JP6495243B2 - Butterfly valve seal structure - Google Patents

Description

  The present invention relates to a seal structure of a butterfly valve, and more particularly, to a seal structure in the vicinity of a seal portion between a valve blade and a valve box of a butterfly valve in which a resin lining is applied to a valve body and an inner peripheral surface of the valve box.

  In the butterfly valve, the seal around the stem shaft attachment part is secured by the boss part formed at the root of the stem shaft of the valve body and the boss part contact surface of the seat ring, and the valve blade outer peripheral surface of the valve body and the seat ring are secured. The valve blade contact surface provides a seal structure that ensures the peripheral surface sealability on the valve blade side with respect to the stem shaft attachment portion. When such a butterfly valve is used in a soda industry or semiconductor manufacturing plant to flow a highly corrosive fluid, or in a chemical fluid such as chlorine gas or hydrochloric acid, a chemical solution, a solvent, a food-related flow path, etc. In many cases, a resin lining is applied to the valve body and the inner peripheral surface of the valve box in contact with the fluid. As this resin lining material, a fluororesin with excellent chemical resistance and heat resistance is usually used. However, since fluororesin is poor in elasticity, the sealing performance on the peripheral surface on the valve blade side may be reduced and valve seat leakage may occur. There is. Therefore, in order to improve the sealing performance on the valve blade side of the butterfly valve, a rubber ring is arranged on the back side of the resin lining material, and the elastic repulsive force of this rubber ring is used to make the elastic force near the valve blade insufficient. In general, a butterfly valve that improves the sealing performance by compensating for the above has been proposed.

As this type of butterfly valve, for example, the butterfly valve of Patent Document 1 is disclosed. In this butterfly valve, a resin lining layer made of a fluororesin seat ring is provided on the inner surface of the valve body, which is a valve box, and a rubber backup ring is inserted between the seat ring and the valve body. An elastic force is exerted on the seal portion by the backup ring to ensure a sealing property with the valve body. When providing such a butterfly valve seal structure, a backup ring is mounted in a recessed groove formed in the valve body, and a seat ring is mounted on the body via this backup ring, and then this seat ring is mounted. The valve body is attached to the valve body through the stem.
In this butterfly valve, when the valve element is rotated by a stem operation and the valve blade side of the valve element is pressed against the seat ring, the seat ring is sealed with the backup ring while being compressed in the outer diameter direction together with the backup ring. Yes.

  A similar technique is also disclosed in Patent Document 2. In this butterfly valve, the radius of the outer peripheral edge of the valve body is equal to the radius of the inner peripheral surface of the valve seat tightened in the radial direction by an elastic member made of an annular rubber or the like, or from the radius of the inner peripheral surface of the valve seat Is set to be slightly larger.

JP 2003-166654 A JP 2012-219819 A

  However, the butterfly valve of Patent Document 1 requires a force for compressing the seat ring itself in addition to a force that resists the elastic force of the backup ring when the valve is closed, leading to an increase in operating torque. In this case, if the compression of the seat ring is suppressed, it is possible to reduce the operating torque while ensuring the sealing performance. However, the shape and structure for suppressing the compression of the seat ring are described and suggested. It has not been. Furthermore, the force for compressing the seat ring when the valve is closed increases as the thickness of the seat ring increases, and there is a problem that the operating torque further increases. For this reason, with this type of butterfly valve, it is difficult to improve the chemical resistance and heat resistance by providing a thick seat ring.

On the other hand, in the butterfly valve of Patent Document 2, the radius of the inner peripheral surface of the valve seat indicates a dimension in a state where an elastic member corresponding to a knock-up ring is mounted (see FIG. 2 of Patent Document 2). When the valve is closed, a force for compressing the seat ring itself is required in addition to the force resisting the elastic force of the backup ring as in the case of Patent Document 1.
In both Patent Documents 1 and 2, since the backup ring has a flat shape whose thickness is smaller than the width dimension, it is necessary to improve the backup ring in order to smoothly reduce or increase the diameter as the valve is opened and closed. It is.

  The present invention has been developed to solve the conventional problems, and the object of the present invention is to suppress the force of compressing the resin lining layer during the valve closing operation while improving the sealing performance particularly near the valve blades. An object of the present invention is to provide a sealing structure for a butterfly valve that can be opened and closed while securing sealing performance with a certain low operating torque even when the thickness of the resin lining layer is increased.

  In order to achieve the above object, the invention according to claim 1 provides a lining layer made of a resin material on a disk surface and an inner peripheral surface of a body that rotatably supports the disk. A butterfly valve for mounting a stem in a valve shaft hole provided at a diametrically opposed position of a seat liner, which is a lining layer, and sealing at least the valve blade portion of the disc to the inner peripheral surface of the body when the stem is rotated. In the seal structure, a seat liner is covered on the inner peripheral surface of the body with a backup rubber on the inner peripheral side. The inner diameter of this seat liner is smaller than the outer diameter of the disc due to the elastic force of the backup rubber when the valve is opened. On the other hand, the inner diameter of the seat liner when the valve is closed is the elasticity of the backup rubber when the disc presses the seat liner. In it sets the inner diameter before deformation to the small diameter, a sealing structure of a butterfly valve provided with a inner diameter before the deformation disuccinimidyl outer diameter and the same diameter (including the tolerance).

  The invention according to claim 2 is a butterfly that makes it easy to restore the inner diameter of the seat liner to the inner diameter before deformation when the valve is closed by providing the thickness of the backup rubber substantially the same as or slightly longer than the width of the backup rubber. This is a valve seal structure.

  According to the third aspect of the present invention, when the inner diameter of the seat liner is restored to the inner diameter before deformation when the valve is closed, the bulging portion in which the backup rubber bulges in the width direction as the diameter increases is formed between the body and the seat liner. It is a seal structure of a butterfly valve adapted to be accommodated in a gap portion provided therebetween.

  The invention according to claim 4 is the butterfly valve seal structure in which the width of the back-up rubber is set to be approximately the same as the disc blade difference value.

  The invention according to claim 5 is the butterfly valve seal structure in which the lining layer is a fluororesin.

  The invention according to claim 6 provides a taper surface of a predetermined angle on both sides of the valve blade side tip of the disc lining which is a disc side lining layer, and forms a seal portion that presses and seals the seat liner between these taper surfaces, This is a seal structure of a butterfly valve in which the width of the seal portion is set to be approximately the same as the width of the disc on the front end side of the metal core.

