Valve body of double-eccentric butterfly valve and double-eccentric butterfly valve

Abstract

Provided are a valve body of a double eccentric butterfly valve and a butterfly valve, which suppress the occurrence of deflection of the valve body when the valve is closed by a high-pressure fluid while achieving a light weight, reduce the difference in deflection amounts at the left and right ends of the valve body, ensure sealing properties, prevent the occurrence of stress concentration due to a load acting from the fluid, and improve the reliability of the valve body. The operability, reliability and durability are improved. On one surface of the valve disc (2), boss parts (3, 4) for accommodating the valve stem (8) and ribs (6, 7) extending from the boss parts (3, 4) to both outer edge parts of the valve body in a direction intersecting the valve stem (8) are provided, and the ribs (6, 7) except for the boss parts (3, 4) are provided so that the ribs (6, 7) are aligned with the boss parts (3, 4) when compared at positions equidistant from the central axis (20) of the valve stem (8), and the ribs (6, 7) are aligned with the boss parts (3, 4) at positions equidistant from the central axis (20) of the valve stem (8) in a direction intersecting the central axis (20) of the valve stem (8) in a direction intersecting the central axis (20) of the valve stem (8). The height of the surface (2a) of the valve disc (2) from the side with a longer distance to the edge side end of the valve body is greater than the height of the surface (2a) of the valve disc (2) from the side with a shorter distance to the edge side end of the valve body.

Description

Technical Field

[0001] The present invention relates to a valve body of a double eccentric butterfly valve in which the center of a valve stem is installed double eccentrically, and in particular, to a valve body suitable for a flow path of a high-pressure fluid and a butterfly valve provided with the valve body. Background Art

[0002] Generally, butterfly valves are simple in structure, small in size and lightweight. Compared with other valve types, they have the structural advantage of being able to make the surface dimensions small, the ability to open and close the valve within a 90-degree operating range so that it is suitable for automation, and the functional advantage of excellent flow control. Therefore, they are widely used in various ways in various situations such as water supply and drainage, air-conditioning equipment, and factory processes. Recently, there is a need for butterfly valves that can handle fluids with higher pressures than before.

[0003] In the past, a double eccentric butterfly valve was known as a valve suitable for a flow path of a high-pressure fluid. The double eccentric butterfly valve is installed in a manner that the position of the valve stem is double eccentric relative to the valve body. With this double eccentricity, good sealing performance can be ensured even under high pressure, and wear of the sealing surface can be prevented.

[0004] When a butterfly valve is used under high pressure, a large fluid resistance acts on the valve body when the valve is open and at intermediate openings. In particular, when the valve is fully closed, the fluid pressure in the pipeline is all applied to the surface of the valve body, and the load from the fluid acting on the valve body becomes the maximum. The valve body deforms when receiving load from the fluid, and the deflection of the end portion of the valve body becomes larger. When the end portion moves from the seated position of the sealing ring, the sealing performance is impaired. Therefore, it is necessary to ensure the strength of the valve body so that it is difficult to bend. However, if the wall thickness of the valve body is increased to ensure strength, the weight of the valve body increases, the cost increases, and the operability of the valve is impaired. In order to avoid this, it is necessary to reduce the weight of the valve body and ensure its strength, reduce deflection and stress concentration, and reduce the fluid resistance when the valve is open and at intermediate openings.

[0005] As a butterfly valve body with improved strength, for example, a butterfly valve body is disclosed in Patent Document 1. This butterfly valve body is used for a center-shaped butterfly valve, and a plurality of transverse ribs extending in the X direction starting from the Y axis are formed, thereby reducing the wall thickness, improving the rigidity, and achieving weight reduction.

[0006] In addition, in the valve body of the center-type butterfly valve of Patent Document 2, a valve body is disclosed in which a plurality of circular ribs intersecting with the boss portion are raised concentrically on the front and back surfaces of the base plate. In this valve body, by means of the circular ribs, a substantially uniform cross-sectional modulus is obtained in any cross section at any angle relative to the center line of the valve body, so that the rigidity of the valve body is substantially uniform throughout the valve body, thereby obtaining a valve body with high rigidity.

[0007] Patent document 1: Japanese Patent No. 3676785.

[0008] Patent document 2: Japanese Patent No. 4659927.

[0009] However, the butterfly valve of Patent Document 1 has ribs provided on the valve body to reinforce the valve body and thus improve the rigidity of the valve body. However, if stress concentration occurs when the ribs are provided on the valve body to reinforce the valve body, cracks and fractures are likely to occur in the portion, and the durability of the valve body may be insufficient.

