Center-type butterfly valve

Abstract

To provide a center-type butterfly valve which can secure seal surface pressure between a lining layer of a valve body and a body-side seal face according to a rise of the pressure, and can surely prevent the leakage of fluid even if the seal lining layer is formed at the valve body side, and fluid pressure equal to or higher than prescribed pressure is applied at valve-closing.SOLUTION: A center-type butterfly valve is opened and closed by turning a valve body 3 which is coated with a lining layer 25 at an external peripheral face of a core grid 20 with respect to an internal peripheral seal face 10 of a cylindrical body 2. The butterfly valve comprises a seal salient part 30 which is protrusively formed at a primary side with a center line L of the valve body in a vertical shaft diameter direction as a boundary, a crush region 35 in which the seal salient part serves as the internal peripheral seal face when the valve body is in a full-closed position, and which is crushed to a primary-side region, and a crush grip part 36 for gripping the crush region between the internal peripheral seal face and an outer end face 21 of the core grid. By increasing the surface pressure of a surface pressure increase region 33 between the internal peripheral seal face and the outer end face of the core grid in a state that the crush region is deformed to the crush grip part, and gripped by fluid pressure which is equal to or higher than prescribed pressure, the butterfly valve is tightly sealed.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a center-type butterfly valve, and in particular to a center-type butterfly valve having a structure in which a sealing surface is provided on the inner circumference of a body and a lining layer is coated on the outer circumference of a valve disc, and when the valve is closed, the lining layer of the valve disc abuts against the sealing surface on the inner circumference of the body to ensure sealing. [Background technology]

[0002] Conventionally, when providing a lining layer on a center type butterfly valve, a lining layer is applied to the inner circumference of the body, and when the valve is closed, the outer peripheral seal surface of the metal valve body is made to bite into this lining layer to ensure sealing, or a lining layer is applied to the surface of the core metal of the valve body, and when the valve is closed, the lining layer on the outer periphery of the valve body is made to abut against the seal surface on the inner circumference of the body to ensure sealing.

[0003] For example, when a central butterfly valve is provided at the end of a water pipe or the like, a butterfly valve with a connection method called a groove connection type is sometimes used for connection. In a groove connection type butterfly valve, the body is formed long in the flow path direction compared to a flange connection type, so it is difficult to apply a sealing lining layer to the inner circumference side of the body. Therefore, when providing a lining layer to a butterfly valve with a long body structure such as a groove connection type, the lining layer is usually provided on the valve body side.

[0004] As an example of a butterfly valve having a lining layer applied to the valve body side of this type, the valve device disclosed in Patent Document 1 is disclosed. In this butterfly valve, the valve body is configured by covering the outer surface of a disk-shaped core metal with an elastic material made of synthetic rubber, and a convex arc surface portion that is convex outward is formed on the outer periphery of this valve body. Meanwhile, the valve body is made of stainless steel material on the flow path side, and a concave arc surface portion shaped to follow the rotation trajectory of the valve body is formed on the side facing the valve body. In this butterfly valve, when the valve body is in a closed state when the valve is closed, the convex arc surface portion of the valve body comes into close surface contact with the concave arc surface portion of the valve body, and this surface contact seal is intended to increase the sealing area and improve sealing performance.

[0005] In the butterfly valve of Patent Document 2, a circumferential groove is formed along the outer periphery of the valve body (core metal), and a seal material made of a flexible material is coated on the outer periphery of the valve body so as to fill the circumferential groove. In this butterfly valve, the sealing material reaches the bottom of the circumferential groove, increasing the thickness of that part in the outer circumferential direction. This absorbs the pressing force applied from the valve body when the valve is closed, reducing the torque required when operating the handle, and also relieves the stress acting on the sealing material, thereby improving durability. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 8-277942 [Patent Document 2] Japanese Patent Application Laid-open No. 60-101367 Summary of the Invention [Problem to be solved by the invention]

[0007] Butterfly valves of conventional construction in which the valve body is rubber lined are not suitable for use with high-pressure fluids. When a high-pressure fluid pressure of, for example, about 1 MPa (approximately 150 PSI) or more is applied to butterfly valves of constructions such as those described in Patent Documents 1 and 2, the problem arises that as the pressure rises, the likelihood of fluid leakage from between the outer periphery of the valve body and the inner periphery of the body when the valve is closed increases.

[0008] Regarding the cause of this, the inventors have focused on the changes in the shape of the lining layer on the outer periphery of the valve body and the seal surface pressure when the fluid pressure changes from low pressure to high pressure while the valve is closed, and have analyzed and investigated these changes due to pressure changes through tests.

[0009] As a result, the following findings were obtained: In other words, it was confirmed that when high fluid pressure is applied to the valve disc in a closed state of the valve, this fluid pressure displaces the lining layer on the outer periphery of the valve disc toward the secondary side relative to the core metal, and this displacement reduces the seal surface pressure with the body side seal surface, thereby affecting the sealing performance.

