Center-type butterfly valve

Abstract

The present invention provides a center-type butterfly valve in which a sealing lining layer is provided on the valve body side, thereby exhibiting high sealing performance while suppressing an increase in the compression ratio of the outer sealing portion of the valve body when the valve is closed, and reducing the force applied to the sealing surface side of the valve body to improve durability. [Solution] The valve body 11, which has an outer peripheral sealing portion 30 on the outer peripheral end side of the valve blade 11a, is rotated to open and close relative to the inner peripheral sealing surface 14 of the body 10. The outer peripheral sealing portion 14 has a seal projection 31 that is located on the primary side in the thickness direction at the outer edge of the valve body 11 and protrudes in a rounded, mountain-like shape. This seal projection 31 is formed in a shape that is inclined and curved inward toward the primary side with respect to the center line L in the direction of the valve blade of the valve body 11. When fully closed, the seal projection 31 side is in close contact with the inner peripheral sealing surface 14 while being more inclined toward the primary side with respect to the center line L.

Description

Technical Field

[0001] The present invention relates to a center butterfly valve, and particularly to a center butterfly valve having a seal surface provided on the inner peripheral side of the body, a lining layer covering the outer periphery of the valve body, and ensuring sealing performance by bringing the lining layer of the valve body into contact with the seal surface on the inner periphery of the body when the valve is closed.

Background Art

[0002] Conventionally, when providing a lining layer on a center butterfly valve, a lining layer is provided on the inner periphery of the body, and when the valve is closed, the outer peripheral seal surface of the metal valve body is bitten into this lining layer to ensure sealing performance, or a lining layer is provided on the surface of the valve stem of the valve body, and when the valve is closed, the lining layer on the outer periphery of the valve body is brought into contact with the seal surface on the inner periphery of the body to ensure sealing performance.

[0003] For example, when a center butterfly valve is provided on the end side of a water supply pipe or the like, a butterfly valve with a connection method called a grooved connection type may be used for connection. In a grooved connection type butterfly valve, since the body is formed in a long shape in the flow path direction as compared with a flange connection type, it is difficult to provide a lining layer for sealing on the inner peripheral side of the body. Therefore, when providing a lining layer on a butterfly valve having a long body structure such as this grooved connection type, usually, the lining layer is often provided on the valve body side.

[0004] As a butterfly valve having a structure in which a lining layer is provided on the valve body side of this type, the applicant has applied for a center butterfly valve of Patent Document 1. In this butterfly valve, the outer peripheral seal portion of the valve body is provided with a cross-sectional M shape, and the cross-sectional shape on the apex side of this outer peripheral seal portion is arranged on the primary and secondary sides by an arc shape (arc shape) that is line-symmetrical with respect to the center line in the valve wing direction of the valve body, and each outer peripheral seal portion on the primary and secondary sides is formed in a mountain shape so as to be substantially parallel to the center line in the valve wing direction.

[0005] Due to the shape of the outer periphery seal, when the valve is fully closed, the peaks of each peak are compressed perpendicular to the sealing surface on the inner circumference of the valve body, approximately parallel to the centerline in the direction of the valve blade. At this time, the parts of the outer periphery seal other than the two peaks move in the spatial direction of the valley bottoms, and the peaks form two linear seal sections, causing the outer edge of the valve blade of the valve body to contact the sealing surface of the body and seal. In this way, the formation of linear seal sections by the peaks of the outer periphery seal generates high sealing pressure, resulting in good sealing performance.

[0006] Incidentally, when installing such groove-connected butterfly valves in water supply piping, they are installed in a manner that allows for manual operation using a handle or automatic operation using an actuator, just like ordinary valves. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] WO2020 / 138347 publication [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] In the butterfly valve described in Patent Document 1, the coating layer on the outer circumference of the valve blade of the valve body has a double-peak shape. When the valve is closed, the peak portion, which is the outer sealing portion, is compressed and further pushed between the core metal and the body-side sealing surface by fluid pressure. At this time, the outer sealing portion is compressed perpendicular to the inner sealing surface of the body, and deforms under a high compression ratio, generating high sealing surface pressure and ensuring a reliable seal. In order to close the valve in a high-seal state, the valve body must rotate reliably against the high sealing pressure. In this case, opening and closing the valve by automatic operation using an actuator makes it possible to forcibly rotate the valve body through its high torque.

[0009] However, if the valve body is rotated by automatic operation with an excessive number of repetitions, the outer seal portion near the apex of the outer circumference of the valve body will be repeatedly crushed and moved between it and the inner seal surface of the body. In this case, the outer seal portion undergoes repeated deformation with a high compression ratio applied to the entire structure, as described above, due to elastic deformation in the direction of vertical crushing. As a result, the outer seal portion deteriorates severely, especially near the apex, and may even lead to the rupture of the coating layer that constitutes the outer seal portion.

