluid flows through the openings 24 from the inlet 10a to the outlet 10b inside the seat retainer 13. The seat retainer 13 is placed on the upper surface of the seat ring 11 mounted inside the body 10, and is disposed in the mounting recess 10c substantially concentric with the seat ring 11.

[0034] The bonnet 14 is made of the same metal material as the body 10, such as carbon steel casting, and is formed into a generally cylindrical shape that can be mounted on top of the body 10, and the actuator 3 is attached to the body 10 via this bonnet 14. A plug insertion hole 25 is provided on the lower inner periphery of the bonnet 14, and an annular mounting portion 26 for mounting the plug guide 15 is formed in the shape of an enlarged groove on the opening side of the lower inner periphery of this plug insertion hole 25.

[0035] 4, an annular protrusion 27 is formed in a slightly protruding manner in the center of the bottom surface of the bonnet 14, and the upper end opening of the seat retainer 13 is attached to the outer periphery of this annular protrusion 27. In this case, a gap S of approximately 0.2 to 0.3 mm is provided in the radial direction between the outer periphery of the annular protrusion 27 and the inner periphery of the seat retainer 13, and the position of the seat retainer 13 can be adjusted through this gap S. The size of the gap between the tip end of the plug 16 and the seat retainer 13 may affect the Cv value when adjusting the flow rate, so the outer diameter of the seat retainer 13 should be set taking this gap into consideration.

[0036] 1 to 5 , plug guide 15 is made of a metal material such as a stainless steel alloy and is formed into a cylindrical shape with an appropriate thickness separately from bonnet 14, and is attached to one location within bonnet 14. In this case, the outer periphery of plug guide 15 is set to an outer diameter that allows it to be press-fitted into annular mounting portion 26. Plug guide 15 is attached to plug insertion hole 25 and its lower end is spot-welded to bonnet 14, thereby firmly attaching it to bonnet 14 in a state that prevents it from slipping out. The inner diameter of plug guide 15 is set to a size that allows plug 16 to slide up and down, thereby enabling it to guide the movement of plug 16.

[0037] A groove 28 is formed on the outer periphery of the plug guide 15, and this groove 28 allows communication between the small diameter portion 30 and the large diameter portion 31 of the plug 16 (described later) journaled within the body 10 and the bonnet 14.

[0038] The bonnet 14 is attached to the opening 10d of the body 10 with mounting bolts and nuts 33 via a bonnet gasket 32 ​​made of a resin material such as PTFE, and the bonnet 14 and body 10 are integrated in a sealed state. As a result, the seat ring 11 is pressed by the bonnet 14 via the seat retainer 13, and is fixed between the bonnet 14 and the body 10.

[0039] The bonnet 14 is structured so that it protrudes toward the body 10 in two stages from its outer periphery toward its inner periphery, and a corresponding stepped structure is provided on the body 10 at its innermost periphery, with these steps fitting together. The fitting portion at the innermost periphery is machined with particular precision, enabling the bonnet 14 and body 10 to be aligned radially and the two components to be accurately centered. This prevents radial displacement or tilt of the plug 16 due to misalignment between the bonnet 14 and body 10, ensuring accurate centering of the valve body 40.

[0040] The plug 16 is formed into an elongated shape from a metal material such as a stainless steel alloy, and includes, in the axial direction, a small-diameter portion 30 attached to the drive side of the actuator 3, and a large-diameter portion 31 that is larger in diameter than the small-diameter portion 30 and is provided on the seat ring 11 side. The plug 16 is inserted into the plug insertion hole 25 while the large-diameter portion 31 is inserted and guided by the inner periphery of the plug guide 15, and is attached to the bonnet 14 in a state where it can advance and retreat relative to the seat ring 11.

[0041] The large diameter portion 31 of the plug 16 is provided at a portion of the overall length of the plug 16 on the valve body 2 side, and in this example, is formed to a short length so that its upper end touches the upper surface of the plug guide 15 when the valve is closed. As a result, when the plug guide 15 guides the large diameter portion 31 during valve closing operation, the axial distance from this guide portion to the sealing position between the tip end of the plug 16 and the seat ring 11 is also short.