[0010] From this, it can be inferred that even when high-pressure fluid is applied to a butterfly valve with the structure of Patent Documents 1 and 2, the lining layer on the outer periphery of the valve body moves further toward the secondary side compared to the case of low-pressure fluid, and as a result, the volume of the lining layer sandwiched between the core metal and the body side seal surface becomes insufficient, reducing the sealing surface pressure provided by the lining layer and leading to fluid leakage.

[0011] In the case of a conventional butterfly valve in which a lining layer is provided on the inner circumference of the body, the fluid pressure applied to the lining layer is a force from the inner diameter side to the outer diameter side of the flow passage, i.e., a force in the direction pressing the lining layer against the inner circumference of the body. Therefore, there is no displacement of the lining layer from the primary side to the secondary side, and no reduction in the sealing surface pressure is caused, so it is presumed that a reduction in sealing performance is unlikely to occur.

[0012] Based on the above speculation, the inventors focused on the relationship between changes in fluid pressure and the displacement of the lining layer, and came up with the idea that if the lining layer on the outer periphery of the valve body is previously positioned at an appropriate position on the primary side of the opposing position between the outer periphery of the core bar and the body side seal surface opposing this core bar, and the lining layer is displaced between the outer periphery of the core bar and the body side seal surface opposing this outer periphery when pressure from a high-pressure fluid of a predetermined pressure or greater is applied to the valve body, sufficient volume can be secured between them and the lining layer can be appropriately crushed.As a result, sufficient surface pressure can be applied by the lining layer between the body side seal surface, thereby exhibiting high sealing properties against high-pressure fluid and preventing fluid leakage.

[0013] The present invention was developed to solve the above-mentioned problems, and its object is to provide a center-type butterfly valve in which a sealing lining layer is provided on the valve body side, and which, even when fluid pressure above a predetermined pressure is applied when the valve is closed, can ensure sealing surface pressure between the lining layer of the valve body and the body side seal surface in response to the pressure increase, thereby reliably preventing fluid leakage. [Means for solving the problem]

[0014] In order to achieve the above object, the invention of claim 1 is a butterfly valve which opens and closes by rotating a valve element having a lining layer coated on the outer peripheral surface of a core against the inner peripheral seal surface of a cylindrical body, and which comprises a seal protrusion formed on the primary side defined by the center line in the vertical radial direction of the valve element, with the outer end in the thickness direction of the lining layer as a reference, a crushing region in which the seal protrusion is crushed into the primary side region by the inner peripheral seal surface when the valve element is in the fully closed position, and a crushing clamping portion which clamps the crushing region between the inner peripheral seal surface and the outer end surface of the core, and which increases the surface pressure in the increased surface pressure region between the inner peripheral seal surface and the outer end surface of the core to provide an airtight seal when the crushing region is displaced into the region of the crushing clamping portion and clamped when a fluid pressure equal to or greater than a predetermined pressure in the body is applied.

[0015] The invention of claim 2 is a central type butterfly valve in which the thickness of the lining layer in the outer end face region of the valve body is the size from the outer end face of the core bar to the apex of an imaginary sphere whose radius is from the center of the valve body to the tip position of the seal protrusion, and this thickness is set to approximately 3 to 7 mm.

[0016] The invention according to claim 3 is a center type butterfly valve, wherein the fluid pressure equal to or higher than a predetermined level is a fluid pressure of approximately 1 MPa or higher, and the hardness of the lining layer is within a range of 75±3 Hs. Effect of the Invention

[0017] According to the invention of claim 1, when the valve body is in the fully closed state due to fluid pressure equal to or higher than a predetermined pressure, the seal protrusion provided on the primary side is displaced by the extrusion clamping portion and is clamped, increasing the surface pressure in the surface pressure increased area, making it possible to reliably seal even under high pressure conditions, making this a very valuable butterfly valve.

[0018] According to the invention of claim 2, the thickness of the lining layer in the outer end face region of the valve disc is set to about 3 to 7 mm, so that even when no fluid pressure is applied, when a fluid pressure less than a predetermined pressure is applied to the valve disc, or when a fluid pressure equal to or greater than a predetermined pressure is applied to the valve disc, the crushing region can be displaced to an appropriate state according to the magnitude of the fluid pressure while maintaining a substantially constant crushing rate when the valve is closed, thereby exerting a seal surface pressure according to the magnitude of the fluid pressure. By setting the lining layer to a predetermined thickness in this way, the crushing rate can be set to a substantially constant value, and excessive deformation of the lining layer can be prevented to ensure stable sealing performance.