[0010] In addition, in the valve body of the butterfly valve of Patent Document 2, the rigidity of the valve body is to be increased by making the rigidity of the valve body as a whole roughly equal, but the magnitude of the bending moment that causes the valve body to bend due to the load from the fluid acting on the valve body varies depending on the part of the valve body. That is, the longitudinal center of the valve body is supported by the valve stem, and on the other hand, there is no supporting part at the left and right ends of the valve body, so the largest bending moment acts on the horizontal center line of the valve body in particular, and the bending amount of this part is the largest. In the valve body of the butterfly valve of Patent Document 2, if it is to be applied with rigidity that does not impair the sealing performance even when the left and right ends are bent to close the valve, it is necessary to make the rigidity of the valve body as a whole consistent with the rigidity of the part with the largest bending moment, which causes the wall thickness of the valve body as a whole to increase, resulting in an increase in manufacturing cost, and the operability of the valve is also deteriorated due to the increase in weight of the valve body.

[0011] In addition, in the case of a double eccentric butterfly valve, the valve stem center axis and the valve body center axis are not aligned and are in a displaced positional relationship, so the distance from the valve stem center axis to the two ends of the valve body is different on the left and right sides. As a result, there is an inherent problem that the deflection amount of the left and right ends of the valve body when the fluid is subjected to pressure is greater on the side with a longer distance from the valve stem center axis. In a butterfly valve, the outer edge of the disc-shaped valve body is in close contact with the valve seat of the valve body to perform a seal, but if the deflection amount of the left and right ends of the valve body is different when the fluid pressure is applied, the surface pressure in close contact with the valve seat on one side is insufficient, which becomes a cause of reduced sealing performance. Summary of the invention

[0012] The present invention is developed to solve the above-mentioned problems, and its purpose is to provide a valve body and a butterfly valve of a double eccentric butterfly valve, which can suppress the deflection of the valve body when the high-pressure fluid is closed while achieving lightweight, and reduce the difference in the deflection between the left and right ends of the valve body, thereby ensuring sealing, and preventing the occurrence of stress concentration due to the load from the fluid, thereby improving operability, reliability and durability.

[0013] In order to achieve the above-mentioned purpose, the invention of technical solution 1 is a valve body of a double-eccentric butterfly valve with a circular shape, characterized in that a boss portion and a rib portion are provided on the surface of one side of the valve disc, the boss portion is used to accommodate the valve stem, and the rib portion extends from the boss portion to the two outer edge portions of the valve body in a direction intersecting the valve stem, and the valve stem center axis passing through the center of the valve stem is in a position deviated from the valve body center axis. At the rib portion except the boss portion, it is arranged that, when compared at positions equidistant from the valve stem center axis, the side with a longer distance to the edge portion side end of the valve body is higher than the side with a shorter distance to the edge portion side end of the valve body in height from the surface of the valve disc.

[0014] The invention of technical solution 2 is a valve body of a double eccentric butterfly valve, characterized in that the rib is arranged so as to gradually become higher from the end portion on the outer edge side of the valve body toward the boss portion.

[0015] The invention of technical solution 3 is a valve body of a double eccentric butterfly valve, characterized in that the upper surface of the rib is inclined in a manner that descends from the boss portion toward the outer edge portion of the valve body at a substantially constant angle, and the rib center axis formed by imaginary extension of the inclined surface in the central direction of the valve body is located on the opposite side of the valve stem center axis relative to the valve body center axis.

[0016] The invention of technical solution 4 is a valve body of a double eccentric butterfly valve, characterized in that the boss portion is divided into multiple parts in a manner that the valve stem is partially exposed, and the ribs are arranged on each of the divided boss portions, and are continuously connected in a manner that the ribs and the boss portion do not produce steps in the height direction observed from the surface of the valve disc and do not produce a linear boundary portion on the side wall surface of the boss portion.

[0017] The invention of technical solution 5 is a valve body of a double eccentric butterfly valve, characterized in that the boss portion is divided into two in such a manner that the valve stem is exposed near the center of the valve body, the rib portion is formed close to the center side of the valve body of the boss portion, and the side wall surface of the boss portion on the center side of the valve body and the side wall surface of the rib portion on the center side of the valve body are arranged to be a continuous single plane.

[0018] The invention of technical solution 6 is a double eccentric butterfly valve, characterized in that a valve stem is axially mounted on the upper and lower axial mounting parts of a short cylindrical valve body, and a valve body is arranged in the valve body so that the valve body can be freely opened and closed via the valve stem.

[0019] Effects of the Invention

[0020] According to technical solution 1, at the ribs except the boss portion, it is arranged that, when compared at positions equidistant from the center axis of the valve stem, the side with a longer distance to the edge portion side end of the valve body is higher from the surface of the valve disc than the side with a shorter distance to the edge portion side end of the valve body. Therefore, the cross-sectional modulus of the rib on the side with a longer distance to the edge portion side end of the valve disc having a larger deflection when receiving pressure from the fluid is larger than the cross-sectional modulus of the transverse rib on the side with a shorter distance to the edge portion side end of the valve disc having a smaller deflection. The bending rigidity of the side with a larger deflection becomes higher and is difficult to bend, so the difference in deflection at the left and right ends of the valve disc can be reduced.