[0042] A valve body portion 40 is integrally formed on the tip side of the plug 16, with a diameter greater than that of the large-diameter portion 31 near the boundary with the plug 16. This valve body portion 40 can close the flow path or adjust the flow rate when the valve is open. A flow rate adjustment portion 41, which is generally truncated cone-shaped and gradually reduces in diameter as it extends downward, is provided on the lower side of the valve body portion 40. The bottom side of this flow rate adjustment portion 41 is provided with a generally conical inclined surface 42 that becomes increasingly convex toward the center. The fluid flows through this inclined surface 42, allowing the flow rate to be adjusted while maintaining a high Cv value when the valve is open. Meanwhile, a tapered portion 43, with approximately the same angle as the tapered surface 23 of the seat ring 11, is provided on the upper part of the flow rate adjustment portion 41. This tapered portion 43 is capable of abutting and sealing against the tapered surface 23 when the valve is closed.

[0043] The plug 16 is advanced and retracted by the actuator 3 to adjust the degree of contact and separation between the valve element 40 and the seat ring 11, thereby enabling fluid control. In this case, when the tapered portion 43 of the valve element 40 and the tapered surface 23 of the seat ring 11 come into contact (abut) with each other as described above, the valve is closed, providing high sealing performance and reliably preventing fluid leakage. On the other hand, when the plug 16 is raised from the valve closed state of the valve element 40, the tapered portion 43 moves away from the tapered surface 23, establishing an open state. In this state, the plug 16 is advanced and retracted to finely change the size of the gap between the flow rate adjustment portion 41 of the valve element 40 and the tapered surface 23 of the seat ring 11, enabling flow rate adjustment from very small to large flow rates while finely adjusting the valve opening.

[0044] An output shaft 50 of an actuator 3 that applies a driving force to operate the plug 16 is attached to the end of the plug 16 opposite the valve body portion 40, and the plug 16 can be raised and lowered through this output shaft 50 to close the valve or adjust the flow rate.

[0045] The actuator 3 is a diaphragm-type pneumatic actuator, which is smaller and lighter than other actuators that use air pressure, such as cylinder-type pneumatic actuators, and allows for fine flow rate adjustment. The actuator 3 is provided with a rotary handle 51 for manual operation, and in an emergency or other situation where the actuator 3 cannot be operated automatically, the rotary handle 51 can be manually operated to advance and retract the plug 16. The actuator 3 is provided with the output shaft 50, which is attached via a bearing 52 so that it can advance and retract in the output direction.

[0046] The actuator 3 is attached to the top of the valve body 2 via a yoke 55 formed in a frame shape. In this case, a mounting hole 56 into which a bearing 52 can be fitted is provided on the top surface of the yoke 55, and with the output shaft 50 and bearing 52 inserted into this mounting hole 56, the actuator 3 is attached to the top surface of the yoke 55 via this bearing 52. Meanwhile, the top of the bonnet 14 of the valve body 2 is fixedly provided on the bottom of the yoke 55, and the valve body 2 and the actuator 3 are thereby integrated by the yoke 55 to form the control valve body 1.

[0047] In this case, the plug 16 of the valve body 2 and the output shaft 50 of the actuator 3 are connected concentrically by a connector 57, so that the output from the output shaft 50 can be transmitted to the plug 16 in a centered state. In this way, by connecting the plug 16 and the output shaft 50 using the connector 57, a plug rod 60 is formed in which the plug 16 and the output shaft 50 are integrated, and this plug rod 60 functions as a plug, and a deflection width A and a clearance B, which will be described later, are generated in this plug rod 60.

[0048] The plug rod 60 is attached to the actuator 3 through a bearing 52, and moves axially back and forth when driven by the actuator 3. Because a driving force is applied to the plug rod 60 near the bearing 52 on the output shaft 50 side, radial vibration is likely to occur in this vicinity. It is difficult to completely prevent such vibration of the plug rod 60 that occurs on the actuator 3 side. In particular, in the case of a diaphragm-type actuator, the output shaft is held in a manner that allows it to move in conjunction with the diaphragm, so vibration is likely to become large.

[0049] The vibrations that may occur at this time include (1) vibrations relative to the axis P of the plug rod (the entire plug) 60, i.e., vibrations of the plug rod 60 perpendicular to the seat ring 11, and (2) vibrations centered on the mounting side of the plug rod (the entire plug) 60 on the actuator 3 side, i.e., pendulum-like vibrations of the plug rod 60.

