JPWO2006118097A1 - Eccentric butterfly valve and seat ring used therefor - Google Patents

Abstract

An attempt is made to provide an eccentric butterfly valve having a stable sealing performance while simplifying the structure of a seat ring used for the eccentric butterfly valve, reducing the torque of rotating the valve body of the eccentric butterfly valve. The seat ring is composed of a flat plate with a uniform thickness X in an annular shape, the inner peripheral surface is convex in section, and an annular groove is concentrically drilled only on one flat surface of the annular body. The depth of the groove is set within the range of 1/5 to 3/4 of the thickness X, and the groove bottom is located away from the inner peripheral surface by the length of the annular body at the groove bottom. In addition, the groove bottom exists between a curved surface formed by a perpendicular line passing through the contact point between the seat ring and the valve body and perpendicular to the outer peripheral surface of the valve body, and a parallel surface passing through the contact point and parallel to the surface. A ring. The outer half of the seat ring is sandwiched between the valve body and the retainer and fixed to the valve body, and the inner half is separated from the valve body and the retainer, and a gap exists between them to form an eccentric butterfly valve.

Description

  The present invention relates to an eccentric butterfly valve, and also relates to a seat ring used for an eccentric butterfly valve.

  The butterfly valve is mainly composed of a valve main body having a fluid passage and a valve body attached rotatably in the fluid passage. In addition, the butterfly valve requires a valve shaft to rotatably support the valve body, and requires a seat ring to keep the fluid passage wall surface and the outer periphery of the valve body airtight when fully closed. Yes. The seat ring has an annular shape, and is attached to the fluid passage with its inner peripheral surface exposed. The surface where the seat ring and the outer periphery of the valve body are in close contact with each other when the valve is fully closed is called a valve seat surface.

  In the butterfly valve, since the valve body is rotated by the valve shaft about the valve shaft, the valve shaft is often attached through the center of the valve body. However, in the case of flowing a high-temperature and high-pressure fluid, the valve shaft may be attached at a position off the center of the valve body in order to facilitate and ensure full closure of the fluid passage by the valve body. Such a butterfly valve is particularly called an eccentric butterfly valve because the valve shaft is eccentric with respect to the valve body. A typical eccentric butterfly valve is one in which a valve shaft is attached to a position outside the plane connecting the outer periphery of the valve body, and a flat piece connecting the valve seat surface protrudes on the side. In such an eccentric butterfly valve, the outer peripheral surface of the valve body is formed of a tapered conical surface or a part of a spherical surface.

  In the eccentric butterfly valve, a high-temperature and high-pressure fluid flows, so the seat ring is made of a heat-resistant material. A metal may be used as the heat resistant material, but in many cases, a fluorine resin is used. Since the fluororesin has an extremely low rebound resilience compared to other resins, it is necessary to devise to increase the elasticity of the valve seat surface when the seat ring is made of the fluororesin. For this reason, it has been proposed so far that the seat ring made of fluororesin has a complicated shape.

Japanese Laid-Open Patent Publication No. 55-10104 proposes that the eccentric butterfly valve has a cross section as shown in FIG. According to this, the seat ring C is fixed with the outer peripheral portion E sandwiched between the valve body A and the retainer B, but the inner peripheral portion F is bent in a cross-sectional shape and the inner peripheral portion F. It is necessary to taper the inner peripheral surface. Further, it is said that a perpendicular Q extending from the bending point P of the seat ring C to the outer peripheral surface of the valve body D needs to penetrate the inside of the inner peripheral portion F. As a result, the seat ring C is formed with a groove on the valve body A and a groove on the retainer B side, and the cross section has a complicated shape.
Japanese Patent Laid-Open No. 55-10104