[0010] Therefore, there was a need for the development of a butterfly valve equipped with a lined valve body that suppresses the compression ratio generated in the outer sealing portion of the valve body during opening and closing operations, exhibits high sealing performance when the valve is closed, and prevents deterioration and exhibits high durability even when the valve body is repeatedly and excessively opened and closed.

[0011] The present invention was developed to solve the above-mentioned problems, and its objective is to provide a central-type butterfly valve in which a sealing lining layer is provided on the valve body side, which exhibits high sealing performance while suppressing an increase in the compression ratio of the outer peripheral sealing portion of the valve body when the valve is closed, and improves durability by reducing the force applied to the sealing surface side of the valve body. [Means for solving the problem]

[0012] To achieve the above objective, the invention according to claim 1 is a butterfly valve that opens and closes by rotating a valve body having an outer peripheral sealing portion on the outer peripheral end side of the valve blade relative to the inner peripheral sealing surface of the body, wherein the outer peripheral sealing portion has a seal projection that is located on the primary side in the thickness direction at the outer edge of the valve body and protrudes in a rounded, mountain-like shape, and this seal projection is formed in a shape that is inclined and curved in the primary side with respect to the center line in the direction of the valve blade of the valve body, and when fully closed, the seal projection side is in a state in close contact with the inner peripheral sealing surface while being inclined more towards the primary side with respect to the center line, making it a central type butterfly valve.

[0013] The invention according to claim 2 is a central butterfly valve in which the top of the seal projection is provided in a shape that is located outside the virtual valve surface that extends outward from the front and back surfaces of the outer peripheral seal portion excluding the seal projection, parallel to the center line in the direction of the valve blade, toward the outer diameter.

[0014] The invention according to claim 3 is a central butterfly valve in which the outer peripheral seal portion has seal protrusions on the primary and secondary sides in the thickness direction at the outer edge of the valve body, and these are smoothly connected in a cross-sectional M-shaped double-peak form. [Effects of the Invention]

[0015] According to the invention of claim 1, the primary side seal projection is formed in a shape that is inclined and curved toward the primary side with respect to the center line in the direction of the valve blade of the valve body. As a result, the primary side seal projection has a shape that spreads toward the primary side, and when it comes into contact with the body side seal surface when the valve is closed, the area around the seal projection elastically deforms so as to flow toward the surface of the valve blade, making it less likely for excessive stress to be applied to the entire outer peripheral seal portion compared to when it is pressed between the core metal of the valve body and the body side seal surface. This makes it possible to keep the compression ratio of the outer peripheral seal portion of the valve body low when the valve is closed. By reducing the force applied to the seal surface side of the valve body in this way, the outer peripheral seal portion is prevented from being damaged or broken, and its durability is improved. During sealing, the outer seal portion is elastically deformed toward the flow path, and fluid pressure is applied. The fluid causes the area near the seal projection to move and deform, covering the region between the core metal inside the valve body and the sealing surface on the body side, thereby exhibiting high sealing performance and reliably sealing the fluid. In this way, the area near the top is pushed in toward the secondary side of the inner seal surface while deforming due to the fluid pressure, forming a so-called self-sealing structure, which provides sufficient sealing performance. Since there is no need to increase the amount of deformation of the seal projection to increase surface pressure, the amount of deformation of the outer seal portion is kept to a minimum, improving durability. Furthermore, the seal projection is elastically deformed so as to flow toward the surface of the valve blade when the valve is closed, and when fluid pressure is applied, it deforms in a direction that returns it to its original shape. Therefore, when deformation is caused by fluid pressure, it is difficult for a force that would cause tension to be applied to the surface near the base of the seal projection. As a result, fracture originating from this point is prevented.

[0016] According to the invention of claim 2, the top of the seal projection is located outside the virtual valve surface obtained by extending the surface of the valve body on the vane side, excluding the seal projection, toward the outer diameter. Therefore, when the valve is closed, the area near the projection deforms to curve toward the primary side in the direction of the surface of the vane, thereby reliably providing high sealing performance and reducing the compressibility of the seal projection, thereby increasing the durability of the outer peripheral seal portion.

