JP2005121160A - Opening and closing valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an opening and closing valve capable of effectively exercising a center adjusting function of a stem by using a stem guide and a member of a simple inverted seat seal, simultaneously providing a back seat function, being easily assembled, skipping machining processes and remarkably reducing the cost. <P>SOLUTION: In this opening and closing valve wherein the stem 5 is vertically movably mounted on a shaft part 4 of a valve cage 2, and a valve seat 2a in the valve cage 2 can be opened and closed by a valve element mounted on a lower end of the stem 5, a resin back seat member 11 is formed by a guide cylindrical part 12 guiding between the shaft part 4 and the stem 5, and a flange part 13 integrated with a lower end of the guide cylindrical part 12, the guide cylindrical part 12 is guidably mounted between an inner peripheral face 4a of the shaft part 4 and an outer peripheral face 5a of the stem 5, and the flange part 13 is held by a lower face 14c of the shaft part 4 and an upper face 6a of the valve element 6 to constitute the inverted seat seal structure. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an on-off valve that moves a valve body up and down to open and close a flow path inside a valve box, and more particularly, to an on-off valve having a long neck structure that handles a low-temperature fluid such as LPG or LNG.

There are globe valves, gate valves, needle valves, plug valves, and the like as on-off valves that open and close by moving the valve body up and down, and a globe valve will be described as an example.
Among these globe valves, for example, a low temperature valve to which a low temperature fluid such as liquefied natural gas (LNG) is applied employs a bonnet extension structure in which an extension pipe is provided between an upper bonnet and a lower bonnet. In this case, a stem guide is generally provided between the stem and the bonnet in order to prevent stem misalignment (see, for example, Patent Document 1 and Patent Document 2).
Note that the room temperature valve that does not extend the bonnet does not require the above-described stem guide because the distance to the packing that seals the stem is short.

On the other hand, when the valve body is lifted to open the valve seat, there is known one provided with a back sheet that seals the valve body in contact with the lower surface of the bonnet (see, for example, Patent Document 3 and Patent Document 4). .
As shown in Patent Document 3, a conventional backsheet is provided with a backsheet on a screw ferrule, or as shown in Patent Document 4, a backsheet is provided in a concave portion of a screw ferrule provided on a shaft mounting portion of a valve box. There is something fitted. In this case, the back seat structure is configured such that the outer diameter stepped taper surface of the valve operating rod raised to the tapered surface formed at the periphery of the opening of the back seat is pressed.
In the case of a structure with a back seat, the seal can be sealed between the back seat and the valve body when the valve is open, so that the packing can be replaced even when fluid is flowing inside the valve. In this respect, the structure is advantageous compared to a structure without a back sheet.
Japanese Utility Model Publication No. 3-105779 Japanese Utility Model Publication No. 2-12375 Japanese Utility Model Publication No. 1-2268 Japanese Utility Model Publication No. 3-19666

In Patent Document 1 and Patent Document 2, an attempt is made to prevent misalignment by guiding the stem using a stem guide, but the upper part of the valve body when the valve body is opened and the bonnet in contact with the valve body Since both of the contact portions are made of metal such as stainless steel, there is a possibility that the pressing surface is damaged when the contact portions of the valve body and the bonnet are pressed against each other. When galling occurs, the sealing performance deteriorates, and there is a possibility that leakage will occur from this portion when the valve is opened.
For this reason, for example, a seat structure, which is a seat called a reverse seat structure, is separately provided in the contact portion with the valve body when the valve is opened on the bonnet side, or each press face of the contact portion has a hardness difference. However, there is a problem in that these both increase the cost and require time for construction.
In particular, in low-temperature valves that handle low-temperature fluids such as LPG and LNG, if oil and moisture remain inside the valve, they may solidify and damage the seat surface. It is necessary to apply oil-free / water-free treatment to completely remove moisture.In this case, in order to ensure the sealing performance of the abutting part, the processing accuracy of the pressure sliding surface must be further increased. It was costly.
In addition, these valves have a complicated internal structure, so that they are difficult to be assembled at the time of assembly, and there is a problem in durability.

