Valve device

Abstract

To provide a valve device which enables easy attachment of a packing which is a consumable component.SOLUTION: A valve device 1 opens or closes an internal passage 23 between a fluid inflow passage 21 and an outflow passage 22 to control flow of a fluid 20 and includes: a valve body 2; and a stem unit 3 which is detachably attached to the valve body 2. The stem unit 3 includes: a stem 4 which allows a tip part to open or close the internal passage 23; a stem holder 6; a packing 7 which is inserted into the stem 4; and a first stem guide 8 which is attached to the stem holder 6 with the packing 7 sandwiched therebetween. The stem holder 6 includes a second stem guide 11 which guides the stem 4 to a lower end part. A packing attachment part 12 is provided on the upper side of the second stem guide 11. An inclined guide surface 13 which is formed continuously from the upper side of the packing attachment part 12 and gradually separates from the stem 4 as it goes upward is formed.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a valve device that facilitates the assembly and replacement of a packing, which is a consumable part. [Background technology]

[0002] Conventionally, various valve devices have been proposed for fluid control. For example, according to the description in Patent Document 1, a valve has four components: a valve body, an actuator, and a yoke and bonnet between them. The valve body is provided with an inlet, an inlet passage, an outlet, and an outlet passage, and a valve seat is provided between the inlet passage and the outlet passage. A valve element having a contact surface that abuts against and separates from the valve seat is provided vertically, and the valve element is formed on the lower tip side of the stem. The stem is connected to a shaft that is the axis of the actuator, and is driven up and down by the actuator.

[0003] A bonnet is attached to the top of the valve body by a bonnet nut, a yoke is attached to the top of the bonnet, and an actuator is attached to the upper end of the yoke.

[0004] The inside of the bonnet is provided with a through hole through which the stem passes, and a gland packing through which the stem is inserted is provided. A fitting ring is provided on the underside of the gland packing, and an O-ring holder is provided on the upper side of the gland packing. The fitting ring and the O-ring holder are made of metal, and the surfaces thereof are provided with a coating layer that is the same as the fluororesin-based resin coating layer. The resin coating layer is in close contact with the outer peripheral surface of the stem and the inner peripheral surface of the internal recess of the bonnet. This ensures sealing performance and reduces deterioration of the gland packing over time due to long-term use caused by opening and closing high-pressure fluid.

[0005] This makes it possible to permit or block the flow of fluid from the inlet flow path to the outlet flow path, thereby enabling fluid control. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2020-159479 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the conventional example shown in Patent Document 1, a gland packing through which the stem is inserted is provided to prevent leakage of fluid, a fitting ring is provided on the lower surface side, and an O-ring holder is provided on the upper surface side. The gland packing requires adjustment of the tightening amount during assembly and part replacement, which poses a problem in terms of workability. The gland packing is a consumable part and needs to be replaced after the valve device is operated for a certain period of time, which requires a certain amount of assembly work each time, which is a problem.

[0008] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a valve device in which a packing, which is a consumable part, can be easily attached. [Means for solving the problem]

[0009] A valve device according to an aspect of the present invention is a valve device that opens and closes an internal flow path between an inflow path and an outflow path for a fluid to control the flow of the fluid, and includes a valve body in which the inflow path, the outflow path, and the internal flow path are formed, and a stem unit that is detachable from the valve body, and when the bottom surface of the valve body is installed horizontally, in a state in which the stem unit is attached facing vertically upward relative to the valve body, the stem unit includes a stem whose tip portion opens and closes the internal flow path, a stem holder that is installed in the valve body and into which the stem is inserted, and a stem holder that is inserted into the stem and has a predetermined length in the direction in which the stem extends. and a packing having a packing width of 1 mm and attached to the stem holder, and a first stem guide that is inserted into the stem and attached to the stem holder across the packing, the stem holder has a second stem guide which is an opening hole at its lower end that guides the stem, a packing attachment portion formed on the upper side of the second stem guide, and an inclined guide surface formed continuously with the upper side of the packing attachment portion and which moves away from the stem as it extends upward, the packing is attached by being sandwiched between the first stem guide and the second stem guide, and the stem operates by being guided by the first stem guide, the packing, and the second stem guide.

[0010] According to this, the valve device operates with the stem guided by the first stem guide, the packing, and the second stem guide inside the stem holder. This provides a sealing effect that prevents fluid leakage and allows for stable operation. Furthermore, the packing is guided by the inclined guide surface when attached to the stem holder, making it easy to attach. Furthermore, the packing is sandwiched between the first stem guide and the stem holder inside the stem holder, making it possible to prevent fragments of the packing from diffusing inside the valve device when the packing is damaged.

[0011] The valve device may also include an air cylinder for operating the stem, and a valve holder connected to the air cylinder and detachable from the valve body, the stem holder having a flange formed on its outer periphery, and when the stem unit is oriented in a vertical direction, the stem unit is installed with a gasket sandwiched between the lower surface of the flange of the stem holder and the valve body, and the valve holder is attached to the valve body in a state of contact with the upper surface of the flange of the stem holder.

[0012] In this case, the stem unit is installed with a gasket sandwiched between the lower surface of the flange of the stem holder and the valve body, thereby preventing fluid from leaking out from the gap between the stem holder and the valve body.

[0013] Furthermore, the valve device may be configured so that the packing mounting portion is provided with a packing shelf portion formed at the boundary with the second stem guide in a direction intersecting the direction in which the stem is inserted, and the inclined guide surface guides the packing when the packing is inserted into the stem and mounted to the stem holder, thereby enabling the packing to be mounted to the packing mounting portion, and the packing shelf portion engages the packing when the stem is pulled toward the tip end of the stem with the packing mounted in the packing mounting portion, enabling the packing to be separated from the stem and the packing mounting portion.

[0014] In this case, the inclined guide surface guides the packing when the packing is inserted into the stem and attached to the stem holder, so that the packing can be easily attached to the packing attachment part. Also, when the stem is pulled out toward the tip end of the stem from the state where it is attached to the packing attachment part, the packing shelf part locks the packing and enables the packing to be separated from the stem and the packing attachment part. Therefore, the packing can be easily attached to and detached from the stem holder, so that replacement work is easy.

[0015] In addition, in the valve device, when the stem unit is oriented vertically, with the tip side of the stem on the lower side and the opposite side on the upper side, and the direction perpendicular to the direction in which the stem extends is horizontal, the gasket mounting portion is formed with a constant vertical spacing in the vertical direction, and when the gasket is mounted on the stem holder, the gasket width may be smaller than the vertical spacing of the gasket mounting portion.

[0016] In this case, the valve device has a constant vertical spacing between the packing mounting parts in the stem unit, and the packing width is smaller than the vertical spacing. Therefore, the packing can be easily assembled without adjusting its position when it is attached to the stem and stem holder. Since the packing is not subjected to pressure from above or below, it is possible to prevent localized stress from occurring between the packing and the stem due to deformation caused by pressure from above or below. Therefore, it is possible to prevent localized sliding resistance from occurring between the packing and the stem, thereby improving the durability of the packing.

