Butterfly valve body and butterfly valve

Abstract

To provide a valve body of a butterfly valve which secures strength of the entire part including an area near a valve vane part to improve sealability when a valve is closed, achieves high flow characteristics by reducing flow resistance when the valve is open while reducing the weight to achieve improvement of operability and reduction of the material even if the valve body is provided having a large diameter and is excellent in assemblability and maintainability.SOLUTION: A valve body of a butterfly valve is rotatably provided in a cylindrical body 3 through upper and lower stems 4, 5. Cylindrical boss parts 21, 22 including stem insertion holes 26, 27 are formed at upper and lower parts of a disc 20 having a discoid shape, and rib parts 23 are provided along a rotation axis P of the stems between the upper and lower boss parts. Each rib part is provided in a smooth surface shape in which a height decrease rate gradually reduces toward a valve vane part 24 in a border region with the valve vane part, and a gap chamber 25 communicating with the stem insertion holes is provided within the rib part. The gap chamber has a shape in which a size in a width direction is larger than a size in a thickness direction of a valve body main unit 2 and an area near a center as seen in the thickness direction is the widest on a cross section intersecting with a longitudinal direction of the rib part.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a valve element for a butterfly valve, and in particular to a butterfly valve and a valve element that are lightweight and easy to operate even when installed in a large diameter, while ensuring sealing performance when the valve is closed and high flow characteristics when the valve is open. [Background technology]

[0002] Typically, the disc of a butterfly valve is rotatably mounted within the body by a stem, and it is required to ensure a large flow rate while improving operability by reducing its weight and preventing an increase in operating torque. Also, there are often demands for reduction in material and ease of assembly and maintenance. For this reason, a structure in which the stem is divided into upper and lower halves to support the upper and lower sides of the disc is known. With this type of stem mounting structure, compared to a one-piece stem that is attached so that it penetrates the disc vertically, it is possible to make the inside of the disc hollow and reduce its weight, which allows for improved operability even when the valve diameter is large. Even when the valve body is supported by a stem with a split structure like this, it is required to ensure strength against fluid pressure when the valve is closed, improving sealing performance, as with a stem that penetrates the valve body, while reducing flow resistance when the valve is open and ensuring high flow characteristics.

[0003] In response to these demands, for example, the applicant has filed a patent application in Patent Document 1. The butterfly valve in this document is attached to the body via separate upper and lower stems, with the upper and lower bosses of a disc-shaped disk connected by vertical ribs, and horizontal ribs that intersect with the vertical ribs on the front and back surfaces of the disk, with flattened arcs. A circular hollow portion is provided inside the vertical rib so as to communicate with the stem insertion holes inside the upper and lower bosses. The formation of this hollow portion and the thinning of the disk reduce the weight of the valve body, improving operability, while also achieving both improved rigidity due to the vertical and horizontal ribs and smoother flow due to reduced physical resistance when the valve is open.

[0004] On the other hand, in Patent Document 2, a cylindrical portion is formed on a base plate constituting a valve body, protruding in the direction of stem insertion, and multiple circular ribs are formed on the front and back sides of the base plate, intersecting the cylindrical portion and protruding concentrically. A cylindrical core portion is provided between the upper and lower cylindrical portions, and stem insertion holes for inserting the upper and lower stems are formed inside the cylindrical portion. The core portion has an outer diameter larger than the outer diameter of the stem insertion holes and an inner diameter larger than the inner diameter of the stem insertion holes, resulting in a hollow portion (inside the core portion) between the upper and lower stem insertion holes having a larger diameter.

[0005] Generally, in a butterfly valve, when fluid pressure is applied to the disc when the valve is closed, the disc is supported by the stem, and the fluid pressure applied at a position away from the stem applies a deflection (bending) force to the surface of the disc around the stem, which causes tensile stress on the primary side of the disc (the side that receives fluid pressure) and compressive stress on the secondary side (the side that does not receive fluid pressure).In this case, the fluid pressure received on the blade side causes the greatest force to act on the disc near the center axis of the stem, and this force decreases as you move closer to the blade side. Therefore, some butterfly valves, such as those disclosed in Patent Documents 1 and 2, are designed to be reinforced mainly around the stem shaft to prevent deflection and deformation due to fluid pressure. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6546377 [Patent Document 2] Patent No. 4659927 Summary of the Invention [Problem to be solved by the invention]

[0007] In the butterfly valve disc of Patent Document 1, if the horizontal rib's planar size or thickness were increased to accommodate larger flow path diameters or to increase the strength of the valve blades, the weight of the entire valve disc would increase, which would increase the operating torque and reduce operability. To address this issue, a hollow section is provided to reduce weight. Considering the weight increase that would result from larger valve discs (larger diameters) and larger, thicker horizontal ribs, even further weight reductions are desirable.