[0019] According to the invention of claim 3, the predetermined fluid pressure is a fluid pressure of about 1 MPa or more, and the hardness of the lining layer is set to a range of 75±3Hs, so that it can handle excessive fluid pressure that may occur in an emergency in water piping of a building facility, for example, and even if a fluid pressure of about 1 MPa or more, which is the predetermined pressure, is applied when the valve is closed, the lining layer has a hardness of 75±3Hs, ensuring the durability of the lining layer and exhibiting excellent sealing properties. As a result, even when the valve body is connected to the end of the piping, leakage from the end of the pipe is reliably prevented, and the valve can be used in a state of improved safety. [Brief description of the drawings]

[0020] [Figure 1] FIG. 2 is a central vertical cross-sectional view showing a center type butterfly valve according to the present invention. [Diagram 2] 2 is an enlarged cross-sectional view taken along the line AA in FIG. 1. [Diagram 3] FIG. 4 is a schematic diagram showing the vicinity of an inner peripheral seal surface of a body. [Figure 4] 4 is a schematic diagram showing a state in which the seal protrusion in FIG. 3 is crushed in the primary side region. FIG. [Diagram 5] 11 is a schematic diagram showing a state in which a crushed region is displaced to a surface pressure increased region. FIG. [Figure 6] FIG. 2 is a schematic diagram showing the analysis results of the internal stress of the lining layer at low pressure. [Figure 7] FIG. 2 is a schematic diagram showing the analysis results of the internal stress of the lining layer under high pressure. [Figure 8] FIG. 13 is a schematic diagram showing an analysis result of internal stress in a comparative example under high pressure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] An embodiment of the center type butterfly valve of the present invention will be described in detail below with reference to the drawings. Fig. 1 is a central vertical cross-sectional view of the center type butterfly valve of the present invention, and Fig. 2 is an enlarged cross-sectional view taken along line AA in Fig. 1. Figs. 3 to 5 are schematic diagrams showing the vicinity of the inner peripheral seal surface of the body in Fig. 2.

[0022] In the figure, a central type butterfly valve (hereinafter referred to as valve body 1) has a cylindrical body 2, a valve element 3, an upper stem 4, and a lower stem 5, and is provided so that a flow path 11 can be opened and closed by rotating the valve element 3, which has a lining layer 25 coated on the outer peripheral surface of a core metal 20 (described later), relative to an inner peripheral seal surface 10 formed within the body 2. The valve body 1 may be used, for example, connected to water piping in a building such as a building facility (not shown).

[0023] The body 2 is made of a metal material such as ductile cast iron, has a flow passage 11 formed therein, and the inner peripheral surface of the flow passage 11 is painted or the like. In Fig. 1, the upper part of the body 2 is provided with an upper shaft insert 14 into which the upper stem 4 can be inserted, and the lower part is provided with a lower shaft insert 15 into which the lower stem 5 can be inserted.

[0024] 2, an inner peripheral seal surface 10 is formed in an arc shape near the center in the flow path 11 direction of the inner peripheral surface of the body 2, depending on the radius of the center (rotation axis) P of the valve body 3. This inner peripheral seal surface 10 is provided over the entire circumference except for the vicinity of the opening sides of upper and lower insertion holes 16, 17 through which the upper stem 4 and lower stem 5 are inserted. Between the inner peripheral seal surface 10 of the body 2 and the outer end surface 21 of the core bar 3, an increased surface pressure region 33, which will be described later, is provided.

[0025] Grooves 18 are formed by cutting out circumferentially near both sides of the outer circumferential surface of the body 2, and the valve body 1 is connectable to an external pipe through these grooves 18. The grooves 18 of the valve body 1 are fixed in place by a connecting member (not shown) so as to be sandwiched together with a groove provided in the external pipe, and thus the valve body 1 and the pipe are connected by a connection method known as a groove connection.

[0026] The valve body 3 has a core metal 20, which is coated with a lining layer 25. The lining layer 25 coats the outer peripheral surface (outer end surface 21), the front surface 22, and the back surface 23 of the core metal 20 to form the valve body 3.

[0027] The core 20 is formed in a disk shape from a metal material such as stainless steel, and its outer circumferential surface (outer end surface) 21 is formed in a substantially cylindrical shape with a predetermined width. Bosses 20a are formed near the top and bottom of the core 20, respectively.

[0028] On the other hand, the lining layer 25 is made of a soft material such as EPDM (ethylene propylene diene rubber), and in this embodiment, is provided by rubber lining molding using EPDM as a material. The lining layer 25 is provided with a hardness in the range of magnitude 75±3Hs.

[0029] 2, an outer end surface side lining layer 26 is formed in an outer end surface region 34 of the lining layer 25, which represents a region near the outer end surface of the valve body 3, and this outer peripheral surface side lining layer 26 is provided circumferentially on the outer end surface 21 side of the core bar 20. The lining layer 26 is formed in a spherical shape from the center P of the valve body 3 near the boss portion 20a, which is the outer peripheral region of the upper and lower stem insertion portions of the core bar 20.

[0030] A seal protrusion 30 is provided with a predetermined thickness in a portion of the outer end surface region 34 other than the vicinity of the boss portion of the lining layer 26. The seal protrusion 30 is provided on the primary side (left side in the drawing) of the center line L in the vertical axis radial direction of the valve body 3, so as to protrude with respect to the outer end 26a of the lining layer 26 in the thickness direction.

[0031] A crushing region 35 is provided between the valve disc 3 and the body 2, where the seal protrusion 30 is crushed into the primary side region D by the inner circumferential seal surface 10 when the valve disc 3 is in the fully closed position. The crushing region 35 is a region formed by elastic deformation of the lining layer 25 including the seal protrusion 30, and is provided so as to be displaced by a fluid pressure in the body 2 that is equal to or greater than a predetermined pressure.