[0017] In addition, the stem holder may have a stem holder shelf portion connected to the upper end of the inclined guide surface and formed horizontally, and the first stem guide may have a first stem guide convex portion protruding horizontally, and when the first stem guide is attached to the stem holder, the lower surface of the first stem guide convex portion is placed on the stem holder shelf portion and the lower end of the first stem guide faces the gasket mounting portion, and the vertical spacing in the gasket mounting portion may be formed at a constant interval between the top surface portion of the gasket mounting portion formed by fixing it in a predetermined position by the lower end of the first stem guide, and the bottom surface portion formed at the upper end of the second stem guide.

[0018] In this case, the vertical spacing of the packing mounting portion is formed at a constant interval when the lower surface of the first stem guide protrusion is placed on the stem holder shelf portion. The width of the packing is smaller than the vertical spacing. Therefore, the packing can be easily assembled without position adjustment when it is attached to the stem and the stem holder.

[0019] The valve device may further comprise a packing formed in a circular ring shape and comprising an inner side member and an outer side member, a friction coefficient between the inner side member and the stem being smaller than a friction coefficient between the outer side member and an inner periphery of the packing mounting portion, the outer side member comprising an elastic member, an inner diameter of the packing being smaller than an outer diameter of the stem at a portion where the packing is inserted, and an outer diameter of the packing being larger than an inner diameter of the packing mounting portion when mounted on the stem, the outer side member elastically deforms in a horizontal direction when mounted on the packing mounting portion to seal against the inner periphery of the packing mounting portion, and the inner side member presses against the stem as the outer side member elastically deforms, thereby sealing against the stem.

[0020] In this case, the friction between the outer peripheral member and the packing mounting portion reduces the vertical displacement of the packing, enhancing the sealing effect. The friction coefficient between the inner peripheral member and the stem is smaller than that between the outer peripheral member and the packing mounting portion, so the stem moves smoothly even when it moves up and down, maintaining the sealing effect.

[0021] In addition, the valve device may have a packing width shorter than the maximum movable amount of the stem. In this case, since the packing width is shorter than the maximum movable amount of the stem, the size of the valve device in the vertical direction can be reduced. Therefore, the valve device can be made compact in the vertical direction.

[0022] In addition, in the valve device, a stem support length, which is a total length of the stem guided by the first stem guide, the packing, and the second stem guide, may be three times or more the maximum movable amount of the stem. In this case, since the stem support length is three times or more the maximum movable amount of the stem, the stem can operate more stably.

[0023] In addition, in the valve device, when the tip of the stem closes the internal flow path, the distance between the end of the stem holder on the tip side of the stem and the tip of the stem may be less than twice the stem support length.

[0024] In this case, the distance between the end of the stem holder on the stem tip side and the tip of the stem tip is less than twice the stem support length, so that the stem tip at the tip of the stem can open and close the internal flow path without wobbling. [Brief description of the drawings]

[0025] [Figure 1] FIG. 2 is a diagram showing the entire valve device 1, showing a state in which the stem tip 5 closes the internal flow path 23. [Diagram 2] 1 is a diagram showing the entire valve device 1, in which the stem tip 5 opens the internal flow passage 23, and the fluid 20 flows from the inflow passage 21 through the internal flow passage 23 and out of the outflow passage 22. FIG. [Diagram 3] 1 is a cross-sectional view showing a main part of a valve device 1. FIG. [Figure 4] This figure shows the configuration and installation procedure of the first stem unit 3a, where (a) shows the state before each component is installed, (b) shows the state after each component is installed, and (c) shows the first stem guide 8 with the fixing means 9 formed integrally therewith. [Diagram 5] 2 is a diagram showing a state in which a first stem unit 3a is attached to a valve body 2. FIG. [Figure 6] This figure shows the procedure for disassembling the components from the first stem unit 3a, where (a) shows the state in which the stem 4 has been pulled downward from the first stem unit 3a, and (b) shows the state in which the fixing member 9a(9), the stem 4 whose tip opens and closes the internal flow path 23 and the first stem guide 8, and the gasket 7 are removed. [Figure 7] 4A and 4B are cross-sectional views illustrating the configuration of gasket 7, where (a) shows the gasket 7 alone, (b) shows the gasket attached to a stem, and (c) shows lip gasket 7c. [Figure 8] FIG. 4 is a detailed view of part A in FIG. [Figure 9] 5A and 5B are diagrams showing the configuration and installation procedure of a second stem unit 3b, where FIG. 5A shows the state before each component is installed, and FIG. 5B shows the state after each component is installed. [Figure 10] 5A and 5B are diagrams showing the configuration and installation procedure of a third stem unit 3c, in which (a) shows the state before each component is installed, and (b) shows the state after each component is installed. [Figure 11] 1A and 1B are diagrams showing a diaphragm-type valve device 40, which is a conventional device, and an evaluation machine used for comparative evaluation with the present invention, in which (a) shows a state in which the internal flow path 23 is closed, and (b) shows a state in which the internal flow path 23 is open. [Figure 12] 1A and 1B are diagrams showing an evaluation machine for a bellows seal valve device 50, which is a conventional device, used for comparative evaluation with the present invention, in which (a) shows a state in which the internal flow path 23 is closed, and (b) shows a state in which the internal flow path 23 is open. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Hereinafter, a valve device 1 embodying the present invention will be described with reference to the drawings. Note that the description of the embodiment of the invention and the drawings referred to are used to explain technical features that may be adopted by the present invention. The present invention is not limited thereto. The configuration of the device shown in the drawings is merely an illustrative example and is not intended to limit the present invention.

[0027] <Overall configuration of the valve device 1> The overall configuration of a valve device 1 according to an embodiment of the present invention will be described with reference to Figures 1 to 3. As shown in Figures 1 and 2, in the valve device 1, a stem 4 in a stem unit 3 is actuated in the vertical direction by the action of an air cylinder 31, and the tip of the stem 4 opens and closes an internal flow path 23 between an inflow path 21 and an outflow path 22 of the fluid 20, thereby controlling the flow of the fluid 20. The valve device 1 includes a valve body 2 in which the inflow path 21, the outflow path 22, and the internal flow path 23 are formed, and a stem unit 3 that is detachable from the valve body 2.

[0028] Next, we will explain each component in the main part of the valve device 1. As shown in Figure 3, the positional relationship of each component will be explained assuming that the bottom surface 2a of the valve body 2 is installed horizontally and the stem unit 3 is attached facing vertically upward relative to the valve body 2.