[0021] In addition, a transverse rib of maximum length is provided near the center of the valve disc where the greatest bending moment occurs due to the pressure of the fluid when the valve is closed. This increases the lateral bending rigidity of the valve disc and suppresses the deflection of the left and right ends of the valve disc. Therefore, reinforcement of other parts of the valve disc is not necessary, which can suppress the increase in weight of the valve disc.

[0022] According to the invention of technical solution 2, the rib is arranged to gradually become higher from the end of the outer edge side of the valve body toward the boss portion, so that the height of the rib set to improve the lateral bending rigidity of the valve disc is minimized, which can suppress the increase in weight of the valve body.

[0023] According to the invention of technical solution 3, the upper surface of the rib is inclined in a manner that descends at a substantially constant angle from the boss portion toward the outer edge portion of the valve body, and the rib center axis formed by imaginary extension of the inclined surface in the central direction of the valve body is located on the opposite side of the valve stem center axis relative to the valve body center axis. Therefore, when the pressure of the fluid acts when the valve is closed, the cross-sectional coefficient of the side that is easy to bend is made larger than the cross-sectional coefficient of the side that is difficult to bend to improve the rigidity, thereby achieving equalization of the deflection amount of the left and right ends of the valve disc.

[0024] According to the invention of technical solution 4, a rib is provided extending from the boss portion toward the two outer edge portions of the valve body in a direction intersecting with the valve stem, so that the load acting in the direction intersecting with the valve stem of the valve body can be directly transmitted to the boss portion by means of the rib, and the rigidity in the direction intersecting with the valve stem of the valve body is improved, thereby suppressing the deflection of the left and right ends of the valve disc caused by the bending moment of the fluid load, thereby ensuring the sealing performance, so that the overall wall thickness of the valve disc can be suppressed and the valve disc can be made lighter.

[0025] Furthermore, the ribs and the bosses are continuously connected in a manner that does not generate steps in the height direction observed from the surface of the valve disc and does not generate linear boundary portions at the side wall surfaces of the bosses to form smooth R-surfaces. Therefore, when the load of the fluid acts on the valve body, there are no stress concentration portions such as steps and linear boundary portions at the connection portions of the bosses and ribs that support the load, and the stress is appropriately dispersed. As a result, cracks and ruptures due to stress concentration are less likely to occur, thereby improving the durability of the valve body.

[0026] According to the invention of technical solution 5, the boss portion is divided into two in such a manner that the valve stem is exposed near the center of the valve body, and the rib portion is formed on the central side of the valve body close to the boss portion. Therefore, the rib portion is arranged to ensure the maximum length near the center of the valve body where the bending moment acts most due to the load of the fluid. Therefore, the lateral bending rigidity of the central portion of the valve body can be improved, and the deflection of the left and right ends of the valve disc can be suppressed to ensure the sealing performance.

[0027] In addition, the side wall surface of the valve body on the central side of the boss portion and the side wall surface of the valve body on the central side of the rib portion are arranged as a continuous single plane, so there are no steps, linear boundary portions, or other portions where stress concentration occurs. The stress of the connection portion between the boss portion and the rib portion can be more effectively dispersed, and cracks and breakages caused by stress concentration are less likely to occur, thereby obtaining a valve body with excellent durability.

[0028] According to the invention of technical solution 6, a valve body is provided which is lightweight, has high rigidity, has excellent sealing properties and is less susceptible to cracks and breakage due to stress concentration. Therefore, a butterfly valve which is excellent in operability, reliability and durability and is suitable for high-pressure fluids can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a perspective view showing a preferred embodiment of the valve body of the double eccentric butterfly valve of the present invention.

[0030] Figure 2 yes Figure 1 main view.

[0031] Figure 3 yes Figure 1 Top view of the .

[0032] Figure 4 yes Figure 2 AA section view of the.

[0033] Figure 5 It is a front view of a valve body of a double eccentric butterfly valve of a comparative example.

[0034] Figure 6 It is a perspective view showing an embodiment of a double eccentric butterfly valve. DETAILED DESCRIPTION

[0035] Hereinafter, preferred embodiments of a butterfly valve in which a valve body of a double eccentric butterfly valve according to the present invention is provided with the valve body will be described in detail based on the drawings. Figure 1 , Figure 2 , Figure 3 , Figure 4 , a three-dimensional view, a front view, a top view and a cross-sectional view of a valve body of a double eccentric butterfly valve of the present invention are shown.