[0017] According to the invention according to claim 3, the outer peripheral seal portion has seal protrusions on the primary side and the secondary side in the thickness direction at the outer edge portion of the valve body, and is provided in a two-peak shape with a cross-section M shape that gently connects them. Therefore, the seal force is also exerted by the seal protrusion on the secondary side centering on the seal protrusion on the primary side, and good sealing performance can be obtained. According to the opening and closing of the valve, the outer peripheral seal portion on the outer peripheral end side of the valve flap is repeatedly pressed, and particularly near the valley bottom portion of the cross-section M shape, it receives repeated compressive force. However, the cross-section M shape suppresses the generation of stress concentration and prevents the occurrence of a fracture origin, and the durability of the outer peripheral seal portion can be improved. Since the outer peripheral seal portion can be provided in a symmetrical shape with respect to the flow path direction, even when the flow direction of the fluid changes, the durability of the outer peripheral seal portion on the primary side is particularly improved, and high sealing performance is surely exhibited to ensure high sealing property.

Brief Description of Drawings

[0018] [Figure 1] It is a central longitudinal sectional view showing a center type butterfly valve in the present invention. [Figure 2] It is an enlarged sectional view taken along line A-A in FIG. 1. [Figure 3] It is a schematic view showing the vicinity of the inner peripheral seal surface of the body. [Figure 4] It is a schematic view showing the deformed state of the outer peripheral seal portion at the fully closed state of FIG. 3. [Figure 5] It is a schematic view showing the analysis results of internal stress and internal pressure. [Figure 6] It is a schematic view showing the analysis results of internal stress and internal pressure of a comparative example.

Mode for Carrying Out the Invention

[0019] Hereinafter, an embodiment of the center type butterfly valve in the present invention will be described in detail based on the drawings. FIG. 1 is a central longitudinal sectional view of the center type butterfly valve of the present invention, and FIG. 2 shows an enlarged sectional view taken along line A-A of FIG. 1.

[0020] In the figure, a flow path 2 is provided inside a center-type butterfly valve (hereinafter referred to as the valve) 1. In this example, the left side of the valve 1 indicates the primary side of the flow path 2, and the right side indicates the secondary side of the flow path 2. Fluids such as water and warm water flow from the primary side (left side) to the secondary side (right side) of the flow path 2.

[0021] The valve 1 has a body 10, a valve element 11, an upper stem 12, and a lower stem 13. The valve element 11, which has a lining layer 21 coated on the outer peripheral surface of a core metal 20 to be described later, is rotatably attached to an inner peripheral seal surface 14 formed inside the body 10. The valve 1 is provided, for example, with a diameter of about φ2 to φ6 inches and is connected to and used in a water pipe in a building such as a building equipment not shown.

[0022] The body 10 is provided in a substantially cylindrical shape with a metal material such as ductile cast iron, and the above-mentioned flow path 2 is provided inside it. A coating treatment or the like is applied to the inner peripheral surface of this flow path 2. In FIG. 1, an upper shaft insertion cylinder 22 into which the upper stem 12 can be inserted is formed at the upper part of the body 10, and a lower shaft insertion cylinder 23 into which the lower stem 13 can be inserted is formed at the lower part.

[0023] As shown in FIG. 2, an arcuate inner peripheral seal surface 14 is formed near the center in the flow path direction of the body 10. The inner peripheral seal surface 14 is provided in a spherical shape with a constant radius distance from the center of the valve element 11 over the entire circumference except near the opening sides of the upper and lower insertion holes 24 and 25 through which the upper stem 12 and the lower stem 13 are inserted.

[0024] Near both sides of the outer peripheral surface of the body 10, circumferentially notched grooves 26 are provided. Through this groove 26, the valve 1 is provided so as to be connectable to an external pipe. The groove 26 is fixed by being sandwiched together with a groove provided in an external pipe by a connecting member not shown. Thereby, the valve 1 and the pipe are connected by a connection method called a groove connection. <00001​​The valve body 11 has a core metal 20, which is formed in a disc shape from a metal material such as stainless steel, and its outer surface (outer end surface) is formed in a substantially cylindrical shape with a predetermined width. The core metal 20 is covered with a lining layer 21, which covers the outer surface (outer end surface), the front side, and the back side of the core metal 20, thereby forming the valve body 11.

[0026] The lining layer 21 is provided from a soft material such as EPDM (ethylene propylene diene rubber), and in this example, it is provided by rubber lining molding using EPDM as the material.

[0027] As shown in Figure 2, an outer peripheral seal portion 30 is formed in the region of the lining layer 21 on the outer peripheral end side of the valve blade 11a of the valve body 11. The outer peripheral seal portion 30 is provided circumferentially on the valve blade side of the core metal 20, and the lining layer 21 near the boss portion of the core metal 20, excluding the outer peripheral seal portion 30, is formed in a substantially spherical shape from the center (rotation axis) N of the valve body. As described above, the valve 1 is opened and closed by rotating the valve body 11, which has an outer sealing portion 30, against the inner sealing surface 14 of the body 10.