[0008] On the other hand, in the valve body of the butterfly valve of Patent Document 2, the inner diameter of the core portion is larger than the inner diameter of the valve stem insertion hole, and the hollow portion of this core portion has a larger diameter, which makes it possible to reduce the weight of the valve body.

[0009] However, with this structure, it is difficult to sufficiently reduce the weight of the valve disc, which increases with its size. Furthermore, this valve disc has multiple concentric circular ribs to increase the strength of the valve disc on the wing side, which results in an increase in the overall weight compared to when horizontal ribs are provided as in Patent Document 1, and this may also lead to an increase in the amount of material required to mold the valve disc.

[0010] The present invention was developed to solve the problems of the past, and its purpose is to provide a butterfly valve and a butterfly valve that are easy to assemble and maintain, while also achieving overall weight reduction, improved operability, and reduced material use even when installed in a large diameter valve, while ensuring the strength of the entire disc including the valve blades when the valve is closed and improving sealing performance, and reducing flow resistance when the valve is open, thereby achieving high flow rate characteristics. [Means for solving the problem]

[0011] In order to achieve the above object, the invention of claim 1 is a butterfly valve body rotatably mounted within a cylindrical body via upper and lower stems, in which cylindrical bosses with stem insertion holes are formed above and below a disc-shaped disk, and ribs are provided between the upper and lower bosses along the axis of rotation of the stem, and the ribs have a gentle surface shape in which the rate of decrease in height gradually decreases toward the valve blades in the boundary region between the ribs and the valve blades, and a void chamber is provided inside the ribs that communicates with the stem insertion hole, and in a cross section intersecting the longitudinal direction of the ribs, the void chamber has a shape that is wider in the width direction than in the thickness direction of the valve body body and is widest near the center in the thickness direction. The outer wall of the void chamber is formed in a shape that follows the surface of the rib portion, and the outer wall of the void chamber has a portion that is approximately parallel to the surface shape of the rib portion. This is the valve body of a butterfly valve.

[0013] Claim 2 The invention relates to a butterfly valve body in which the surface of the rib portion has a generally hexagonal cross section, with a flat portion chamfered near the top and an inclined surface portion consisting of a flat or curved surface that slopes toward the valve blade portion, and the outer wall of the gap chamber is formed by surfaces that are generally parallel to the flat portion and the inclined surface.

[0014] Claim 3 The invention relates to a valve body of a butterfly valve, in which, in a cross section intersecting the longitudinal direction of the rib portion, the rib portion is formed into a substantially flat cross section in which the valve wing direction is longer than the thickness direction.

[0015] Claim 4 The invention relates to a butterfly valve body in which the thickness of the rib portion is substantially uniform over the entire circumference in a cross section intersecting the longitudinal direction of the rib portion except for the connection portion with the valve blade portion.

[0016] Claim 5 The invention relates to a butterfly valve body in which the thickness of the void chamber portion of the rib portion in a cross section intersecting the longitudinal direction of the rib portion gradually decreases toward the upper and lower boss portions.

[0017] Claim 6 The invention relates to a valve body of a butterfly valve in which a curved surface is formed at least on the valve blade side of the gap chamber.