[0029] <Configuration of first stem unit 3a> In the following description, the stem unit 3 will be described taking the first stem unit 3a as a first example as an example. As shown in FIG. 3, the first stem unit 3a includes the following components. The first stem unit 3a is incorporated into a valve device 1 that opens and closes an internal flow path 23 between an inflow path 21 and an outflow path 22 of a fluid 20 to control the flow of the fluid 20. The first stem unit 3a includes a stem 4 whose tip opens and closes the internal flow path 23. The first stem unit 3a includes a stem holder 6 that is installed in the valve body 2 and into which the stem 4 is inserted. The first stem unit 3a includes a packing 7 that is inserted into the stem 4, has a predetermined packing width W1 in the direction in which the stem 4 extends, and is attached to the stem holder 6. The first stem unit 3a includes a first stem guide 8 that is inserted into the stem 4 and is attached to the stem holder 6 with the packing 7 sandwiched between them. The first stem unit 3a may be formed integrally with the first stem guide 8 or may be formed separately, and may include a fixing means 9 that fixes the first stem guide 8 to the stem holder 6. The stem 4 may also be provided with a stem tip 5 at its tip, which opens and closes an internal flow path 23 between an inflow path 21 and an outflow path 22 of the fluid 20 by approaching and separating it to control the flow of the fluid 20. The material of the stem tip 5 is mainly polyimide or a fluororesin such as PCTFE, but other materials may also be used.

[0030] The first stem unit 3a has the following configuration when the tip of the stem 4 is on the lower side and the stem 4 is oriented vertically. The stem holder 6 has a second stem guide 11, which is an opening hole that guides the stem 4 at its lower end. The second stem guide 11 has a packing attachment portion 12 formed on the upper side thereof. In addition, an inclined guide surface 13 is formed continuously with the upper side of the packing attachment portion 12, and is spaced apart from the stem 4 as it moves upward. As shown in FIG. 3 etc., a part of the lower side of the first stem guide 8 may be inserted into the packing attachment portion 12. In this configuration, the inner diameter of the packing attachment portion 12 is formed to correspond to the outer shape of the first stem guide 8.

[0031] As shown in Figure 4(b), the gasket 7 is sandwiched and installed between the first stem guide 8 and the second stem guide 11, and the stem 4 moves in the vertical direction while being guided by the first stem guide 8, the gasket 7, and the second stem guide 11.

[0032] Furthermore, the following configuration may be provided. As shown in Fig. 8, the packing mounting portion 12 has a constant vertical distance W2 in the vertical direction. The packing width W1 is formed to be smaller than the vertical distance W2 of the packing mounting portion 12 when the first stem guide 8 is mounted on the stem holder 6.

[0033] <Effects of the Overall Configuration of the Valve Device 1> As described above, the valve device 1 according to the embodiment of the present invention has the following effects. As shown in FIG. 3 and other figures, the valve device 1 operates with the stem 4 guided by the first stem guide 8, the packing 7, and the second stem guide 11 inside the stem holder 6. This provides a sealing effect that prevents the fluid 20 from leaking, and allows for stable operation. In addition, the packing 7 can be easily attached because it is guided by the inclined guide surface 13 when attached to the stem holder 6. In addition, the packing 7 is sandwiched between the first stem guide 8 and the stem holder 6 inside the stem holder 6, so that fragments of the packing 7 can be prevented from diffusing inside the valve device 1 when the packing 7 is broken.

[0034] 4, the valve device 1 requires no adjustment when mounting the packing 7 to the stem holder 6 due to the configuration of the first stem unit 3a, which is an example of the stem unit 3. The packing 7 is configured so that it can be mounted by simply inserting it into the packing mounting portion 12 in a state where it is mounted on the stem 4, since the inclined guide surface 13 is formed on the stem holder 6. Therefore, the first stem unit 3a is easy to assemble, and the number of steps required for assembling the packing 7 can be reduced.

[0035] As already explained, in the conventional example, a gland packing is used, so the amount of tightening must be adjusted during assembly and part replacement, which poses a problem in terms of workability. In contrast, the valve device 1 of the present invention solves this problem and makes assembly easier.

[0036] 8, in the first stem unit 3a, the packing width W1 may be formed smaller than the vertical distance W2 of the packing mounting portion 12 when the first stem guide 8 is mounted on the stem holder 6. In this case, the packing 7 is not subjected to pressure from the vertical direction, so that it is possible to prevent localized stress from occurring between the packing 7 and the stem 4 due to deformation caused by pressure from the vertical direction. The sealing effect between the packing 7 and the stem 4 can be improved.

[0037] Furthermore, the first stem unit 3a is detachable as a unit from the valve body 2. Therefore, the first stem unit 3a exhibits the advantage of excellent assembly and replaceability with respect to the valve device 1. The second stem unit 3b and the third stem unit 3c described below also exhibit the same advantage.

[0038] <Components associated with the main part of the valve device 1> 1 to 3, the components associated with the main portion of the valve device 1 will be described. The valve device 1 comprises an air cylinder 31 for actuating the stem 4, and a valve holder 32 that is connected to the air cylinder 31 and is detachable from the valve body 2.

[0039] The stem holder 6 has a flange 16 formed on the outer periphery at approximately the center in the up-down direction. When the first stem unit 3a is oriented vertically, the first stem unit 3a is installed with the gasket 17 sandwiched between the lower surface 16a of the flange 16 of the stem holder 6 and the valve body 2. The valve holder 32 is attached to the valve body 2 in a state of contact with the upper surface 16b of the flange 16 of the stem holder 6.

[0040] As shown in Fig. 3, the valve body 2 has a male thread formed on part of the outer periphery on the upper side in the vertical direction, which is screwed into a female thread formed on the valve holder 32, thereby joining the two together. In Fig. 3, the valve holder 32 is indicated by a two-dot chain line, and is made up of multiple members, but it may be formed as a single unit.

[0041] As described above, the components associated with the main parts of the valve device 1 provide the following effects. The stem unit 3, such as the first stem unit 3a shown in Figures 3, 5, etc., is installed with the gasket 17 sandwiched between the lower surface 16a of the flange portion 16 of the stem holder 6 and the valve body 2, so that leakage of the fluid 20 from the gap between the stem holder 6 and the valve body 2 can be prevented.

[0042] <Configuration regarding installation and replacement of packing 7> Next, a configuration for allowing the packing 7 to be attached and replaced to the stem holder 6 will be described with reference to Figures 3, 4, 6, and 8. A configuration for mounting the packing 7 to the packing mounting portion 12 will be described. The packing mounting portion 12 has a packing shelf portion 12a formed in a direction intersecting the direction in which the stem 4 is inserted, at the boundary with the second stem guide 11. As shown in Figures 4(a) and 8, when the packing 7 is mounted to the stem holder 6 in a state in which the packing 7 is inserted into the stem 4, the inclined guide surface 13 guides the packing 7, thereby enabling the packing 7 to be mounted to the packing mounting portion 12.

[0043] A description will be given of the configuration for removing the packing 7 from the packing mounting part 12. As shown in Fig. 6(a), when the stem 4 is pulled toward the tip end side (the stem tip 5 side) of the stem 4 with the packing 7 mounted on the packing mounting part 12, the packing shelf part 12a engages the packing 7, making it possible to separate the packing 7 from the stem 4 and the packing mounting part 12.

[0044] 4(a), when the first stem guide 8 is formed separately from the fixing means 9, the first stem guide protrusion 8c may be cylindrical or polygonal prism-shaped. In either shape, the first stem guide protrusion 8c is formed so as to be mountable on the stem holder shelf 18. The portion of the stem holder 6 into which the first stem guide protrusion 8c is inserted is formed with a shape and dimensions that allow the first stem guide protrusion 8c to be inserted.