  According to the first aspect of the invention, the inner diameter of the seat liner is restored to the inner diameter deformed to be smaller than the outer diameter of the disc by the elastic force of the backup rubber when the valve is opened, and the disc is pressed when the valve is closed. The inner diameter before deformation to a small diameter by the elastic force of the backup rubber, and the inner diameter before this deformation is set to the same diameter (including tolerance) as the disk outer diameter, compresses the resin lining layer during valve closing operation. It is possible to prevent an increase in the operating torque without requiring a force to perform. Moreover, even when the thickness of the resin lining layer is increased, the valve can be operated in a closed state without applying a force for compressing the lining layer, so that the opening / closing operation can be easily performed with a constant low operating torque.

  According to the second aspect of the present invention, the thickness of the backup rubber is set to be approximately the same as or slightly longer than the width, so that there is a large room for deformation in the radial direction. Since the inner diameter of the seat liner is easily restored to the inner diameter before deformation by reducing or expanding the diameter, it is possible to prevent an increase in operating torque.

  According to the third aspect of the present invention, by accommodating the expanded portion of the expanded back-up rubber in the gap portion, it is possible to exhibit an even pressure sealing force and maintain a reasonable sealing state.

  According to the invention of claim 4, within the range where the back-up rubber is provided, it is possible to ensure the sealing performance between the seat liner and the disc when the valve is closed and to prevent the valve seat from leaking, and the disc rotates completely to the closed state. Even if not, it absorbs the error and exhibits high sealing performance.

  According to the invention which concerns on Claim 5, the operating torque at the time of a valve closing operation can be restrained low, improving chemical resistance and heat resistance by making a lining layer into a fluororesin, and by the disc seal of this lining layer Durability can be improved by suppressing wear and deterioration.

  According to the invention of claim 6, when the valve is closed, the pressing force is transmitted almost uniformly from the cored bar to the disc lining which is the sealing surface with the seat liner, and excellent torque characteristics are exhibited by the uniform surface pressure sealing force. However, the sealing performance between the valve blade and the inner peripheral surface of the body is improved to prevent the valve seat leakage.

It is a partially cutaway perspective view of a butterfly valve. It is a center longitudinal cross-sectional view of the butterfly valve of FIG. FIG. 2 is a central lateral enlarged sectional view of the butterfly valve of FIG. 1. FIG. 3 is a central longitudinal sectional view of the butterfly valve of FIG. 2. It is a principal part expanded sectional view of FIG. FIG. 4 is a partially omitted cross-sectional view showing a seat liner mounted state in the central lateral enlarged cross-sectional view of FIG. 3. It is sectional drawing which shows the state in which the disc in FIG. 3 rotated. It is the partially expanded sectional view which showed the valve blade part vicinity of a disk. It is sectional drawing which shows a sheet liner. It is a center cross-sectional view which shows the comparative example of a butterfly valve. (A) is a perspective view which shows a sheet liner. (B) is a longitudinal cross-sectional view of a sheet liner. (A) is a perspective view which shows a disc. (B) is a longitudinal cross-sectional view of a disc. It is sectional drawing which shows the state which deform | transformed the sheet liner. It is AA sectional drawing of FIG. (A) is a perspective view of a seat liner equipped with a disc. (B) is a longitudinal cross-sectional view of a seat liner equipped with a disc. (A) is a perspective view of a seat liner equipped with a stem. (B) is a longitudinal sectional view of a seat liner equipped with a stem. It is the side view which showed the backup rubber.

DESCRIPTION OF SYMBOLS 1 Valve body 2 Disc 3 Body 4 Backup rubber 5 Stem 10 Lining layer 11 Seat liner 12 Disc clinking 12a Inclined surface 12b Tapered surface 12c Seal part 13 Valve shaft hole 20 Valve blade part φD1 Disc outer diameter φd2 Inner diameter φd1 Seat liner inner diameter when the valve is closed L Backup rubber width S Valve blade differential value Wa Seal width Wb Disc core width

  Hereinafter, preferred embodiments of the seal structure of the butterfly valve according to the present invention and the operation thereof will be described in detail with reference to the drawings. 1 and 2 show an example of a butterfly valve using the seal structure of the present invention, and FIG. 3 shows an enlarged cross-sectional view of the center of the butterfly valve of FIG. Hereinafter, description will be made while showing an example of dimensions of a butterfly valve having a nominal diameter of 100A.

  The butterfly valve (hereinafter referred to as a valve body 1) in FIG. 1 is used, for example, in a semiconductor manufacturing plant, a food-related pipeline, or the like. The valve body 1 includes a stem 2 including a disc 2, a cylindrical body 3, a backup rubber 4, an upper stem 5 a and a lower stem 5 b, and the disc 2 can rotate via the surface of the disc 2 and the backup rubber 4. A lining layer 10 including a seat liner 11 and a disc lining 12 is provided on the inner peripheral side of the body 3 that is pivotally supported on the body.

  As shown in FIG. 5, in the valve body 1, a stem 5 is mounted in a valve shaft hole 13 provided at a position opposite to the diameter direction of the seat liner 11, and in the vicinity of the stem shaft mounting portion 14, the rotation of the stem 5 is performed. During operation, the boss 15 provided on the disk 2 side and the boss seal surface 16 provided on the body 3 side seal the top and bottom of the disk 2, thereby ensuring the sealing performance of a so-called top-and-bottom seal (primary seal). The As shown in FIG. 3, the valve blade portion 20 of the disc 2 and the inner peripheral seal surface 21 of the body 3 are pressed and sealed in the circumferential direction on the inner peripheral side of the valve body 1. The peripheral sealing property on the 20 side is ensured, and valve seat leakage is prevented.

  1 to 5, the disk 2 of the valve body 1 has a cored bar 22, and the cored bar 22 is formed in a disk shape using, for example, a stainless alloy. The core metal 22 is covered with the disc lining 12 with a thickness of, for example, about 3 mm, and the disc lining 12 becomes the surface of the disc 2, that is, the lining layer 10 on the liquid contact side. The disc lining 12 is made of a resin material, and in this embodiment, is provided with a fluororesin such as PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer), and can exhibit high corrosion resistance and heat resistance. The disc lining 12 is integrally covered on the outer periphery of the front and back surfaces of the cored bar 22 through a through hole 23 formed at an appropriate position of the cored bar 22, and is prevented from being detached from the cored bar 22.

  As shown in FIGS. 2, 4, and 5, on the top of the disk 2, a hexagonal rectangular hole 24 for inserting the upper and lower stems 5 a and 5 b is provided on the top of the lining cylindrical portion 26 described later. It is formed as a hole. Hexagonal square portions formed as connecting portions 25 are respectively inserted and fitted into the stem hole portions 24 at the tip ends of the upper and lower stems 5a and 5b, whereby the disc 2 is inserted into the upper and lower stems 5a and 5b. Is pivotally mounted in the body 3 via the. With such an attachment structure, the upper and lower stems 5a and 5b are provided to be detachable from the disc 2 mounted on the body 3. The stem hole 24 on the disk 2 side and the connection part 25 on the upper and lower stems 5a, 5b side may be polygonal shapes other than hexagonal shapes as long as they can be fitted to each other. It can be provided in various fitting structures in which the upper and lower stems and the disc can be disassembled, such as spline connection.

