JP6592275B2 - Lining type butterfly valve - Google Patents

Description

  The present invention relates to a lining-type butterfly valve in which resin linings are applied to the inner surfaces of a valve body and a valve box, and more particularly, to a butterfly valve that prevents fluid leakage to the flow path direction and to the outside on the valve body lower side.

Conventionally, the metal core of the valve body has been used as a butterfly valve with corrosion resistance when used in chemical industry plants to flow highly corrosive fluids and high-temperature fluids, and for food-related flow paths. A butterfly valve having a so-called lining structure in which a resin sheet ring is mounted on the inner peripheral surface of a valve box and covered with a resin lining layer is used.
In the lining type butterfly valve, since the fluid is a chemical, etc., especially the fluid leakage in the fluid flow direction on the top (upper and lower) side of the valve element and the external leakage of fluid from the shaft seal part of the valve stem It is necessary to ensure operability while preventing it. Therefore, in this type of butterfly valve, the shaft cylinder lining is usually extended from the lining of the valve body surface, and the upper and lower stems, which are separate from the valve element, are inserted into the inner periphery of the shaft cylinder lining. The box-side seal portion is provided so as to tightly seal.

On the other hand, Patent Document 1 discloses a lining-type butterfly valve having a structure in which a disk is pivotally supported by an upper stem without providing a stem on the lower side of the disk (see FIG. 4 of Patent Document 1). In this valve, the lower surface of the disc is brought into direct contact with the seat ring, and the lower portion of the seat ring is elastically pressed in the disc direction, so that the surface pressure between the lower surface of the disc and the seat ring is ensured from the lower side of the valve body. It is intended to prevent fluid leakage in the flow path direction.
In addition to this, there is also known a valve in which a protrusion that protrudes slightly at the lower part of the disk is integrally provided, and the protrusion is inserted into a through hole provided on the body side so that the lower part of the disk is held by the body.

  In the butterfly valve of Patent Document 2, one of the upper and lower valve rods is provided separately from the valve body. Each valve stem is inserted into a cylindrical resin lining portion formed above and below the resin lining layer covering the valve body, thereby securing a shaft seal of the valve stem to prevent external leakage.

JP 61-119881 A JP-A-9-292037

When assembling the butterfly valve with the shaft cylinder lining extended above and below, it is necessary to insert the upper and lower cylinder linings from the inner peripheral side of the mounting hole formed in the resin sheet ring. At that time, since the height of the shaft cylinder lining is larger than the inner diameter of the seat ring, it becomes difficult to incorporate the valve body particularly when the diameter is small. For example, in the case of a small diameter of 65 A or less, further assembly is required. It becomes difficult.
In this structure, the thickness of the insertion hole for inserting the stem above and below the valve body is required, so the ratio of the thickness of the valve body to the valve diameter increases, and as the diameter decreases, The proportion is even higher. As a result, it becomes difficult to secure the flow rate in the intermediate opening or in the fully opened state.

  On the other hand, as in Patent Document 1, in the case of a structure that supports the disc only by the upper stem, by not providing the lower side support, it becomes easier to incorporate the valve body than in the case of supporting by the upper and lower stems, The flow rate also increases. However, in this case, the surface pressure on the boss side at the bottom of the valve body is weaker than that on the upper boss side and the valve body is likely to be displaced, and the surface pressure distribution at the time of pressure contact between the valve body and the seat ring is In this case, fluid may leak in the direction of the flow path. In order to prevent the displacement of the lower part of the valve body, it is conceivable to provide the upper stem with a large diameter or to form it with a high strength material, but this leads to an increase in cost and the lower surface pressure is equal to the upper surface pressure. It is also difficult to improve to this state.

For valves with a structure in which the protrusion provided on the lower part of the disc is inserted into the insertion hole of the body, external leakage of fluid can occur between the protrusion and the through hole because the through hole of the body penetrates to the outside of the body There is sex. In this valve, the balance of the surface pressure on the upper and lower sides is not taken into consideration, so the surface pressure on the upper and lower sides is different as in Patent Document 1, and it is difficult to keep the stem in a stable state.
Furthermore, in these valves, if creep occurs at the upper and lower seals, for example, if the upper lining thickness is reduced by this creep, the upper spring will extend, reducing the load and lowering the upper and lower surface pressure. The risk of unbalance increases.

  In the case of the butterfly valve of Patent Document 2, it is difficult to incorporate the valve body because the upper and lower resin lining portions are long. In particular, it is more difficult to assemble a small-diameter valve. Since the valve stem is provided separately from the valve body and this valve stem is also attached to the through hole formed in the resin lining portion, it is difficult to eliminate external leakage of fluid from the valve stem side. Since parts for sealing the valve stem are also required, the number of parts increases, leading to an increase in cost.