[0028] In Figure 3, the dashed line shows the outer seal portion 30 before deformation, and the solid line shows the outer seal portion 30 after elastic deformation when the valve body 11 is in the closed valve state. In Figure 4, the state when fluid pressure is applied to the valve body 11 from the primary side of the flow path 2 is shown in Figure 3, and the dashed line shows the state of the outer seal portion 30 in Figure 3 when the valve body 11 is in the closed valve state.

[0029] The outer periphery seal portion 30 includes a seal projection portion 31 and a valley bottom portion 32. The seal projection 31 is formed to protrude in a rounded, mountain-like shape, located at least on the primary side in the thickness direction of the outer edge of the valve body 11. In this embodiment, the seal projection 31 has a left (primary side) seal projection 31 and a right (secondary side) seal projection 31, separated by the center line L in the direction of the valve blade 11a of the valve body 11. These are formed to protrude in a rounded, mountain-like shape on the outer edge of the valve body 11, located on the primary and secondary sides in the thickness direction, respectively.

[0030] As described above, the outer peripheral seal portion 30 has seal protrusions 31 on the primary and secondary sides in the thickness direction at the outer edge of the valve body, and these primary and secondary seal protrusions 31 are smoothly connected in a cross-sectional M-shaped double-peak form. On the other hand, the valley bottom portion 32 is located between the primary and secondary side seal protrusions 31 and is formed in a rounded valley shape.

[0031] In valve 1, at least the primary side seal projection 31 is formed in a shape that is inclined and curved toward the primary side with respect to the center line L in the direction of the valve blade 11a of the valve body 11. In this example, both the primary and secondary side seal projections 31 are formed in a shape that is inclined and curved toward the primary and secondary sides with respect to the center line L, respectively. As a result, when a line L1 parallel to the center line L in the direction of the valve blade 11a is drawn from near the top 33 of each seal projection 31, each seal projection 31 has an asymmetrical shape on its left and right sides with respect to this line L1. A rounded portion 34 is provided on the side of the primary and secondary side seal projections 31 that faces the inner circumferential sealing surface 14 of the body at the tip end, and the asymmetrical shape of the seal projection 31 is smoothly connected via this rounded portion 34.

[0032] The angle θ of the curvature of the seal projection 31 should be, for example, about 10° to the primary and secondary sides relative to the lining layer 21 on the front and back sides of the valve body 11. The curvature angle θ is the magnitude of the inclination to the primary and secondary sides relative to the lining layer 21 formed on the front and back sides of the valve body 11, with respect to the surface of the lining layer 21 formed on the front and back sides of the valve body 11. Furthermore, the aforementioned centerline L in the direction of the valve blades represents a line in Figure 2 that passes through the center (axis of rotation) N of the valve body and is perpendicular to this axis of rotation N in the direction of the valve blades 11a.

[0033] Furthermore, the primary and secondary side seal protrusions 31 are provided in such a shape that each of their apex portions 33 is located outside a virtual valve body surface 35 that extends outward from the front and back surfaces of the outer peripheral seal portion 30 on the valve blade 11a side, parallel to the center line L in the direction of the valve blade. In other words, the virtual valve body surface 35 is located on the side of the center line L1 mentioned above. As a result, a portion of each of the primary and secondary side seal protrusions 31 is also positioned to protrude outward from the virtual valve body surface 35. The apex portion 33 of the seal protrusion 31 refers to the point on the outer peripheral end face 20a of the core metal 20 of the seal protrusion 31 that is furthest from the primary and secondary side edges 20b.

[0034] As described above, the primary and secondary side seal protrusions 31 are arranged in a shape that curves outward toward the primary and secondary sides, with a portion of them protruding outward from the hypothetical valve body surface 35. This allows them to exhibit a unique wedge function against the inner circumferential sealing surface 14 of the body 10 when the valve is closed, thereby improving sealing performance.

[0035] Here, if the aforementioned seal projection 31 and valley bottom portion 32 are provided on the outer peripheral seal portion 30 in a predetermined shape, one example is to set their shape as follows. First, the starting position for the curvature of the seal projection 31 is set relative to the lining layer 21 on the front and back sides of the valve body 11. In this case, the position of the core metal 20 inside the valve body 11 relative to the lining layer 21 is also taken into consideration, and the starting position for the curvature is set to be below the outer peripheral end face 20a of the core metal 20 in the left-right direction of Figure 3, that is, to be a position that overlaps with the side surface of the core metal 20 in the flow path 2 direction. This starting position for the curvature becomes the inflection point 36 when the lining layer 21 is changed to form the shape of the seal projection 31 from the front and back sides of the valve body 11.