[0032] Between the inner peripheral seal surface 10 and the outer end surface 21 of the core metal 20, there is provided a pressing and holding portion 36 for holding the above-mentioned pressing region 35. When the pressing region 35 is displaced to the region of the pressing and holding portion 36, the pressing region 35 is held by the pressing and holding portion 36.

[0033] 3, the seal protrusion 30 is set so that when the lining layer 26 of the outer end surface region 34 is crushed in the fully closed state, the crush amount T1 of the crushed portion is approximately 19% of the thickness of the lining layer 26 before being crushed, regardless of the compression state. That is, the crush rate of the valve body 3 from the valve open state to the fully closed state is expressed by crush rate (%) = crush amount T1 / thickness T of the lining layer (lining layer 26 on the outer end surface side), and in this example, the cross-sectional shape of the seal protrusion 30, i.e., the height from the outer end 26a of the lining layer 26 and the thickness are set so that the crush rate is approximately 19% as described above.

[0034] 1 and 2, the left side of the valve body 1 indicates the primary side of the flow path 11, and the right side indicates the secondary side of the flow path 11, with a fluid such as water or hot water flowing through the flow path 11 from the primary side to the secondary side.

[0035] In this embodiment, the sealing protrusion 30 is also provided in the outer end surface region 34 on the secondary side (right side) separated by the center line L in the vertical axis radial direction of the valve body 3, and the lining layer 25 is provided so that the left-side sealing protrusion 30 and the right-side sealing protrusion 30 have approximately symmetrical cross-sectional shapes with respect to the center line L, and the lining layer 26 of the outer end surface region 34 is provided so as to have an approximately M-shaped cross-section.

[0036] An upper stem insertion hole 31 and a lower stem insertion hole 32 are provided in the center of the lining layer 26 near the top and bottom of the valve disc 3, and an upper stem 4 and a lower stem 5 are inserted into these stem insertion holes 31, 32, respectively. The valve disc 3 is inserted into an upper shaft insert cylinder 14 and a lower shaft insert cylinder 15 through the upper stem 4 and the lower stem 5, respectively, and attached to a predetermined position within the body 2, and the valve main unit 1 is configured as a central type butterfly valve.

[0037] After the valve body 3 is installed, the boss surface 25a of the lining layer 25 of the valve body 3 seals around the upper stem insertion hole 31 and the lower stem insertion hole 32 on the inner seal surface 10 of the body 2, ensuring airtightness near the upper and lower parts on the shaft mounting side of the valve body 3. Meanwhile, the entire lining layer 26 of the outer end surface region 34 is provided in a sealable manner over the entire inner seal surface 10 except for the sealing areas near the upper and lower stem insertion holes 31, 32.

[0038] The valve body 3 is provided so that the upper and lower stems 4, 5 can be rotated manually or automatically, and the flow passage 11 can be adjusted to an open / closed state or an intermediate opening state by the rotation.

[0039] 3 to 5 are schematic diagrams showing the operation of the seal protrusion 30 of the valve body 1 in Fig. 2. In this example, only the primary side seal protrusion 30 is shown, with the secondary side seal protrusion 30 omitted. 3, the thickness T of the lining layer 25 in the outer end surface region 34 of the valve body 3 is represented by the distance from the outer end surface 21 of the core metal 20 to the vertex S1 of an imaginary spherical surface S having a radius R from the center P of the valve body 3 to the tip position of the seal protrusion 30. In this example, the thickness T of the lining layer 26 in the outer end surface region 34 is set to approximately 5 mm. On the other hand, the thickness (not shown) of the lining layer 25 on the front and back sides of the valve body 3 is set to an appropriate value according to the thickness T of the lining layer 26.

[0040] FIG. 4 shows the state where the valve body 3 is rotated to the right from the state in FIG. 3 to the valve closing position and is fully closed. When the valve body 3 is in the fully closed position, the seal protrusion 30 is crushed by the primary side region 37 at the inner peripheral seal surface 10 of the body 2, and in this state, the crushed region 35 is formed when the lining layer 26 of the outer end face region 34 is crushed in the primary side region 37 opposite the inner peripheral seal surface 10, as shown by the two-dot chain line. In this state, if no fluid pressure is applied to the valve body 3 from the primary side, the crushed region 35 of the lining layer 26 can escape in the crushed direction because there is no core metal 20 on the center side of the valve body 3. Therefore, the compressive stress of the crushed region 35 does not increase in proportion to the amount of crushing, and the surface pressure between the crushed region 35 and the inner peripheral seal surface 10 does not increase, but if the fluid pressure applied to the valve body 3 is less than about 1 MPa, the fluid can be sealed in this state.