Japanese Examined Patent Publication No. 58-25910 proposes an eccentric butterfly valve whose partial cross section is shown in FIG. There, the seat ring C is sandwiched and fixed between the valve body A and the retainer B, and the seat ring C has a taper attached to the valve seat surface H, and faces to the valve body A and the retainer B, respectively. Grooves K and J are required to be drilled, and gaps L and M are required to be formed from the valve seat surface H to the grooves K and J. Accordingly, the seat ring C has a complicated shape.
Japanese Patent Publication No. 58-25910

Japanese Laid-Open Patent Publication No. 56-124770 proposes an eccentric butterfly valve whose partial cross-sectional structure is shown in FIG. There, the seat ring C is sandwiched and fixed between the valve body A and the retainer B, but the seat ring C has an outer flange area P, an intermediate support area Q, an inner sealing area R and the tip of the end. The support section Q and the sealing section R are formed in a simple shape having a substantially U-shaped cross section, but the flange section P protrudes outward from the support section Q and is sealed. Since the valve seat surface of the section R is tapered and the structural portion S protrudes from the tip of the sealed section R, the seat ring C has a complicated shape as a whole.
JP 56-124770 A

  Thus, the seat ring for the eccentric butterfly valve has been tapered on the inner peripheral surface so as to be in close contact with the outer peripheral surface of the valve body over a wide area. Conventional seat rings have been supposed to have a complicated cross-sectional shape with many irregularities. Therefore, it took time and effort to manufacture the seat ring. Not only that, the valve body must also have a complicated shape in contact with the seat ring, and the retainer must also have a complicated shape. Therefore, it takes time to manufacture them, and as a result, the eccentric butterfly valve cannot be easily manufactured, and as a result, the eccentric butterfly valve becomes expensive.

  If a valve with a fluororesin seat ring is used as a flammable fluid, the seat ring may be burned down in the event of a disaster such as a fire. If the seat ring is burned out, sealing at the valve seat becomes impossible, which may increase the damage caused by the disaster. In order to prevent this damage from spreading, a structure that can exhibit sealing performance even in the event of a fire has been proposed, and this structure is called a fire-safe structure.

As a fire-safe structure valve, a valve using only a metal seat ring has been proposed, which is described in JP-A-10-281304 and JP-A-10-292869. However, the metal seat ring and the valve seat surface of the valve body are always in contact with each other during the opening / closing operation and slide, so that a fine scratch is generated on the sealing surface, resulting in fluid leakage. .
Japanese Patent Laid-Open No. 10-281304 JP-A-10-292869

In order to solve this drawback, a butterfly valve incorporating a metal backup seat ring that does not easily burn out in addition to a fluorine resin seat ring is described in Japanese Patent Laid-Open No. 5-10457. However, since this backup seat ring has to be a complicated shape having three bent portions, there is a problem that it takes time to manufacture.
JP-A-5-10457

  In order to solve the above-mentioned problems and to provide an eccentric butterfly valve at a lower cost, the present invention simplifies the structure of the seat ring used in the eccentric butterfly valve, thereby reducing the torque of the valve body rotation. Thus, it is an object of the present invention to provide an eccentric butterfly valve that can provide a stable sealing performance and can be constructed to withstand a fire by adding a simple shape backup seat ring.

  In the present invention, a valve body provided with an eccentric valve shaft is rotatably provided in a fluid passage of a valve body, a seat ring is provided on a wall surface of the fluid passage, and an inner peripheral surface of the seat ring is provided as a valve. This is based on an eccentric butterfly valve that can be brought into close contact with the outer peripheral surface of the body.

  In the present invention, in order to simplify the structure of the seat ring, a flat plate having a uniform thickness X in an annular shape is used as a material for the seat ring. According to the present invention, a groove extending annularly only on one flat surface of such a material is formed concentrically with the center of the annular ring. The groove has a uniform width and depth in the circumferential direction.

  This inventor makes the above-mentioned groove a specific depth, and when the groove bottom is present at a specific position, the obtained seat ring can appropriately displace the inner peripheral surface. It has been found that the torque of the valve can be reduced and the valve body can be easily brought into close contact with the valve body, and therefore fluid leakage can be easily prevented.