[0036] Next, the angle θ for the curvature from the starting position to the primary and secondary sides is set. In this case, if the angle θ is too large, the resistance of the seal projection 31 to the inner circumferential seal surface 14 during deformation will increase, making it difficult for it to deform in the sealing direction due to the fluid pressure of the fluid flowing inside the body 10. On the other hand, if the angle θ is too small, the overall size (volume) of the seal projection 31 will decrease, making it impossible to ensure sufficient strength. For these reasons, as mentioned above, it is desirable that the curvature angle θ be about 5 to 30°, preferably about 10°. In this case, when a fluid with a pressure of approximately 1 MPa or more flows inside the body 10, it will be possible to deform appropriately in response to that fluid pressure.

[0037] Next, the position of the valley bottom 32 of the seal projection 31, that is, the height from the outer peripheral end face 20a of the core metal 20 to the valley bottom 32, is set so as to ensure a predetermined wall thickness from the outer peripheral end face 20a of the core metal 20. The size of the rounded portion 34 and the curved portion connecting the rounded portion 34 and the valley bottom 32 are then set to be smooth so as to connect the valley bottom 32 and the curved portion. The rounded portion 34 is not limited to an arc shape centered on the edge 20b of the core metal 20, and its trajectory can be set with any point on the valve body 11 as the center. At this time, care must be taken not to make the size of the rounded portion 34 too large, as this will increase the cross-sectional shape of the seal projection 31 and make it difficult to elastically deform.

[0038] Furthermore, the curved section between the seal projection 31 and the valley bottom 32 is provided with a gentle downward slope from the top 33 of the seal projection 31 to the secondary side (towards the center of the outer peripheral end face 20a of the core metal 20), connecting the curved section 34 and the valley bottom 32. By setting the shape as described above, the outer peripheral seal portion 30 is provided with a double-peaked M-shaped cross-section, in which the seal projection portion 31 and the valley bottom portion 32 are smoothly connected in the cross-sectional direction.

[0039] The seal projection 31 and valley bottom 32 described above are set to an appropriate shape and size, taking into consideration the size of the valve 1 (diameter of the valve body) and the flow velocity of the fluid flowing inside it. In particular, the position of the top 33 of the seal projection 31 and the size of the radius of the radius 34 have a significant impact on the sealing performance and durability of the seal projection 31 when the valve is closed, and must be set appropriately according to the size of the valve 1, etc.

[0040] When an outer peripheral seal portion 30 is provided, as an alternative configuration of the outer peripheral seal portion 30 to that shown in Figure 3, for example, in Figure 3, when a distance H1 equal to the distance H from the edge 20b of the outer peripheral end face 20a of the core metal 20 to the top 33 of the rounded portion 34 of the seal projection 31 is marked on the front and back surfaces of the core metal 20 from the edge 20b toward the center of the core metal 20, the inflection point 36 may be defined as the point at which an auxiliary line, shown by a dashed line, is drawn horizontally from this marking position and intersects with the lining layers 21 on the front and back surfaces of the valve body.

[0041] Furthermore, although not shown in the figures, for example, a line L1 drawn parallel to the center line L in the direction of the valve blade of the valve body 11 from near the top 33 of the seal projection 31 may be used as an inflection point when a line is drawn parallel to the center C of the flow path 2 from the position where the thickness of the lining layer 21 on the front and back surfaces of the valve body 11 is bisected by this line L1. In this case as well, the shape of the seal projection 31 can improve the sealing performance when the valve is closed.

[0042] In Figure 3, the front and back surfaces of the core metal 20 are inclined with respect to the center line L in the direction of the valve blade of the valve body, resulting in differences in the position of the inflection point 36 as shown in the two examples above. However, by arranging the front and back surfaces of the core metal 20 approximately parallel to the center line L, the position of the inflection point 36 can be brought closer to a more desirable position in the two outer peripheral seal portions 30 using the formation method described above.

[0043] Due to the shape of the seal projection 31 described above, when the valve 1 is fully closed, the primary side of the outer peripheral seal portion 30, specifically the seal projection 31, is tilted more towards the primary side with respect to the center line L and is in close contact with the inner peripheral seal surface 14. In this example, the primary side of the outer peripheral seal portion 30, specifically the seal projection 31, has a line segment connecting its top 33 and the edge 20b of the outer peripheral end face of the core metal 20 that is tilted towards the primary side with respect to the center line L in the direction of the valve blade of the valve body when it contacts the inner peripheral seal surface 14. As a result, the seal projection 31 is flexibly deformed to be tilted relative to the inner peripheral seal surface 14 and makes contact to seal.