[0041] When a fluid pressure equal to or greater than a predetermined pressure is applied from the primary side into the body 2, the fluid pressure displaces the crushing region 35 into the region of the crushing and holding portion 36, and the crushing region 35 is held by the crushing and holding portion 36. The crushing region 35 displaced into the crushing and holding portion 36 cannot escape to the center of the valve body 3, because the core metal 20 is located at the center of the valve body 3. Therefore, the crushing region 35 is compressed between the core metal outer end face 21 and the inner peripheral seal surface 10, and the resulting compressive stress increases the surface pressure of the surface pressure increase region 33, indicated by the broken line between the inner peripheral seal surface 10 and the core metal outer end face 21, to hermetically close the valve body 1.

[0042] In the above, the fluid pressure applied to the body 2 at or above the predetermined pressure is, for example, a fluid pressure of approximately 1 MPa or more. When a fluid pressure higher than this is applied, the crushing region 35 is reliably displaced into the increased surface pressure region 33, making it possible to prevent leakage of fluid. The fluid pressure above the predetermined pressure is the minimum pressure value required to prevent leakage from the valve body 1 when fully closed. In addition, for a fluid pressure of approximately 1 MPa or more, the lining layer of the outer end surface region 34 is preferably configured to have the above-mentioned crushing ratio of 13 to 19%. If this crushing ratio is within the range of 13 to 19%, it is possible to satisfactorily increase the surface pressure while preventing the torque during opening and closing of the valve body 3 from excessively increasing.

[0043] In the valve body 1 of the above embodiment, the cross-sectional shape of the lining layer 26 of the outer end surface region 34 is symmetrical with the seal protrusions 30 provided on the first and secondary sides with respect to the center line L in the vertical axis radial direction of the valve body 3, but this seal protrusion 30 may be provided only on the primary side with respect to the center line L, and the seal protrusion 30 on the secondary side may be omitted. If the seal protrusion 30 is provided at least only on the primary side of the center line L, the sealing function due to the increased surface pressure of the increased surface pressure region 33 described above can be exerted. When the seal protrusions 30 are provided on both the first and secondary sides as in the above embodiment, even when the primary side and secondary side of the valve body 1 are interchanged (when the direction of the flow path 11 is interchanged), the hermetic sealing function of the increased surface pressure region 33 on the primary side can be exerted in each flow path direction.

[0044] In addition, the thickness T of the lining layer 26 of the outer end surface region 34 of the valve body 3 may be other than 5 mm, and this thickness T may be set to an appropriate value depending on the diameter of the flow path 11, the magnitude of the fluid pressure, and the like. As a result, for example, if the thickness T is made larger than 5 mm, it becomes possible to further increase the sealing surface pressure. In this case, since the torque at the time of valve opening operation increases in proportion to the increase in the sealing surface pressure, which may lead to deterioration of operability, it is desirable to set the thickness T to an appropriate value taking into consideration both the sealing property and the torque property. The thickness of the lining layer 26 is preferably in the range of 3 to 7 mm regardless of the diameter of the valve body 1. If it is 3 mm or more, sufficient penetration resistance is obtained, and if it is 7 mm or less, it is easy to obtain a good sealing surface pressure while avoiding an excessive increase in torque.

[0045] The fluid pressure equal to or greater than the predetermined pressure when the crushing region 35 is displaced to the region of the crushing and holding portion 36 may be set to a fluid pressure equal to or greater than approximately 1 MPa. In this way, the crushing region 35 can be displaced to the region of the crushing and holding portion 36 by a fluid pressure of any magnitude to effect a hermetic seal.

[0046] The lining layer 25 may be made of a soft material other than rubber, for example, a resin lining using resin as the soft material. In this case, the hardness is preferably in the range of 75±3Hs, but the hardness can be set appropriately depending on the type of soft material used as the lining material.

[0047] In this way, the type of soft material constituting the lining layer 25 may be changed, or the aforementioned crushing ratio may be changed in response to different types of fluids, fluid pressures, etc. In this case, for example, the cross-sectional shape of the seal protrusion 30 may be appropriately changed to easily set a desired crushing amount (crushing ratio). By appropriately setting the position of the seal protrusion 30 and the hardness of the lining layer 25 according to the fluid pressure of the fluid to be sealed, it becomes possible to reliably keep the crushing region 35 within the crushing and holding portion 36 when the fluid pressure is applied, and by appropriately setting the crushing ratio, it becomes possible to adjust the surface pressure in the crushing and holding portion 36 to a suitable range.

[0048] The body 2 of the valve main body 1 may be connected to an external pipe by a connection method other than a groove connection, and for example, it is also possible to connect to the pipe by various connection methods such as a flange connection.

[0049] Next, the operation of the center type butterfly valve of the present invention in the above embodiment will be described. In the valve body 1 in the above embodiment, the valve body 3 is formed by covering the core metal 20 with the lining layer 25 made of rubber lining, and in particular, the outer peripheral surface (outer end surface 21) of the core metal 20 is covered with the lining layer 26, so that the lining layer 26 can ensure sealing between the outer peripheral side of the valve body 3 and the inner peripheral surface side of the body 2 without providing a lining layer on the inner peripheral surface side of the cylindrical body 2. Therefore, even in the case of a valve having a long cylindrical body 2 and a structure in which it is difficult to provide a lining treatment on the inner circumference of the body 2, the lining layer 25 provided on the valve body 3 side can provide sealing when the valve is closed.