  The present invention was developed in order to solve the conventional problems, and the object of the present invention is a lining-type butterfly valve having corrosion resistance against fluids, ensuring a large flow rate and exhibiting ease of assembly. However, an object of the present invention is to provide a lining-type butterfly valve with excellent operability that can reliably prevent fluid leakage to the outside in the direction of the flow path on the lower side of the disk.

In order to achieve the above-described object, the invention according to claim 1 is directed to a disc device in which upper and lower boss surfaces slide on an inner periphery of a resin sheet liner coated on an inner peripheral surface of a cylindrical body via an upper stem. In the lining-type butterfly valve, the disk is formed by covering a substantially circular cored bar and an outer peripheral surface of a projecting part protruding from a lower part of the cored bar with a resin lining. A portion of the protruding portion covered with the lining is a bottom stem portion , a holding body is provided in a mounting cylinder provided at a lower portion of the body, and the seat liner and the seat liner are disposed in a recess formed on an upper surface of the holding body. This is a lining-type butterfly valve in which a bag-like portion provided integrally is positioned, the bottom stem portion is fitted into the bag-like portion, and the bottom stem portion is pivotally supported .

According to the second aspect of the present invention, the spring force of the upper spring mounted on the shaft mounting cylinder mounted with the upper stem and the lower spring mounted on the mounting cylinder is made substantially the same, and the sealing area of the lower boss surface is set to the upper boss surface. This is a lining-type butterfly valve in which the sealing performance on the lower side of the disc is improved by making the surface area of the lower boss surface smaller than the sealing area.

According to a third aspect of the present invention, there is provided a disc lower portion by increasing the surface pressure of the lower boss surface by increasing the spring force of the lower spring mounted on the mounting cylinder from the upper spring mounted on the shaft mounting cylinder mounted with the upper stem. A lining-type butterfly valve with improved side sealability.

The invention according to claim 4 is the lining-type butterfly valve in which the bottom stem portion is pivotally supported between the upper surface of the annular portion of the holding body having the concave portion and the lower surface of the protruding portion.

The invention according to claim 5 is the lining-type butterfly valve in which the thickness of the resin lining of the bottom stem portion is set to be smaller than the thickness of the other resin lining.

  According to the first aspect of the invention, the bottom stem of the disc, which can exhibit corrosion resistance against the fluid and is coated with a resin lining, is pivotally supported non-penetratingly in the mounting cylinder at the lower part of the body. Since it is not necessary to attach a stem to the lower part, the thickness of the lower part of the disk can be reduced, and even in the case of a small bore size, the ratio of the thickness of the disk to the bore can be lowered to ensure a large intermediate opening and a fully opened flow rate. Since it does not have a lower stem, it can be easily assembled even in the case of a small diameter, and the number of parts is reduced because the internal structure is simplified. Since the bottom stem side of the disc is pivotally attached to the body, displacement of the lower side of the disc in the flow direction is prevented, sealing performance in the flow direction is ensured, and external leakage from the vertical direction of the disc is ensured. In addition, the structure in which the upper and lower sides of the disc are attached to the shaft prevents the increase of the operation torque and exhibits excellent operability.

Moreover, the bottom stem is provided by providing a bag-shaped portion integral with the sheet liner in the concave portion of the holding body, and fitting the bottom stem portion covered with the resin lining to the bag-shaped portion to pivotally support the bottom stem. There is no external leakage in the axial direction from the side, and the body-side boss surface and the disc-side boss surface are tightly sealed with resin to reliably prevent leakage in the flow path direction. Since the thickness of the disc on the bottom stem side can be reduced, a large flow rate can be secured even in the case of a small diameter. The holding body can prevent deformation of the bag-like portion, can prevent the bottom stem from swinging, and can be mounted at a predetermined position in a centered state.

According to the second aspect of the present invention, the bottom boss surface is supported non-penetratingly by increasing the surface pressure of the lower boss surface to be higher than the surface pressure of the upper boss surface and improving the sealing performance on the lower side of the disc. As a result, it is possible to improve the assembling property while ensuring the flow rate while securely preventing fluid leakage in the flow path direction on the lower side of the disc, and to secure the operability by firmly holding the upper and lower sides of the disc with different surface pressure balances. For this reason, even when it is provided with a small diameter, disc displacement in the direction of the flow path can be prevented, and even when creep or temperature changes occur, the upper and lower surface pressure balance can be maintained and sealing performance can be ensured. By using the same spring for the upper and lower springs, the types of parts can be reduced.