  4 and 5, a lining cylindrical portion 26 is formed integrally with the disc lining 12 on the insertion side of the upper and lower stems 5 a and 5 b of the disc lining 12 on the top of the disc 2. The lining cylindrical portion 26 covers the connection side of the upper and lower stems 5a and 5b in the axial direction.

  As shown in the partially enlarged cross-sectional view of FIG. 8, inclined surfaces 12a are provided on both sides of the disc lining 12 from the center side of the disc 2 to the vicinity of the distal end side, and the valve blade portion 20 follows the inclined surface 12a. A tapered surface 12b is provided at a predetermined angle at the side tip. Between the tapered surfaces 12b on both sides, a seal portion 12c is formed in the vertical direction in the figure, and this seal portion 12c can be pressed against the seat liner 11 when the valve is closed.

  In the present embodiment, the tapered surface 12b is provided with an inclination angle α from the inclined surface 12a, and the inclination angle α is set to 20 °. In this case, the inclination angle β from the vertical surface side is provided to be 45 °, so that the width Wa of the seal portion 12c and the width Wb of the distal end portion 22a of the cored bar 22 are provided at substantially the same width W. It has been. For example, when the width Wb on the front end side of the cored bar 22 is 3 mm, the width Wa of the seal portion is also set to 3 mm. Thus, the seal portion 12c is formed into a sheet by the structure in which the front end side of the disk is width Wa = width Wb. The force received by the press with the liner 11 can be received at the tip 22a of the core metal 22 with the same width as the seal portion 12c, preventing a decrease in the seal surface pressure at this portion, and high torque performance and seal when the valve is closed. A seal structure having both properties is provided. The outer diameter φD1 (see FIG. 3) of the disc 2 on which the disc lining 12 is formed is provided at an outer diameter of φ100 mm in the present embodiment.

  As shown in FIGS. 1 and 2, the body 3 to which the above-described disc 2 is mounted includes an upper body 3 a and a lower body 3 b, which are formed by cast iron such as ductile cast iron and are mutually connected by bolts 27. It is detachably fixed. Shaft mounting holes 28, 28 are provided on the stem 5 shaft mounting side of the upper and lower bodies 3a, 3b, and the upper and lower stems 5a, 5b are mounted in the shaft mounting holes 28, respectively. Following this shaft mounting hole 28, mounting recesses 29 and 29 having an enlarged diameter are provided on the holding side of the disc 2, and a sealing bush 30, a seal member 31, a disc spring 32, and a plate member are provided through the mounting recess 29. 33 is mounted as a shaft seal member 17 and a bearing 34 is mounted thereon.

  A mounting groove 35 having a width of 10 mm and a depth shallower than the thickness of the backup rubber 4 is formed on the peripheral surface seal side of the valve blade portion 20 of the upper and lower bodies 3a and 3b. The backup rubber 4 is formed in the mounting groove 35. Removably mounted. Bolt holes 36 that can be fixed to each other by bolts 27 are provided on both sides of the upper and lower bodies 3a and 3b.

  The seat liner 11 shown in FIG. 9 is mounted on the inner peripheral side of the body 3 while covering the body 3 with a thickness of 3 mm, for example, and this sheet liner 11 becomes the lining layer 10 on the liquid contact surface side. The sheet liner 11 is made of a resin material. In the present embodiment, as in the case of the disc lining 12, the sheet liner 11 is provided by a fluororesin such as PFA. The seat liner 11 includes an annular portion 40 that is mounted on the inner peripheral side of the body, and flange portions 41 that are formed so as to protrude from both outer peripheral edges of the annular portion 40. Shaft-mounted cylinder portions 42 and 42 are formed at the mounting position, and upper and lower stems 5a and 5b are respectively provided in the shaft-mounted tube portion 42 so as to be insertable.

The boss seal surface 16 is formed so as to project in the axial direction of the stem 5 on the axial side of the upper and lower stems 5a, 5b and the disc 2 on the inner circumference of the annular part 40. The inner circumferential sealing surface 21 having an arc shape is formed on the side of the valve blade portion 20 that contacts the sealing portion 12c so as to sandwich the partial sealing surface 16 therebetween.
The inner peripheral sealing surface 21 is a plane parallel to the axial direction of the flow path, and the seal portion 12c of the disk 2 is a part of a spherical surface concentric with the disk-shaped disk 2 in an R shape. Is formed. The valve seat seal constituted by the inner peripheral seal surface 21 and the seal portion 12c is a so-called “line seal” in which the contact area of both portions is linearly thin, so that the frictional force is small, and the operation when the valve is closed is performed. This contributes to keeping the torque increase low.

  The inner peripheral seal surface 21 in the present embodiment is provided such that the inner diameter φd1 in FIG. 6 formed by the locus thereof is φ100 mm, and the width L of the inner peripheral seal surface 21 is provided at 10 mm in FIG. 6B. . On the back side of the inner peripheral seal surface 21, a backup rubber 4 is disposed between the inner peripheral seal surface 21 and the body 3, and the inner peripheral seal surface 21 of the seat liner 11 is pressed in a direction to reduce the diameter by the backup rubber 4.

  The two left and right backup rubbers 4 and 4 shown in FIG. 3 are formed to have a width and a length dimension that can be attached to the attachment groove 35 by, for example, fluororubber, and in FIG. Arranged on the left and right sides. In FIG. 7, the backup rubber 4 is provided with a width substantially the same as the valve blade difference value S of the disc 2, and is provided with a length substantially the same as the width L of the inner peripheral seal surface 21 on the valve blade seal side. In FIG. 6B, the thickness T of the backup rubber 4 is set to the same dimension as the width L, and the width L and the thickness T in this embodiment are set to about 10 mm. Here, the valve blade difference value S indicates the limit value of the inclination of the valve blade portion 20 that can be closed with the disc 2, and the length S1 from the end surface of the body 3 to the tip of the valve blade portion 20 on one end side. And the length S2 from the end face of the body 3 to the tip of the valve blade 20 on the other end side.

  The thickness T of the backup rubber 4 is set to the same dimension as the width L as described above, so that an appropriate crushing allowance is secured for a certain crushing rate. If the thickness T is thin, the fluctuation range of the crushing rate increases due to the dimensional variation, and the operation torque at the time of closing the valve suddenly increases or the sealing is likely to deteriorate.