[0044] In Figure 1, an upper stem insertion hole 40 and a lower stem insertion hole 41 are provided in the center of the lining layer 21 near the top and bottom of the valve body 11, and the upper stem 12 and lower stem 13 are inserted into these stem insertion holes 40 and 41, respectively. The valve body 11 is inserted into the upper shaft insertion cylinder 22 and the lower shaft insertion cylinder 23 through the upper stem 12 and the lower stem 13, respectively, and mounted in a predetermined position within the body 10, so that the valve 1 is configured as a central butterfly valve.

[0045] After the valve body 11 is installed, the boss surface of the lining layer 21 of the valve body 11 seals the area around the upper stem insertion hole 40 and the lower stem insertion hole 41 on the inner circumferential sealing surface 14 of the body 10, ensuring airtightness in the upper and lower parts of the valve body 11 that are on the shaft mounting side. Meanwhile, the entire lining layer 21 of the valve body 11 is provided to seal over the entire inner circumferential sealing surface 14, excluding the sealing areas around the upper and lower stem insertion holes 40 and 41.

[0046] The valve body 11 is rotatable by automatic or manual operation of the upper and lower stems 12 and 13, and the flow path 2 inside the body 10 can be adjusted to an open / closed state or an intermediate open state.

[0047] Furthermore, the outer peripheral seal portion 30 in the central butterfly valve of the present invention has a seal projection as described above, and this seal projection is curved inclined with respect to the center line L. When fully closed, the primary side of the outer peripheral seal portion with the seal projection is tilted further towards the primary side with respect to the center line L and is in close contact with the inner peripheral seal surface 14. In other words, it can be provided in various shapes other than those described above. For this reason, the overall shape and details can be arbitrarily changed depending on the type of fluid flowing inside the valve 1 and the sealing performance required when the valve is closed.

[0048] Furthermore, it is also possible to provide only the primary side seal protrusion 31 of the outer peripheral seal portion 30, and omit the secondary side seal protrusion. In the above embodiment, the left side of the valve 1 is the primary side of the flow path 2 and the right side is the secondary side. However, since the outer circumference of the lining layer 21 is provided in a substantially symmetrical shape with an M-shaped cross-section, the right side of the valve 1 may be the primary side of the flow path 2 and the left side may be the secondary side.

[0049] The angle θ of the curvature of the seal projection 31 can be set to a range other than 5 to 20°, and this angle θ can be arbitrarily set depending on the size of the valve 1 or the size of the radius portion 34 of the seal projection 31.

[0050] The lining layer 21 may be formed from a soft material other than rubber, for example, a resin lining with resin as the soft material. In this way, the hardness of the lining layer 21 can be set appropriately depending on the type of soft material used as the lining material.

[0051] The body 10 of valve 1 may be connected to the external piping using a connection method other than groove connection, for example, by a commonly used connection method such as flange connection.

[0052] Next, the operation and function of valve 1 in the above embodiment of the present invention when it is closed will be described. When the valve body 11 is rotated from the valve open position to the valve closed position, the primary and secondary side seal protrusions 31 come into contact with the inner circumferential seal surface 14 of the body 10, respectively. As the rotation continues in the valve closed position, the primary and secondary side seal protrusions 31 are pushed against the inner circumferential seal surface 14, causing them to deform and tilt toward the primary and secondary sides, resulting in a sealed state against the inner circumferential seal surface 14.

[0053] Figure 3 shows the state after the valve is closed, when no fluid pressure is applied to the body 10 from the primary side. At this time, the primary and secondary seal protrusions 31 are elastically deformed by pressure contact with the inner circumferential seal surface 14, and the primary side seal protrusion 31 tilts toward the primary side with respect to the center line L in the direction of the valve blade of the valve body, while the secondary side seal protrusion 31 tilts toward the secondary side with respect to the center line L, thereby sealing.

[0054] The force from the inner circumferential sealing surface 14 is applied to the tip side of the primary and secondary sealing protrusions 31, and each sealing protrusion 31 tilts more toward the primary and secondary sides when fully closed compared to when the valve is first closed. At this time, each sealing protrusion 31 deforms so as to bend around the inflection point 36. In this case, since there is no core metal 20 in the direction in which each sealing protrusion 31 deforms, no compressive force is applied to each sealing protrusion 31, and it can deform flexibly within the rigidity range of the lining layer 21 without excessive stress. As a result, the pressure from the inner circumferential sealing surface 14 is less likely to be applied to the front and back sides of the valve blade 11a, excluding the tilted outer circumferential sealing portion 30.