According to the invention according to claim 3 , by using upper and lower springs with different spring forces, the surface pressure of the lower boss surface is made higher than the surface pressure of the upper boss surface to improve the sealing performance on the lower side of the disk. The bottom stem is pivotally supported non-penetratingly to prevent fluid leakage in the direction of the flow path on the lower side of the disc, while ensuring the flow rate and improving the assemblability, and the upper and lower sides of the disc can be balanced with different surface pressures. It can be held firmly to ensure operability. For this reason, disc displacement in the direction of the flow path can be prevented even when it is provided in a small diameter, and the disc can be easily discriminated using upper and lower springs with different spring forces without adjusting the size and shape of the upper and lower boss surfaces. The upper and lower surface pressure balance can be set.

According to the invention which concerns on Claim 4 , the bottom stem part which has the protrusion part formed short and can hold | maintain a disc, ensuring sealing performance and torque property, restraining a protrusion part to the minimum length, and the mounting cylinder of a body It can be easily mounted and assembled easily.

According to the invention of claim 5 , even in the case of a small bore size, the bottom stem portion is secured to the seat liner while ensuring the surface pressure of the lower boss surface and reliably preventing fluid leakage from the lower disk side to the flow path direction. Assembling performance can be ensured by easy insertion.

It is a center longitudinal cross-sectional view which shows embodiment of the lining type butterfly valve of this invention. It is a center longitudinal cross-sectional view of the lining type butterfly valve of FIG. It is a principal part expanded sectional view of FIG. It is the schematic diagram which showed the surface pressure distribution state of the upper seal surface and the lower seal surface. It is principal part sectional drawing which showed the comparative example of the butterfly valve. It is the schematic diagram which showed the surface pressure distribution state of FIG.

  Embodiments of a butterfly valve according to the present invention will be described below in detail with reference to the drawings. 1 and 2 show sectional views of an embodiment of the butterfly valve according to the present invention, and FIG. 3 shows an enlarged sectional view of a main part of FIG.

  1 and 2, a butterfly valve (hereinafter referred to as a valve body 1) is used, for example, in a chemical industry plant or a food-related pipeline, and has a cylindrical body 2, a disc 3, an upper stem 4, For example, the holding body 5 is provided at a diameter of a nominal diameter of 100A.

  The body 2 is formed in a substantially cylindrical shape by combining an upper body 2a and a lower body 2b formed of cast iron such as ductile cast iron, and the side portions are integrally fixed by bolts 6. The inner peripheral surface 7 of the body 2 is covered with a resin sheet liner 10 in a substantially annular shape. A shaft mounting cylinder 11 is formed on the upper portion of the body 2, and a mounting cylinder 12 is formed on the lower portion thereof. The upper stem 4, the ring body 13, the bowl-shaped member 14, the O-ring 15, and the bearing 16 are mounted.

  The sheet liner 10 is formed of a fluororesin such as PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer) to a thickness of about 3 mm, and is provided so as to exhibit high corrosion resistance and heat resistance. On the side of the mounting cylinder 12 of the seat liner 10, a concave bag-like portion 20 is provided integrally with the seat liner 10. An inner peripheral seal surface 21 is provided on the inner periphery of the seat liner 10, and an upper seal surface 22 is provided on the shaft-mounted cylinder 11 side of the inner peripheral seal surface 21, and a lower seal surface 23 is provided on the mounting cylinder 12 side. On the upper seal surface 22 side, a cylindrical portion 24 is formed to extend upward.

  The thickness of the sheet liner 10 on the upper seal surface 22 and the lower seal surface 23 side is formed so as to gradually decrease toward the axis of the disc 3. Specifically, as shown in FIG. 3, for example, the lower seal surface 23 is formed so as to be inclined in the axial direction of the disc 3, and the back surface of the lower seal surface 23 is formed substantially parallel to the flow path. As a result, the wall thickness gradually decreases.

  1 and 2, the disc 3 is mounted on the inner periphery of the seat liner 10 via the upper stem 4 and is rotatably provided in the body 2. In the center of the disc 3, a substantially disc-shaped cored bar 30 made of stainless alloy is provided, and a short and cylindrical projecting portion 31 is integrally provided at the lower part of the cored bar. The outer diameter dimension of the protruding portion 31 is set to be smaller than the outermost diameter dimension of the upper stem 4. The surface of the metal core 30 having the projecting portion 31 is covered with a resin lining 32 to constitute the disk 3. The resin lining 32 is coated on the outer periphery of the front and back surfaces of the core metal 30 with a thickness of, for example, 3 mm through a through hole 33 formed at an appropriate position of the core metal with a resin material such as a fluororesin such as PFA. The Thus, the disc 3 is provided in a state where the resin lining 32 is prevented from being detached from the core metal 30.

