The valve body of a double eccentric butterfly valve and the double eccentric butterfly valve

Abstract

A valve body and a butterfly valve of a double eccentric butterfly valve are provided, which suppress the occurrence of flexure of the valve body when closing high-pressure fluid while achieving light weight, reduce the difference in the amount of flexure at the left and right ends of the valve body, ensure sealing performance, and prevent the occurrence of stress concentration caused by the load acting from the fluid, thereby improving operability, reliability and durability. A boss portion (3, 4) and a rib portion (6, 7) are provided on one surface of the valve disc (2). The boss portion (3, 4) is used to accommodate the valve stem (8). The rib portion (6, 7) extends from the boss portion (3, 4) to the two outer edge portions of the valve body in a direction intersecting with the valve stem (8). At the rib portion (6, 7) except for the boss portion (3, 4), it is arranged that when comparing at positions equidistant from the center axis (20) of the valve stem, the height from the surface (2a) of the valve disc (2) to the side with a longer distance to the side end of the edge portion of the valve body is higher than that to the side with a shorter distance to the side end of the edge portion 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 mounted with double eccentricity, and particularly to a valve body suitable for a flow path of high-pressure fluid and a butterfly valve provided with the valve body. Background Art

[0002] Generally, a butterfly valve is simple in structure, small and lightweight, and has structural advantages such as a small face-to-face dimension compared with other valves, and functional advantages such as being suitable for automation because it can perform opening and closing operations of the valve within an operating range of 90 degrees and having excellent flow control. Therefore, it is widely used in various situations such as water supply and drainage, air conditioning equipment, and factory processes in various ways. Recently, there has been a need for a butterfly valve that can handle fluids at higher pressures than in the past.

[0003] Conventionally, as a valve suitable for a flow path of high-pressure fluid, a double eccentric butterfly valve is known. The double eccentric butterfly valve is mounted in such a way that the position of the valve stem is double eccentric with respect to the valve body. By means of this double eccentricity, good sealing performance can be ensured even under high pressure, and at the same time, 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 at the time of valve opening and intermediate opening. In particular, when fully closed, the entire fluid pressure in the pipeline is applied to the surface of the valve body, and the load from the fluid acting on the valve body becomes maximum. When the valve body deforms when receiving the load from the fluid, the deflection of the end portion of the valve body becomes large. When this end portion moves from the seating 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 flex. However, if the wall thickness of the valve body is increased to ensure strength, problems such as an increase in the weight of the valve body, an increase in cost, and impaired operability of the valve occur. In order to avoid this, it is necessary to reduce the weight of the valve body and ensure its strength, reduce flexure and stress concentration, and reduce the fluid resistance at the time of valve opening and intermediate opening.

[0005] As a valve body of a butterfly valve with improved strength, for example, the valve body of the butterfly valve disclosed in Patent Document 1 is known. The valve body of this butterfly valve is for a center type butterfly valve, and forms a plurality of transverse ribs extending in the X direction starting from the Y axis, thereby attempting to make the wall thickness thinner and increase rigidity, and also achieve weight reduction.

[0006] In addition, in the valve body of the center type butterfly valve of Patent Document 2, a valve body in which a plurality of circular ribs intersecting with a boss portion bulge concentrically on the front and back surfaces of a substrate is disclosed. In this valve body, by means of these circular ribs, it is intended to obtain a substantially uniform section modulus in a cross section at any angle with respect to the center line of the valve body, and make the rigidity of the valve body substantially uniform throughout the valve body to obtain a valve body with high rigidity.

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

[0008] Patent Document 2: Japanese Patent Publication No. 4659927.

[0009] However, in the valve body of the butterfly valve of Patent Document 1, ribs are provided at the valve body to reinforce it, thereby improving the rigidity of the valve body. However, if a stress concentration part occurs when ribs are provided at the valve body for reinforcement, cracks and fractures are likely to occur at this part, and there is a possibility that the durability of the valve body is insufficient.

[0010] In addition, in the valve body of the butterfly valve of Patent Document 2, in order to improve the rigidity of the valve body by making the rigidity of the entire valve body substantially uniform, the magnitude of the bending moment that causes the valve body to deflect due to the load acting on the valve body from the fluid varies depending on the part of the valve body. That is, the central part in the longitudinal direction of the valve body is supported by the valve stem. On the other hand, there is no support part at the left and right ends of the valve body. Therefore, in particular, the maximum bending moment acts on the center line in the lateral direction of the valve body, and the deflection amount of this part is the largest. In the valve body of the butterfly valve of Patent Document 2, if it is desired to apply rigidity such that the sealing performance is not impaired even when the left and right ends are deflected and closed, it is necessary to make the rigidity of the entire valve body consistent with the rigidity of the part where the bending moment is the largest, resulting in an increase in the wall thickness of the entire valve body, an increase in manufacturing cost, and a deterioration in the operability of the valve due to an increase in the weight of the valve body.

[0011] In addition, in the case of a double eccentric butterfly valve, the center axis of the valve stem and the center axis of the valve body are not coincident and are in a displaced positional relationship. Therefore, the distances from the center axis of the valve stem to both ends of the valve body are different on the left and right. As a result, there is an inherent problem that the deflection amounts of both ends of the valve body when receiving pressure from the fluid are larger on the side where the distance from the center axis of the valve stem is longer. In a butterfly valve, the outer edge part of the disk-shaped valve body is in close contact with the valve seat of the valve body to achieve sealing. However, if the deflection amounts of both ends of the valve body are different when fluid pressure is applied, the surface pressure in contact with the valve seat on one side is insufficient, which causes a decrease in sealing performance. Summary of the Invention

[0012] The present invention has been developed to solve the above problems, and its object is to provide a valve body and a butterfly valve of a double eccentric butterfly valve that, while achieving weight reduction, suppress the occurrence of deflection of the valve body when closing under high-pressure fluid, reduce the difference in deflection amounts between the left and right ends of the valve body, ensure sealing performance, and prevent the occurrence of stress concentration caused by the load acting from the fluid, thereby improving operability, reliability, and durability.