[0050] Such vibration of the plug rod 60, which occurs in the actuator 3 portion, is suppressed to some extent by the bearing 52, and the vibration is transmitted to the valve body 40 side (the side that moves toward and away from the seat ring 11). At this time, (1) the vibration of the plug rod 60 in the direction perpendicular to the seat ring 11 occurs by approximately the same amount of vibration from the side attached to the actuator 3 to the valve body 40 side, and (2) the pendulum-like vibration of the plug rod 60 occurs with a larger amount of vibration on the valve body 40 side than on the actuator 3 side, because the plug rod 60 has an elongated shape that extends from the actuator 3 side to the seat ring 11 side.

[0051] The clearance between the outer peripheral surface of the plug 16 and the inner peripheral surface of the plug guide 15 is adjusted to a certain range to accommodate the above-mentioned runout of the plug rod 60, and the seat ring 11 is placed in the valve seat retaining portion 17 with a clearance on its outer peripheral side so that it can move circumferentially.

[0052] In the control valve body 1 of this embodiment, on the actuator 3 side, the deflection width of the entire plug (plug rod) 60 generated by the gap between the outer periphery 50a of the output shaft 50 and the inner periphery 52a of the bearing 52 is defined as A, the clearance between the outer periphery of the plug 16 and the inner periphery of the plug guide 15 (specifically, the clearance between the outer periphery 31a of the large diameter portion 31 and the inner periphery 15a of the plug guide 15) is defined as B, and the clearance between the outer periphery 11a of the seat ring 11 and the inner periphery 17a of the valve seat retainer is defined as C. The overall deflection width A of the plug, clearance B, and clearance C are each defined as radial lengths relative to the direction of the axis P. Furthermore, clearances B and C each represent the deflection width of the plug 16 generated within that range.

[0053] In this way, by setting the clearance B at the opposing position between the outer circumferential surface 31 a of the plug 16 and the inner circumferential surface 15 a of the plug guide 15 to be smaller relative to the swing width A generated on the actuator 3 side of the plug rod (the entire plug) 60, (1) the swing of the plug rod (the entire plug) 60 in the perpendicular direction relative to the seat ring 11 and (2) the magnitude of the pendulum swing of the plug rod (the entire plug) 60 are kept smaller at the position of clearance B, and at the position of clearance C below this clearance B, the magnitude of (1) the swing of the plug rod 60 in the perpendicular direction and (2) the magnitude of the pendulum swing of the plug rod 60 are each reduced.

[0054] In the above cases, the magnitude of each clearance is set in accordance with the swing width A of the plug 16 of the actuator 3 to be installed. Specifically, for example, if the diameter size of the control valve body 1 is 2 inches or less, the swing width A on the actuator 3 side is about 0.4 mm, and if it exceeds 2 inches, the swing width A on the actuator 3 side is about 0.7 mm. In either case, it is preferable to set clearance B to 0.1 to 0.2 mm and clearance C to 0.2 to 0.4 mm, and to set them so that the above formula A>C>B is satisfied based on the magnitude of these clearances C.

[0055] The magnitudes of the deflection width A, clearance B, and clearance C of the plug 16 can be set to various dimensions according to various specifications such as the bore size of the valve body 2 and the output of the actuator 3, as long as the above formula A>C>B is satisfied.

[0056] The plug rod 60 is provided by connecting the plug 16 and the output shaft 50 with the connector 57, but these may be provided integrally in advance to provide the plug 16. In this case, the swing width A on the actuator 3 side is the swing width of the plug 16.

[0057] The plug guide 15 is fixed to the bonnet 14 at its end by spot welding, but may be fixed to the bonnet 14 by welding means other than spot welding or by other fastening means.

[0058] The actuator 3 may be any actuator other than a diaphragm-type pneumatic actuator, and may be any of various actuators such as a cylinder-type pneumatic actuator.

[0059] Next, the operation of the control valve of the above embodiment of the present invention will be described. When assembling the above-described control valve main body 1, first, the seat ring 11 is attached to the valve seat holding portion 17 of the body 10 via the gasket 12, and then the seat retainer 13 is placed on top of the seat ring 11. At this time, it is advisable to attach the seat retainer 13 so that the position of the outer peripheral surface of the seat retainer 13 is aligned with the outer peripheral surface 11a of the seat ring 11.