On the other hand, if the thickness T is too thick, the mounting groove 35 must be set to a deep dimension under the condition that the maximum outer diameter and the minimum outer diameter of the body 3 are limited by the dimensions of the pipe, and the body pressure resistance strength is reduced. There is a possibility that the minimum wall thickness for satisfying cannot be secured. On the other hand, if it is too thick, the influence of thermal expansion becomes large, and the operating torque when the valve is closed may increase suddenly.
Therefore, the thickness T of the backup rubber is preferably set in a range of 0.9L ≦ T ≦ 1.1L, and is preferably set to T = L or T ≦ 1.1L.

  As described above, the thickness T of the backup rubber 4 is set to be approximately the same as or slightly longer than the width L of the backup rubber 4, and the backup rubber 4 is narrower than the flat backup rubber 4 as in the prior art. By using the rubber 4, it becomes easy to expand the diameter, and it becomes easy to restore the inner diameter of the seat liner 11 to the inner diameter before the deformation when the valve is closed, thereby preventing an increase in operating torque.

  The inner circumferential dimension x of the backup rubber 4 shown in FIG. 17 is formed to have substantially the same dimension as the arc length y corresponding to the central diameter of the mounting groove 35 shown in FIG. The entire end 4a of the backup rubber 4 is cut obliquely so that the entire surface of the end 4a can be brought into close contact with the outer peripheral surface of the sealing bush 30. With these configurations, the back-up rubber 4 mounted in the mounting groove 35 is not locally bent, and the back surface of the inner peripheral seal surface 21 of the seat liner 11 is pressed uniformly.

Here, in order to show the feature of the seal structure in the present invention, it will be described in three states.
As shown in FIG. 6A, if the seat liner 11 is attached to the body 3 without the backup rubber 4 and the disc 2 attached, that is, when the seat liner 11 is formed, the inner peripheral seal of the seat liner 11 is provided. The inner diameter φd1 of the surface 21 is set to φ100 mm which is the same diameter as the disk outer diameter φD1.

  At this time, in the figure, the distance HA from the bottom surface of the mounting groove 35 to the inner peripheral seal surface 21 is approximately 11.7 mm, and the distance HB from the bottom surface of the mounting groove 35 to the back surface of the inner peripheral seal surface 21 is It becomes about 8.7 mm. Accordingly, the thickness of the inner peripheral sealing surface 21 of the seat liner is 3 mm. In this state, a gap G ′ is provided between the body 3 and the seat liner 11. The gap G ′ serves as a space for accommodating a bulging portion 37 (described later) at the inner peripheral edge of the backup rubber 4 pressed by the disc 2 via the seat liner 11 at the adjacent position when the valve is closed.

  As shown in FIG. 6B, if the seat liner 11 provided with the backup rubber 4 is attached to the body 3 without mounting the disc 2, the seat liner 11 is contracted by the elastic force of the backup rubber 4. The inner diameter of the inner peripheral seal surface 21, that is, the inner diameter φd2 of the middle-high portion 45 where the seal portion 12c of the so-called disc 2 is pressure-contact sealed is reduced from φ100 mm to φ97.4. At this time, the distance HA1 from the bottom surface of the mounting groove 35 to the inner peripheral seal surface 21 changes from 11.7 mm to 13 mm, but the thickness 3 mm on the inner peripheral seal surface 21 of the seat liner 11 is maintained.

  When the backup rubber 4 is mounted on the body 3, as described above, since the depth of the mounting groove 35 is shallower than the thickness T of the backup rubber 4, the backup rubber 4 is located on the inner peripheral side. In a protruding state, it contacts the back surface of the inner peripheral sealing surface 21 of the seat liner 11, and a gap G is provided between the seat liner 11 and the body 3. That is, the gap portion G is obtained by adding a space for restoring the reduced diameter of the sheet liner 11 to the state shown in FIG.

  3, in the case of the valve body 1 in which the disc 2 is attached to the body 3 provided with the seat liner 11 via the backup rubber 4, the seat liner 11 is opened and closed according to the rotational state of the disc 2. The inner diameter is different. When the valve is opened, the elastic force of the backup rubber 4 deforms in the direction of diameter reduction, so that the inner diameter of the middle and high portions 45 of the seat liner 11 is deformed to a smaller diameter than the disk outer diameter φD1 as described above. The inner diameter in the state of b) is 97.4 mm. On the other hand, when the valve shown in FIG. 3 is closed, the disc 2 presses the seat liner 11 against the elastic force of the backup rubber 4, so that the inner diameter of the middle high portion 45 of the seat liner 11 is increased by the pressing of the disc. The inner diameter before the deformation is restored, and the inner diameter φd1 before the deformation becomes the same disk outer diameter φD1 as the state of FIG. At this time, the distance HA from the bottom surface of the mounting groove 35 to the inner peripheral seal surface 21 is approximately 11.7 mm, and the distance HB from the bottom surface of the mounting groove 35 to the back surface of the inner peripheral seal surface 21 is approximately 8.7 mm. Accordingly, the thickness of 3 mm on the inner peripheral seal surface 21 of the seat liner 11 is maintained.

  Thus, when the disc 2 presses the seat liner 11 and closes the valve seat when the valve is closed, the middle high portion 45 (inner peripheral seal surface 21) of the seat liner 11 is not attached with the backup rubber 4. That is, only the dimensions at the time of forming the seat liner 11 are returned, and the seat liner 11 is not compressed, so that the seat liner 11 does not have permanent distortion, and a good inner peripheral seal surface 21 is maintained, and a high valve seat seal is maintained. Sex can be maintained for a long time.

Moreover, since the torque required for the valve closing operation is generated only by the force that elastically deforms the backup rubber 4 in the diameter expansion direction, the operating torque is greatly reduced, and this reduced operating torque is maintained over a long period of time. Can do.
These characteristics do not depend on the thickness of the seat liner 11. For example, if the butterfly valve having a large diameter exceeding the nominal diameter 125 A is increased to a thickness of about 4 mm, the thickness is within 5 mm. Even if it is set to, high valve seat sealing performance and low torque performance can be maintained.

  In the above-described peripheral seal portion formed by the valve blade portion 20 of the disc 2 and the inner peripheral seal surface 21 of the body 3, when the disc 2 is rotated from the closed state to the valve open side in FIG. In the range where the blade difference value S is rotated (the range in which the middle and high portions 45 are provided), the backup rubber 4 is formed in the same width dimension as the inner peripheral seal surface 21 as described above. The elastic force is exerted to ensure high sealing performance. Also in the range of the valve blade difference value S, the compression of the seat liner 11 is prevented as in the above case, and the sealing performance and the operating torque performance are ensured.