[0045] The inclined guide surface 13 described above provides the following effects. As shown in Figures 3, 4, and 8, when the packing 7 is attached to the stem holder 6 while inserted in the stem 4, the inclined guide surface 13 of the stem holder 6 guides the packing 7, so that the packing 7 can be easily attached to the packing attachment part 12. Furthermore, as shown in Figure 6(a), when the stem 4 is pulled out from the state where it is attached to the packing attachment part 12 toward the tip end side of the stem 4 (the side of the stem tip 5), the packing shelf part 12a locks the packing 7, so that the packing 7 can be separated from the stem 4 and the packing attachment part 12.

[0046] Therefore, the packing 7 can be easily attached to and detached from the stem holder 6, making replacement easy. Since the packing 7, which is a consumable item, can be easily replaced in the valve device 1, the maintenance costs associated with the labor required can be kept low. Additionally, the downtime of the valve device 1 can be shortened, thereby increasing productivity.

[0047] <Relationship between packing 7 and elements related to packing 7> Next, the relationship between the packing 7 and elements related to the packing 7 will be described in detail with reference to Figures 3, 4, and 8. The following description is based on the premise that the first stem unit 3a is oriented vertically, with the tip side (the stem tip 5 side) of the stem 4 being the lower side and the opposite side being the upper side, and the direction perpendicular to the direction in which the stem 4 extends being the horizontal direction.

[0048] 8, the packing mounting portion 12 is formed with a constant vertical gap W2 in the up-down direction. When the packing 7 is mounted on the stem holder 6, the packing width W1 is smaller than the vertical gap W2 of the packing mounting portion 12.

[0049] As explained above, in the first stem unit 3a, the vertical spacing W2 of the packing mounting portion 12 is constant, and the packing width W1 is smaller than the vertical spacing W2. Therefore, the packing 7 can be easily assembled without adjusting its position when it is attached to the stem 4 and the stem holder 6. Since the packing 7 is not subjected to pressure from above or below, it is possible to prevent local stress from occurring between the packing 7 and the stem 4 due to deformation caused by pressure from above or below. Therefore, it is possible to prevent local sliding resistance from occurring between the packing 7 and the stem 4, thereby improving the durability of the packing 7.

[0050] The following describes the configuration of the first stem unit 3a, which defines the relationship between the packing width W1 and the vertical distance W2 of the packing attachment portion 12. The stem 4 has a cylindrical shape with a constant outer diameter at least in the portion that is guided by the first stem guide 8, the packing 7, and the second stem guide 11. The stem holder 6 is connected to the upper end of the inclined guide surface 13 and has a stem holder shelf portion 18 formed in the horizontal direction.

[0051] The vertical interval W2 in the packing mounting portion 12 is formed constant by the following configuration. As shown in FIG. 4 and other figures, the first stem guide 8 is formed with a first stem guide protrusion 8c that protrudes in the horizontal direction. When the first stem guide 8 is mounted on the stem holder 6, the lower surface 8b of the first stem guide protrusion 8c is placed on the stem holder shelf 18, and the lower end 8a of the first stem guide 8 faces the packing mounting portion 12 (see FIG. 4(b) and other figures). The vertical interval W2 in the packing mounting portion 12 is formed at a constant interval between the top surface of the packing mounting portion 12, which is fixed in a predetermined position by the lower end 8a of the first stem guide 8, and the bottom surface formed at the upper end of the second stem guide 11. The packing width W1 is formed smaller than the vertical interval W2 of the packing mounting portion 12. The bottom surface of the packing mounting portion 12 is a packing shelf portion 12a, and the vertical distance W2 is the distance between the lower end portion 8a of the first stem guide 8 and the packing shelf portion 12a in the vertical direction.

[0052] The packing mounting portion 12 is a cylindrical recess formed in the stem holder 6. The inclined guide surface 13 is formed in a truncated cone shape so as to move away from the stem 4 from the upper end of the cylindrical recess of the packing mounting portion 12 toward the upper side. The upper end of the inclined guide surface 13 is connected to the stem holder shelf portion 18. The first stem guide 8 has a cylindrical shape below the first stem guide protrusion 8c, and its outer diameter is formed to have a clearance fit with the inner diameter of the packing mounting portion 12. The inner diameter dimension of the packing mounting portion 12 and the outer dimension of the portion corresponding to the first stem guide 8 may be adjusted to suppress horizontal backlash.

[0053] The configuration of the fixing means 9 will be described with reference to Figure 4. Figure 4(a) shows a case where the fixing means 9 is configured separately from the first stem guide 8. The fixing means 9 has a male thread formed on its outer periphery, and the stem holder 6 has a female thread formed on its inner periphery where the fixing means 9 is attached. Figure 4(c) shows a case where the fixing means 9 is formed integrally with the first stem guide 8. In this case, a male thread is formed on part of the outer periphery of the first stem guide 8. The stem holder 6 has a female thread formed in the same manner as in Figure 4(a). The assembly procedure for the first stem unit 3a will be described later. Note that, as will be described later, the fixing means 9 is not necessarily provided.

[0054] Due to the relationship between the packing width W1 and the vertical interval W2 of the packing mounting portion 12 described above, the valve device 1 has the following effects. As shown in FIG. 3 and FIG. 4, the first stem guide 8 is formed with the first stem guide protrusion 8c, and when the first stem guide 8 is mounted on the stem holder 6, the lower surface 8b of the first stem guide protrusion 8c is placed on the stem holder shelf 18. The lower end 8a of the first stem guide 8 faces the packing mounting portion 12, and the top surface of the packing mounting portion 12 is formed by the lower end 8a of the first stem guide 8. Therefore, the vertical interval W2 of the packing mounting portion 12 is formed at a constant interval between the lower end 8a of the first stem guide 8 and the packing shelf 12a when the first stem guide 8 is mounted on the stem holder 6. The packing width W1 is smaller than the vertical interval W2. Therefore, the packing 7 can be easily assembled without position adjustment when mounted on the stem 4 and the stem holder 6. The valve device 1 can reduce the number of steps required for assembling the packing 7.

[0055] Furthermore, the packing 7 is formed so that the packing width W1 is smaller than the vertical distance W2 of the packing mounting portion 12 when the first stem guide 8 is attached to the stem holder 6. Since the packing 7 is not subjected to pressure from the vertical direction, it is possible to prevent localized stress from occurring between the packing 7 and the stem 4 due to deformation caused by pressure from the vertical direction. This prevents localized sliding resistance from occurring between the packing 7 and the stem 4, thereby improving the durability of the packing 7. Additionally, it is possible to improve the sealing effect between the packing 7 and the stem 4.