  In that case, the depth of the groove is within the range of 1/5 to 3/4 of the thickness X of the flat annular body. The position of the groove bottom is positioned away from the inner peripheral surface of the annular body by a distance equal to or longer than the thickness of the annular body at the groove bottom, and passes through the contact point between the seat ring and the valve body, It is necessary to be between a curved surface formed by a perpendicular perpendicular to the plane and a plane passing through the contact point and parallel to the plane of the toroid.

  A seat ring with such a groove should be divided into an annular outer half located outside the groove and an annular inner half located inside the groove. Can do.

  The outer half is a portion that is sandwiched between the valve body and the retainer and fixed to the valve body. Accordingly, the outer half portion may be a flat plate as it is, but it can also have a shape that is convenient for pinching and fixing.

  On the other hand, since the inner half part includes an inner peripheral surface that should be in close contact with the valve body, the inner half part has a special shape. One of the special shapes is that the inner peripheral surface is not tapered, but the cross section of the inner peripheral surface is convex and the central portion of the thickness protrudes inward. As a result, the inner peripheral surface of the seat ring is in close contact with a line extending in the peripheral direction without contacting the outer peripheral surface of the valve body in a wide area.

  Another feature of the inner half is the relationship between the inner half and the valve body and the relationship between the inner half and the retainer. In other words, the inner half portion forms a slight gap between the valve body and the retainer. As a result, the inner half is not restrained by either the valve body or the retainer, and can be bent slightly in the direction in which the fluid flows. As a result, the inner peripheral surface of the seat ring can move under the pressure of the fluid.

  The slight gap described above may be formed by retreating the surface of the inner half of the seat ring, but can also be formed by retreating the valve body and the surface on the retainer side.

  Thus, according to the present invention, the valve body provided with the valve shaft eccentric is attached to the fluid passage of the valve body so as to be rotatable, the seat ring is attached to the wall surface of the fluid passage, and the inner peripheral surface of the seat ring is provided. In the eccentric butterfly valve that can be brought into close contact with the outer peripheral surface of the valve body, the seat ring is formed of a flat annular body having a substantially uniform thickness X, and the inner peripheral surface is formed in a convex shape in cross-section so that the center of the thickness A groove having a uniform width and depth is formed concentrically with the center of the annular ring on one substantially flat surface of the annular body. And the depth of the groove is 1/5 or more and 3/4 or less of the thickness X, and the groove bottom is present at a position away from the inner peripheral surface by the length of the annular body at the groove bottom or more. And the groove bottom passes through the contact point between the seat ring and the valve element, and the curved surface is perpendicular to the outer peripheral surface of the valve element. The seat ring is located between the parallel plane parallel to the surface, and the seat ring is fixed to the valve body with the annular outer half located outside the groove facing the retainer side and held by the retainer. The eccentric butterfly valve is characterized in that an annular inner half part inside the groove is separated from the valve body and the retainer, and a slight gap exists between them.

  The present invention also provides a seat ring for an eccentric butterfly valve. The seat ring is composed of a flat plate-like annular body having a substantially uniform thickness X, the inner peripheral surface is convex in cross section, and the central part of the thickness protrudes inward. A groove having a uniform width and depth is drilled in an annular shape concentrically with the ring on one substantially flat surface of the groove. The groove bottom is present at a distance from the inner peripheral surface by a distance equal to or greater than the length of the annular body at the groove bottom, and the groove bottom passes through the contact point between the seat ring and the valve body. It is characterized in that it is integrally formed with a fluorine resin in a shape that exists between a curved surface formed by a perpendicular line to the outer peripheral surface of the valve body and a parallel surface passing through the contact and parallel to the surface.