  In any of the valve closing seals, when the inner diameter of the seat liner 11 is restored to the inner diameter before deformation when the valve is closed, a bulging portion 37 in which the backup rubber 4 bulges in the width direction as the diameter increases is provided. The gap 3 ′ between the body 3 and the seat liner 11 is deformed so as to be crushed and accommodated in the gap G ′. For this reason, a uniform pressure sealing force is exhibited over the circumferential direction, and an unreasonable sealing state can be maintained.

  Here, FIG. 10 shows a comparative example for comparison with the seal structure of the butterfly valve of the present invention. When the seat liner 50 is attached to the body 3 in a state where the backup rubber 4 and the disc 2 are not attached in FIG. 10A, the seat liner 50 extends from the bottom surface of the attachment groove 35 to the back surface of the inner peripheral seal surface 51. The distance HC is 10 mm, and the inner diameter seal surface 51 has an inner diameter φdA1 of φ97.4 mm. As a result, even if the backup rubber 4 having a thickness of 10 mm is mounted in the mounting groove 35, no force in the direction of diameter reduction is applied from the backup rubber 4.

  In FIG. 10B, when the seat liner 50 is attached to the body 3 via the backup rubber 4, the diameter of the seat liner 50 is reduced due to the elastic force of the backup rubber 4, and the inner peripheral sealing surface 51. The inner diameter is reduced. Then, the disc 2 is attached to the body 3, and when the valve is opened, the inner diameter φdA2 of the inner peripheral seal surface 51 is smaller than φ97.4 mm. The diameter is enlarged to φ100 mm.

  Thus, in the case of the seat liner 50 in which the inner diameter φdA1 before deformation by the disc 2 is smaller than the disc outer diameter φD1, in addition to the pressing deformation of the backup rubber 4 when the disc 2 is rotated to the valve closed state, An extra force is required to compress the seat liner 50, that is, to elastically deform the seat liner 50 by reducing its thickness. In addition, as the seat liner 50 becomes thicker, the compression force increases, and the operating torque increases in proportion to the thickness of the seat liner 50. However, since the operating torque has an allowable limit, it is difficult to set the thickness of the seat liner 50 to a certain level or more. On the other hand, if the thickness of the sheet liner 50 is reduced, it becomes difficult to satisfy chemical resistance and heat resistance necessary for permeation resistance degradation.

  In addition, when the maximum torque at the time of valve closing operation of the butterfly valve having the nominal diameter of 100A in the present embodiment and the butterfly valve having the same nominal diameter corresponding to FIG. 10 was measured, the butterfly valve of the present embodiment corresponds to FIG. It was confirmed that about 23% torque reduction can be achieved for the same nominal diameter butterfly valve.

  Next, at the shaft seal seal portion of the stem 5 of the seat liner 50, as shown in FIG. 9B, an outer peripheral tapered surface 60 at the outer peripheral tip of each shaft-mounted tube portion 42 is provided at an appropriate angle. The shaft-mounted tube portion 42 is formed in a wedge shape by the tapered surface 60, and the base portion 64 of the shaft-mounted tube portion 42 is provided thicker than the outer peripheral tapered surface 60. Furthermore, the height of the shaft mounting cylinder portion 42 is relatively short. With such a shape, when an external force is applied to the outer peripheral tapered surface 60 from the outer peripheral direction, only the vicinity of the outer peripheral tapered surface 60 is deformed, and deformation near the base of the shaft mounted tubular portion 42 is prevented, thereby preventing the shaft mounted cylinder. The roundness of the valve shaft hole 13 that is a stem insertion hole formed in the inner periphery of the portion 42 is ensured without deformation.

  An annular projecting seal portion 61 projecting toward the inner periphery is provided on the inner periphery of each shaft-mounted cylinder portion 42, and the projecting seal portion 61 is provided on the outer periphery of the lining cylindrical portion 26 so as to be capable of pressure contact sealing. ing. Thereby, the sealing force in the vicinity of the projecting seal portion 61 is increased, and leakage between the shaft-mounted cylinder portion 42 and the lining cylinder portion 26 is prevented.

  An annular groove 62 is formed on the outer peripheral side of the base portion of the shaft-mounted cylinder portion 42 so as to be recessed, and the shaft-mounted tube portion 42 is formed so as to protrude from the annular portion 40 via the annular groove portion 62. The By providing the annular groove 62, a shaft-mounted cylinder can be obtained even when a force is applied to the seat liner 11 to deform the annular portion 40 and the flange portion 41 into a substantially elliptic shape in the mounting direction of the upper and lower stems 5a, 5b. The portion 42 is less susceptible to the influence and deformation is prevented.

  4 and 5, the mounting bushes of the upper and lower body 3a, 3b in which the sealing bush 30, which is the shaft sealing member 17, the sealing member 31, the disc spring 32, and the plate member 33 are covered with the above-described sheet liner 11, are provided. 29, and is positioned and held in a state where the upper and lower stems 5a and 5b are respectively inserted into the inner periphery thereof. The bearing 34 is provided between the upper and lower stems 5a and 5b and the shaft mounting hole 28 so as to be interposed from the annular groove 62 side at a position farther than the mounting recess 29 of the upper and lower body 3a and 3b. The bearing 34 makes the upper and lower stems 5a and 5b rotate smoothly.

  The disc spring 32 is provided with an outer diameter that can be mounted on the mounting recess 29 by, for example, surface-treated spring steel, and is disposed on the distal side of the sealing bush 30 of the mounting recess 29. Between the disc spring 32 and the sealing bush 30, for example, a flat plate member 33 made of stainless steel is provided. Through the plate member 33, the pressing force by the disc spring 32 is on the upper surface side of the sealing bush 30. The above-mentioned ceiling seal (primary seal) functions.

  The sealing bush 30 is formed in a substantially annular shape that can be attached to the attachment recess 29 by using, for example, a fluororesin such as carbon-containing PTFE (polytetrafluoroethylene), and is attached to the attachment recess 29 so as to be in direct contact with the seat liner 11. An inner peripheral taper surface 63 is formed on the lower side of the inner periphery of the sealing bush 30 facing the outer peripheral taper surface 60. The inner peripheral taper surface 63 and the outer peripheral taper surface 60 have the same inclination with respect to the vertical surface. It is provided at an angle θ and seals by pressure contact by surface contact. In the present embodiment, the inclination angle θ between the inner circumferential tapered surface 63 and the outer circumferential tapered surface 60 is set to 20 °, and when the pressing force is applied to the sealing bush 30 by the disc spring 32, these inner circumferential tapered surfaces. Due to the wedge effect of the surface 63 and the outer peripheral tapered surface 60, a pressing force due to a component force is generated in the direction of the stem diameter. With this pressing force, the shaft-mounted cylindrical portion 42 is brought into close contact with the lining cylindrical portion 26. The shaft seal (secondary seal) functions by being in close contact with the outer peripheral surface of the stem 5. Furthermore, an annular projection (not shown) may be provided on the inner peripheral side of the lining cylindrical portion 26. In this case, the surface pressure of the shaft seal can be increased.