  By covering the resin lining 32 with the resin lining 32, a bottom stem portion 35 in which the protruding portion 31 is covered with the resin lining 32 is provided at the lower portion of the disc 3, and this bottom stem 35 portion is not attached to the mounting cylinder 12 below the body 2. It is mounted with a through-shaft support. A shaft cylinder portion 36 that covers the outer periphery of the upper stem 4 is formed on the upper portion of the disk 3.

  An upper boss surface 37 and a lower boss surface 38 are formed on the bottom stem portion 35 of the disc 3 and the top and bottom sides (upper and lower sides) of the outer peripheral side of the shaft tube portion 36 by a resin lining 32, respectively. In some cases, the upper boss surface 37 and the lower boss surface 38 slide in close contact with the upper seal surface 22 and the lower seal surface 23, respectively. Due to the close contact between the boss surfaces 37 and 38 and the seal surfaces 22 and 23, fluid leakage in the flow path direction can be prevented, and so-called valve seat sealability can be obtained. The cylinder portion 24 of the seat liner 10 is disposed on the outer periphery of the shaft cylinder portion 36, and the cylinder portion 24 seals the space between the shaft cylinder portion 36.

  A square hole 39 is formed on the top side (upper side) of the disc 3, and the connecting side of the upper stem 4 is inserted and fitted into this square hole 39 and is axially mounted on the shaft mounting cylinder 11. 3 The upper part is attached to the body 2. Thus, the assembly is facilitated by providing the upper stem 4 and the disc 3 separately.

The holding body 5 is made of, for example, a metal material such as stainless steel, and is provided on the mounting side of the bottom stem portion 35 of the mounting cylinder 12. The holding body 5 is provided in a substantially cylindrical shape, and an annular portion 40 is provided on the upper portion. A concave portion 41 is formed on the inner upper surface of the annular portion 40, and a bag shape integral with the sheet liner 10 described above is formed in the concave portion 41. Part 20 is mounted. The bottom stem portion 35 is fitted to the bag-like portion 20 provided in the concave portion 41 and is pivotally supported in a non-penetrating manner so that the bottom stem portion 35 is attached to the body 2 side and the disk 3 is rotatably held. The
After the bottom stem portion 35 is mounted, a slight gap is formed between the bottom stem portion 35 and the bag-like portion 20 and between the bag-like portion 20 and the concave portion 41 in the axial direction of the disc 3.

  As shown in FIG. 1, a stepped portion 42 is provided on the outer periphery of the holding body 5, and the diameter-expanded side of the stepped portion 42 is fitted into the mounting cylinder 12, and the stepped portion 42 is placed on the outer peripheral side of the seat liner 10. The rubber backup rubber 43 to be attached is attached with the opening side locked. When forming the stepped portion 42, the length between the corner portion 2c of the lower body 2b is about 1 mm in order to eliminate the assembling property when the holding body 5 is mounted and the escape place of the deformation of the backup rubber 43. It is good to provide.

  In FIG. 3, when the bottom stem portion 35 is attached to the concave portion 41 via the bag-like portion 20, the bottom stem portion has a length L between the upper surface 40 a of the annular portion 40 and the lower surface 31 a of the protruding portion 31. 35 core metal regions are pivotally supported.

  Since the resin lining 32a on the bottom stem portion 35 side is not in contact with the liquid and there is no need to consider permeation resistance, the thickness D of the resin lining 32a on the bottom stem portion 35 side is set to the thickness D1 of the other resin lining. It may be set thinner. For example, when the thickness D1 of the resin lining on the flow path side of the disk 3 is 4 mm, the resin lining thickness D in the vicinity of the bottom stem portion 35 can be set to 1.0 mm, and at the same time, the height H of the bottom stem portion 35 is set. Assembling is improved by setting as low as possible.

  The same applies to the sheet liner 10, and the thickness E of the bag-like portion 20 may be set thinner than the thickness E1 of the other linings. For example, when the thickness E1 of the lining on the outermost peripheral side of the lower seal surface 23 is 3 mm, the thickness E of the lining near the bag-like portion 20 can be 1.5 mm.

  As shown in FIG. 2, a lower spring 50 made of a coil spring is mounted on the back side of the holding body 5 of the shaft mounting cylinder 11, and the annular portion 40 of the holding body 5 is moved by the elastic force of the lower spring 50. Accordingly, the lower seal surface 23 is pressed against the lower boss surface 38. A bearing 16 is mounted on the shaft mounting cylinder 11 on the upper portion of the body 2, and an upper spring 51 is mounted on the back side of the bearing 16 in the same manner, and the upper sealing surface 22 is moved upward by the elastic force of the upper spring 51. Pressed against the boss surface 37.