  The present invention also provides an eccentric butterfly valve having a fire-safe structure using the butterfly valve seat ring according to the present invention. An eccentric butterfly valve having a fire-safe structure is the above-described eccentric butterfly valve according to the present invention, wherein a backup seat ring is interposed between the seat ring and the retainer, and the backup seat ring is a circle made of a metal plate having elasticity. Annular body with inner end bent along the retainer to the retainer side, inner half part with a gap between the retainer and outer half part between the retainer and the valve body It is characterized by being fixed.

  In the present invention, the seat ring is formed of a flat plate-like annular body having a substantially uniform thickness X, and the inner peripheral surface has a convex cross section, and on the substantially flat surface of the annular body. A groove with a uniform width and depth is formed in a circular shape concentrically with the ring. Since the shape of the seat ring is simple, the surface of the valve body and retainer in contact with it is simple. Therefore, it is possible to supply the eccentric butterfly valve at low cost without requiring labor.

  Moreover, in this invention, since the inner peripheral surface of the seat ring has a cross-sectional convex shape and the central portion in the thickness direction protrudes inward, the seat ring comes into contact with the outer periphery of the valve body at the protruding portion. It becomes easy to be in close contact with the body, and the torque for rotating the valve body can be reduced.

  Further, according to the present invention, since the groove is formed in an annular shape concentrically with the center of the annular ring on the one surface of the annular body, the groove can be easily formed. . The depth of the groove is not less than one fifth and not more than three quarters of the thickness X, and the groove bottom is present at a distance from the inner peripheral surface of the annular body by a length equal to or greater than the thickness of the annular body at the groove bottom. And the groove bottom exists between a curved surface formed by a perpendicular passing through the contact point between the seat ring and the outer peripheral surface of the valve body and perpendicular to the outer peripheral surface of the valve body, and a parallel surface passing through the contact point and parallel to the surface. Therefore, the inner half can be bent slightly with the groove as a boundary while being firmly connected to the outer half, so that the inner peripheral surface located at the end of the inner half has moderate elasticity. Operates on. As a result, the seat ring is easily brought into close contact with the valve body and serves as a fluid-free leak.

  Further, in the butterfly valve of the present invention, the surface of the inner half of the seat ring is separated from the surface of the valve body and the retainer, and there is a slight gap between them, so the seat ring has an inner half with the groove as a boundary. Can be slightly bent in the axial direction of the fluid passage. For this reason, the torque of valve body rotation becomes small and can open and close a valve easily.

  In addition, in the present invention, since a backup sheet ring made of a metal plate annular body is interposed between the seat ring and the retainer, even when the resin seat ring is burnt down by a fire or the like. Thus, the backup seat ring remains and can be maintained in a fully closed state between the valve body, and thus serves as a fire-resistant butterfly valve.

  Further, since the seat ring has a simple shape as described above, it can be easily formed integrally with a fluorine resin as a material, and therefore can be supplied at low cost and can be easily attached to the valve body. It is.

It is a partially cutaway sectional view of a known eccentric butterfly valve. It is a partially cutaway sectional view of another known eccentric butterfly valve. It is a partially cutaway sectional view of another known eccentric butterfly valve. It is sectional drawing perpendicular | vertical to the valve shaft of the eccentric butterfly valve concerning this invention. FIG. 5 is a partial enlarged cross-sectional view indicated by V in FIG. 4. It is a partially cutaway perspective view of an eccentric butterfly valve seat ring according to the present invention. It is explanatory drawing of the operation state of the eccentric butterfly valve which concerns on this invention. It is explanatory drawing of the other operating state of the eccentric butterfly valve which concerns on this invention. It is a partially cutaway expanded sectional view of the other eccentric butterfly valve concerning this invention. It is a partially cutaway expanded sectional view of another eccentric butterfly valve concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Valve body 2 Fluid passage 3 Valve body 4 Seat ring 5 Retainer 6 Valve shaft 7 Groove 8 Air gap 9 Backup seat ring 10 Gasket 31 Outer surface 41 Outer half 42 Inner half 43 Inner surface 45 Concave 47 Indent 90 Backup seat ring 9 tip 91 outer half of backup sheet ring 9 92 inner half of backup sheet ring 9

  Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 4 is a cross-sectional view when passing through the center of the eccentric butterfly valve according to the present invention and cut perpendicularly to the valve shaft. FIG. 5 is an enlarged cross-sectional view of a portion V in FIG. FIG. 6 is a partially cutaway perspective view of the seat ring used in FIGS. 4 and 5. 7 and 8 are explanatory diagrams of the usage state of the eccentric butterfly valve according to the present invention. FIG. 9 is a partially cutaway enlarged cross-sectional view of another eccentric butterfly valve according to the present invention. FIG. 10 is a partially cutaway sectional view of still another eccentric butterfly valve according to the present invention.

  When the butterfly valve according to the present invention is cut along a plane that passes through the center of the valve body and is perpendicular to the valve shaft, the butterfly valve appears as shown in FIG. In FIG. 4, a valve body 3 is rotatably attached in the fluid passage 2 of the valve body 1. A seat ring 4 is sandwiched and fixed between the valve body 1 and the retainer 5 in the fluid passage 2, and an inner peripheral surface of the seat ring 4 is exposed in the fluid passage. The valve shaft 6 is eccentrically fixed to the valve body 3. That is, the valve shaft 6 is attached to the lower part of the valve body 3 so as to be offset from the plane connecting the outer peripheral surfaces of the valve body 3. Since the valve body 3 rotates about such a valve shaft 6, this butterfly valve is an eccentric butterfly valve.

  The valve body 3 in FIG. 4 has an intersection point (hereinafter referred to as a center line in the fluid passage direction of the seat ring whose outer peripheral surface 31 is an annular body and a plane passing through the axis of the valve shaft 6 and perpendicular to the fluid passage direction. This is called a spherical center. In the process in which the valve body 3 rotates about the valve shaft 6, the outer peripheral surface 31 of the valve body 3 comes into close contact with the seat ring 4 or leaves the seat ring 4. FIG. 4 shows a state in which the outer peripheral surface 31 is in close contact with the inner peripheral surface of the seat ring 4 and the valve body 3 completely stops the flow of the fluid, that is, a fully closed state of the valve.

  As shown in an enlarged view in FIG. 5, the seat ring 4 has a shape in which a flat plate having a substantially uniform thickness X is punched into an annular shape. The seat ring 4 is provided with a groove 7 formed in an annular shape concentrically with the annular shape on one flat surface of the annular shape. The seat ring 4 is divided into an annular outer half 41 and an annular inner half 42 with the groove 7 as a boundary. The outer half portion 41 is a portion that is fitted into a recess formed in the valve body 1 and is pressed by the retainer 5 to be fixed to the valve body. On the other hand, the inner half 42 is a portion that is given flexibility by the groove 7 and is in close contact with the valve body.

  The groove 7 is drilled at a specific location on one flat surface of the seat ring and should have a specific depth. The specific depth is a depth within a range of 1/5 to 3/4 of the thickness X of the flat plate. Since the depth of the groove is in the thickness direction of the flat plate, the depth is a value measured perpendicular to the surface of the flat plate. The groove 7 has a uniform width and depth in the circumferential direction.

  The groove 7 is supposed to have a groove bottom at a specific position of the annular body from two viewpoints. One of them is that the groove bottom must have a length c equal to or greater than the thickness a of the annular body at the groove bottom along the direction parallel to the surface from the inner peripheral surface. The other is that the vertical line L2 perpendicular to the valve body outer peripheral surface L1 passes through the contact point between the seat ring and the valve body and rotates around the spherical center, and the surface through the contact point. It must be between parallel planes (including both ends).