  A seal member 31 is mounted between the sealing bush 30 and the lining cylinder portion 26 on the inner circumference upper side. The seal member 31 includes a metal coil spring 65 formed of a corrosion-resistant metal and an annular cover member 66 formed of fluororesin, and the annular mounting groove 67 formed in the cover member 66. It is inserted into and integrated. With this configuration, the sealing member 31 is provided so as to be able to exert an elastic sealing force in the radial direction while the low elastic force of the fluororesin is supplemented by the elastic force of the coil spring 65, and by the elastic force of the coil spring 65 at a low pressure, When the pressure is high, a high sealing force is exhibited by the fluid pressure and the elastic force of the coil spring 65.

  With this seal member 31, the inner peripheral taper surface 63 of the sealing bush 30 is brought into close contact with the outer peripheral taper surface 60 of the shaft-mounted tube portion 42, while the inner peripheral side of the lining cylindrical portion 26 is brought into close contact with the outer peripheral surface of the stem 5. (Tertiary seal) functions, and the dynamic sealability during rotation of the upper and lower stems 5a and 5b is ensured while ensuring chemical resistance and resistance to ultra-high temperature and ultra-low temperature. In order to secure the position of the tertiary seal between the seal member 31 and the lining cylindrical portion 26, the length of the lining cylindrical portion 26 needs to reach this position. Is determined.

  The seal member 31 according to the present embodiment has an opening 31 a disposed toward the outside of the disk 2. Thereby, even if the performance of the primary seal and the secondary seal described above is deteriorated and the fluid reaches the seal member 31, the tertiary seal function can be maintained without the coil spring 65 of the seal member 31 coming into contact with the liquid. Such an arrangement direction of the seal member 31 is particularly effective when a liquid that is highly likely to corrode metal is handled.

  As shown in FIG. 5, a first gap 71 and a second gap 72 are formed between the sealing bush 30 and the shaft-mounted cylinder portion 42 of the seat liner 11. By providing the first gap portion 71 and the second gap portion 72, when the tightening force of the body 3 is increased in order to increase the shaft sealing force when the disc 2 is mounted on the body 3, the disc lining 12 side A strong pressing force is applied to the sheet liner 11 to release the deformed lining layer 10 meat. Specifically, the shaft mounting cylinder portion 42 in which the first gap portion 71 is deformed, the lining cylinder portion 26, and a space for escaping the meat of the sealing bush 30, and the sealing bush 30 in which the second gap portion 72 is deformed, the shaft mounting It becomes a space for escaping the meat of the cylinder part 42. By providing the first gap portion 71 and the second gap portion 72, the pressure contact force between the seal portions is not increased more than necessary, and high sealing performance is exhibited while the operation torque is suppressed.

  Since the first gap 71 and the second gap 72 are provided between the seat liner 11 and the sealing bush 30, the deformed meat escapes when a strong pressing force is applied by the disc spring 32, The resistance during rotation is relaxed and the operating torque is reduced. Further, the parts are prevented from being damaged, deformed or broken, and high sealing performance at both the upper and lower shaft seal parts is maintained.

  As described above, the seal structure of the valve body 1 is such that the inner diameter of the seat liner 11 when the valve is opened is deformed to be smaller than the disk outer diameter φD1 by the elastic force of the backup rubber 4, and the inner diameter of the seat liner 11 when the valve is closed. φd1 is the inner diameter before it is deformed to a small diameter by the elastic force of the backup rubber 4, and the inner diameter φd1 before this deformation is the same as the disk outer diameter φD1 (including tolerance) or slightly larger than the disk outer diameter φD1. As a result, no force is applied to compress the seat liner 11 from the seal portion on the outer periphery of the disc 2 when the valve is closed, so that an increase in operating torque can be prevented while ensuring high sealing performance. In addition, even when the thickness of the resin lining layer 10 is increased, the valve can be operated in a closed state without applying a force for compressing the lining layer 10, so that the opening / closing operation can be easily performed with a constant low operating torque.

  In this case, by providing the lining layer 10 with a fluororesin, the operation torque at the time of closing the valve is kept low while improving the chemical resistance and heat resistance, and the wear and deterioration at the time of sealing the disc 2 are suppressed. Durability can be improved.

In this embodiment, the inner diameter φd1 of the inner peripheral seal surface 21 of the seat liner 11 is set to φ100 mm, which is the same diameter as the disk outer diameter φD1, but each component has a processing tolerance of about ± 0.1 mm. There is.
Therefore,
The outer diameter φD1 of the disk 2 is φ99.9 mm, whereas the inner diameter φd1 of the inner peripheral seal surface 21 of the seat liner 11 is φ100.1 mm.
The outer diameter φD1 of the disc 2 is φ100.1 mm, whereas the inner diameter φd1 of the inner peripheral seal surface 21 of the seat liner 11 is φ99.9 mm.
As described above, the case where the inner diameter φd1 of the inner peripheral seal surface 21 of the seat liner 11 is substantially the same diameter as the outer diameter φD1 of the disc 2 is a structure in which the seat liner 11 is not compressed and sealed when the valve is closed. It is included in the present invention.
Further, the inner diameter φd1 of the inner peripheral seal surface 21 of the seat liner 11 is equal to the outer diameter φD1 of the disc 2 so that the inner diameter of the inner peripheral seal surface 21 of the seat liner 11 is φ102 mm, whereas the outer diameter φD1 of the disc 2 is φ100 mm. A case with a slightly larger diameter, which is about 2% larger than the above, has a structure in which the seat liner 11 is not compression-sealed when the valve is closed, and is included in the present invention.

If the value when the inner diameter φd1 of the seat liner 11 is larger than the outer diameter φD1 of the disc 2 exceeds 2%, the change in the diameter before and after the seat liner 11 is deformed to a small diameter by the elastic force of the backup rubber 4. Since it becomes large, durability may be affected.
Therefore, the inner diameter φd1 before the seat liner 11 is deformed to a small diameter by the elastic force of the backup rubber 4 is substantially the same as the disc outer diameter φD1 from the viewpoint of ensuring the sealing performance with the disc 2 and the durability of the seat liner 11. Is preferred. The inner diameter φd1 before deformation of the seat liner 11 in the present embodiment may be set to 99.9% to 102%, and more preferably set to 100% to 102% with respect to the disc outer diameter φD1. Good.