[0060] Meanwhile, with the plug 16 inserted from below into the plug insertion hole 25 of the bonnet 14 to which the plug guide 15 is fixed, the bonnet 14 is temporarily fixed via a bonnet gasket 32 ​​to the upper part of the body 10, on which the seat ring 11 and gasket 12 are disposed, with bolts and nuts 33 sandwiching the seat retainer 13. At this time, the annular protrusion 27 of the bonnet 14 is inserted into the upper end opening of the seat retainer 13, and the valve body 2 is temporarily assembled while the body 10 and bonnet 14 are fixed in place with the seat retainer 13 sandwiched between the seat ring 11 and the bottom surface of the bonnet 14 on the outer circumferential side of the annular protrusion 27. After the valve body 2 is temporarily assembled, the relationship of clearance C>clearance B is ensured, and the provision of clearance C allows the seat ring 11 to move freely in the circumferential direction.

[0061] Next, the actuator 3 is attached to the bonnet 14 of the valve body 2 via a yoke 55. In this case, the output shaft 50 and bearing 52 of the actuator 3 are inserted into the yoke 55 through a mounting hole 56 on the top surface of the yoke 55, and in this state the output shaft 50 is concentrically connected to the plug 16 by a connector 57, while the lower part of the yoke 55 is fixed to the upper part of the bonnet 14 of the valve body 2. By connecting the output shaft 50 and the plug 16 in this manner, a plug rod 60 is formed, and the valve body 40 at the lower part of the plug rod 60 is provided on the seat ring 11 side, and the upper side of the plug rod 60 is provided on the actuator 3 side via the bearing 52.

[0062] At this time, as described above, the plug rod 60 (the entire plug) experiences either (1) swing in a direction perpendicular to the seat ring 11 or (2) pendulum-like swing, or both. The largest of these swings is due to swing amplitude A generated on the actuator 3 side. Even if these swings cause the axial center P of the plug rod 60 to deviate from the center of the seat ring 11, causing the center of the valve body 40 to be misaligned with the center of the seat ring, the bonnet 14 is temporarily fixed to the body 10, so that the swing amplitude A on the actuator 3 side is limited to the clearance B of the plug guide portion 15. Furthermore, because clearance C is greater than clearance B, the position of the valve body 40 at the tip of the plug 16 can change relative to the seat ring 11 on the side of clearance C, which has the larger clearance dimension.

[0063] Therefore, when the bolts and nuts 33 are tightened to fix the bonnet 14 to the body 10, the tapered surface 23 is guided along the tapered portion 43 of the valve body portion 40, and the seat ring 11 moves within the valve seat holding portion 17 to follow the position of the valve body portion 40, thereby automatically aligning the seat ring 11 with the valve body portion 40.

[0064] By providing such an automatic centering structure, during assembly, the actuator 3 and the valve body 40 can be integrated to form the control valve body 1 while centering the seat ring 11 with respect to the valve body 40 of the plug 16. That is, due to the relationship of overall plug swing width A > clearance C > clearance B, the swing width A of the plug rod 60 on the actuator 3 side is restricted by the smallest clearance B in the above formula, while the center of the seat ring 11 attached to the body 10 side is centered with the center of the large diameter portion 31 of the plug 16 by the clearance C larger than this clearance B.

[0065] During operation of the plug 16 (valve body portion 40) by the actuator 3, even if the plug rod 60 is displaced on the actuator 3 side, i.e., swings perpendicular to the seat ring 11 or swings like a pendulum, the swing width A of the plug rod 60 is significantly reduced by being suppressed by the position of the plug guide 15 in the large diameter portion 31 due to the relationship of overall swing width A > clearance C > clearance B of the plug. The operation of the plug rod 60 is then transmitted in an aligned state to the seat ring 11, which is attached concentrically with the large diameter portion 31.

[0066] This makes it less likely that problems such as uneven contact between the valve body 40 and the seat ring 11 due to vibration of the plug 16 will occur, and when the valve is closed, the tapered portion 43 of the valve body 40 will come into close contact with the tapered surface 23 of the seat ring 11, providing a high level of sealing and reliably preventing fluid leakage. On the other hand, when controlling the flow rate with the valve open, the increase in the gap between the flow rate adjusting portion 41 and the tapered surface 23 is kept approximately constant, allowing for accurate flow rate control.

[0067] Factors that affect alignment include components that are in close contact with the plug (stem) 16 and the output shaft 50, such as the O-ring in the bearing 52 that contacts the output shaft 50 and the packing disposed in the insertion hole 25. These components also contact the plug 16 and the output shaft 50 with a certain amount of pressure to seal the gap between them, and therefore affect their axial position. However, since the O-ring and packing are made of a flexible material for sealing purposes, even if they are misaligned with the center position adjusted by the plug guide 15, they will deform to align with the plug guide 15. In other words, the clearance B at the plug guide 15 is the most important factor that determines the alignment between the valve body 40 and the seat ring 11 at the sealing position. As long as this clearance B is set appropriately, reliable alignment can be achieved even if there are slight misalignments in other elements.