  As shown in FIG. 5, it is preferable that the groove 7 has a cross-sectional shape in which the width of the groove is larger than the depth of the groove and the bottom of the groove is curved with a large roundness, and has a bowl shape. However, the shape is not limited to this, and the width may be narrow and the groove may be narrow.

  The inner peripheral surface 43 of the seat ring 4 is not tapered as in the conventional case, and has a shape in which the cross section is convex and the central portion of the thickness protrudes as shown in FIG. The convex shape may be a simple arc shape, but it is preferable that the central portion in the thickness direction is slightly sharpened as shown in FIG.

  As shown in FIG. 5, the flat surface of the inner half portion 42 of the seat ring 4 is not in close contact with the surface of the retainer 5, and forms a gap with a slight width Y between the surface of the retainer 5. Similarly, the back surface of the inner half portion 42 of the seat ring 4, that is, the flat surface toward the valve body 1 forms a slight width gap with the valve body.

  The gap between the seat ring 4 and the retainer 5 is formed in the entire region from the groove 7 to the inner peripheral surface 43 of the seat ring 4. The width of the gap need only be small, and it is sufficient that the fluid flowing in the fluid passage can easily flow into the groove. Further, it is desirable that the width Y of the gap is the same over the entire region. In addition, it is preferable that recesses extending in the radial direction are formed in some regions, and the recesses extend from the inner peripheral surface to the groove. It is preferable that the hollow extends radially with a plurality of strips at equal intervals.

  The clearance between the seat ring 4 and the valve body 1 is formed in the entire region from the vertical foot U passing through the bottom of the groove 7 to the flat back surface of the seat ring 4 to the inner peripheral surface 43. The seat ring 4 has the outer half 41 sandwiched between the valve body 1 and the retainer 5 and is fixed. Therefore, the gap has the inner peripheral surface 43 with the cross section of the leg U as the apex. It is preferable that it is a triangle that opens toward the side. The apex angle θ of the triangle is preferably 3 to 5 degrees. In other words, the gap is a rotational space formed around the central axis of the seat ring, and when cut along a plane passing through the central axis, the vertical angle U is always 3 to 5 degrees with the vertical foot U as the apex. It is preferably one that appears as a triangle that forms an angle.

  FIG. 6 is a perspective view showing a part of the seat ring 4 according to the present invention. In the seat ring 4 shown in FIG. 6, the surface of the outer half portion 41 forms a substantially flat surface, but a concave surface 45 that is slightly recessed in a circular arc shape is formed at the center of the surface. Also good. The concave surface 45 is provided to firmly fix the seat ring between the valve body and the retainer, and is not necessarily required. That is, the surface of the outer half 41 may be the same as the surface of the flat plate that is the material. In addition, a recess 47 that reaches the groove 7 from the inner peripheral surface 43 is provided at some places on the inner half 42. When the inner half 42 is pushed toward the retainer 5 and comes into close contact with the retainer, the recess 47 facilitates the inflow of fluid into the groove 7 or the outflow of fluid from the groove 7 to bend the inner half 42. This is to make it easier.

  Since the inner half 42 of the seat ring 4 has a gap between the valve body 1 and the retainer 5, the inner half 42 is not directly restrained by the valve body 1 and the retainer 5, and is in a free state. Yes. Therefore, the inner peripheral surface 43 can move in the axial direction of the fluid passage by the gap. Furthermore, the inner peripheral surface 43 is movable in the direction of the outer half due to the presence of the groove 7. Therefore, the inner peripheral surface 43 of the seat ring 4 can act like a thing having a large rebound resilience. Thus, the seat ring 4 can reduce the torque when the valve body rotates, and can easily come into close contact with the valve body to expect complete fluid leakage.