Next, the manufacturing method of the valve body 1 described above will be described.
The valve body 1 described above can be formed through a deformation process, a centering process, a cylindrical part insertion process, a stem connection process, a body integration process, and a stem positioning process.
FIG. 11 shows the above-described seat liner 11 that can seal the outer peripheral side of the disc 2 shown in FIG. 12. First, the seat liner 11 is deformed in a deformation process.

  13 and 14 show a state in which the seat liner 11 is deformed by an external force, and the sheet liner 11 is deformed into an oval shape by applying an external force in a normal temperature state. Before applying the external force, as shown in FIG. 13, the disk 2 is rotated to the fully open state, and when applying the external force, the outer periphery of the seat liner 11 is parallel to the flange portion 41 of the seat liner 11. In addition, the back surface of the inner peripheral seal surface 21 of the seat liner 11 is pressed between the vise base 90 from a direction orthogonal to the axis of the shaft-mounted tube portion 42, and the direction of the shaft-mounted tube portion 42 is the long side. To be transformed into an ellipse.

In this case, the long side R1 of the inner peripheral seal surface 21 of the seat liner 11 deformed in an elliptical shape is pressed from the outside so as to be longer than the full length R2 including the lining cylindrical portion 26 of the disc 2.
This pressing operation may be performed directly by the operator's hand, but it is preferable to use an apparatus that can hold the seat liner in an elliptical shape, such as a vise or a vice. By holding the sheet liner 11 in an elliptical shape in this manner, the centering operation with the disc 2 during the centering process described later is facilitated.

  As the magnitude of the force applied to the sheet liner 11 at the time of pressing, a state in which the elastic force of the sheet liner 11 can be maintained, specifically, from an ellipse to a perfect circle or a state close to a perfect circle by releasing the press as described later. The force is set so that it can be restored, that is, in a so-called elastically deformable range. The seat liner 11 does not need to be completely round before assembly, and may be round after being assembled in the body 3 and providing the valve body 1.

  As described above, the shaft-mounted tube portion 42 is formed short, and the shaft-mounted tube portion 42 is provided with the outer peripheral tapered surface 60 so that the base portion 64 of the shaft-mounted tube portion 42 becomes thicker. By providing 62, deformation of the valve shaft hole 13 is prevented when the stem is sandwiched between the cap portions 90, and the roundness thereof is maintained.

  Subsequently, in the centering step, the disc 2 is inserted into the inner periphery of the sheet liner 11 in a deformed state. At this time, the axis of the lining cylinder portion 26 on the disk 2 side and the axis of the shaft mounting cylinder portion 42 on the seat liner 11 side are parallel to each other, and the opening side of each valve shaft hole 13 in the disk 2 and the top and bottom The disc 2 is moved to the inner periphery of the seat liner 11 so that the lining cylindrical portion 26 and the shaft core of the shaft-equipped cylindrical portion 42 are aligned with each other while maintaining the position of the disc 2 so that the distance between them is the same. At this time, a cylindrical jig (not shown) may be inserted into the valve shaft hole 13 in advance, and the valve shaft hole 13 may be reinforced from the inner periphery with this jig. The length of the jig is shorter than the upper and lower part stems 5a and 5b.

  After the centering step, the external force on the sheet liner 11 is gradually weakened in the cylindrical portion insertion step. As a result, the seat liner 11 is automatically restored from an elliptical shape to a perfect circle shape by its elastic force, and in FIG. 15, the top and bottom lining cylindrical portion 26 of the disk 2 is inserted into the shaft-equipped cylindrical portion 42 constituting the stem hole. While the disc 2 is mounted on the seat liner 11, the cylindrical portion insertion process is completed. As a result, the disc 2 and the seat liner 11 can be unitized in a state where the upper and lower stems 5a and 5b can be connected while the lining cylindrical portion 26 of the disc 2 is supported by the shaft mounting cylinder portion 42 of the seat liner 11. Is done. Note that a gap may be provided between the top and bottom of the disc 2 and the seat liner 11, and this gap is combined with a shaft seal member 17 shown in FIG. The shaft seal portion on the disk 2 top and bottom side is configured.

In the stem connection step, in FIG. 16, the connection portions 25 at the distal ends of the upper and lower stems 5 a and 5 b are gradually inserted into the stem hole portion 24 while aligning the axes, and the upper and lower stems 5 a and 5 b are connected to the disc 2. . The upper and lower stems 5a and 5b are provided with a tapered surface portion 91 between the boundary between the columnar portion and the connecting portion 25, and the tapered surface portion 91 allows the lining cylinder to be inserted when the upper and lower stems 5a and 5b are inserted into the disc 2. The portion 26 is prevented from being damaged.
When these upper and lower stems 5a and 5b are inserted, air may accumulate in the stem hole portion 24 with the insertion, but this air may escape from between the upper and lower stems 5a and 5b and the lining cylindrical portion 26. it can.

  In the body integration step, the upper and lower stems 5a, 5a, 5b, with the seat liner 11 containing the disc 2 with the upper and lower stems 5a, 5b connected to the upper and lower bodies 3a, 3b fitted with the shaft seal member 17 are sandwiched. The upper and lower body bodies 3a and 3b are integrated in a state where 5b is connected to the disk 2 and the disk 2 can be rotated by the upper and lower stems 5a and 5b.

More specifically, first, the shaft seal member 17 is mounted in the mounting recess 29 of the upper body 3a in advance. At that time, the disc spring 32, the seal member 31, the plate member 33, and the sealing bush 30 are arranged in this order from the back side of the mounting recess 29 to which the bearing 34 is attached.
Thus, the seat liner 11 incorporating the disc 2 to which the upper and lower stems 5a and 5b are connected is incorporated into the upper body 3a to which the shaft seal member 17 is mounted. Thereby, the upper half of the sheet liner 11 is incorporated into the upper body 3a.

On the other hand, as with the upper body 3a, the shaft seal member 17 is mounted in the mounting recess 29 in advance on the lower body 3b.
In this state, the lower half side of the seat liner 11 incorporated in the upper body 3a is incorporated in the lower body 3b, and the upper liner 3a and the lower body 3b sandwich the seat liner 11.

  In this state, as shown in FIG. 2, the bolts 27 are screwed into the bolt holes 36 of the upper and lower bodies 3a and 3b to fix the upper and lower bodies 3a and 3b to each other. As a result, the upper and lower bodies 3a, 3b are tightened in the screwing direction to compress the disc spring 32, and the pressing force of the disc spring 32 described above acts on the sealing bush 30, so that the seat liner 11 on the top and side of the disc 2 is placed. And a shaft that is a secondary seal in which the inner periphery of the shaft-equipped cylindrical portion 42 is in close contact with the outer periphery of the lining cylindrical portion 26 and the lining cylindrical portion 26 is in close contact with the outer peripheral surface of the stem 5. The seal and the shaft seal that is the tertiary seal by the seal member 31 function in a complex manner at the shaft attachment portions of the upper and lower stems 5a and 5b, and the above-described seal function on the valve blade side is synergistically combined with this shaft seal function. By being exhibited, it is possible to ensure high sealing performance on the entire circumferential surface of the disc 2 after assembly.