[0050] A seal protrusion 30 is formed to protrude from the thickness direction outer end 26a of the lining layer 26 on the primary side, which is defined by the center line L in the vertical axis direction of the valve body 3, so that this seal protrusion 30 can be displaced toward the secondary side by fluid pressure and seal against the inner sealing surface 10 of the body 2.

[0051] 3 shows the state immediately before the valve element 3 of the valve body 1 is closed. In this state, the seal protrusion 30 is not in contact with the inner peripheral seal surface 10 of the body 2, and is not crushed between the inner peripheral seal surface 10 and the core metal 20. In this state, fluid is allowed to flow.

[0052] Figure 4 shows a state in which the valve body 3 has been rotated to the right from the state shown in Figure 3 to the fully closed position with no fluid pressure being applied inside the body 2. At this time, the seal protrusion 30 is elastically deformed by being pressed against the inner seal surface 10 and is crushed in the primary side region 37, and a crushed region 35 is formed in the lining layer 26 of the outer end face region 34.

[0053] In this way, a crushing region 35 is provided in which the seal protrusion 30 is crushed against the primary side region 37 by the inner seal surface 10 when the valve body 3 is in the fully closed position. Therefore, when the valve body 3 is in the fully closed position and no fluid pressure is applied to the valve body 3, or when a fluid pressure less than a predetermined pressure is applied, the seal protrusion 30 is maintained in a state where it is crushed against the primary side region 37 by the inner seal surface 10 of the body 2, and displacement of the seal protrusion 30 toward the secondary side is suppressed, thereby suppressing wear and damage to the lining layer 26 of the outer end face region 34 of the valve body 3, while exhibiting the sealing performance required for sealing and preventing leakage.

[0054] In this case, the seal protrusion 30 crushed by the inner circumferential seal surface 10 tries to deform so as to escape toward the lining layer 25 on the front and back sides of the core metal 20, but by ensuring a crushing rate of approximately 19% in this valve open state, the volume of the crushed region 35 when the seal protrusion 30 is crushed increases more than in the case of Fig. 3. By ensuring a sufficient volume, a predetermined seal surface pressure can be exerted between the lining layer 26 and the body inner circumferential seal surface 10. As a result, in the fully closed state of Fig. 4, fluid pressures below approximately 1 MPa can be reliably sealed off, preventing leakage.

[0055] In the above case, the apex 30a of the elastically deformed seal protrusion 30 is in a position tilted by an angle θ from a direction approximately perpendicular to the flow path 11 relative to the inner seal surface 10, and the vicinity of the seal protrusion 30 is crushed.

[0056] At this time, a pressing force F1 inclined by an angle θ acts on the inner circumferential seal surface 10 from near the apex 30a of the deformed seal protrusion 30, and a resisting force R1 in a vector direction opposite to the pressing force F1 acts from the inner circumferential seal surface 10. Because these pressing force F1 and resisting force R1 are inclined with respect to a direction approximately perpendicular to the direction of the flow path 11, component forces F1x, R1x, F1y, and R1y in the X direction (horizontal direction in the figure) and Y direction (vertical direction in the figure) act in the directions shown in the figure, respectively.

[0057] Of these, when the Y-direction component forces F1y, R1y act on the apex 30a where the pressing force 1F and the reaction force R1 act, the apex 30a is located at a position outside the increased surface pressure region 33. Therefore, the component force R1y (reaction force R1) generated against the component force F1y (pressing force F1) acts on a position away from the apex 30a, which is the point of action of the force, and away from the outer end surface 21 of the core bar 20. As a result, the vicinity of the seal protrusion 30 is crushed at a position shifted toward the primary side from the increased surface pressure region 33 in the Y direction. In addition, since the pressing force F1 and the reaction force R1 have X-direction component forces F1x and R1x, the Y-direction component forces F1y and R1y become smaller than the pressing force F1 and the reaction force R1, respectively.

[0058] As described above, even if the compressive force in the vicinity of the seal protrusion 30 in the Y direction is kept small, no force in the fluid pressure direction acts on the lining layer 26 of the outer end surface region 34 because no fluid pressure is applied to the valve body 3. Therefore, there is no risk of fluid leakage from between them.

[0059] When fluid pressure is applied from left to right in the state shown in Fig. 4 and the magnitude of this fluid pressure increases, the crushing region 35 is gradually elastically deformed and displaced toward the secondary side in proportion to the increase in fluid pressure. This improves the surface pressure between the lining layer 26 of the outer end face region 34 and the inner peripheral seal surface 10 in response to the increase in fluid pressure, ensuring the sealing between them.