  FIG. 7 shows a deformed state of the seat ring 4 when the valve body 3 is in the fully closed state and the fluid pressure is applied from the top to the bottom as indicated by the arrows. Since the fluid enters the groove 7 and the fluid pressure pushes the inner half 42 of the seat ring 4 downward with the vertical foot U passing through the bottom of the groove 7 as a fulcrum, the back surface Q1 of the inner half 42 is the valve body. Close to the surface of 1, the seat ring 4 exhibits a sealing effect.

  FIG. 8 shows a deformed state of the seat ring 4 when the valve body 3 is in the fully closed state and the fluid pressure is applied from the lower side to the upper side as indicated by an arrow. The fluid pressure presses the inner half 42 of the seat ring 4 upward with the bottom O of the groove 7 as a fulcrum, but the surface Q2 of the inner half 42 is in close contact with the surface of the retainer 5 and cannot be pushed any further. Closeness is maintained in this state.

  Thus, the eccentric butterfly valve according to the present invention can reliably prevent fluid leakage.

  As shown in FIG. 8, if the air gap 8 is provided on the surface of the valve body that is in contact with the end of the outer half 41 of the seat ring 4, the thermal expansion of the seat ring 4 at a high temperature is released to the air gap 8. Therefore, the close contact of the valve body 3 to the seat ring 4 can be more stably maintained regardless of the temperature condition. The gap 8 is preferably in the range of 30 to 70% located on the retainer side of the valve body surface in contact with the end of the seat ring 4.

  In the example shown in FIG. 5, a part of the surface of the retainer 5 is notched and a gap with a width Y is provided between the retainer 5 and the seat ring. That is, the surface portion of the retainer 5 that faces the inner half 42 of the seat ring 4 is cut out, and a step is provided in the notched portion to provide a gap between the seat ring 4 and the retainer 5. On the other hand, in the example shown in FIG. 9, the surface of the inner half portion of the seat ring 4 facing the retainer 5 is retracted to provide a gap between the seat ring 4 and the retainer 5. In the case where the seat ring 4 is formed integrally with a fluorine resin, it is preferable to use the structure shown in FIG.

  FIG. 10 is a partially cutaway enlarged sectional view of an eccentric butterfly valve having a fire-safe structure according to the present invention. In FIG. 10, a backup seat ring 9 is further added to the seat ring 4 according to the present invention. The backup seat ring 9 is made of an annular body and is interposed between the seat ring 4 and the retainer 5.

  The backup sheet ring 9 is made of an elastic metal plate having a substantially uniform thickness, and is divided into an outer half 91 and an inner half 92 in terms of function. The outer half 91 extends outside the seat ring 4 and is sandwiched between the valve body 1 and the retainer 5 to fix the backup seat ring 9.

  On the other hand, the inner half portion 92 not only covers the inner half portion of the seat ring 4 but also extends inward from the inner half portion of the seat ring 4, and the leading end 90 is bent toward the retainer 5 side. It is set as the shape in alignment with the 5 inner peripheral surface.

  While the valve body 3 is open, the inner half 92 of the backup seat ring 9 always has a gap between it and the retainer 5. When the valve body 3 rotates in the direction of the arrow, contacts the seat ring 4 and presses the seat ring 4, the backup seat ring 9 is bent by the curvature of the seat ring 4 and comes into close contact with the retainer 5. At this time, the valve body 3 has an outer peripheral surface on a spherical surface centered on the above-mentioned spherical center, and on the other hand, the thickness of the backup seat ring is reduced. Will not contact the outer peripheral surface of the valve body 3. For this reason, when the seat ring 4 is bent toward the retainer 5 in a normal state, the inner half 92 of the backup seat ring 9 only applies a reaction force to the bending.

  However, in the event of a disaster such as a fire, the backup seat ring 9 plays a major role. This is because the seat ring 4 is made of a fluororesin, so that the seat ring 4 may be burned down in the event of a fire. However, since the backup seat ring 9 is made of metal, it does not easily burn out even in the event of a fire. For this reason, even when the seat ring 4 is burned out, the backup seat ring 9 still remains and functions to stop the fluid. Therefore, the butterfly valve shown in FIG. 10 is useful as a butterfly valve having high fire resistance.