[0018] Claim 7 The invention relates to a butterfly valve in which a valve element of the butterfly valve is mounted in a body via upper and lower stems so as to be able to be opened and closed freely. [Effects of the Invention]

[0019] According to the invention of claim 1, a void chamber is provided inside the rib portion. This void chamber is wider in width than in the thickness direction of the valve body, and is widest near the center of the thickness direction. This allows for a lightweight design, improved operability, and reduced material requirements, even when used with large-diameter valves. Furthermore, the void chamber provided inside the rib portion between the upper and lower bosses ensures sufficient strength against stress. When the valve is closed, its smooth surface shape ensures the strength of the entire disc, including the valve blades, improving sealing performance. Because the height of the rib portion and the upper and lower bosses can be kept low, when the valve is open, flow resistance is reduced, smoothing the flow of fluid and suppressing the occurrence of cavitation, resulting in high flow characteristics. Furthermore, the structure in which the valve body is attached using the upper and lower stems also provides excellent assembly and maintenance. By forming the outer wall of the void chamber in a shape that follows the surface of the rib portion, further weight reduction is achieved, while suppressing the overall stress applied when the valve is closed to below the allowable stress, preventing stress concentration and reliably preventing deformation such as bending when force is applied in the deflection direction due to fluid pressure, etc. By forming the outer wall of the void chamber in a shape that follows the surface of the rib portion in this way, the periphery of the void chamber has a substantially uniform thickness except for the connection portion with the valve blade portion. As a result, there are no areas where the thickness is small and stress is likely to concentrate, and it is possible to expand the void chamber while maintaining strength throughout the entire radial direction of the rib portion, thereby achieving efficient weight reduction.

[0021] Claim 2 According to the invention, by forming the surface of the rib portion into a generally hexagonal cross section having flat and inclined surfaces, the valve body can be formed into a flat structure, thereby improving the grounding property during processing of the valve body and assembly of the valve. By providing the outer wall of the void chamber with surfaces generally parallel to the flat and inclined surfaces, respectively, the void chamber can be maximized while maintaining a generally uniform thickness of the rib portion. The stress applied to the entire valve body when fully closed can be distributed generally evenly and kept below the allowable stress, thereby suppressing deflection and ensuring sufficient strength. By making the thickness near the rib portion, which is thicker than the valve blade portion, generally uniform, when the valve body is formed by casting, the cooling rate near the rib portion is generally constant, similar to that of the surrounding area, making it less likely to produce casting defects such as warping, deformation, or blowholes.

[0022] Claim3 According to the invention, by forming the rib portion into a generally flat cross section, the inclination angle from the rib portion to the valve wing portion is formed into a gentle shape, which reduces stress concentration when force is applied to the valve body and prevents deflection. By keeping the height near the top of the stem insertion side low and forming the rib portion with a gentle surface shape in the direction of the valve wing portion, flow resistance is reduced and excellent flow characteristics are achieved.

[0023] Claim 4 According to the invention, the thickness of the rib is made substantially uniform around the entire circumference except for the connection with the valve blade, thereby maximizing the size of the void chamber and effectively reducing the weight while ensuring a constant strength for the entire rib. When the valve body is cast, the cooling rate of the rib is made substantially constant, which also reduces the occurrence of casting defects such as warpage, deformation, and blowholes.

[0024] Claim 5 According to the invention, by gradually reducing the thickness of the void chamber portion of the rib portion as it approaches the upper and lower boss portions, it is possible to ensure strength while reducing excess thickness in the portion where strength is ensured by the boss portion, thereby achieving further weight reduction and improved operability.

[0025] Claim 6 According to the invention, by providing a curved surface at least on the valve wing side of the void chamber, not only can the valve body be made even lighter while ensuring the strength of the rib portion, but the curved surface also makes it easier to cast out the core when forming the void chamber, so that the valve body body can be easily molded as a single unit by casting.

[0026] Claim 7According to the invention, it is possible to provide a butterfly valve that is lightweight overall, improves operability, and reduces material usage even when installed in a large diameter. Furthermore, the provision of a void chamber ensures the necessary strength against stress, and when the valve is closed, the strength of the entire disc, including the valve blades, is ensured, improving sealing performance. Meanwhile, when the valve is open, flow resistance is reduced, enabling high flow characteristics to be achieved. Furthermore, the valve body can be easily attached by attaching and detaching the upper and lower stems, making it easy to assemble and maintain. [Brief explanation of the drawings]