[0036] like Figure 1 , Figure 2 As shown, the valve body 1 of the double eccentric butterfly valve has a disc-shaped valve disc 2, bosses 3 and 4 are provided on the upper and lower parts of a surface 2a of one side of the valve disc 2, and an annular rib 5 and ribs 6 and 7 are provided on the surface 2a.

[0037] The boss portion is divided into an upper boss portion 3 and a lower boss portion 4 of the valve disc 2, and is arranged so that the valve stem 8 is exposed. Holes 10 and 11 for installing the valve stem 8 are formed in the boss portion 3 and the boss portion 4, so that the valve stem 8 can be inserted through.

[0038] like Figure 3 As shown in FIG. 1 , the boss portion 3 is provided on the surface 2a of the valve disc 2 in a state where the center S of the hole portion 10 is spaced a distance C from the sealing position 2b of the valve disc (single eccentricity) and a distance D from the center line of the valve body main body 1 (the valve body center axis 12) (double eccentricity). Figure 2 As shown, the hole portion 10 and the hole portion 11 are formed coaxially with the boss portion 3 being arranged symmetrically with the valve body horizontal axis 14 as the symmetry axis.

[0039] When the valve stem 8 is inserted into the hole 10 of the boss 3 and the hole 11 of the boss 4, the center S of the hole 10 and the hole 11 is the rotation center of the valve stem 8. When the valve stem 8 is rotated, the valve body 1 can close the valve by eccentrically rotating around the center S of the hole 10 and the hole 11. The valve body 1 is made of metal, for example, stainless steel such as SCS13A and SCS14A.

[0040] The annular rib 5 is concentric with the valve disc 2, that is, it is formed protruding on the surface 2a of the valve disc in a ring shape shorter than the diameter of the valve disc 2, with the intersection O of the valve body central axis 12 and the valve body horizontal axis 14 of the valve disc 2 as the center. Figure 2 As shown, the side walls 3a and 3b of the boss portion 3 and the side walls 4a and 4b of the boss portion 4 are connected, and the cross-sectional shape is as follows: Figure 4 Thus, the annular rib 5 is formed to protrude from the surface 2a of the valve disc 2, thereby increasing the strength and bending rigidity of the valve disc 2 as a whole.

[0041] Rib 6 Figure 2As shown in the figure, it is arranged in a substantially horizontal state at the side wall surface 3a of the valve body center side (the side of the horizontal axis 14 of the valve body) near the boss portion 3, and is composed of a long rib 15 connected to the side wall surface 3b of the boss portion 3 and a short rib 16 connected to the side wall surface 3c of the boss portion 3. In addition, the ends of the long rib 15 and the short rib 16 on the outer edge side of the valve body are connected to the annular rib portion 5 to form a whole.

[0042] Similarly, the rib 7 is horizontally arranged at the side wall surface 4a on the valve body center side (valve body horizontal axis 14 side) close to the boss portion 4, and is composed of a long rib 17 connected to the side wall surface 4b of the boss portion 4 and a short rib 18 connected to the side wall surface 4c of the boss portion 4. In addition, the ends of the long rib 17 and the short rib 18 on the valve body outer edge side are connected to the annular rib 5 to form a whole.

[0043] in addition, Figure 2 In order to clarify the positional relationship between the ribs 6, 7 and the annular rib 5, the boundaries between the ends of the valve body outer edge of the long rib 15 and the short rib 16, and the long rib 17 and the short rib 18 and the annular rib 5 are indicated by lines, but in fact, these boundaries are also connected continuously in a smooth R-surface in a manner that does not produce steps and linear boundary portions, so that stress concentration does not occur. ( Figure 1 , Figure 3 , Figure 4 The same is true in ).

[0044] like Figure 2 As shown, the boss portions 3 and 4, and the rib portions 6 and 7 are constructed similarly except for the linear symmetry about the valve body horizontal axis 14 as the axis of symmetry, so the details of the rib portions 6 and 7 will be described below with reference to the rib portion 6.

[0045] like Figure 2 As shown, the rib 6 forms the long ribs 15 and the short ribs 16 from the side wall surfaces 3b, 3c of the boss portion 3 to the two outer edge sides of the valve body 1 to the annular rib portion 5, but the annular rib portion 5 is formed concentrically with the valve disc 2 with the center point O of the valve disc 2 as the center. In contrast, the valve stem center axis 20, which is the center of the boss portion 3, deviates from the valve body center axis 12 by a distance D. Therefore, even if the same side wall surfaces 3b, 3c of the boss portion 3 are used as the starting point, the length of the long rib 15 is 2D longer than the length of the short rib 16.