  In Patent Document 3 and Patent Document 4, it is necessary to separately provide a back sheet together with a screw snap ring. Also, a male thread part is formed on the outer periphery of this thread ferrule, and a male thread part is also threaded on the valve box side. It was necessary to bother to form a female thread part for mating. In addition, since the male threaded portion and the female threaded portion are required to have high sealing performance, it is also necessary to increase the processing accuracy of the screw. In addition, new parts such as packing rings have been required. For these reasons, in the case of the structure in which the back sheet is provided, there is a problem that the cost is greatly increased and the number of assembling steps at the time of assembling is increased.

  The present invention has been developed in order to solve various conventional problems. The purpose of the present invention is to provide a stem alignment function by using a member that simplifies the stem guide and the reverse seat seal structure. In addition to being effective, the back sheet function can also be used, and not only the assembly is facilitated, but also the processing steps can be omitted, which leads to a significant cost reduction.

  In order to achieve the above object, according to the first aspect of the present invention, the stem is mounted on the shaft mounting portion of the valve box so as to be movable up and down, and the valve seat in the valve box is opened and closed by the valve body provided at the lower end of the stem. In a freely provided on-off valve, a resin-made back seat member is formed by a guide tube portion that guides between the shaft mounting portion and the stem, and a flange portion that is integrally formed at the lower end of the guide tube portion. A guide member interposed between the inner peripheral surface of the shaft mounting portion and the outer peripheral surface of the stem, and the reverse seat seal structure by sandwiching the flange portion between the lower surface of the shaft mounting portion and the upper surface of the valve body, Open / close valve.

  The invention according to claim 2 is an on-off valve in which the guide tube portion of the back seat member is slidably inserted into the stem.

  The invention according to claim 3 is an on-off valve in which a space in which the guide cylinder portion slides on the stem is provided between the shaft mounting portion and the stem.

  According to a fourth aspect of the present invention, the valve body includes a valve portion provided at the lower end of the stem and a valve presser, and a flat surface is formed on the upper surface of the valve portion, and the lower surface of the flange portion of the back sheet member is formed on the flat surface. Is an on-off valve in which the upper surface of the flange portion is in contact with a recess formed on the lower surface of the shaft mounting portion.

  According to the first aspect of the present invention, by using a member that simplifies the stem guide and the reverse seat seal structure, the centering function of the stem can be effectively exhibited, and the back seat function can also be used, thereby facilitating assembly. In addition, the processing steps can be omitted, resulting in a significant cost reduction.

  According to the invention concerning Claim 2 and 3, there is little sliding resistance when a stem is moved up and down, and the raise of valve operation torque can be suppressed.

  According to the invention which concerns on Claim 4, it is an on-off valve which can seal reliably the bonnet and the valve part provided in the stem by high sealing performance.

An example of the on-off valve of the present invention will be described based on the embodiment shown in FIGS.
In FIG. 1, reference numeral 1 denotes an on-off valve body, and the on-off valve body 1 in this embodiment is a globe valve. However, as long as the valve body is opened and closed to open and close, the gate valve and needle are not limited to the globe valve. The present invention may be applied to on-off valves having various structures such as valves and plug valves.

  The valve box 2 is provided with a substantially horizontal annular valve seat 2a at the center, and a substantially horizontal S-shaped fluid flow path 2b is formed with the valve seat 2a as a boundary. A flange portion 2c for connecting the shaft mounting member 4 is formed on the upper side of the valve box 2, and an opening portion 2d communicating with the flow path 2b is formed in the flange portion 2c.