[0027] [Figure 1] 1 is a front view showing an embodiment of a butterfly valve using a valve element of a butterfly valve according to the present invention. FIG. [Figure 2] FIG. 2 is a central longitudinal cross-sectional view of FIG. [Figure 3] FIG. 2 is a front view showing the valve body of the butterfly valve of the present invention. [Figure 4] 4(a) is an enlarged horizontal cross-sectional view of the center of FIG. 3, and FIG. 4(b) is a perspective view of FIG. [Figure 5] FIG. 4 is a longitudinal sectional view of FIG. 3. [Figure 6] FIG. 6 is a central longitudinal cross-sectional view of FIG. 5. DETAILED DESCRIPTION OF THE INVENTION

[0028] Hereinafter, the valve element of the butterfly valve and the butterfly valve according to the present invention will be described in detail based on embodiments. Figures 1 and 2 show an embodiment of a butterfly valve using the butterfly valve disc of the present invention, and Figures 3 to 6 show the butterfly valve disc. In the figures, a butterfly valve main body 1 comprises a valve disc main body 2, a cylindrical body 3, an upper stem 4, a lower stem 5, and a seat ring 6.

[0029] The body shown in Figures 1 and 2 3 The body is cylindrical. 3The upper and lower shaft portions 10 and 11 are formed to protrude from the upper and lower parts of the seat ring 6, and insertion holes 12 and 13 for mounting the upper and lower stems 4 and 5 are formed inside the upper and lower shaft portions 10 and 11, respectively. The seat ring 6 is made of a rubber material or the like and is cylindrical in shape. 3 This is attached to the inner surface of the body. 3 A flow path 14 is provided therein.

[0030] 3 to 6, the valve body 2 is formed by casting, and includes a disc 20, an upper boss portion 21, a lower boss portion 22, a rib portion 23, a valve blade portion 24, and a gap chamber 25. The disk 20 is formed in a circular disk shape large enough to open and close the flow path 14, and a cylindrical upper boss portion 21 and a cylindrical lower boss portion 22 are formed on the top and bottom of the disk 20. The upper and lower boss portions 21, 22 are provided therein with stem insertion holes 26, 27, respectively, into which the upper stem 4 and the lower stem 5 can be inserted, respectively. The valve body 2 is rotatably mounted in the body 3 via the seat ring 6 by the upper and lower stems 4 and 5 in the valve body 1, and the flow path 14 of the valve body 1 can be opened and closed by rotating the upper stem 4.

[0031] A rib portion 23 is formed between the upper and lower boss portions 21, 22 to protrude along the rotation axis P of the stems 4, 5. The rib portion 23 is provided with a gentle surface shape in which the rate of decrease in height gradually decreases toward the valve wing portion 24 in the boundary region between the rib portion 23 and the valve wing portion 24.

[0032] As shown in Figure 4, an open void chamber 25 is provided inside the rib portion 23 so as to communicate with the stem insertion holes 26, 27. In a cross section intersecting the longitudinal direction of the rib portion 23, the void chamber 25 is wider in the width direction than in the thickness direction of the valve body 2, and has a shape that is widest near the center in the thickness direction. The void chamber 25 can be formed using a core (not shown).

[0033] In the cavity 25 , the outer wall 28 is formed in a shape that follows the surface 29 of the rib portion 23 . In this embodiment, the widthwise length W of the gap chamber 25 is set to be at least twice the outer diameter φD of the stem 4 (5) shown in Fig. 2, and in this state, the gap chamber 25 is provided so as to have a shape that is approximately similar to that of the rib portion 23. Increasing the widthwise length W of the gap chamber 25 in this way increases the volume of the gap chamber 25, but the size (volume) of this gap chamber 25 needs to be set to an appropriate size, taking into consideration the durability of the valve body 2 against deflection.

[0034] 3 and 4, the surface 29 of the rib portion 23 has a flat portion 30 that is chamfered near the top, and an inclined surface portion 31 that is a flat surface or a curved surface that slopes toward the valve wing portion 24, thereby providing the rib portion 23 with a substantially hexagonal cross section. In this embodiment, the inclined surface portion 31 is formed by a curved surface. 25 The outer wall 28 is provided by surfaces that are approximately parallel to the flat surface portion 30 and the inclined surface portion 31 of the rib portion 23 .