[0060] In Fig. 5, when the fluid pressure further increases and a fluid pressure equal to or higher than a predetermined pressure is applied inside the body 2, for example, a fluid pressure of about 1 MPa or more in this embodiment, an even larger pressure is applied to the lining layer 26 of the outer end surface region 34. In this case, the pressing force of the fluid pressure presses the crushing region 35 formed on the primary side in the direction of the two-dot chain arrow, displaces to the region of the crushing and holding portion 36, and is held by the crushing and holding portion 36. At this time, unlike the case of Fig. 4, the crushing region 35 is in a state where there is no escape route in the direction of the core bar 20 between the body 2 (inner peripheral seal surface 10) which is made of a rigid metal material and the core bar 20 (core bar outer end surface 21), as shown by the dashed line.

[0061] The crushed region 35, including the seal protrusion 30 that has been crushed at a crushing rate of approximately 19%, becomes a compressed lump-like portion, and a stronger compressive force is applied to this crushed region 35 from the inner circumferential seal surface 10 and the outer end face 21 of the core bar compared to Fig. 4. In this way, the inner circumferential seal surface 10 and the outer end face 21 of the core bar are sealed with the increased surface pressure in the increased surface pressure region 33.

[0062] As described above, the crushing and holding portion 36 that holds the crushing region 35 is provided between the inner seal surface 10 and the outer end surface 21 of the core metal 20, and when the fluid pressure in the body 2 is equal to or higher than a predetermined pressure, the crushing region 35 is displaced to the crushing and holding portion 36 and held therein, and the surface pressure of the surface pressure increase region 33 between the inner seal surface 10 and the outer end surface 21 of the core metal is increased to provide a hermetic seal. Therefore, when a fluid pressure equal to or higher than a predetermined pressure is applied to the valve body 3, the volume of the lining layer 26 in the crushing and holding portion 36 is increased to increase the repulsive force in the sealing direction, and even when a pressure of a high-pressure fluid of about 1 MPa is applied, the surface pressure during sealing is increased to a predetermined value according to the magnitude of the fluid pressure, thereby reliably preventing fluid leakage. Moreover, the displacement amount of the crushing region 35 toward the crushing and holding portion 36 gradually changes in proportion to the increase in fluid pressure, so that the deformation amount of the lining layer 26 can be kept to a minimum and durability can be improved.

[0063] Moreover, the top portion 30a of the elastically deformed seal protrusion 30 is located at a position substantially perpendicular to the flow passage 11 with respect to the inner circumferential seal surface 10. Therefore, a pressing force F2 in a direction approximately perpendicular to the flow path 11 acts on the inner circumferential seal surface 10 from near the apex 30a of the deformed seal protrusion 30, and a reaction force R2 in a vector direction opposite to this pressing force F2 acts from the inner circumferential seal surface 10. For this reason, there is no risk of component forces being generated in these pressing force F2 and reaction force R2, and the pressing force F2 and the component force R2 are applied in directions opposing each other at the apex 30a, which is the point of application of the forces.

[0064] In this way, by applying the force in the pressing direction between the lining layer 26 and the inner circumferential seal surface 10 without dispersing it, the crushing region 35, which is the lining layer 26 of the outer end face region 34 including the seal protrusion 30, can be efficiently crushed by the crushing and holding portion 36, and the sealing can be achieved in a state where the surface pressure of the increased surface pressure region 33 is effectively increased. In this case, for example, a seal surface pressure of about 4.2 MPa can be generated between the inner circumferential seal surface 10 and the outer end 26a of the lining layer, and a high-pressure fluid of about 1 MPa or more can be reliably sealed.

[0065] Even in the above case, the crushing rate of the seal protrusion 30 is maintained at approximately 19%, so that the seal protrusion 30 is not crushed more than necessary, and the sealing performance can be improved while preventing wear and damage to the lining layer 26. When the fluid pressure from the primary side is reduced while the valve is closed, the seal protrusion 30 will try to return to its original shape, i.e., the state shown in Fig. 4, due to its elasticity depending on the magnitude of the fluid pressure. This improves the durability of the lining layer 26.

[0066] In addition, when the valve is fully closed as described above, the lining layer 25 covering the front and back surfaces 22 and 23 of the core metal 20 is pressed toward the core metal 20 by the fluid pressure, so that the sealing performance with the core metal 20 can be maintained. EXAMPLES

[0067] Next, an analysis of internal stress when fluid pressure is applied near the lining layer 26 was performed by simulation for the valve body 1 of the above-mentioned embodiment of the present invention and a comparative example. Figures 6 to 8 show the results of these analyses, and in each figure, the differences in the magnitude of internal stress occurring near the lining layer 26 and on the inner circumferential seal surface 10 are roughly divided into regions α, β, γ, and δ. The magnitude of internal stress is in the order of region α > region β > region γ > region δ, and region α, where the highest internal stress occurs, is shown with narrow hatching intervals. Region β, where the next highest internal stress occurs after region α, is shown with wider hatching intervals than region α.

[0068] FIG. 6 shows the analysis results of the internal stress when a low pressure, that is, a small fluid pressure of less than 1 MPa, is applied to the vicinity of the lining layer 26 from the primary side. In the case of such low pressure, the crushing area 35 does not undergo large displacement due to the fluid pressure, and the force with which the seal protrusion of the lining layer 26 is crushed by the inner peripheral seal surface 10 on the body 2 side is released downward in the figure on the side of the core metal 20. However, since the fluid pressure is originally low, it was confirmed that even if such a force is released, a certain degree of seal surface pressure is secured by the crushing of the seal protrusion. Therefore, it can be said that leakage to the secondary side does not occur.