  The spring forces of these upper and lower springs 50 and 51 are set to be substantially the same, and are provided so as to be able to exert the same elastic force. In the present embodiment, the same spring is used. The seal area S1 of the lower boss surface 38 when the lower seal surface 23 is pressed against the lower boss surface 38 is the seal of the upper boss surface 37 when the upper seal surface 22 is pressed against the upper boss surface 37. It is smaller than the area S2. As a result, the surface pressure by the lower boss surface 38 is higher than the surface pressure by the upper boss surface 37, and the valve seat sealability on the lower side of the disc 3 is improved.

  FIG. 4 shows the surface pressure distribution on the upper seal surface 22 and the lower seal surface 23 of the valve body 1 in the valve closed state of FIG. As shown in the figure, the lower seal area S1 is set smaller than the upper seal area S2 in the figure, and the surface pressure in the lower seal area S1 is higher than the surface pressure in the upper seal area S2.

  Further, the spring force of the lower spring 50 attached to the mounting cylinder 12 is set to be larger than that of the upper spring 51 mounted to the shaft mounting cylinder 11 on which the upper stem 4 is mounted with the seal area S1 set equal to the seal area S2. By increasing the surface pressure, the surface pressure of the lower seal area S2 by the lower boss surface 38 may be increased, thereby improving the valve seat sealability on the lower side of the disc 3. In this case, since the disc 3 may be displaced from the center of the flow path due to different spring forces of the springs 50 and 51, it is necessary to adjust so that the disc 3 is positioned at the center.

1 and 2, a ring body 13 and a bowl-shaped member 14 are provided on the back side of the upper seal surface 22 on the upper side of the disc 3.
The ring body 13 is formed in a cylindrical shape from a metal material such as stainless steel, and is provided on the shaft mounting cylinder 11 so as to be sandwiched between the bearing 16 provided on the outer peripheral side of the upper stem 4 and the seat liner 10. The elastic force of the upper spring 51 is transmitted to the ring body 13 via the bearing 16, and the elastic force is transmitted from the ring body 13 to the seat liner 10 to seal the upper boss surface 36 and the upper seal surface 22. In addition, the shaft seal state between the shaft tube portion 36 and the tube portion 24 is held from the outer peripheral side by the ring body 13. Thereby, the sealing performance on the upper side of the disc 3 is improved, and the shaft sealing portion is prevented from being deformed in the diameter increasing direction, thereby maintaining a strong sealing performance.

  The springs 50 and 51 are formed to have a diameter that transmits elastic force to the outer peripheral side of the upper and lower boss surfaces 37 and 38 of the disc 3. As a result, the upper boss surfaces 37 and 38 and the upper and lower seal surfaces 22 and 23 are intensively brought into close contact with each other while suppressing an increase in operating torque, thereby exhibiting high sealing performance. At that time, as described above, on the lower side of the disc 3, the lower seal surface 23 of the annular portion upper surface 40 a of the holding body 5 is formed by the gap between the bottom stem portion 35 and the bag-like portion 20 and between the bag-like portion 20 and the concave portion 41. The back side is intensively pressed, and the surface pressure between the lower seal surface 23 and the lower boss surface 38 increases.

  The eaves member 14 is formed of a resin material such as PTFE (polytetrafluoroethylene) containing carbon fiber, and is provided as a seal member between the ring body 13, the sheet liner 10, and the resin lining 32. A cylindrical portion 14a is formed in the flange-shaped member 14, and an annular flange portion 14b bent in the outer peripheral direction is provided on the lower side of the cylindrical portion 14a. The end surface 13a of the ring body 13 is brought into contact with the flange portion 14b, whereby the ring body 13 presses the sheet liner 10 through the flange portion 14b. A sealing O-ring 15 is mounted on the inner peripheral side of the cylindrical portion 14a.

  By the flange-shaped member 14, the pressing force from the ring body 13 is transmitted through the flange portion 14b so as to be dispersed to the sheet liner 10 side, and stress concentration is prevented. In addition, a sealing function is exhibited around the upper stem 4 by the O-ring 15, and leakage around the upper stem 4 is prevented when the disc 3 is moved downstream by the fluid pressure.

  The bearing 16 is formed in a cylindrical shape and is disposed between the upper spring 51 and the ring body 13 of the shaft-mounted cylinder 11, and the upper stem 4 is rotatable and aligned in the vicinity of the O-ring 15 by the upper spring 51. It is supported by.