[0068] During flow rate control, in the globe valve-type valve body 2 of this embodiment, when fluid pressure is applied from below the valve element 40 due to the underflow of fluid from the inlet 10a, even if this fluid pressure rises, the vibration of the plug 16 on the valve element 40 side can be suppressed, maintaining high-precision flow rate control and suppressing the generation of turbulence on the secondary side (outlet 10b side) due to core vibration. As a result, even in the opening range of the valve element 40 that is particularly susceptible to the influence of fluid pressure, around 20 to 70% opening of the valve element 40, lateral vibration of the valve element 40 due to fluid pressure can be suppressed, maintaining precise flow rate adjustment.

[0069] Furthermore, even when using a diaphragm-type pneumatic actuator like the one in this example, which has a weaker driving force (output) for advancing and retracting the plug 16 than a cylinder-type actuator and is prone to a larger amplitude of vibration at the tip of the plug, it is possible to achieve a high level of sealing when the valve is closed and precise flow rate regulation when the valve is open by assembling the valve body 40 of the plug 16 and the seat ring 11 in a centered state. Therefore, by attaching a diaphragm-type actuator, which can be made smaller and lighter than a cylinder-type actuator, it becomes possible to install the diaphragm-type actuator in a wide range of locations, including narrow installation spaces.

[0070] Because the large diameter portion 31 of the plug 16 is guided by the plug guide 15, the contact area between the inner peripheral surface 15a of the plug guide and the outer peripheral surface 31a is larger than that of the small diameter portion 30, thereby improving the effect of suppressing runout of the plug 16. Furthermore, the large diameter portion 31 is located closer to the seat ring 11 on the plug 16, and the height from the seat ring 11 to the guide position by the plug guide 15 is kept low, thereby reducing runout of the valve body portion 40. Meanwhile, because the small diameter portion 30 of the plug 16 is provided on the drive side of the actuator 3, the diameter of the packing 61 provided in the bearing 52 to seal this position can be reduced, and the contact area with the packing 61 can be reduced during the advance / retract movement of the plug 16, thereby suppressing sliding resistance.

[0071] Furthermore, by making the distance between (b) and (c) closer than the distance between (a) and (b) regarding the positional relationship between (a) the connection portion of the output shaft 50 with the actuator 3 (the portion where runout A occurs), (b) the plug guide 15 portion (the portion with clearance B), and (c) the portion of the seat ring 11 (the portion with clearance C), it is possible to contain the runout of the plug 16 within the width of the clearance B at a position closer to the seat ring 11 where alignment is required, and therefore it is possible to narrow the range of alignment at the seat ring 11, enabling more precise alignment and also suppressing runout of the plug 16 during operation.

[0072] As described above, runout of the plug 16 is suppressed by the plug guide 15 (clearance B), and providing this plug guide 15 on the bonnet 14 is also a favorable point for achieving the effects of the present invention. First, the plug guide 15 is attached to the annular attachment portion 26 on the lower inner periphery of the bonnet 14. In this way, by positioning the plug guide 15 at the position of the bonnet 14 closest to the body 10, the seat ring 11 and the plug guide 15 are positioned close to each other, which means that runout of the plug 16, which is suppressed by clearance B, is less likely to become large by the time it reaches the position of the seat ring 11, which is advantageous for alignment at the seat ring 11.

[0073] Furthermore, bonnet 14 has a step structure that protrudes toward body 10, which allows for accurate centering with body 10, and disposing plug guide 15 on this bonnet 14 also makes it easier to align plug guide 15 with body 10. In particular, because the step structure that mates with body 10 and annular mounting portion 26 can be machined on bonnet 14 all at once while bonnet 14 is being held, the center positions of these step structures and annular mounting portion 26 can also be accurately aligned, allowing for even more accurate centering of plug guide 15 with body 10.

[0074] When runout (runout width A) occurs at the connection part of output shaft 50 with actuator 3, even if the runout at plug guide 15 is limited to clearance B, if the center positions of plug guide 15 and body 10 (valve seat retaining portion 17) are significantly misaligned, it is conceivable that alignment within the width of clearance C would not be possible. However, in the present invention, as described above, the center positions of plug guide 15 and body 10 (valve seat retaining portion 17) are accurately aligned, so that the small runout width limited by clearance B can be accommodated, and alignment of seat ring 11 can also be performed with an extremely small width, making it possible to perform alignment, which is important in a control valve, with great accuracy.