[0056] Next, the packing 7 and the relationship between the packing 7 and the components related thereto will be described in detail with reference to Figs. 7(a), (b) and 8. The packing 7 is formed in an annular shape and includes an inner circumferential member 7a and an outer circumferential member 7b. The friction coefficient between the inner circumferential member 7a and the stem 4 is smaller than the friction coefficient between the outer circumferential member 7b and the inner circumferential portion 12b of the packing mounting portion. The outer circumferential member 7b includes an elastic member. For example, the inner circumferential member 7a is a sheet-like member containing fluororesin formed in an annular shape, and the elastic member of the outer circumferential member 7b is formed in a ring shape containing nitrile rubber or fluororubber. The inner circumferential member 7a and the outer circumferential member 7b are formed separately, and are combined by fitting the outer circumferential member 7b into the inner circumferential member 7a.

[0057] The packing inner diameter D3 is smaller than the stem outer diameter D1 at the portion where the packing 7 is inserted. The packing outer diameter D4 is larger than the packing mounting portion inner diameter D2 when attached to the stem 4. When attached to the packing mounting portion 12, the outer peripheral side member 7b elastically deforms in the horizontal direction to form a seal with the packing mounting portion inner peripheral portion 12b.

[0058] The inner peripheral side member 7a presses the stem 4 in accordance with elastic deformation of the outer peripheral side member 7b, thereby forming a seal between the stem 4. Furthermore, when the first stem guide 8 is attached to the stem holder 6, a gap is formed in the packing 7 in the up-down direction at the packing attachment portion 12.

[0059] Next, lip packing 7c, which is another example of packing 7, will be described with reference to Fig. 7(c). When lip packing 7c is attached to stem 4, a U-shaped recessed groove 7e is formed in tip portion 7d on the lower side. Lip packing 7c is formed as a single piece, and when alone, groove 7e in tip portion 7d is in a V-shaped widened state. When attached to stem 4 and inserted into stem holder 6, the lip packing 7c is tightly attached to stem 4 and stem holder 6 due to elastic force generated when tip portion 7d is deformed inward.

[0060] The above-described packing 7 and the components related to the packing 7 provide the following effects. As shown in Figs. 7 and 8, since the outer peripheral member 7b is made of an elastic member, even if the outer dimensions of the packing 7 vary, the outer peripheral member 7b can elastically deform to fill the gap between the packing mounting portion inner peripheral portion 12b. When the valve device 1 is in an operating state, pressure is generated in the inflow passage 21 and the outflow passage 22 by the fluid 20 inside the valve body 2. The packing 7 is pushed up to the surface of the lower end portion 8a of the first stem guide 8 by the internal pressure of the valve body 2. Therefore, the packing 7 is compressed in the vertical direction and distorted so as to extend in the outer diameter direction and the inner diameter direction, thereby improving the sealing effect between the packing 7 and the second stem guide 11.

[0061] Furthermore, the inner peripheral side member 7a applies pressure to the stem 4 as the outer peripheral side member 7b elastically deforms, so no gap is generated between the packing 7 and the stem 4. The coefficient of friction between the inner peripheral side member 7a and the stem 4 is smaller than that between the outer peripheral side member 7b and the packing mounting portion 12, so the stem 4 operates smoothly and maintains a sealing effect even when it moves up and down.

[0062] Furthermore, lip packing 7c is in close contact with stem 4 and stem holder 6 due to elastic deformation of tip 7d, so that it can operate smoothly and maintain a sealing effect even when stem 4 moves up and down. When lip packing 7c is in an operating state, the pressure of the fluid acting from below causes tip 7d to deform in a direction that expands (the inner diameter side expands toward stem 4, and the outer diameter side expands toward stem holder 6), enhancing the sealing effect.

[0063] <Relationship between maximum movement amount L2 of stem 4 and packing width W1 of packing 7> Next, the relationship between the maximum movable amount L2 of the stem 4 and the packing width W1 of the packing 7 will be described. The packing width W1 of the packing 7 is shorter than the maximum movable amount L2 of the stem 4. As shown in FIG. 3, the maximum movable range of the stem 4 is between the end 6a of the stem holder 6 on the stem tip 5 side and the upper end of the step portion 4a of the stem 4 when the stem tip (stem tip 5) closes the internal flow path 23, and is the maximum movable amount L2. The packing width W1 is formed to be shorter than the maximum movable amount L2.

[0064] The relationship between the maximum movement amount L2 of the stem 4 and the packing width W1 of the packing 7 described above provides the following effects. As shown in Figures 3 and 8, the packing width W1 is shorter than the maximum movement amount L2 of the stem 4, so the vertical size of the valve device 1 can be reduced. If the packing width W1 were long, the stem 4 would need to be longer, which would result in an increase in the size of the valve device 1 in the vertical direction. In contrast, the valve device 1 can be made more compact in the vertical direction.

[0065] <Relationship between stem support length L1 and maximum movement amount L2 of stem 4> Next, the relationship between the stem support length L1 and the maximum movable amount L2 of the stem 4 will be described with reference to FIG. 3. The stem support length L1 is the total length of the first stem guide 8, the packing 7, and the second stem guide 11 guiding the stem 4. The stem support length L1 is three times or more the maximum movable amount L2 of the stem 4. The stem support length L1 may be the total length of the first stem guide 8, the packing 7, and the second stem guide 11 guiding the stem 4, and the respective lengths of the first stem guide 8, the packing 7, and the second stem guide 11 may be changed. In the example shown in FIG. 3 etc., the length of the first stem guide 8 guiding the stem 4 is the longest, but this is not limited thereto, and for example, the length of the second stem guide 11 guiding the stem 4 may be the longest.

[0066] The relationship between the stem support length L1 and the maximum movable amount L2 of the stem 4 is an index of whether the stem 4 operates stably or not. The longer the stem support length L1 is relative to the movable range of the stem 4, the more stably the stem 4 operates.

[0067] The above-described relationship between the stem support length L1 and the maximum movement amount L2 of the stem 4 provides the following effects. As shown in FIG. 3, in the valve device 1, the stem support length L1 is three or more times the maximum movement amount L2 of the stem 4. Conventionally, the length of L1 has generally been about twice the length of L2. The longer the length of L1 is compared to the length of L2, the more stable the operation of the stem 4, so it is preferable that L1 is as long as possible compared to L2. Therefore, the stem 4 can operate more stably.

[0068] <Relationship between stem support length L1 and distance L3> 3, the relationship between the stem support length L1 and the distance L3 between the end 6a on the tip side (the stem tip 5 side) of the stem 4 in the stem holder 6 and the tip of the stem 4 (the tip of the stem tip 5) will be described. When the tip of the stem 4 (stem tip 5) closes the internal flow path 23, the distance L3 between the end 6a on the tip side of the stem 4 in the stem holder 6 and the tip of the stem 4 is equal to or less than twice the stem support length L1.

[0069] Distance L3 indicates the length of the member at which stem 4 has a so-called cantilever structure. The shorter distance L3 is relative to stem support length L1, the more stable the state. Conventionally, distance L3 has generally been more than twice the length of L1. The shorter distance L3 is relative to L1, the shorter the length at which stem 4 has a so-called cantilever structure.