[0055] As described above, when no fluid pressure is applied to the valve body 11 in the fully closed state, the seal projection 31 side is curved inward, tilting towards the primary and secondary sides, respectively, with respect to the center line L in the direction of the valve blade of the valve body. In this case, as shown in Figure 4, an inclined pressing force due to the angle φ of inclination from the vertical acts on the vicinity of the top 33 of the deformed seal projection 31, indicated by the dashed line, from the inner circumferential seal surface 14 side. This inclined force F can be divided into component forces Fx and Fy in the X direction (horizontal direction in the figure) and Y direction (vertical direction in the figure), respectively, and the force F is given by the relationship F = component force Fx + component force Fy.

[0056] From this relationship, the component force Fy in the Y direction can be expressed as Fy = Fcosφ. For example, when force F acts at an angle φ = 45° with respect to the vertical direction, the component force Fy in the vertical direction (Y direction) becomes Fy = force F × cos45° ≈ force F × approximately 0.71. This means that the vertical component force can be reduced to about 0.71 times its original value. As a result, the force can be reduced compared to the case where the force from the inner circumferential seal surface is applied vertically to the seal protrusion.

[0057] In addition, when a force F is applied to the top 33 side of the seal projection 31, the seal projection 31 deforms while releasing the force by sliding along the inner circumferential sealing surface 14 due to its inclined shape, thereby mitigating the force applied to the seal projection 31 and the area near the inflection point 36.

[0058] When fluid pressure is applied from the primary side to the valve body 11 in the fully closed state described above, and this fluid pressure increases to a predetermined pressure or higher, the tip of the seal projection 31 facing the primary side of the flow path 2 elastically deforms toward the secondary side due to the fluid pressure. At this time, the tip of the seal projection 31 deforms between the inner circumferential seal surface 14 and the core metal 20 so as to be guided by the inner circumferential seal surface 14, and as a result, the entire primary side seal projection 31 is slightly elastically deformed toward the secondary side. As a result, the surface pressure between the area near the top 33 of the seal projection 31 and the inner circumferential seal surface 14 increases with increasing fluid pressure, improving sealing performance.

[0059] At this time, the fleshy portion of the seal projection 31 protruding towards the flow path 2 exhibits a self-sealing function due to the pressure seal of the fluid pressure. In this process, the outer peripheral seal portion 30 exhibits a so-called wedge effect, deforming to plug the inner peripheral seal surface 14 on the inlet side, thereby improving the sealing performance. Moreover, the seal projection 31 makes surface contact with the inner peripheral seal surface 14, improving the sealing performance and exhibiting excellent sealing performance.

[0060] The seal projection 31 is less likely to be compressed and deformed as a whole between the inner circumferential sealing surface 14 and the core metal 20. Instead, the tilting of the outer circumferential sealing portion 30 minimizes the amount of deformation, allowing it to seal at a position away from the opposing position between the core metal 20 and the inner circumferential sealing surface 14, on the primary side. This allows the sealing position to be moved away from the position where the most torque is applied when the valve body 11 is opened and closed, on the primary side of the flow path 2, thereby reducing the amount of deformation of the seal projection 31. This prevents excessive stress from acting on the seal projection 31, improving durability and suppressing deterioration. Moreover, the reduced operating torque improves operability.

[0061] Since the entire seal projection 31 does not tilt significantly towards the secondary side, it also prevents a strong pulling force from acting on its primary-side inclined surface 42 towards the secondary side. Therefore, it prevents cracks, fractures, and breakages of the seal projection 31, improving the durability of the valve body 11, suppressing deterioration, and maintaining sealing performance. The seal projection 31 increases the overall thickness of the outer peripheral seal portion 30, thereby improving the overall strength of the outer peripheral seal portion 30.

[0062] Furthermore, since the inflection point 36, which is the starting point of deformation of the seal projection 31, is located closer to the center of the valve body than the end of the core metal 20, shear force applied from the corner of the core metal 20 can be suppressed. Also, because the inflection point 36 is connected to the seal projection 31 by a gentle curve, areas where stress concentrates are less likely to occur, and these factors also help to prevent fracture and other damage.

[0063] In the above embodiment, the valve 1 is constructed by covering the core metal 20 with a lining layer 21 made of rubber lining to form the valve body 11. In particular, the lining layer 21 provided on the outer surface of the core metal 20 ensures sealing between the outer surface of the valve body 11 and the inner surface of the body without requiring a lining layer to be applied to the inner surface of the body 10. Therefore, even in cases where the body 10 is a long cylindrical shape, as in this embodiment, and it is difficult to apply a lining treatment to the inner circumference of the body 10, the lining layer 21 provided on the valve body 11 ensures sealing when the valve is closed. [Examples]

[0064] Next, the "internal stress" and "contact pressure" when fluid pressure is applied near the lining layer were analyzed by simulation for the valve of the embodiment of the present invention described above and comparative examples. Here, "internal stress" refers to the stress generated on the inner circumferential sealing surface of the body when the valve is closed due to deformation of the lining layer and fluid pressure, and "contact pressure" refers to the pressure generated between the lining layer of the valve body and the inner circumferential sealing surface of the body when the valve is closed.