  In FIG. 1, the shaft mounting cylinder 11 of the upper body 2 a is arranged in a state where a bearing member 70 is locked by a holding ring 71, so that the upper spring 51 can be repelled downward by the bearing member 70. Supported. On the other hand, on the mounting cylinder 12 of the lower body 2b, the top member 72 is disposed in a state of being locked by the holding ring 71, and the lower spring 50 is supported in a state in which the lower spring 50 can be repelled upward. Is done. By the bearing member 70 and the top member 72, the upper and lower springs 50 and 51 are respectively ejected in the direction of the disc 3. Dustproof and waterproof O-rings 74 and 75 are mounted on the inner and outer peripheries of the bearing member 70 and the top member 72, respectively.

  In the above embodiment, the upper and lower springs 50 and 51 are provided by coil springs. However, the upper and lower springs 50 and 51 are not limited to coil springs. Good.

  Further, a cylindrical body (not shown) may be mounted on the mounting cylinder 12 instead of the substantially cylindrical holding body 5 and the bottom stem portion 35 may be fitted from above the cylindrical body to be pivotally supported.

Then, the effect | action in the said embodiment of the lining type butterfly valve of this invention is demonstrated.
As shown in FIGS. 1 to 3, the valve main body 1 according to the present invention is provided with a disc 3 by rotating a disc 3 by pivotally supporting a bottom stem portion 35 non-through the mounting cylinder 12 of the body 2. This disk 3 can be attached to the body 2 without providing a separate stem at the bottom of the body 3.
From this, the thickness in the vicinity of the lower portion of the disc 3 can be formed to be particularly thin, and the ratio of the thickness of the disc 3 to the channel diameter when the valve is opened can be reduced. This is particularly effective in the case of a small diameter (for example, a valve having a diameter of 65 A or less) in which the ratio of the thickness of the insertion hole for the stem is large with respect to the valve diameter, and the thickness of the entire disc 3 is provided thin. Thus, it is possible to ensure a large intermediate opening and a fully open flow rate.

  The spring force of the lower spring 50 is made larger than that of the upper spring 51, and as shown in FIG. 4, the surface pressure of the lower seal area S2 on the lower boss surface 38 side rather than the surface pressure of the upper seal area S1 on the upper boss surface 37 side. As a result, the valve seat sealability on the lower side of the disc 3 is improved, and the lower side of the disc 3 is pivoted in a non-penetrating manner, thereby improving the operability while preventing external fluid leakage.

  Here, the surface pressure applied to the seal area will be described in detail. 4 (a) and 4 (b) show the surface pressure distributions of the upper seal area S2 and the lower seal area S1 when the upstream fluid pressure is 0 MPa, respectively. FIG. 4 (c) and FIG. (D) shows the surface pressure distribution of the upper seal area S2 and the lower seal area S1 when the upstream fluid pressure is 1.0 MPa. In FIG. 4 and FIG. 6 described later, the right side of the drawing shows the upstream side and the left side shows the downstream side, and surface pressure is applied to the hatched portion. A portion where the hatching interval is narrow shows a state where the seal surface pressure is high, and a portion where the hatching interval is wide indicates a state where the seal surface pressure is low.

In the case of the fluid pressure of 0 MPa in FIGS. 4A and 4B, the disc 3 in FIG. 2 is not displaced downstream, so that the surface pressures in the upper and lower seal areas S2 and S1 are equal.
On the other hand, in the case of the fluid pressure of 1.0 MPa in FIGS. 4C and 4D, the surface pressure on the upstream side is slightly lower than that on the downstream side because the disc 3 is displaced downstream. . However, since the lower seal area S1 is set small, the downstream side pressure in FIG. 4 (d) is also higher than the downstream side pressure in FIG. 4 (c). Since the surface pressure is higher than when the fluid pressure is 0 MPa, the same high sealing performance as that of the upper seal surface pressure is exhibited, and the balance of the surface pressure in the upper and lower seal areas S2 and S1 is maintained. Deviation (displacement) can be suppressed. Since the shaft is supported by the bottom stem portion 35 at the center between the upstream side and the downstream side, in the upper and lower seal areas S2 and S1 in FIGS. 4C and 4D, the upstream side and the downstream side respectively. The surface pressure difference is suppressed, and stable sealing performance and torque performance are exhibited.

  On the other hand, FIGS. 5 and 6 show comparative examples of butterfly valves. In this example, as shown in FIG. 5, the bottom stem portion and the lower stem are not provided, and the core member 80 is made of resin lining. The upper side of the valve body 82 covered with the portion 81 is pivotally supported by the upper stem 4 of FIG. 1, and the lower contact surface 83 of the resin lining portion 81 is the inner peripheral surface portion of the seat liner portion 84 on the lower side of the valve body 82. 85 is abutting and sealing. 6 (a) and 6 (b) show the surface pressure distributions of the upper seal area T2 and the lower seal area T1 when the fluid pressure from the upstream side is 0 MPa, respectively. 6 (d) shows the surface pressure distribution of the upper seal area T2 and the surface pressure distribution of the lower seal area T1 when the upstream fluid pressure is 1.0 MPa.