  In the stem positioning step, the upper stem 5a and the lower stem 5b are positioned and fixed in a rotatable state on the upper body 3a and the lower body 3b, respectively, thereby preventing these jumping out.

  In FIG. 2, the upper stem 5 a is mounted via a dust-proof O-ring 80, a thrust washer 81, and a C-type retaining ring 82. In this case, in a state where the upper stem 5a is inserted into the disc 2, an O-ring 80 and a thrust washer 81 are mounted at the corresponding positions on the upper outer periphery of the upper stem 5a, and a C-type retaining ring 82 is mounted on the upper stem 5a. Engage with. In this state, a lid ground plate 83 is arranged via a thrust washer 81 above the C-type retaining ring 82, and the ground plate 83 is fixed from above the valve body 1 with screws (not shown). By assembling the upper body 3a side in this way, a structure for preventing the upper stem 5a from popping out by the C-type retaining ring 82 and the ground plate 83 via the thrust washer 81 can be provided.

  The lower stem 5b is mounted via an O-ring 80, a thrust washer 81, and a lid end plate 84. In this case, an O-ring 80 is mounted on the outer periphery of the thrust washer 81, the thrust washer 81 is installed in the shaft mounting hole 28 formed in the lower body 3b, and is disposed opposite to the valve outer side end face of the lower stem 5b. In this state, the shaft mounting hole 28 is closed with an end plate 84, and the end plate 84 is fixed from below the valve body 1 with fixing bolts 85. Thereby, the shaft mounting on the lower stem 5b side is completed.

  Further, when disassembling the valve main body 1, it may be carried out by the reverse procedure of the above-described assembly. In this case, after removing the upper and lower body 3a, 3b from the seat liner 11, the seat liner 11 may be disassembled as follows.

  At the upper and lower parts of the seat liner 11, the sealing bush 30 is removed from the seat liner 11 so as to be gradually removed. When removing the upper and lower stems 5a and 5b, the upper and lower stems 5a and 5b are gradually pulled out from the valve shaft hole 13 of the disc 2 while being gripped.

  After the upper and lower stems 5a and 5b are extracted, the disc 2 is rotated to the fully open position as shown in FIG. 13, the outer periphery of the flow path portion of the seat liner 11 is parallel to the flange portion 41, and the shaft-mounted cylinder portion 42 The shaft is pressed from the direction orthogonal to the shaft core, and is deformed into an ellipse in which the direction of the shaft-mounted tube portion 42 is a long side. This pressing is continued until the long side of the sheet liner 11 deformed into an elliptical shape exceeds the height of the disc 2, the axis of the shaft-mounted cylinder portion 42 and the axis of the lining cylinder portion 26 are parallel, and the disc 2 The disc 2 is gradually removed from the seat liner 11 while maintaining the same height and the distance to the shaft mounting cylinder portions 42. It becomes possible to disassemble as described above.

  As described above, in a state where an external force is applied to the seat liner 11 and deformed into an elliptical shape, the disc 2 is inserted into the inner periphery of the seat liner 11 in a centered state. The disc 2 is mounted on the seat liner 11 by restoring the circular cylindrical portion 26 into the shaft-mounted cylinder portion 42, and then the upper and lower stems 5a and 5b are connected to the stem hole 24 of the disc 2. 25 is gradually inserted to connect them, and the valve body 1 is manufactured by sandwiching and integrating the seat liner 11 containing the disc 2 with the upper and lower bodies 3a, 3b fitted with the shaft seal member 17. As a result, the disc 2 can be easily attached while preventing the resin liner covering the seat liner 11 and the stem 5 from being damaged while improving the sealing performance near the boss 15 of the seat ring 11. It can be set up. In addition, the disassembly work can be easily performed as in the case of assembly.

  In this case, by deforming the seat liner 11 into an elliptical shape and pressing the long side R1 of the inner peripheral seal surface 21 of the seat liner 11 from the outside so as to be longer than the full length R2 of the disc 2, the disc 2 is While reliably preventing contact with the seat liner 11, the disc 2 is attached to and detached from the seat liner 11 to ensure a shaft seal seal near the boss 15 portion.

Claims (6)

  A valve provided on the disk surface and on the inner peripheral surface of the body that rotatably supports the disk, and a lining layer made of a resin material is provided at a position opposite to the diameter direction of the seat liner that is the body-side lining layer. In the butterfly valve seal structure in which a stem is mounted in the shaft hole, and when the stem is rotated, at least the valve blade portion of the disc is sealed against the inner peripheral surface of the body, the body with the back-up rubber mounted on the inner peripheral side. A seat liner is coated on the inner peripheral surface of the inner sleeve, and the inner diameter of the seat liner is an inner diameter deformed to be smaller than the outer diameter of the disc by the elastic force of the backup rubber when the valve is opened, The inner diameter of the seat liner is deformed to a small diameter by the elastic force of the backup rubber when the disc presses the seat liner. Seal structure is set to the inside diameter of the butterfly valve, characterized in that a inner diameter before the deformation to the disuccinimidyl outer diameter and the same diameter (including the tolerance).   The thickness of the backup rubber is set to be approximately the same as or slightly longer than the width of the backup rubber, so that the inner diameter of the seat liner can be easily restored to the inner diameter before the deformation when the valve is closed. Butterfly valve seal structure.   When the valve liner is closed, when the inner diameter of the seat liner is restored to the inner diameter before the deformation, a bulging portion in which the backup rubber bulges in the width direction as the diameter increases is provided between the body and the seat liner. The butterfly valve seal structure according to claim 1 or 2, wherein the seal structure is accommodated in a gap portion.   The butterfly valve seal structure according to any one of claims 1 to 3, wherein a width of the backup rubber is set to be substantially the same as a valve blade difference value of the disc.   The butterfly valve seal structure according to any one of claims 1 to 4, wherein the lining layer is made of a fluororesin.   A taper surface having a predetermined angle is provided on both sides of the tip of the valve wing side of the disc lining which is the disc side lining layer, and a seal portion is formed between the taper surfaces to be pressed against the seat liner, and the width of the seal portion is increased. The butterfly valve seal structure according to any one of claims 1 to 5, wherein the seal is provided with a width substantially equal to a width of the disc on the front end side.

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