[0046] In addition, if Figure 3 As shown, the shape of the long ribs 15 and the short ribs 16 observed from the end face 3d of the boss portion 3 on the outer peripheral side of the valve body is a roughly right triangle, and the inclined upper surface 15c of the long rib 1 and the inclined upper surface 16c of the short rib 16 corresponding to the hypotenuse of the roughly right triangle are arranged so that the height from the surface 2a of the valve disc 2 gradually decreases from the side wall surfaces 3b, 3c of the boss portion 3 toward the two outer edges of the valve body 1.

[0047] The side wall surface 3a of the boss portion 3 on the valve body center side, the side wall surface 15a of the long rib 15 on the valve body center side, and the side wall surface 16a of the short rib 16 on the valve body center side are connected in a manner of forming a single plane, that is, in a so-called coplanar manner. Therefore, the length of the rib portion 6 can be ensured to the maximum extent, and the stress of the connection portion between the boss portion 3 and the rib portion 6 can be more effectively dispersed.

[0048] like Figure 2 and Figure 3 As shown, the side wall surface 15b on the opposite side of the side wall surface 15a of the long rib 15 is continuously connected to form a smooth R surface in a manner that does not produce a linear boundary portion with the side wall surface 3b of the boss portion 3, and the inclined upper surface 15c of the long rib 15 is continuously connected to form a smooth R surface relative to the side wall surface 3c of the boss portion 3 in a manner that does not produce a step in the height direction observed from the surface 2a of the valve disc 2.

[0049] Similarly, the side wall surface 16b on the opposite side of the side wall surface 16a of the short rib 16 is continuously connected to the side wall surface 4b of the boss portion 4 by forming a smooth R surface in a manner that does not produce a linear boundary portion, and the inclined upper surface 16c of the short rib 16 is continuously connected to the side wall surface 4c of the boss portion 4 by forming a smooth R surface in a manner that does not produce a step in the height direction observed from the surface 2a of the valve disc 2.

[0050] In this way, the long ribs 15 and the short ribs 16 of the rib portion 6 form a smooth R-surface and are continuously connected to the boss portion 3 in a manner without generating steps or linear boundary portions, and are integrally formed with the boss portion 3. Therefore, there are no stress concentration portions such as steps and linear boundary portions at the connection portion of the boss portion 3 and the rib portion 6 that support the load of the fluid, so there are no stress concentration portions, and the stress is appropriately dispersed. As a result, cracks and ruptures caused by stress concentration at the boss portion 3 and the rib portion 6 are less likely to occur, and the durability of the valve body 1 can be improved.

[0051] Furthermore, the long ribs 15 and the short ribs 16 are directly connected to the extremely rigid boss portion 3. The long ribs 15, the short ribs 16 and the boss portion 3 are integrated to form the rib portion 6, so the bending rigidity of the entire rib portion 6 can be greatly improved.

[0052] Generally, in a butterfly valve, when the fluid load acts on the valve body when the valve is closed, the longitudinal center of the valve body is supported by the valve stem, and on the other hand, there is no support part at the left and right ends of the valve body in the lateral direction. Therefore, the maximum bending moment acts in the lateral direction of the central part of the valve body, and the deflection at the left and right ends of the central part of the valve body is the largest.

[0053] However, in the valve body 1, near the center of the valve body where the maximum bending moment acts due to the pressure of the fluid when the valve is closed, ribs 6 and 7 are arranged in parallel with the horizontal axis 14 of the valve body to ensure the maximum length. This increases the lateral bending rigidity of the central part of the valve disc 2. Therefore, the deflection of the left and right ends of the valve disc 2 caused by the bending moment due to the load of the fluid when the valve is closed can be suppressed to ensure the sealing performance. It is not necessary to reinforce other parts of the valve disc 2, so the weight increase of the valve disc 2 can be suppressed.

[0054] As described above, an annular rib 5 is provided in the valve body 1 to increase the overall strength and rigidity of the valve disc 2, and ribs 6 and 7 are provided in parallel near the center of the valve body where the greatest bending moment occurs due to the pressure of the fluid when the valve is closed, with the lengths of the ribs 6 and 7 being maximized across the horizontal axis 14 of the valve body. This increases the lateral bending rigidity of the central portion of the valve disc 2 and suppresses the deflection of the left and right ends of the valve disc 2 when the valve is closed.

[0055] Furthermore, the annular rib 5 is connected to the bosses 3 and 4, the rib 6 is connected to the boss 3, the rib 7 is connected to the boss 4, the annular rib 5 is connected to the ribs 6 and 7, and the bosses 3 and 4, the annular rib 5, and the ribs 6 and 7 are integrally formed, so they can be integrally formed to bear the load and bending moment acting on the valve body 1. As a result, compared with the case where the annular rib 5 and the ribs 6 and 7 are not connected to the bosses 3 and 4, or the case where the annular rib 5 and the ribs 6 and 7 are not connected, the occurrence of deformation and deflection of the valve body 1 can be more effectively suppressed, and the sealing performance can be ensured.