The shaft mounting portion 4 is connected to a lower bonnet 14 having a connection flange portion 14 a to the valve box 2 at the lower portion, an extension pipe 15 connected to the upper side of the lower bonnet 14, and an upper end on the other end side of the extension pipe 15. The upper bonnet 16 is configured. The lower bonnet 14 and the valve box 2 are fixed by a bolt or the like (not shown) via a gasket 20.
A concave recess 14c is formed in the bottom portion peripheral portion of the stem insertion hole 14b formed in the lower bonnet 14, and a recess 13c of the back sheet member 11 described later can be accommodated in the recess 14c. . The bottom portion of the lower bonnet 14 may have a flat shape (not shown) so that the recess 14c is not provided. However, when the recess 14c is provided, the height of the valve box 2 and the shaft mounting member 4 is suppressed while the valve The opening / closing stroke of the body 6 can be ensured.
In this example, the shaft mounting portion 4 is provided separately from the valve box 2, and the shaft mounting portion 4 is a shaft mounting member composed of the above-described lower bonnet 14, extension pipe 15, and upper bonnet 16. Although the opening 2d of the valve box 2 is connected to be covered, the shaft mounting portion may be provided integrally with the valve box.

  The stem 5 is pivotally supported in a liquid-tight manner on a packing 21 housed in the upper bonnet 16 on the upper side. The packing 21 is made of expanded graphite with a reinforcing material. When sealing, a through hole of a plate-like ground retainer 25 in which a ground bolt 22 pivotally supported on the upper bonnet 16 is inserted through the stem 5 is used. By tightening the gland nut 23 in a state of passing through 25a, the substantially cylindrical gland 24 interposed between the upper bonnet 16 and the gland retainer 25 is pressed against the packing 21 to perform shaft sealing. The sealing performance by the packing 21 is set higher than the sealing performance of the backsheet member 11, and the fluid enclosed in the shaft mounting member 4 caused abnormal pressure increase by causing the backsheet member 11 to function. In this case, the pressure is relieved from the back seat member 11 side to the valve inner side.

The valve body 6 is provided at the lower end of the stem 5, and in the present embodiment, the valve presser 7 in a state where the resin-made annular disc sheet 8 as a seal member is held by the nut 30 via the stop plate 9, The valve presser 7 has a soft seal structure including a valve portion 10 for locking and fixing the lower end of the stem 5 to the lower end of the stem 5. The on-off valve body 1 has a structure in which the valve seat 2a in the valve box 2 is provided to be freely opened and closed by a valve body 6 provided at the lower end of the stem 5 by moving the stem 5 up and down.
The seat structure of the valve body is not limited to the soft seal structure, and may be a metal sheet structure (not shown) in which the valve seat is directly formed on the valve presser. Reference numeral 17 denotes a gasket. By interposing the gasket 17 between the valve presser 7 and the valve portion 10, fluid can be prevented from entering the shaft mounting member 4 from this portion when the valve is fully closed.
When the valve body 6 is configured, the male thread portion 10a formed on the valve portion 10 while interposing the gasket 17 in a state where the lower side of the valve portion 10 is locked to the annular protrusion 5b formed on the lower end of the stem 5. The female screw portion 7a of the valve presser 7 is screwed and integrated. On the upper surface of the valve body 6 (upper surface of the valve portion 10), a flat flat surface 6a is formed so as to protrude, and the lower surface 13a of the flange portion 13 of the back sheet member 11 is brought into contact with the flat surface 6a, Further, the upper surface 13 b of the flange portion 13 is brought into contact with the concave portion 14 c of the shaft mounting member 4.

The back sheet member 11 includes a cylindrical guide tube portion 12 and a flange portion 13 formed integrally with the lower end of the guide tube portion 12. The guide cylinder portion 12 is interposed between the inner peripheral surface 4a provided with the stem insertion hole 14b of the shaft mounting member 4 and the outer peripheral surface 5a of the stem 5 so as to be able to guide, and the flange portion 13 is disposed on the shaft mounting member 4. The reverse seat seal structure is configured so as to be sandwiched between the concave portion 14 c as the lower surface and the flat surface 6 a as the upper surface of the valve body 6. The guide tube portion 12 guides between the shaft mounting member 4 and the stem 5, and the guide tube portion 12 is slidably inserted into the stem 5. At this time, a space in which the guide tube portion 12 slides on the stem 5 is provided between the shaft mounting member 4 and the stem 5.
The back sheet member 11 is made of, for example, a fluororesin such as PTFE, PFA, PCTFE, or the like, but may be made of a material other than these as long as it has a cooling resistance and a strength resistance.