[0070] The relationship between the stem support length L1 and the distance L3 described above provides the following effects. The longer the length at which the stem 4 forms a cantilever structure, the more likely the tip (stem tip 5) will wobble. This will cause a misalignment between the position at which the tip is pressed and the position of the internal flow path 23, resulting in leakage of the fluid 20. The shorter the length L3 at which the stem 4 forms a cantilever structure, the more preferable it is. According to the configuration of the valve device 1, the length L3 at which the stem 4 forms a cantilever structure is formed to be shorter than the stem support length L1, so that wobble of the tip (stem tip 5) is reduced, and the internal flow path 23 can be opened and closed more reliably.

[0071] <Configuration of second stem unit 3b> Next, another example of the stem unit 3 will be described. The stem unit 3 may have the following configuration. Elements having the same functions as those of the first stem unit 3a are given the same reference numerals, and their description may be omitted. FIG. 9 shows a second stem unit 3b, which is a second example of the stem unit 3. The second stem unit 3b is similar to the first stem unit 3a, except for the following configuration. As shown in FIG. 4, the first stem unit 3a has an inclined guide surface 13 formed continuously on the upper side of the packing mounting portion 12 in the stem holder 6, and the inclined guide surface 13 is formed so as to move away from the stem 4 as it moves upward. In contrast, as shown in FIG. 9, the second stem unit 3b has a cylindrical shape that is continuous from the packing shelf portion 12a to the stem holder shelf portion 18 in the stem holder 26.

[0072] As shown in FIG. 4, the first stem unit 3a has a stem tip 5 at the tip of the stem 4. In contrast, as shown in FIG. 9, the second stem unit 3b has a configuration in which the tip 24b of the stem 24 directly contacts and separates from the internal flow path 23. The upper end of the step 24a restricts the upward movement of the stem 4, similar to the upper end of the step 4a of the first stem unit 3a. In other words, when the stem 4 moves upward, the upper end of the step 24a contacts the lower end of the stem holder 6, thereby restricting the movement. Furthermore, the first stem unit 3a has a fixing means 9, but the second stem unit 3b does not have a fixing means configured separately from the first stem guide 8, since the first stem guide 8 also serves as the fixing means. As shown in FIG. 9, the first stem guide 8 is fixed by a press-fit relationship between the first stem guide protrusion 8c and the protrusion 19 of the stem holder 26. It should be noted that the first stem guide 8 does not necessarily have to also serve as the fixing means. For example, although not shown, the valve holder 32 may be provided with a member for pressing the first stem guide 8, thereby stopping the first stem guide 8 from moving upward.

[0073] As shown in Fig. 9, the second stem unit 3b has the following configuration, including the configuration common to the first stem unit 3a. The second stem unit 3b is incorporated into a valve device 1 that opens and closes an internal flow path 23 between an inflow path 21 and an outflow path 22 of a fluid 20 to control the flow of the fluid 20. The second stem unit 3b includes a stem 24 whose tip opens and closes the internal flow path 23, and a stem holder 26 that is installed in the valve body 2 and into which the stem 24 is inserted. The second stem unit 3b includes a packing 7 that is inserted into the stem 24, has a predetermined packing width W1 in the direction in which the stem 24 extends, and is attached to the stem holder 26. The second stem unit 3b further includes a first stem guide 8 that is inserted into the stem 24 and is attached to the stem holder 26 with the packing 7 in between.

[0074] When the stem 24 is oriented vertically with the tip 24b facing downward, the stem holder 26 has a second stem guide 11, which is an opening hole that guides the stem 24 at its lower end, and a packing attachment portion 12 formed on the upper side of the second stem guide 11. The packing 7 is attached by being sandwiched between the second stem guide 11 and the first stem guide 8, and the packing attachment portion 12 has a constant vertical distance W2 in the vertical direction. The packing 7 is formed so that the packing width W1 is smaller than the vertical distance W2 of the packing attachment portion 12 when the first stem guide 8 is attached to the stem holder 26.

[0075] The configuration of the second stem unit 3b described above has the following effects. As shown in FIG. 9, in the second stem unit 3b, the vertical interval W2 of the packing mounting portion 12 is constant, and the packing width W1 is smaller than the vertical interval W2. Therefore, the packing 7 can be easily assembled without adjusting the position when it is attached to the stem 4 and the stem holder 26. Since the packing 7 is not subjected to pressure from the vertical direction, it is possible to prevent local stress from occurring between the packing 7 and the stem 4 due to deformation caused by pressure from the vertical direction. Therefore, it is possible to prevent local sliding resistance from occurring between the packing 7 and the stem 4, and it is possible to increase the durability of the packing 7. Furthermore, like the first stem unit 3a, it is detachable as a unit from the valve body 2. Therefore, the second stem unit 3b has the effect of being excellent in assembling and exchangeability with respect to the valve device 1.

[0076] <Configuration of third stem unit 3c> The stem unit 3 may also be configured as follows. FIG. 10 shows a third stem unit 3c, which is a third example of the stem unit 3. The third stem unit 3c is similar to the first stem unit 3a, except for the following configuration. As shown in FIG. 4, the lower surface 8b of the first stem guide protrusion 8c of the first stem unit 3a is placed on the stem holder shelf 18. The packing mounting portion 12 has a constant vertical distance W2 in the vertical direction, as the top surface of the packing mounting portion 12 is formed by the lower end portion 8a of the first stem guide 8. The packing width W1 is formed smaller than the vertical distance W2 of the packing mounting portion 12.

[0077] In contrast, in the third stem unit 3c, as shown in FIG. 10, the stem holder shelf 18 is not formed in the stem holder 36. As shown in FIG. 10(a), the packing 7 is pressed down by the first stem guide 8 to be attached to the stem 4, and the vertical interval W2 of the packing attachment portion 12 is determined by the position of the lower end 8a when the first stem guide 8 is pressed down. When the first stem guide 8 is pressed down without any gap between the lower end 8a and the packing 7 and the lower end of the packing 7 is in contact with the packing shelf 12a, the vertical interval W2 is the same as the packing width W1. In other words, the vertical interval W2 is formed by pressing the first stem guide 8 toward the packing shelf 12a according to the packing width W1.

[0078] As shown in Fig. 10, the third stem unit 3c has the following configuration, including the configuration common to the first stem unit 3a. The third stem unit 3c is incorporated into a valve device 1 that opens and closes an internal flow path 23 between an inflow path 21 and an outflow path 22 of a fluid 20 to control the flow of the fluid 20. The third stem unit 3c includes a stem 4 whose tip opens and closes the internal flow path 23, and a stem holder 36 that is installed in the valve body 2 and into which the stem 4 is inserted. The third stem unit 3c includes a packing 7 that is inserted into the stem 4, has a predetermined packing width W1 in the direction in which the stem 4 extends, and is attached to the stem holder 36, and a first stem guide 8 that is inserted into the stem 4 and is attached to the stem holder 36 with the packing 7 in between.

[0079] When the stem 4 is oriented vertically with the tip portion facing downward, the stem holder 36 has a second stem guide 11, which is an opening hole that guides the stem 4 at the lower end, and a packing attachment portion 12 formed above the second stem guide 11. The stem holder 36 has an inclined guide surface 13 that is formed continuously with the upper side of the packing attachment portion 12 and that moves away from the stem 4 as it goes upward. The packing 7 is attached by being sandwiched between the second stem guide 11 and the first stem guide 8.