[0035] In a cross section intersecting the longitudinal direction of the rib portion 23, the rib portion 23 is formed to have a generally flat cross section in which the direction of the valve wing portion 24 is longer than the thickness direction, and the rib portion surface 29 is configured to be gently inclined from the rotation axis P of the valve body main body 2 toward the valve wing portion 24. Note that in this embodiment, the "cross section intersecting the longitudinal direction of the rib portion" means a cross section perpendicular to the longitudinal direction of the rib portion 23 provided from near the top to near the bottom of the disc 20 in Figure 3.

[0036] As mentioned above, the outer wall 28 of the void chamber 25 is formed by a surface that is approximately parallel to the flat surface portion 30 and the inclined surface portion 31 of the rib portion 23, so that in a cross section that intersects the longitudinal direction of the rib portion 23, the thickness T of the rib portion 23 is set to be approximately uniform around the entire circumference except for the connection portion with the valve wing portion 24.

[0037] Furthermore, in a cross section intersecting the longitudinal direction of the rib portion 23, the thickness T of the void chamber 25 portion of this rib portion 23 is largest (thickest) when the valve body main body 2 is divided into two equal parts, upper and lower, and the void chamber 25 is shaped so that the thickness T gradually becomes smaller (thinner) from this position as the cross section approaches the upper and lower boss portions 21, 22.

[0038] 4(a) and 4(b), the void chamber 25 has rounded surfaces 32 formed at least on both sides of the wing 24. These rounded surfaces 32 give the void chamber 25 a generally hexagonal cross section. In consideration of manufacturability during casting, which will be described later, it is desirable that the rounded surfaces 32 be rounded to an extent that does not make casting difficult.

[0039] Here, we will describe the minimum requirements for providing the aforementioned rib portion 23. As described above, the rib portion 23 is provided in the central region of the disk 20 along the rotation axis P of the stems 4 and 5, at least between the upper and lower boss portions 21 and 22. This ensures the strength of the central region of the disk along the rotation axis P, where the stress generated by the fluid received on the valve blade portion 24 side is greatest. In this case, as mentioned above, the greatest force acts on the valve body main body 2 near the stem rotation axis P due to the fluid pressure, so theoretically, the thickness T near the top of the rib portion 23 is made the greatest and is formed into an arc-shaped cross section (approximately semicircular cross section) that becomes smaller as it approaches the valve wing portions 24, 24.

[0040] However, forming a rib portion with an approximately semicircular cross section makes the thickness of the center of the valve body unnecessarily large, which may increase physical resistance of the fluid near the center of the valve body when the valve is fully open or at an intermediate opening, or may make turbulence more likely to occur, resulting in a deterioration in flow characteristics. In contrast, in the valve body main body 2 of this embodiment, the thickness T is ensured to provide the minimum necessary strength near the center of the rib portion 23, while the area near the top is chamfered to provide a flat portion 30, thereby ensuring the flow characteristics when the valve is open.

[0041] Furthermore, by forming the aforementioned inclined surface portion 31 consisting of a curved surface that slopes from both sides of the flat portion 30 toward the valve wing portion 24, this inclined surface portion 31 ensures strength from the rib portion 23 to the valve wing portion 24 side, and the shape of the inclined surface portion 31 allows the fluid to flow smoothly. In this way, the rib portion 23 is provided with a substantially hexagonal cross section having the flat surface portion 30 and the inclined surface portion 31. 23 This satisfies both the strength and flow characteristics.

[0042] The thickness of the rib portion 23 equipped with these flat surface portions 30 and inclined surface portions 31 is set to a size that can withstand the tensile stress generated on the primary side of the valve body main body 2 due to fluid pressure and the compressive stress generated on the secondary side. In this case, it is known that the strength of the section modulus increases exponentially as the thickness increases. For this reason, when the outer wall 28 of the void chamber 25 is shaped to conform to the rib surface 29, the thickness of the rib portion 23, calculated by subtracting the size of the void chamber 25 (the dimension in the thickness direction of the void chamber 25) from the size of the rib portion 23 (the dimension in the thickness direction of the rib portion 23), in the thickness direction of the central region of the valve body 2, can be designed in advance so that the section modulus is sufficient to withstand tensile stress and compressive stress.