[0075] On the valve body 2 side, the area near the bonnet 14 supports the sliding plug 16 while preventing eccentric movement or tilt of the plug 16, which raises the risk of galling by the plug 16 or damage to the contact surface. In response to this, the plug guide 15, which is formed separately from the bonnet 14 and is attached to the plug insertion hole 25, is formed of a material with appropriate strength in relation to the plug 16, thereby preventing galling and damage. Furthermore, if galling or damage occurs, the plug guide 15 can be removed and replaced.

[0076] The structure guides the plug 16 with the plug guide 15 provided in one location, which prevents an increase in the height of the bonnet 14 and ensures its strength by providing the plug guide 15 with an appropriate thickness, while attaching it to the large diameter portion 31 at the tip of the plug where vibration is most likely to occur minimizes vibration on the valve body portion 40 side.

[0077] The plug guide 15 is provided with a groove 28 that connects the small diameter portion 30 and large diameter portion 31 of the plug 16, so that if a fluid such as air enters the space above the plug large diameter portion 31 on the bonnet 14 side, the fluid can escape through the groove 28 to a flow path inside the body 10. Therefore, there is no risk of fluid accumulating in the plug insertion hole 25 in the bonnet 14 and interfering with the advance / retract movement of the plug 16, and smooth operation by the actuator 3 is maintained.

[0078] If the internal parts of the valve body 2 deteriorate or wear due to long-term use, the bolts and nuts 33 can be loosened to remove the bonnet 14 side from the body 10, making it easy to replace or maintain the internal parts, including the seat ring 11, bonnet gasket 32, gasket 12, seat retainer 13, and plug (stem) 16.

[0079] The above describes in detail the embodiments of the present invention, but the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the spirit of the invention as described in the claims of the present invention.

[0080] REFERENCE SIGNS LIST 1 Control valve body 2 Valve body 3 Diaphragm actuator (actuator) 10 Body 11 Seat ring 13 Seat retainer 14 Bonnet 15 Plug guide 15a Inner peripheral surface 16 Plug (stem) 17 Valve seat retaining portion 25 Plug insertion hole 28 Groove 30 Small diameter portion 31 Large diameter portion 31a Outer peripheral surface 40 Valve body portion 60 Plug rod A Swing width of plug rod (entire plug) B Clearance between outer peripheral surface side of plug and inner peripheral surface of plug guide C Clearance between outer peripheral surface of seat ring and inner peripheral surface side of valve seat retaining portion

Claims

1. An annular seat ring is placed in a valve seat retaining portion formed in a groove shape within the body, and this seat ring is pressed and fixed from above by the bonnet via a cylindrical seat retainer, and a plug with a valve body portion at its tip is provided so as to be able to move forward and backward relative to the seat ring, and fluid control is possible by adjusting the degree of contact and separation between the valve body portion and the seat ring, and an actuator is attached to the opposite side of the plug from the valve body portion to apply a driving force to operate the plug, and the plug is inserted into a plug insertion hole provided in the bonnet, and a a plug guide is provided to guide the movement of the plug, and a clearance is adjusted to be within a certain range between an inner circumferential surface of the plug guide and an outer circumferential surface of the plug; the seat ring is disposed in the valve seat retaining portion with a clearance on its outer circumferential side so as to be movable in a circumferential direction; and the relationship A > C > B is satisfied, where A is the overall amplitude of vibration of the plug generated on the actuator side, B is the clearance between the outer circumferential surface of the plug and the inner circumferential surface of the plug guide, and C is the clearance between the outer circumferential surface of the seat ring and the inner circumferential surface of the valve seat retaining portion.

2. A control valve as set forth in claim 1, wherein the plug guide is cylindrical and separate from the bonnet, and this plug guide is fitted into the plug insertion hole.

3. A control valve as described in claim 1 or 2, wherein the plug has a small diameter portion attached to the drive side of the actuator and a large diameter portion that is larger in diameter than the small diameter portion and is provided on the seat ring side, and this large diameter portion is inserted into and guided by the plug guide.

4. A control valve as described in claim 3, wherein a groove portion is provided on the outer periphery of the plug guide, which connects the small diameter side and the large diameter side of the plug journaled within the body and the bonnet.

5. A control valve according to claim 1 or 2, wherein the actuator is a diaphragm type actuator.

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