In FIG. 3, the flange outer diameter A ₁ of the flange portion 13 of the back sheet member 11 is formed smaller than the recess inner diameter A ₂ of the recess 14 c of the lower bonnet 14 (shaft mounting member 4). When it presses on the valve body 6, it deform | transforms in an outer-diameter direction so that it may accept | permit. This prevents the outer diameter of the deformed collar 13 from being pressed against the lower bonnet 14 and prevents the valve operating torque from increasing when the valve is closed.
It is possible to raise the seal surface pressure with the valve body 6 and the lower bonnet 14 by providing uneven portions (not shown) on the upper and lower surfaces of the flange portion 13 serving as a pressing surface or by performing serration. Further, when the back seat member 11 performs the back seat function, when the fluid enclosed in the shaft mounting member 4 causes abnormal pressure increase, the pressure surface It is also possible to provide projecting lip portions (not shown) on the upper and lower surfaces of the flange portion 13. When these uneven portions and lip portions are provided, they can be formed by resin injection molding, so that they are easy to manufacture.
Diameter of the guide tube portion 12 between the clearance outside径隙the inner circumferential surface minimum inner diameter B ₂ of the guide tube outer diameter B ₁ and JikuSo member 4 alpha, a guide tube inside diameter C ₁ and the stem outer diameter C ₂ Is set as follows so that the guide cylinder portion 12 does not come into close contact with the stem 5 in consideration of thermal contraction at a low temperature.
At normal temperature: 0 ≦ outer diameter gap α <inner diameter gap β
At low temperature: outer diameter gap α> inner diameter gap β ≧ 0

The processing region of the inner peripheral surface minimum inner diameter B ₂ in the lower bonnet 14, by only a predetermined constant region, the other region of the inner circumferential surface 4a can be a cast part, reducing the machined portion I am doing so. That is, it is only necessary to process only the inner peripheral surface minimum inner diameter B ₂ of the lower bonnet 14 may be a cast for extension pipe 15 and the upper bonnet 16. The length of the guide tube portion 12, on-off valve body 1 as shown in FIG. 2 is also a fully closed state, to form a supportable length by the inner peripheral surface minimum inner diameter B ₂ of the lower bonnet 14 Yes. In addition, S is a space | gap (space) ensured above the guide cylinder part 12 when the back seat | sheet member 11 is mounted | worn in the internal peripheral surface 4a of the shaft mounting member 4. FIG.

Here, as an example of the main dimensions of the back seat member 11, the case where the valve nominal diameter is 1B will be described. For example, the flange outer diameter A ₁ = 24 mm, the cylinder outer diameter B ₁ = 16 mm (processed with a minus tolerance) The cylindrical portion inner diameter C ₁ = 12.7 mm, the thickness 13 of the flange portion 13 which is the thickness of the sealing region of the backsheet member 11, and the corresponding main dimension of the lower bonnet 14 is the concave inner diameter A _2. = 26 mm, inner peripheral surface minimum inner diameter B ₂ = 16 mm (machined with plus tolerance), stem outer diameter C ₂ = 12.5 mm, between the outer diameter A _{1 of the} buttock and the inner diameter A ₂ of the recess of the lower bonnet 14 A gap of 1 mm is formed in the radial direction, and a gap corresponding to a tolerance and a heat shrinkage is formed between the outer diameter B _{1 of} the cylinder portion and the minimum inner diameter B _{2 of the} inner peripheral surface. Further, the thickness t of the flange portion 13 is formed so as to be thicker than the thickness of the guide tube portion 12, so that the seal region by the flange portion 13 has sufficient strength against the pressing force by the valve body 6 when the valve is opened. In addition, the guide cylinder portion 12 unnecessarily expands the accommodation space of the guide cylinder portion 12 in the lower bonnet 14 (the shaft mounting member 4) while ensuring sufficient slidability with the stem 5. There is no minimum wall thickness.