[0043] In this embodiment, the rib surface 29 and the outer wall 28 of the cavity are formed to have a hexagonal cross section that is approximately similar to each other, and the thickness T of the rib 23 from the flat surface 30 to the inclined surface 31 is set to be approximately uniform. 23 The section modulus is set to be large while the overall section modulus is kept substantially constant.

[0044] In the above embodiment, the rib portion 23 has a generally hexagonal cross section with flat portions 30 and inclined portions 31, but it may also have other polygonal or curved shapes such as an ellipse (not shown). In any case, it is desirable to provide the rib portion in a flat shape, form the outer wall of the cavity chamber with a generally parallel surface along the surface of this rib portion, and provide a generally uniform thickness of the rib portion in a cross section intersecting the longitudinal direction of the rib portion, excluding the connection portion with the valve wing portion.

[0045] The width W of the void chamber 25 is set to be at least twice the stem outer diameter φD, but may be set to be less than twice as long as the strength of the rib portion 23 can be ensured.

[0046] When the valve body 2 is formed by casting, the shape of the void chamber 25 can be changed as needed by changing the shape of the core used.

[0047] The inclined surface portion 31 is not limited to a curved surface, but may be formed of a flat surface or a combination of a flat surface and a curved surface.

[0048] Next, the operation of the valve element of the butterfly valve and the butterfly valve according to the present invention in the above embodiment will be described. In the valve body main body 2, a rib portion 23 is provided between the upper and lower boss portions 21, 22, and the void chamber 25 inside this rib portion 23 has a shape that is larger in the width direction than in the thickness direction of the valve body main body 2 in a cross section intersecting the longitudinal direction of the rib portion 23, and is widest near the center in the thickness direction.Therefore, the void chamber 25 can be formed by removing a large amount of material near the center of the valve body main body 2 to match the shape of the rib portion 23, and the void chamber 25 can be expanded to its limit while ensuring the strength of the rib portion 23.

[0049] When fluid pressure is applied to the valve body 2, the outer peripheral edge of the valve wing deforms and bends. In this case, as the valve body 2 bends, the rib portion 23 is subjected to a tensile force on the primary side and a compressive force on the secondary side. These forces act most strongly near the front and back surfaces in the thickness direction of the valve body 2, with the central portion near the rotation axis P being hardly affected. Therefore, as long as the strength of the rib portion 23 near the front and back surfaces is maintained, it can withstand the bending force caused by the fluid pressure. Due to the action of such forces, in this embodiment, the void chamber 25 is provided inside the rib portion 23, and even though this void chamber 25 is hollowed out, it is possible to sufficiently ensure the strength required for the valve body 2.

[0050] In this case, the void chamber outer wall 28 is formed with a generally hexagonal cross section that conforms to the surface shape of the rib portion 23, and the thickness T between the void chamber 25 and the rib portion surface 29 is generally uniform, so that the section modulus corresponding to the thickness T is generally constant and can be secured to a large value. As a result, even in a valve body 1 equipped with a large-diameter valve body 2, the necessary strength can be secured in the central region only with the so-called outer shell portion between the void chamber 25 and the rib portion 23, preventing stress concentration such as tensile stress and compressive stress and reliably reducing bending (deflection) of the valve body 2. This allows the void chamber 25 to be secured large, allowing the valve body 2 to be lightweight while exhibiting sufficient resistance to deflection. The uniform thickness T between the void chamber and the rib portion allows the cooling rate during casting to be approximately constant, making it possible to form a high-quality valve body with reduced casting defects.

[0051] In particular, the rib portions 23 are formed large along the surface of the central region of the disc where the load from fluid pressure is greatest when the valve is fully closed, further increasing the surface strength of this region. Furthermore, the rib portions 23 have a gentle surface shape in which the rate of decrease in height gradually decreases toward the valve wings 24 in the boundary region between the rib portions 23 and the valve wings 24. This ensures the minimum necessary thickness T in response to the load that gradually decreases from the central region of the disc, ensuring strength while also reducing weight.

[0052] If we consider the stem rotation axis P (disc central region) side of the valve body 2 as the support part of the cantilever beam and the valve wing 24 side as the free end, the amount of displacement due to deflection on the support part side increases at the free end side in proportion to the length (radius) of the valve wing 24. Therefore, even if the deflection on the stem rotation axis P side (disc central region side) is very small, it will appear as an enormous deflection on the valve wing 24 side, causing the valve wing 24 to shift position relative to the sealing surface of the seat ring 6, which may result in leakage when the valve is closed.