[0065] Figures 5(a) and 5(b) show the analysis results of internal stress and contact pressure near the valve body 11 and lining layer 21 of the valve 1 of the present invention, respectively. Similarly, Figures 6(a) and 6(b) show the analysis results of internal stress and contact pressure near the valve body 51 and lining layer 52 of the comparative example valve, respectively. In the comparative example butterfly valve, the cross-sectional shape of the outer peripheral seal portions on the primary and secondary sides is a mountain shape symmetrical with respect to the direction of the center line of the valve body in the direction of the valve blade. The arrow P in the figures indicates the direction in which pressure is applied.

[0066] In each figure, the magnitude of internal stress and contact pressure occurring near the lining layer (outer seal area) and on the inner seal surface is broadly represented by regions α, β, γ, and δ. The order of these pressure magnitudes is region α > region β > region γ > region δ. Region α, where the highest internal stress and contact pressure occur, is shown with the narrowest hatching interval, and the hatching interval becomes wider as the internal stress and contact pressure decrease.

[0067] The figure shows the simulation analysis results when the fluid pressure applied to the primary side is approximately 2.2 MPa. From the internal stress results in Figure 5(a), in the butterfly valve of the present invention, the stress is highest in region β in the lining layer 21, and the stress level in region β is lower than the pressure level in region α in the lining layer 52 of the comparative example in Figure 6(a). In other words, the maximum stress occurring in the lining layer 21 in Figure 5(a) is lower than the maximum stress occurring in the lining layer 52 in Figure 6(a).

[0068] Furthermore, the combined range of regions β and γ in Figure 5(a) is narrower than the combined range of regions α, β, and γ in Figure 6(a). In other words, the internal stress occurring throughout the lining layer 21 in Figure 5(a) is smaller than the internal stress occurring in the lining layer 52 in Figure 6(a).

[0069] In addition, Figure 5(a) shows that most of the internal stress in regions β and γ is located on the primary side of the valve body 11, indicating that stress is less likely to occur on the secondary side of the lining layer 21.

[0070] From the above, it can be said that the valve 1 of the present invention shown in Figure 5(a) has lower internal stress in the lining layer than the comparative example valve shown in Figure 6(a), and effectively suppresses internal stress.

[0071] On the other hand, the contact pressure results in Figure 5(b) show that in the valve 1 of the present invention, the highest contact pressure is generated in region α, and the range of this region α is wider than that of region α in Figure 6(b) of the comparative example valve. In other words, it was confirmed that Figure 5(b) seals the valve body and the inner circumferential sealing surface while exhibiting a higher contact pressure over a wider range than Figure 6(b). From this, it can be said that the valve 1 of the present invention shown in Figure 5(a) exhibits higher sealing performance when the valve is closed than the comparative example valve shown in Figure 6(b).

[0072] Although embodiments of the present invention have been described in detail above, the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention as described in the claims of the present invention. [Explanation of Symbols]

[0073] 1 valve 10 Body 11 Valve body 11a Valve blade 14 Inner circumferential sealing surface 30 Outer periphery sealing section 31 Seal protrusion 33 Top 35. Virtual valve surface L: The centerline of the valve body in the direction of the valve blades.

Claims

1. A central-type butterfly valve that opens and closes by rotating a valve body having an outer peripheral sealing portion on the outer peripheral end side of the valve blade relative to the inner peripheral sealing surface of the body, wherein the outer peripheral sealing portion has a seal projection that is located on the primary side in the thickness direction at the outer edge of the valve body and protrudes in a rounded, mountain-like shape, and this seal projection is formed in a shape that is inclined and curved in the primary side with respect to the center line in the direction of the valve blade of the valve body, and when fully closed, the seal projection side is in a state in close contact with the inner peripheral sealing surface while being inclined more towards the primary side with respect to the center line.

2. The central butterfly valve according to claim 1, wherein the top of the seal projection is provided in a shape that is located outside the virtual valve surface that extends outward from the front and back surfaces of the outer peripheral seal portion excluding the seal projection, parallel to the center line in the direction of the valve blade, toward the outer diameter.

3. The central butterfly valve according to claim 1 or 2, wherein the outer peripheral seal portion has the seal protrusions on the primary and secondary sides in the thickness direction at the outer edge of the valve body, and is provided in a two-peak shape with an M-shaped cross-section that smoothly connects them.

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