[0069] FIG. 7 shows the analysis results of the internal stress when high pressure, that is, a fluid pressure of 1 MPa or more, is applied to the vicinity of the lining layer 26 from the primary side. In this case, it was confirmed that the crushing area 35 is displaced from the primary side to the secondary side by the fluid pressure, and this crushing area 35 is displaced into the area of ​​the crushing and clamping portion 36 and is clamped thereby, and remains in the surface pressure increased area 33, so that the crushing force of the seal protrusion of the lining layer 25 is reliably received by the outer end surface 21 of the core metal 20. As a result, the surface pressure between the outer periphery of the lining layer 26 in the surface pressure increased area 33 and the body side inner peripheral seal surface 10 increases while sealing, and it can be said that a reliable seal is possible even when a fluid pressure above a predetermined level is applied.

[0070] 8 shows a comparative example, and shows the analysis result of a structure in which only one seal protrusion of the lining layer 40 is formed along the center line in the radial direction. In the case of such a shape of the lining layer 40, it was confirmed that when a certain level of fluid pressure is applied, the crushed region 44 in which the seal protrusion is crushed between the body side seal surface 41 and the outer end surface 43 of the core metal 42 is removed from the region sandwiched between the body side seal surface 41 and the outer end surface 43 of the core metal. Therefore, the area of ​​increased surface pressure as shown in FIG. 7 is not formed, and as a result, the seal surface pressure between the outer periphery of the lining layer 40 and the body side seal surface 41 is insufficient compared to the case of FIG. 7, and it can be said that it is difficult to ensure the sealing performance for sealing against a fluid pressure of 1 MPa or more.

[0071] Although the embodiment of the present invention has been described in detail above, the present invention is not limited to the description of the embodiment, and various modifications can be made without departing from the spirit of the invention described in the claims of the present invention.

[0072] For example, in this embodiment, the seal protrusion 30 of the lining layer 26 is provided not only on the primary side with the center position L of the thickness as a boundary, but also on the secondary side to form an approximately M-shaped cross section, but is not limited thereto. As described above, in the present invention, the crushed area where the seal protrusion formed near the primary side of the fluid is crushed is displaced by the fluid pressure and is clamped by the crushing clamping part to increase the surface pressure of the surface pressure increased area, but in this effect, the volume of the crushed area on the primary side of the fluid is important, and the seal protrusion on the secondary side of the fluid has almost no effect on the sealing property. Therefore, even if there is no seal protrusion on the secondary side with the center line of the vertical axis direction of the valve body as a boundary, the effect of improving the sealing property can be sufficiently obtained. However, by providing the seal protrusion on both the primary side and the secondary side of the center line as in the above embodiment, the effect of improving the sealing property can be obtained regardless of which direction the fluid flows from, which is very advantageous in dealing with both flows. [Explanation of symbols]

[0073] 1 Valve body 2 Body 3 Valve body 10 Inner sealing surface 20 Core wire 21 Outer end surface (outer peripheral surface) 25 Lining layer 26 Lining layer in outer end area 26a Outer end 30 Seal protrusion 33 Area of ​​increased surface pressure 34 Outer edge area 35 Crushed Area 36 Crushing and clamping part 37 Primary area L Center line of the valve body in the radial direction of the vertical axis P Center of valve body S Virtual sphere S1 vertex T Lining layer thickness

Claims

1. a valve body having an inner circumferential seal surface and an outer circumferential seal layer formed on the outer circumferential surface of a core bar, the valve body having an inner circumferential seal surface and an outer circumferential seal portion and an outer circumferential seal portion formed on the outer ... inner circumferential seal portion and an outer circumferential seal portion formed on the outer circumferential seal surface and an outer circumferential seal portion and an inner circumferential seal portion and an outer circumferential seal portion and an outer circumferential seal portion and an inner circumferential seal portion and an outer circumferential seal portion and an outer circumferential seal portion and an inner circumferential seal portion and an outer circumferential seal portion and an outer circumferential seal portion and an inner circumferential seal portion and an outer circumferential seal portion and an outer circumferential seal portion and an inner circumferential seal portion and an outer circumferential seal portion and an outer circumferential seal portion and an inner circumferential seal portion and

2. 2. A center-type butterfly valve as claimed in claim 1, wherein the thickness of the lining layer in the outer end surface region of the valve body is a dimension from the outer end surface of the core metal to the apex of an imaginary sphere having a radius extending from the center of the valve body to the tip position of the seal protrusion, and this thickness is set to approximately 3 to 7 mm.

3. 3. The center-type butterfly valve according to claim 1, wherein the predetermined fluid pressure or more is a fluid pressure of approximately 1 MPa or more, and the hardness of the lining layer is in the range of 75±3 Hs.

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