[0056] Then, if Figure 3 As shown, the side shape of the long ribs 15 and the short ribs 16 of the rib portion 6 viewed from the end surface 3d of the boss portion 3 is a substantially right triangle. The following is a description of the reason why the long ribs 15 and the short ribs 16 are set to be substantially right triangles and the side shape of the long ribs 15 is set larger than the side shape of the short ribs 16.

[0057] In a butterfly valve, the outer edge of the circular valve disc is sealed by being in close contact with the valve seat of the valve body. However, if the deflection of the outer edge of the valve disc becomes larger, the surface pressure in close contact with the valve seat of the valve body will be insufficient, which will cause a decrease in sealing performance. Therefore, the deflection of the outer edge of the valve disc when the valve is closed must be within a range that provides sufficient sealing performance.

[0058] In addition, in the case of a double eccentric butterfly valve, the valve stem center axis and the valve body center axis are not aligned and are eccentric, so the distance from the valve stem center axis to the left and right ends of the valve disc is different. Therefore, if the fluid receives a load, a larger bending moment is generated on the side with a longer distance from the valve stem center axis (hereinafter referred to as the long side) than on the side with a shorter distance from the valve stem center axis (hereinafter referred to as the short side), and the deflection amount of the outer edge of the long side is larger than the deflection amount of the outer edge of the short side. In a double eccentric butterfly valve, if the deflection amount at the left and right ends of the valve disc is different when the valve is closed, the surface pressure in close contact with the valve seat on one side is insufficient, which causes a decrease in sealing performance.

[0059] Therefore, in a double eccentric butterfly valve, it is necessary to suppress the deflection at the left and right ends of the valve disc when the valve is closed, and to make the difference in the deflection of the left and right ends of the valve disc caused by the eccentricity of the valve stem as small as possible, and if possible, to make the deflection of the left and right ends equal to zero.

[0060] In the valve body of the double eccentric butterfly valve of the present invention, the degree of reinforcement of the valve disc 2 generated by the ribs 6 and 7 is different, thereby, the rigidity of the long side with greater deflection can be made higher than the rigidity of the short side with less deflection, thereby achieving equalization of the deflection amount at the left and right ends of the valve disc 2.

[0061] The higher the height of the ribs 6 and 7 provided on the surface 2a of the valve disc 2 from the surface 2a, the larger the cross-sectional modulus is, which has the effect of making it difficult for the valve disc 2 to bend. Therefore, the height of the long ribs 15 provided on the long side is generally set higher than the height of the short ribs 16 provided on the short side, thereby making it difficult for the long side provided with the long ribs 15 to bend.

[0062] That is, Figure 4 As shown, when comparing positions at an equal distance L from the valve stem center axis 20, the heights of the long ribs 15 and the short ribs 16 are set so that, excluding the boss portion 3, the height H1 of the long ribs 15 arranged on the long side from the surface 2a of the valve disc 2 is higher than the height Hs of the short ribs 16 arranged on the short side from the surface 2a of the valve disc 2.

[0063] By setting the heights of the long ribs 15 and the short ribs 16 in this way, the long side that is more easily bent is reinforced and less likely to bend than the short side, so that the difference in the amount of bending between the outer edge of the long side and the outer edge of the short side can be reduced.

[0064] In addition, the height relationship between the long ribs 15 provided on the long side and the short ribs 16 provided on the short side and the surface 2a does not necessarily need to be established at all rib positions, and the height relationship may be partially reversed according to design conditions, etc. For example, the long ribs 15 may be higher than the short ribs 16 in terms of average height.

[0065] Such ribs for reinforcing the valve body are often arranged to gradually decrease in height from the boss portion toward the outer edge of the valve disc from the viewpoint of manufacturability, and the upper surface of the rib is inclined at a substantially constant angle except near the connection with the boss portion and near the connection with the outer edge of the valve body. In this case, the shape of the rib can be approximated as a right triangle when viewed from the side, which is surrounded by a side (base) corresponding to the position of the surface of the valve disc, a side (hypotenuse) corresponding to the inclined portion of the upper surface of the rib at a constant angle, and a side (height) on the center axis of the valve stem.

[0066] Regarding the strength of the rib having such an imaginary right triangle side shape, there is a case where the idea of ​​a beam of uniform strength (a cantilever beam whose base of the right triangle bears an equally distributed load) in material mechanics can be applied. The deflection of the cantilever beam approximating the rib can be calculated based on the formula of the beam of uniform strength, so based on this formula, the height of the imaginary right triangle on each of the long side and the short side (the height Ha and Hb of the imaginary right triangle on the valve stem center axis 20) can be set in such a way that the difference in the deflection between the rib ends on the long side and the short side becomes small.