  In the case of the fluid pressure of 0 MPa in FIGS. 6A and 6B, the valve body 82 is not displaced downstream, and the surface pressures in the upper and lower seal areas T2 and T1 are equal. Comparing the upper and lower surface pressures, the lower side of the valve body 82 is not pivotally supported, and the lower abutment surface 83 abuts against the inner peripheral surface portion 85 with a large sealing area, so that the surface pressure is higher than the upper side of the valve body. Becomes weaker.

  In the case of the fluid pressure of 1.0 MPa in FIGS. 6C and 6D, the valve body 82 is displaced downstream, and the surface pressure on the upstream side becomes low. At this time, as the lower seal area T1 is increased by the lower contact surface 83 as described above, it is difficult to improve the surface pressure of the lower seal area T1. Furthermore, since the shaft support part is not provided at the lower part of the valve body 82, the difference in the seal surface pressure from the upstream side becomes large and the displacement is easily made downstream, so the sealing performance is lowered and the torque performance is stable. The operability is also likely to deteriorate.

  In the valve body 1 of FIGS. 1 and 2 of the present invention, the spring forces of the upper and lower springs 50 and 51 are made substantially the same, and the seal area S1 of the lower boss surface 38 is made smaller than the seal area S2 of the upper boss surface 37. By increasing the surface pressure of the lower boss surface 38 and improving the sealing performance on the lower side of the disc 3, the sealing performance between the lower sealing surface 23 and the lower boss surface 38 is secured, and the upper and lower sides are improved by creep and temperature change. Even when the thickness of any of the linings is reduced, the balance of the upper and lower surface pressure distribution is maintained by the same upper and lower spring force, and leakage from each seal portion is prevented. Since the upper and lower springs 50 and 51 press the vicinity of the outer periphery of the end surfaces of the holding body 5 and the bearing 16, the upper and lower seal surfaces 22 and 23 are surely pressed against the upper and lower boss surfaces 37 and 38, and their sealing properties are achieved. Has improved.

  As shown in FIG. 3, a concave portion 41 is formed on the upper surface of the holding body 5, and a pressure is applied to the disc 3 by fitting the bottom stem portion 35 to the bag-like portion 20 provided in the concave portion 41. Sometimes this pressure is transmitted from the core 30 of the disc 3 to the side surface of the recess 41. Thereby, the deformation | transformation of the resin-made sheet liner 10 and the resin lining 32 whose intensity | strength is lower than a metal can be prevented with the metal holding body 5, and high sealing performance can be maintained. By providing the bag-like portion 20 in the concave portion 41, even if fluid pressure is applied in the concave portion 41, the concave portion 41 prevents the bag-like portion 20 from being deformed or broken, thereby reliably preventing leakage. .

  At this time, since the core metal region of the bottom stem portion 35 is pivotally supported between the annular portion upper surface 40a of the holding body 5 provided with the recess 41 and the protruding portion lower surface 31a, the bottom stem portion 35 is minimized. It is possible to ensure the strength of the lining while ensuring the ease of assembly by providing it in a limited length.

  Further, since the thickness of the upper and lower sealing surfaces 22 and 23 of the sheet liner 10 is gradually reduced toward the axis of the disc 3, the surface pressure distribution between the sheet liner 10 and the upper and lower boss surfaces 37 and 38 is increased. As a result, the height H of the bottom stem portion 35 can be minimized and the assemblability can be improved. In addition, the dashed-two dotted line in a figure represents the case where the thickness by the side of the lower seal surface 23 is provided uniformly. In this case, the height H of the bottom stem portion 35 is extended, and it becomes necessary to form the recess 41 deeply, making it difficult to incorporate the disc 3.

  When assembling the valve body 1, first, in FIG. 1 and FIG. 2, the disc 3 previously covered with the resin lining 32 is incorporated inside the seat liner 10. In this case, on the upper side of the disc 3, the shaft tube portion 36 is inserted into the tube portion 24 of the seat liner 10. On the other hand, on the lower side of the disc 3, the bottom stem portion 35 is mounted so as to fit into the bag-like portion 20. Thus, there is no need to provide a long shaft tube portion for mounting the stem on the lower side of the disc 3, and the bottom stem 35 in which the short projecting portion 31 is covered with the resin lining 32 on the bag-like portion 20, The liner 10 can be easily inserted with almost no deformation.