In operation of the on-off valve body 1, in the valve closed, the back sheet member 11, the flat surface of the valve body 6 upper surface in a state where the guide tube inner diameter C ₁ side is supported on the stem outer diameter C ₂ of the stem 5 The valve body 6 is lowered so as to slide on the inner peripheral surface 4a of the shaft mounting member 4 as the valve body 6 is lowered in a state where it is placed on 6a. The length of the guide tube portion 12 is such that it can be supported by the inner peripheral surface minimum inner diameter B ₂ even when the on-off valve body 1 is fully closed, so that the back seat member 11 is below the lower bonnet 14. Never come off.

On the other hand, when the valve is opened, the back seat member 11 rises as the valve body 6 rises, and the flange 13 is accommodated in the recess 14 c at the bottom of the lower bonnet 14. When the valve body 6 is further lifted in a state where the upper surface 13b of the flange 13 is in contact with the lower surface of the recess 14c of the lower bonnet 14, the flange 13 is pressed and clamped by the valve body 6 and the recess 14c. The sealing function is demonstrated. At this time, the back sheet member 11 which is pressed against the flat surface 6a of the valve body 6 can exhibit a reverse seat feature the seal area surrounded by the flange outer diameter A ₁ and the circumferential surface minimum inner diameter B ₂ It becomes.
Since the valve body 6 and the lower bonnet 14 and the back sheet member 11 have a seal structure due to contact between the metal and the resin, it is possible to ensure high sealing performance without galling without performing a hardness difference, plating, etc. It is possible to obtain an on-off valve that exhibits high sealing performance in which fluid does not enter the shaft mounting portion 4 and leakage does not occur. Further, since the back sheet member 11 has a simple shape, it can be manufactured at a low cost, and can be assembled with a simple structure in which the back sheet member 11 is placed on the valve body 6.

Since the back seat member 11 is formed by integrally forming the guide tube portion 12 above the flange portion 13, even if it is an open / close valve having a long bonnet structure as in the present embodiment, a long stem is used as the back seat member 11. The shaft can be reliably supported on the lower side, the stem is prevented from being shaken, the valve seat seal performance is deteriorated due to the displacement of the valve body 6, the stem outer peripheral surface 5a and the inner peripheral surface 4a of the shaft mounting member 4 Damage due to contact can be prevented.
Further, since the gap S is provided above the back sheet member 11, even if the back sheet member 11 is pressed and clamped by the valve body 6 and the lower bonnet 4, the guide cylinder portion 12 is not clamped and is slightly held. Since the guide cylinder portion 12 does not protrude to the inner diameter side when the reverse seat seal functions, the sliding resistance between the stem 5 and the guide cylinder portion 12 is prevented from increasing. An increase in valve operating torque when the valve is closed can be suppressed.
Furthermore, since the back seat member 11 can move up and down together with the valve body 6 and the stem 5 even when the diameter of the guide tube portion 12 is reduced, it is necessary to consider the sliding resistance between the guide tube portion 12 and the stem 5. It is possible to open and close the valve smoothly.

The flange portion 13 is bulged when pressed radially outward, since the larger the inner diameter A ₂ of the recess 14c than the flange outer diameter A _1, is not that the bulge is prevented. Further, by allowing the bulging in the outer diameter direction as described above, the amount of bulging of the flange portion 13 in the inner diameter direction (the direction of the stem 5) is suppressed.

  In the state where the reverse seat seal is functioning, for example, when the fluid is abnormally boosted due to a rise in the temperature of the valve or the like, the back sheet member 11 formed of the resin material is the weakest in strength, so this pressure is lower Relief is performed from between the bonnet 14 and the back sheet member 11 or between the back sheet member 11 and the valve body 6, and fluid does not leak to the outside of the on-off valve.

In this valve body operation, in the reverse seat seal structure by pressing and sliding between metal members, it is necessary to raise the stem as much as possible to increase the pressing force in order to improve the sealing performance. The valve operating torque when performing the closing operation is large.
The on-off valve body 1 according to the present embodiment can obtain the necessary sealing performance without excessively increasing the surface pressure of the back seat member 11, so that it is not necessary to raise the stem 5 more than necessary. Accordingly, it is possible to reduce the valve operation torque when performing the valve closing operation, and the operability of the valve is also improved.