[0067] When the side surface shape of the rib is obtained according to this method, the height of the rib provided to increase the lateral bending rigidity of the valve disc can be minimized, thereby suppressing an increase in the weight of the valve body.

[0068] However, in reality, the valve body as a whole, which includes not only the rib part but also the valve disc and the boss part, bears the load of the fluid when the valve is closed, and the deflection amount is also affected by the thickness and size of the valve disc. Therefore, there are many cases where the idea of ​​a beam of uniform strength cannot be directly applied. However, it is preferably set so that the difference in height of the imaginary right triangle between the long side and the short side is at least greater than the difference in height derived based on the idea of ​​a beam of uniform strength.

[0069] like Figure 4 As shown, the long ribs 15 and the short ribs 16 are arranged to be inclined at a substantially constant angle in a manner such that their inclined upper surfaces 15c, 16c gradually become higher from the end portion on the outer edge side of the valve body toward the boss portions 3, 4, and the rib center line 24 passing through the intersection P of imaginary lines 22, 23 that are imaginarily extended along the central direction of the valve body by the inclined upper surfaces 15c, 16c is located on the opposite side of the valve stem center axis 20 relative to the valve body center axis 12.

[0070] Thus, in the valve body 1, the rib triangle ( Figure 4The rib center line 24 at the vertex P of the triangle (formed by an imaginary line 22 extending the inclined upper surface 15C of the long rib 15, an imaginary line 23 extending the inclined upper surface 16C of the short rib 16, and a line 25 representing the surface of the valve disc 2) deviates toward the opposite side of the valve stem center axis 20 relative to the valve body center axis 12. As a result, the cross-sectional coefficient of the side that is easy to bend is made larger than the cross-sectional coefficient of the side that is difficult to bend, thereby improving the rigidity and achieving equalization of the deflection amount at the left and right ends of the valve disc.

[0071] In order to confirm the effect of reducing the difference in deflection at the left and right ends of the valve disc of the valve body of the double eccentric butterfly valve of the present invention and the effect of suppressing the weight of the valve body, Figure 1 Examples and Figure 5 The valve body of the double eccentric butterfly valve of the comparative example shown was analyzed by FEM (Finite Element Method).

[0072] Figure 1 The embodiment is structured as described above, but Figure 5 The valve body 31 of the comparative example shown has a disc-shaped valve disc 32, and is constructed such that boss portions 33 and 34 are provided on the upper and lower portions of the surface 32a on one side of the valve disc 32, an annular rib portion 35 is provided on the surface 32a for reinforcement, ribs 36, 37, 38, 39 for reinforcement, and missing wall portions 40a, 40b, 40c, 40d, 40e, 40f are provided.

[0073] In the valve body 31 of the double eccentric butterfly valve of the comparative example, the annular rib 35 is connected to the ribs 36, 37, 38, 39, but the bosses 33, 34 provided on the upper and lower parts of the valve disc 2 are not connected to the ribs 36, 37, 38, 39. The fact that the bosses are not connected to the ribs is a major difference from the embodiment. In addition, the valve body of the double eccentric butterfly valve of the comparative example has been used in butterfly valves with a maximum allowable pressure of 2Mpa and has excellent sealing performance.

[0074] During the analysis, for each valve body size shown in Table 1, the displacement (bending) of the left and right ends of the valve body on the horizontal axis and the weight of the valve body when the fluid pressure of 5.11 MPa is loaded are calculated for the embodiment and the comparative example. Based on the results, the reduction rate (bending improvement rate) of the difference in the deflection of the left and right ends of the valve body in the embodiment relative to the comparative example is calculated.

[0075] Table 1 shows the deflection improvement rate and valve body weight increase rate for each dimension obtained by analysis. In Table 1, the forward direction means when fluid pressure is applied from the primary side, and the reverse direction means when fluid pressure is applied from the secondary side.

[0076] [Table 1]

[0077]

[0078] As shown in Table 1, according to the valve body structure of the embodiment, it was confirmed that a significant deflection improvement effect of reducing the difference in deflection amount between the left and right ends of the valve body was obtained without significantly increasing the weight of the valve body compared with the comparative example.

[0079] Next, an example in which the valve body 1 of the present invention is mounted on a secondary eccentric butterfly valve will be described. Figure 6 A perspective view of a secondary eccentric butterfly valve 51 showing a state in which the valve body 1 of the present invention is mounted on a valve main body 52 and the valve is fully closed.

[0080] The valve main body 52 has a short cylindrical valve body 53, and shaft mounting portions 54 for mounting the valve stem 8 of the valve body 1 are provided at the upper and lower parts of the valve body 53. The valve body 1 is arranged in the valve body 53, and in this state, the valve stem 8 is mounted in the hole 10 of the boss portion 3 of the valve body 1, and the valve body 1 is integrally fixed to the valve stem 8 by means of a push pin (not shown). Thus, the valve stem 8 is in a state where it can rotate relative to the valve body 53 and cannot move in the up and down directions. The valve body 1 is arranged at a predetermined position in the valve body 53, and the valve stem 8 is rotated, thereby enabling the valve body 1 to be freely rotated to open and close via the valve stem 8.