Next, on the upper side of the disc 3, the hook-like member 14 with the O-ring 15 is attached to the outer periphery of the cylindrical portion 24. At this time, the flange portion 14b is fitted into the outer peripheral side of the cylindrical portion 24, and the upper O-ring 15 is assembled so as to contact the outer periphery of the shaft cylindrical portion 36.
Further, the ring body 13 is mounted on the outer periphery of the flange-shaped member 14 while the bottom surface is in contact with the upper surface of the flange portion 14b. Thereby, the metal ring body 13 holds the cylindrical portion 14a of the bowl-shaped member 14 from the outer peripheral side, and the diameter expansion of the cylindrical portion 24 is prevented.
In this state, the upper stem 4 is inserted inside the shaft tube portion 36 and connected to the disc 3.

The bearing 16, the upper spring 51, and the bearing member 70 are attached to the corresponding positions of the shaft mounting cylinder 11 of the upper body 2 a, and this bearing member 70 is attached in a retaining state by the retaining ring 71.
The holding body 5, the lower spring 50, and the top member 72 are attached to the corresponding positions of the attachment cylinder 12 of the lower body 2 b, and the top member 72 is attached in a retaining state by the retaining ring 71.

  Finally, the above-described sheet liner 10 with the disc 3, the bowl-shaped member 14, and the ring body 13 is disposed between the upper body 2 a and the lower body 2 b, and the bolt 6 is tightened and integrated with the sheet liner 10 sandwiched therebetween. By doing so, the assembly of the valve body 1 is completed.

  As described above, the valve body 1 has a structure in which stems are provided on the upper and lower sides of the disc by pivotally supporting the bottom stem portion 35 of the disc 3 in the mounting cylinder 12 below the body 2 in a non-penetrating manner. Compared with the type butterfly valve, the assembly performance is improved while increasing the flow rate, and the surface pressure in the lower seal area S1 is higher than the surface pressure in the upper seal area S2, thereby ensuring fluid leakage in the flow path direction. In particular, it is effective for a small-diameter butterfly valve in which the presence or absence of the lower stem greatly affects the flow rate securing and assemblability.

DESCRIPTION OF SYMBOLS 1 Valve body 2 Body 3 Disc 4 Upper stem 5 Holding body 7 Inner peripheral surface 10 Seat liner 11 Shaft mounting cylinder 12 Mounting cylinder 20 Bag-shaped part 30 Core metal 31 Protruding part 31a Lower surface 32 Resin lining 35 Bottom stem part 37 Upper boss Surface 38 Lower boss surface 40 Annular portion 40a Upper surface 41 Recessed portion 50 Lower spring 51 Upper spring D Bottom stem portion resin lining thickness D1 Flow path side resin lining thickness H Bottom stem portion height S1 Lower boss surface seal area S2 Sealing area of upper boss surface

Claims (5)

In the lining-type butterfly valve in which the upper and lower boss surfaces slide on the inner periphery of a resin sheet liner coated on the inner peripheral surface of the cylindrical body and the upper and lower boss surfaces are rotatably provided, the disc is the outer peripheral surface of the projecting portion projecting from the bottom of the substantially circular core metal and the metal core is formed by coating a resin lining portion bottom stem portion of the projecting portion covered with the resin lining In addition, a holding body is provided in a mounting cylinder provided in a lower portion of the body, and a bag-like portion provided integrally with the sheet liner is positioned in a recess formed on an upper surface of the holding body. A lining-type butterfly valve characterized in that the bottom stem portion is fitted to and supported by the bottom stem portion .   The spring force of the upper spring mounted on the shaft mounting cylinder on which the upper stem is mounted and the lower spring mounted on the mounting cylinder are substantially the same, and the sealing area of the lower boss surface is greater than the sealing area of the upper boss surface. The lining-type butterfly valve according to claim 1, wherein the sealing performance on the lower side of the disc is improved by decreasing the surface pressure of the lower boss surface. By increasing the spring force of the lower spring mounted on the mounting cylinder from the upper spring mounted on the shaft mounting cylinder on which the upper stem is mounted to increase the surface pressure of the lower boss surface, the sealing performance on the lower side of the disk is improved. The lining-type butterfly valve according to claim 1 or 2, which is improved. Lining Butterfly valve according to any one of claims 1 to 3 obtained by axially supporting the bottom stem portion between the lower surface of the projecting portion from an upper surface of the annular portion of the holding member with the recess. The lining-type butterfly valve according to any one of claims 1 to 4 , wherein a thickness of the resin lining of the bottom stem portion is set to be thinner than that of other resin linings.

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