[0053] In response to this, as mentioned above, by providing the rib portion 23 centered near the stem rotation axis P, the slight distortion near the rib portion 23 is suppressed, thereby reliably preventing distortion on the valve wing portion 24 side and maintaining high sealing performance between the valve wing portion 24 and the sealing surface of the seat ring 6.

[0054] The valve body 1 can be operated to an open / closed state or to an appropriate intermediate opening state either automatically using an actuator (not shown) or manually using an operating handle. During these operations, the lightweight valve body 2 reduces the operating torque and improves operability, and in the case of automatic operation in particular, it is also possible to make the actuator more compact and simplify the internal structure.

[0055] The above describes in detail the embodiments of the present invention, but the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the spirit of the invention described in the claims of the present invention. for example, void chamber 25 The shape of the rib is not limited to a specific shape, and may be any shape as long as it is a flat shape in which the width direction is larger than the thickness direction of the valve body main body 2. If we only consider the counterforce against the deflection, based on the principle that a co-force is applied to the front and back surfaces of the rib portion as described above, void chamber 25 The both end portions of the cross-sectional shape may be gradually tapered to form an acute angle in accordance with the surface shape of the valve body main body 2. However, in this case, when the valve body main body 2 is manufactured by casting, void chamber 25 In contrast, in the present invention, it is difficult to remove the core placed to form the void chamber 25 By providing the rounded surfaces 32 at both ends of the cross section, productivity by casting is improved. [Explanation of symbols]

[0056] 1 Valve body 2 Valve body 3 Body 4 Upper stem 5 Lower stem 20 Jisuk 21 Upper boss part 22 Lower boss part 23 Rib section 24 Valve blade part 25 Cavity chamber 26, 27 Stem insertion hole 28 Cavity chamber outer wall 29 Rib surface 30 Plane section 31 Slope section 32 Curved surface P Stem rotation axis T Thickness

Claims

1. 1. A butterfly valve element rotatably mounted within a cylindrical body via upper and lower stems, the element comprising: cylindrical bosses with stem insertion holes formed above and below a disc-shaped disk; ribs provided between the upper and lower bosses along the axis of rotation of the stem; the ribs having a gentle surface profile with a gradually decreasing height rate toward the valve blades at the boundary between the ribs and the valve blades; a void chamber provided within the ribs and communicating with the stem insertion hole; the void chamber having a shape that is wider in the width direction than in the thickness direction of the valve element body in a cross section intersecting the longitudinal direction of the ribs and is widest near the center in the thickness direction; and the outer wall of the void chamber is shaped to follow the surface of the ribs, with a portion of the outer wall of the void chamber being approximately parallel to the surface profile of the ribs.

2. A valve body of a butterfly valve as described in claim 1, wherein the surface of the rib portion has an approximately hexagonal cross section having a flat portion chamfered near the top and an inclined surface portion consisting of a flat or curved surface that slopes toward the valve wing portion, and the outer wall of the void chamber is formed by surfaces that are approximately parallel to the flat portion and the inclined surface portion, respectively.

3. A valve body of a butterfly valve as described in claim 1 or 2, wherein in a cross section intersecting the longitudinal direction of the rib portion, the rib portion is formed into an approximately flat cross section in which the valve wing direction is longer than the thickness direction.

4. A valve body of a butterfly valve described in any one of claims 1 to 3, wherein in a cross section intersecting the longitudinal direction of the rib portion, the thickness of the rib portion is approximately uniform around the entire circumference except for the connection portion with the valve wing portion.

5. A valve body of a butterfly valve described in any one of claims 1 to 4, wherein, in a cross section intersecting the longitudinal direction of the rib portion, the thickness of the void chamber portion of the rib portion gradually decreases as it approaches the upper and lower boss portions.

6. A valve body of a butterfly valve described in any one of claims 1 to 5, wherein a curved surface is formed on at least the valve wing side of the void chamber.

7. A butterfly valve in which the valve body of the butterfly valve described in any one of claims 1 to 6 is mounted within the body via the upper and lower stems so as to be able to be opened and closed freely.

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