[0081] The double eccentric butterfly valve 51 can respond to either the situation where fluid pressure is applied from the side of the valve body 1 where the boss portion 3 is provided, or the situation where fluid pressure is applied from the opposite side of the surface where the boss portion 3 is provided, and can reliably seal in a closed valve state in both flow directions.

[0082] Furthermore, a handle for manual operation may be mounted on the upper end of the valve stem 8 to manually open and close the valve, or an actuator may be mounted to automatically open and close the valve.

[0083] As described above, the valve body of the double eccentric butterfly valve of the present invention is provided by connecting a transverse rib having a maximum length to a boss portion near the center of the valve disc where a large bending moment is applied due to the pressure of the fluid when the valve is closed, thereby improving the bending rigidity of the valve disc. Therefore, compared with conventional valve bodies, the bending of the left and right end portions of the valve disc generated when the valve is closed can be suppressed without significantly increasing the weight.

[0084] In addition, when ribs are provided to increase the bending rigidity of the valve disc, the rigidity is increased by increasing the cross-sectional modulus of the ribs provided on the side where bending is more likely to occur, thereby achieving equalization of the bending amounts at the left and right ends of the valve disc, so that sufficient sealing can be obtained when the valve is closed.

[0085] Furthermore, when the boss portion and the rib portion are connected, a smooth R-surface is formed to continuously connect them in a manner that does not have steps or linear boundary portions where stress concentration occurs, so the stress in the connection portion between the boss portion and the rib portion can be more effectively dispersed. Therefore, cracks and breakages caused by stress concentration are less likely to occur, and the product has excellent durability.

[0086] The double eccentric butterfly valve of the present invention is provided with the following valve body. The aforementioned valve body is lightweight and has high rigidity, excellent sealing performance, and is unlikely to suffer from cracks and breakages caused by stress concentration. Therefore, the valve body has excellent operability, reliability and durability, and is more suitable for use in high-pressure fluids than ever before.

[0087] Description of Reference Numerals

[0088] 1 Valve body

[0089] 2 Valve disc

[0090] 2a Surface of the valve disc

[0091] 3, 4 Boss part

[0092] 5 Annular ribs

[0093] 6, 7 ribs

[0094] 8 Valve stem

[0095] 51 Secondary eccentric butterfly valve

[0096] 52 Valve body

[0097] C The distance between the sealing position of the valve disc and the center of the hole of the boss

[0098] D The distance between the center axis of the valve body and the center of the hole of the boss

[0099] Ha is the height of the right triangle made by the imaginary long rib on the center axis of the valve stem.

[0100] Hb is the height of the right triangle made by the imaginary short rib on the center axis of the valve stem.

[0101] H1 is the height of the long rib at a distance L from the center axis of the valve stem from the surface of the valve disc

[0102] Hs is the height of the short rib from the valve disc surface at a distance L from the valve stem center axis

[0103] OThe intersection of the valve body center axis and the valve body horizontal axis

[0104] P is the vertex of the rib triangle formed by the long ribs, short ribs, and the surface of the valve disc.

[0105] S is the center of the hole portion of the boss portion.

Claims

1. A double eccentric butterfly valve body, which is a double eccentric butterfly valve body with a circular shape, characterized in that: A boss portion and a rib portion are provided on the surface of one side of the valve disc, the boss portion is used to accommodate the valve stem, the rib portion extends from the boss portion to the two outer edge portions of the valve body in a direction intersecting the valve stem, and the valve stem center axis passing through the center of the valve stem is located at a position deviated from the valve body center axis. The rib portion other than the boss portion is arranged so that, when compared at positions equidistant from the valve stem center axis, the side with a longer distance to the edge portion side end of the valve body becomes higher from the surface of the valve disc than the side with a shorter distance to the edge portion side end of the valve body. The boss portion is divided into two upper and lower portions in such a manner that the valve stem is exposed near the center of the valve body, the rib portion is formed near the center side of the valve body of the boss portion, and is arranged so that the side wall surface of the valve body center side of the boss portion and the side wall surface of the valve body center side of the rib portion are continuous single planes, The bosses and ribs at the upper and lower parts are connected to each other by means of annular ribs. The boss portions and the rib portions at the upper and lower portions are integrally formed by means of the annular rib.

2. A double eccentric butterfly valve, characterized in that: The valve stem is axially mounted on upper and lower axial mounting portions of a short cylindrical valve body, and the valve body according to claim 1 is disposed in the valve body so that the valve body can be freely opened and closed via the valve stem.

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