When the on-off valve body 1 is assembled, the back seat member 11 is placed on the upper surface of the valve body 6 locked to the lower portion of the stem 5 from the upper side with the stem 5 inserted therein. In this state, the lower bonnet 14 By inserting the stem 5 from below, the back sheet member 11 can be easily built in the main body 1.
Alternatively, the stem 5 may be inserted into the stem insertion hole 14b at the bottom of the lower bonnet 14 from the guide tube portion 12 of the back sheet member 11, and then the stem 5 is inserted from below the lower bonnet 14 via the guide tube portion 12. In this case, the flange portion 13 is placed on the upper surface of the valve body 6 when the insertion of the stem 5 into the shaft mounting member 4 is completed. According to this assembling method, the stem 5 can be inserted into the shaft mounting member 4 while being guided by the back sheet member 11, and the stem 5 can be inserted into the packing 21 built in the upper bonnet 16. It becomes possible to perform a smooth insertion by being in a state of being aligned.
Thus, in any case, the structure inside the valve box 2 is simple, and the back sheet member 11 can be disposed in the main body 1 without using fixing means such as screwing. It is not necessary to thread the member 4 or parts such as a screw snap ring, and it can be easily performed without increasing the number of assembling steps when assembling at the time of construction, thereby reducing costs. be able to. Furthermore, since the structure is simple, high durability can be exhibited.

  FIG. 4 is a partially enlarged cross-sectional view showing another example of the on-off valve, in which 31 is an on-off valve body. As shown in the figure, the back sheet member 33 placed on the valve body 36 may be annular, and an annular flat surface 36 a corresponding to the back sheet member 33 may be provided on the valve body 36. In this case, for example, it can be used for an on-off valve having a short shaft mounting portion, and can be applied to various on-off valves such as a plug valve and a gate valve. Thus, even when the shape of the back seat member of the on-off valve is changed, the same sealing performance as the on-off valve of the present invention can be exhibited. In addition, the same part as the on-off valve of this invention is represented by the same code | symbol, and the description is abbreviate | omitted.

  The present invention is particularly suitable for an open / close valve having a long neck structure that handles a low-temperature fluid, but any open / close valve that opens and closes by moving the valve body up and down can be used for any kind of valve such as a globe valve, a gate valve, a needle valve, and a plug valve. It can be applied to any type of valve regardless of the fluid temperature or the length of the shafted part.

1 is a half-sectional view showing an embodiment of an on-off valve of the present invention. It is a partially expanded sectional view which shows the valve closed state of the on-off valve of FIG. It is a partially expanded sectional view of FIG. It is a partially expanded sectional view which shows the other examples of an on-off valve.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 On-off valve main body 2 Valve box 2a Valve seat 4 Shaft mounting member (shaft mounting part)
4a Inner peripheral surface 5 Stem 5a Outer peripheral surface 6 Valve body 6a Flat surface 7 Valve presser 10 Valve portion 11 Back sheet member 12 Guide cylinder portion 13 Gutter portion 13a Lower surface 13b Upper surface 14c Concavity S Space

Claims (4)

  In an on-off valve in which a stem is mounted on a shaft mounting portion of the valve box so as to be movable up and down, and a valve seat provided in a lower end of the stem is provided to be openable and closable. A back tube member made of resin is formed by a guide tube portion that guides the gap and a flange portion that is integrally formed at the lower end of the guide tube portion. An on-off valve characterized by having a reverse seat seal structure in which a flange is interposed between the lower surface of the shaft mounting portion and the upper surface of the valve body while being interposed in a freely guideable manner.   The on-off valve according to claim 1, wherein the guide tube portion of the back seat member is slidably inserted into the stem.   The on-off valve according to claim 2, wherein a space in which the guide tube portion slides on the stem is provided between the shaft mounting portion and the stem. The valve body is composed of a valve portion and a valve presser provided at the lower end of the stem. A flat surface is formed on the upper surface of the valve portion, and the lower surface of the collar portion of the back sheet member is brought into contact with the flat surface. The on-off valve according to any one of claims 1 to 3, wherein the upper surface is brought into contact with a recess formed in the lower surface of the shaft mounting portion.

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