  The backup seat ring 9 can be made of the same metal as the retainer 5, but can also be made of a different metal. The backup sheet ring can be made of, for example, a stainless plate, an Inconel plate, or other metal plate. As shown in FIG. 10, the outer half 91 of the backup seat ring 9 preferably has a gasket 10 interposed between the valve body 1 and the retainer 5 to prevent liquid leakage.

Claims (7)

  A valve body attached with an eccentric valve shaft is rotatably attached to the fluid passage of the valve body, a seat ring is attached to the wall surface of the fluid passage, and the inner peripheral surface of the seat ring is the outer peripheral surface of the valve body. In the eccentric butterfly valve that can be closely contacted, the seat ring is formed of a flat annular body having a substantially uniform thickness X, and the inner peripheral surface is convex in cross section, and the central portion of the thickness is inward. A groove having a uniform width and depth is formed on one substantially flat surface of the annular body so as to be concentric with the annular ring. X is 1/5 or more and 3/4 or less of X, the groove bottom exists at a distance from the inner peripheral surface by a length equal to or more than the length of the annular body at the groove bottom, and the groove bottom is the seat ring. A curved surface that is perpendicular to the outer peripheral surface of the valve body and a parallel surface that passes through the contact point and is parallel to the surface. The seat ring is a seat ring, and the seat ring is fixed to the valve body by holding the outer half of the annular ring outside the groove with the retainer facing the retainer side, and the annular ring located inside the groove An eccentric butterfly valve characterized in that the inner half part is separated from the valve body and the retainer, and a slight gap exists between them.   The eccentric butterfly valve according to claim 1, wherein a recess that is deeper than the gap is provided between the inner half portion and the retainer from the inner peripheral surface toward the groove.   The gap formed between the inner half of the seat ring and the valve body is on the cross section that passes through the center of the seat ring. The eccentric butterfly valve according to claim 1 or 2, wherein the eccentric butterfly valve is expressed as a triangle opening toward the surface, and the apex angle of the triangle has an angle of 3 to 5 degrees.   A backup seat ring is interposed between the seat ring and the retainer. The backup seat ring is an annular body made of a metal plate having elasticity, and its inner end is bent along the retainer toward the retainer. The inner half has a gap between the retainer and the outer half is sandwiched between the retainer and the valve body and fixed. The eccentric butterfly valve according to one item.   It consists of a flat annular body having a substantially uniform thickness X, the inner peripheral surface is convex in cross section, and the central part of the thickness protrudes inward, and the annular body is substantially flat. A groove having a uniform width and depth is formed on one surface in an annular shape concentric with the ring, and the depth of the groove is not less than 1/5 and not more than 3/4 of the thickness X. And the groove bottom is present at a position away from the inner peripheral surface by a length equal to or greater than the length of the annular body at the groove bottom, and the groove bottom passes through the contact point between the seat ring and the valve body to the valve body outer peripheral surface. A seat ring for an eccentric butterfly valve, wherein the seat ring is formed integrally with a fluorine resin in a shape existing between a curved surface formed by a vertical perpendicular and a parallel surface passing through the contact and parallel to the surface.   In the annular inner half located inside the groove, the flat single surface is slightly cut out over the entire surface, and the thickness of the inner half is located outside the groove. The seat ring for an eccentric butterfly valve according to claim 5, wherein the seat ring is thinner.   In the inner half of the annular shape located outside the groove, the back surface located on the opposite side of the flat one surface gradually becomes larger as it approaches the inner peripheral surface, and the surface generated by the notch is removed from the groove bottom. A straight line inclined at an angle of 3 to 5 degrees with respect to the original back surface is a conical curved surface that is generated by rotating around the center of the ring. The eccentric butterfly valve seat ring according to claim 5 or 6, characterized in that

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