[0080] The configuration of the third stem unit 3c described above has the following advantages. As shown in Fig. 10, the third stem unit 3c can be easily attached because the packing 7 is guided by the inclined guide surface 13 when it is attached to the stem holder 36. Furthermore, like the first stem unit 3a, the third stem unit 3c can be attached and detached as a unit to the valve body 2. Therefore, the third stem unit 3c has the advantage of being easy to assemble and replace with respect to the valve device 1.

[0081] <Assembly procedure for valve device 1> Next, the assembly and disassembly procedures for the main parts of the valve device 1 will be described with reference to Figures 4 to 6. As shown in Figure 4(a), the assembly of the stem unit 3 in the vertical direction will be described. Note that the stem unit 3 will be described using the first stem unit 3a as an example. The stem tip 5 is inserted and press-fitted from the underside of the stem 4. The stem tip 5 can be replaced when replacement is necessary depending on the usage situation.

[0082] Next, the stem 4 is inserted from below into the stem holder 6. With the stem 4 inserted into the stem holder 6, the packing 7 is inserted from above. As shown in FIG. 8, the packing 7 does not necessarily have to be inserted all the way up to the packing attachment portion 12 of the stem holder 6 at this point. The first stem guide 8 is inserted into the stem 4 from above the packing 7. At this time, the first stem guide 8 is pushed downward until the packing 7 reaches the packing attachment portion 12.

[0083] The fixing member 9a as the fixing means 9 is inserted into the stem 4 from the upper side of the first stem guide 8, and the male screw part is screwed into the female screw part of the stem holder 6. A hexagonal hole penetrates the inner diameter part of the fixing member 9a in the vertical direction, and it can be tightened to the stem holder 6 using a hexagonal wrench. A spanner hook is provided on the outer diameter of the lower side of the stem holder 6. At this time, the fixing member 9a is moved downward until the lower surface 8b of the first stem guide protrusion 8c contacts the stem holder shelf part 18, resulting in the state of the first stem unit 3a shown in FIG. 4(b). When the first stem guide 8 is integrated with the fixing means 9 (see FIG. 4(c)), the first stem guide 8 is attached and fixed to the stem holder 6 at the same time.

[0084] Next, as shown in FIG. 5, the first stem unit 3a is attached to the valve body 2. The male threaded portion at the upper end of the stem 4 is screwed into the rod (female threaded portion) of the air cylinder 31, and the first stem unit 3a is attached to the air cylinder 31. The first stem unit 3a is attached so that the lower surface 16a of the flange portion 16 of the stem holder 6 is placed on the upper end surface of the valve body 2 via a gasket 17. The horizontal position of the stem unit 3 is determined by the outer periphery of the step portion 6b of the stem holder 6 and the inner periphery 2b of the valve body 2. Furthermore, as shown in FIG. 3, the valve holder 32 is screwed and attached to the valve body 2.

[0085] As shown in Fig. 4, a spanner hook 15 having a hexagonal outer shape in plan view is formed below the step portion 4a of the stem 4. As shown in Fig. 3, the spanner hook 15 is used when screwing the male thread portion formed on the upper end portion of the stem 4 into the air cylinder 31. In the second stem unit 3b described later, the spanner hook 15 is also formed on the stem 24 as shown in Fig. 9.

[0086] Next, the procedure for replacing the packing 7 will be described. As shown in Fig. 6(a), the stem 4 is pulled downward from the stem holder 6. At this time, the packing 7 is held inside the stem holder 6 by the packing shelf 12a. The first stem guide 8 is also held inside the stem holder 6 by the stem holder shelf 18. The fixing member 9a is pulled upward from the stem holder 6 while being rotated in the opposite direction to that during assembly.

[0087] Next, the first stem guide 8 and the packing 7 are sequentially removed from the stem holder 6. As shown in FIG. 6(b), the outer peripheral member 7b of the packing 7 may be elastically deformed relative to the packing mounting portion 12, but the inner diameter of the inner peripheral member 7a is small when the packing 7 is removed from the stem 4. The packing 7 can be easily removed by inserting a jig J that corresponds to the shaft diameter of the stem 4 from the lower side of the stem holder 6. Note that it is not necessary to use the jig J when removing the packing 7. If the outer peripheral member 7b is not elastically deformed, the packing 7 can be easily removed without using the jig J. Alternatively, the packing 7 can be pushed out with a flat-head screwdriver or the like without using the jig J.

[0088] Next, the case where the stem unit 3 is the second stem unit 3b will be described as an example. The differences from the first stem unit 3a are as follows. The second stem unit 3b has a tip 24b directly inserted into the internal flow path 23, so there is no need to insert a stem tip 5 into the stem 24. Also, instead of being provided with a fixing member 9a, the second stem unit 3b is fixed in place by inserting the first stem guide 8 into the stem holder 26 in a press-fit state.

[0089] Next, the case where the stem unit 3 is the third stem unit 3c will be described as an example. The third stem unit 3c differs from the first stem unit 3a in the following points. As shown in FIG. 10, the stem holder 36 of the third stem unit 3c does not have a stem holder shelf 18 formed thereon. As shown in FIG. 10(a), the packing 7 is pressed down by the first stem guide 8 to be attached to the stem 4, and the vertical interval W2 of the packing attachment portion 12 is determined by the position of the lower end 8a when the first stem guide 8 is pressed down. When the first stem guide 8 is pressed down without any gap between the lower end 8a and the packing 7 and the lower end of the packing 7 is in contact with the packing shelf 12a, the vertical interval W2 is the same as the packing width W1. That is, the vertical interval W2 is formed by pressing the first stem guide 8 toward the packing shelf 12a according to the packing width W1.

[0090] As described above, the packing 7 can be easily assembled and replaced in the stem unit 3. The packing 7 is a consumable part that is often replaced in order to prolong the use of the valve device 1. With the configuration of the valve device 1, no adjustment is required for assembly and replacement of the packing 7, and the number of steps required can be reduced compared to the conventional method.

[0091] <Explanation regarding durability of valve device 1> Next, the durability of the valve device 1 will be described in comparison with the conventional technology. As shown in Fig. 11, conventionally, a diaphragm type valve device 40 has been used as a first device. The diaphragm type valve device 40 includes a valve body 42 having an inlet passage 21 and an outlet passage 22, a diaphragm 43 that allows or blocks the flow of fluid 20 in an internal flow passage 23 from the inlet passage 21 to the outlet passage 22 of the valve body 42, and an actuator (not shown) that operates a plunger 44 directly connected to the diaphragm 43.

[0092] 12, there has conventionally been a bellows sealed valve device 50 as a second device. A stem 54 of the bellows sealed valve device 50 is sealed by a bellows 53. The stem 54 is actuated by an actuator (not shown), so that a stem tip 55 at the end of the stem 54 allows or blocks the flow of fluid 20 in the internal flow path 23 from the inlet path 21 to the outlet path 22 of the valve body 52. ​​The relationship between the stem 54 and the stem tip 55 is the same as in the valve device 1 of the present invention.

[0093] In order to compare the valve device 1 of the present invention with the conventional device, the valve body 2 shown in Figures 3 and 4 was reused to create valve bodies 42 and 52, respectively. As shown in Figures 11 and 12, the diaphragm type valve device 40, which is a first conventional device, and the bellows seal valve device 50, which is a second conventional device, were evaluated by creating evaluation machines by replacing the part corresponding to the stem unit 3 with the corresponding one. A closing valve (not shown) was attached to the inflow path 21 and the outflow path 22, respectively.

[0094] The evaluation was performed according to the following procedure. First, the valve device was filled with polyol, which is a raw material for urethane foam, with the internal flow path 23 open. When the air in the valve device was released, the closing valve on the side of the outflow path 22 was closed, and the closing valve on the side of the inflow path 21 was also closed. The filling pressure in the valve device was adjusted to 9 to 10 MPa, and the internal flow path 23 was blocked. That is, in the case of the diaphragm-type valve device 40, the diaphragm 43 was closed (see FIG. 11(a)), and in the case of the bellows seal valve device 50 and the valve device 1 of the present invention, the stem tip 55 (5) was closed the internal flow path 23 (see FIG. 12(a)).

[0095] Next, the internal flow path 23 is continuously opened and closed in each valve device. The opening and closing time is one second each in the open and closed states. Opening and closing are repeated 30 times per minute. In the open state, in the case of the diaphragm type valve device 40, the diaphragm 43 is released from the pressure from the plunger 44 and deforms upward, opening the internal flow path 23, as shown in FIG. 11(b). In the case of the bellows seal valve device 50, as in the valve device 1, the stem 54 moves upward and the stem tip 55 opens, as shown in FIG. 12(b).

[0096] The following indicators were used to monitor leakage of the fluid 20 inside the valve device and damage to each diaphragm 43, bellows 53, and packing 7. The first indicator was monitoring the pressure inside the valve device, and it was determined that an abnormality had occurred when it became 9 MPa or less. The second indicator was measuring the pressure on the inlet path 21 side and the pressure on the outlet path 22 side, and determining whether an abnormality had occurred based on whether the pressure difference was 1 MPa or less. The third indicator was monitoring the temperature of the liquid (polyol) in the flow path inside the valve device.

[0097] The test results were as follows. In the diaphragm-type valve device 40, which is the first device, the diaphragm 43 was damaged and liquid leakage occurred after 650,000 cycles of opening and closing the internal flow path 23. In the bellows-sealed valve device 50, which is the second device, the bellows 53 was damaged and liquid leakage occurred after 39,000 to 84,000 cycles of opening and closing the internal flow path 23. In contrast, in the valve device 1 of the present invention, no abnormality was detected even after 1,300,000 cycles of opening and closing the internal flow path 23.

[0098] From the above, the valve device 1 of the present invention has higher durability performance compared to the conventional diaphragm type valve device 40 and the bellows seal valve device 50. Therefore, it can be said that the valve device 1 of the present invention is a device with higher reliability compared to the conventional devices.

[0099] In addition, the diaphragm type valve device 40 has the following problem due to damage to the diaphragm 43. As the diaphragm 43 was continued to be used in a damaged state, pieces of the diaphragm 43 hit the inside of the valve device, causing damage and roughening the surface. In this case, in the conventional diaphragm type valve device 40, it is necessary not only to replace the diaphragm 43 but also to repair or replace the internal parts of the valve device.

[0100] The valve device 1 of the present invention solves this problem as well. The packing 7 is attached by being sandwiched between the first stem guide 8 and the second stem guide 11. Therefore, even if the packing 7 is damaged, fragments are prevented from scattering inside the valve device 1, and damage caused by impacts on the inside or surface roughness can be prevented. [Explanation of symbols]

[0101] 1 Valve device 2 Valve body 2a Bottom 2b Inner circumference 3 Stem unit 4. Stem 5 Stem Chip 6 Stem holder 6a end 7 Packing 7a Inner circumference side member 7b Outer periphery member 7d Tip 8 First stem guide 8a Lower end 8b Bottom side 8c First stem guide protrusion 9 Fixing means 11 Second stem guide 12 Packing attachment part 12a Packing shelf 12b Inner circumference of packing mounting part 13 Inclined guideway 16 Flange 16a Lower side 16b Top side 17 Gasket 18 Stem holder shelf 20 fluid 21 Inflow channel 22 Outflow channel 23 Internal flow path 24 Stem 24b Tip 26 Stem holder 31 Air Cylinder 32 Valve holder 36 Stem holder 42 Valve body D1 Stem outer diameter D2 Inner diameter of packing attachment part D3 Packing inner diameter D4 Packing outer diameter L2 maximum movement amount L3 Distance W1 Packing width W2 Vertical Spacing

Claims

1. A valve device that controls a flow of a fluid by opening and closing an internal flow path between an inflow path and an outflow path of the fluid, a valve body in which the inlet passage, the outlet passage, and the internal flow passage are formed; A stem unit is provided which is detachable from the valve body, The stem unit includes: A stem having a tip portion for opening and closing the internal flow passage; a stem holder that is installed in the valve body and into which the stem is inserted; Equipped with packing, The stem holder includes a packing mounting portion, The packing is The bearing is formed in an annular shape and includes an inner peripheral member and an outer peripheral member. A valve device having a predetermined packing width in the direction in which the stem extends, and which is attached to the stem holder with the stem inserted therein.

2. a friction coefficient between the inner peripheral member and the stem is smaller than a friction coefficient between the outer peripheral member and an inner peripheral portion of a packing mounting portion, The outer circumferential member includes an elastic member, The inner diameter of the packing is smaller than the outer diameter of the stem at the portion where the packing is inserted, The outer diameter of the packing is larger than the inner diameter of the packing mounting portion when the packing is mounted on the stem, When the outer circumferential member is attached to the packing attachment portion, the outer circumferential member elastically deforms in a horizontal direction to form a seal between the outer circumferential member and an inner circumferential portion of the packing attachment portion, The valve device according to claim 1 , wherein the inner peripheral member presses the stem in accordance with elastic deformation of the outer peripheral member, thereby forming a seal between the inner peripheral member and the stem.

3. A stem unit to be incorporated into a valve device that opens and closes an internal flow path between an inflow path and an outflow path of a fluid to control the flow of the fluid, A stem having a tip portion for opening and closing the internal flow passage; a stem holder into which the stem is inserted; Packing and A first stem guide is provided. The stem holder includes: A second stem guide, which is an opening hole at a lower end portion to guide the stem; A packing mounting portion is provided on an upper side of the second stem guide, The packing is The bearing is formed in an annular shape and includes an inner peripheral member and an outer peripheral member. The packing has a predetermined packing width in the direction in which the stem extends, and is attached to the stem holder with the stem inserted therein; the first stem guide is attached to the stem holder with the packing sandwiched therebetween in a state in which the stem is inserted; The packing is sandwiched and attached between the first stem guide and the second stem guide, The stem is guided by the first stem guide, the packing, and the second stem guide. A stem unit that operates internally.

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