[0013] In order to achieve the above object, the invention of Technical Solution 1 is a valve body of a double eccentric butterfly valve with a circular shape. It is characterized in that a boss portion and a rib portion are provided on one side surface of the valve disc. The aforementioned boss portion is used to accommodate the valve stem. The aforementioned rib portion extends from the boss portion to the two outer edge portions of the valve body in a direction intersecting with the aforementioned valve stem. The valve stem central axis passing through the center of the valve stem is in a position offset from the valve body central axis. At the rib portion except the boss portion, it is arranged that when comparing at positions equidistant from the valve stem central axis, the height from the surface of the valve disc of the side with a longer distance to the side end of the edge portion of the valve body is higher than that of the side with a shorter distance to the side end of the edge portion of the valve body. The upper surface of the rib portion is inclined in a manner of descending at a substantially constant angle from the boss portion towards the outer edge portion of the valve body. The rib central axis formed by hypothetically extending this inclined surface in the valve body central direction is located on the opposite side of the valve stem central axis with respect to the valve body central axis.

[0014] The invention of Technical Solution 2 is a valve body of a double eccentric butterfly valve, which is characterized in that the rib portion is arranged to gradually become higher from the end portion on the outer edge side of the valve body towards the boss portion.

[0015] The invention of Technical Solution 3 is a valve body of a double eccentric butterfly valve, which is characterized in that the boss portion is divided into a plurality of parts in such a way that the valve stem is partially exposed, and the rib portion is provided on each of the divided boss portions and is continuously connected in such a way that there is no step in the height direction when observing from the surface of the valve disc and there is no linear boundary portion at the side wall surface of the boss portion.

[0016] The invention of Technical Solution 4 is a double eccentric butterfly valve, which is characterized in that the valve stem is axially mounted on the upper and lower shaft mounting portions of a short cylindrical valve body, and the valve body is arranged inside the valve body and is arranged to freely open and close the valve body via the valve stem.

[0017] Advantages of the Invention

[0018] According to Technical Solution 1, at the rib portion except the boss portion, it is arranged that when comparing at positions equidistant from the valve stem central axis, the height from the surface of the valve disc of the side with a longer distance to the side end of the edge portion of the valve body is higher than that of the side with a shorter distance to the side end of the edge portion of the valve body. Therefore, the section modulus of the rib on the side with a longer distance to the side end of the edge portion of the valve disc where the deflection amount is more when receiving pressure from the fluid is larger than the section modulus of the transverse rib on the side with a shorter distance to the side end of the edge portion of the valve disc where the deflection amount is less. The bending rigidity on the side with a larger deflection amount becomes higher and it is difficult to deflect. Therefore, the difference in the deflection amounts at the left and right ends of the valve disc can be reduced.

[0019] In addition, near the center of the valve disc where the maximum bending moment acts due to the pressure of the fluid when the valve is closed, a transverse rib portion with the maximum ensured length is provided, thereby improving the lateral bending rigidity of the valve disc, suppressing the occurrence of deflection at the left and right ends of the valve disc, so that reinforcement at other parts of the valve disc is not very necessary, and the weight increase of the valve disc can be suppressed.

[0020] According to the invention of Technical Solution 2, the rib portion is arranged to gradually increase in height from the end on the outer edge side of the valve body towards the boss portion, so that the height of the rib provided to improve the lateral bending rigidity of the valve disc is minimized as necessary, and the weight increase of the valve body can be suppressed.

[0021] According to the invention of Technical Solution 3, the upper surface of the rib portion is inclined so as to descend at a substantially constant angle from the boss portion towards the outer edge portion of the valve body, and the rib center axis formed by hypothetically extending the inclined surface in the direction of the valve body center is located on the opposite side of the valve stem center axis with respect to the valve body center axis. Therefore, when the pressure of the fluid acts during valve closing, the section modulus of the side that is easily deflected is made larger than the section modulus of the side that is difficult to deflect to improve rigidity, and the equalization of the deflection amounts at the left and right ends of the valve disc can be achieved.

[0022] According to the invention of Technical Solution 4, a rib portion is provided that extends from the boss portion in a direction intersecting the valve stem towards the two outer edge portions of the valve body. Therefore, the load acting in the direction intersecting the valve stem of the valve body can be received by this rib portion and directly transmitted to the boss portion, and the rigidity in the direction intersecting the valve stem of the valve body is improved. As a result, the deflection amounts at the left and right ends of the valve disc caused by the bending moment due to the load of the fluid can be suppressed, ensuring the sealing performance, so that the wall thickness of the entire valve disc can be suppressed and the valve disc can be lightened.

[0023] Furthermore, the rib portion and the boss portion are configured to form a smooth R surface without a step in the height direction when viewed from the surface of the valve disc and without a linear boundary portion on the side wall surface of the boss portion, and are continuously connected. Therefore, when the load of the fluid acts on the valve body, there is no stress concentration portion such as a step or a linear boundary portion at the connection portion of the boss portion and the rib portion that supports the load, and the stress is moderately dispersed. As a result, the occurrence of cracks, fractures, etc. caused by stress concentration is difficult to occur, so that the durability of the valve body can be improved.

[0024] According to the invention of Technical Solution 5, the boss portion is divided into two such that the valve stem is exposed near the center of the valve body, and the rib portion is formed closer to the center side of the valve body near the boss portion. Therefore, the rib portion is provided with the maximum ensured length near the center of the valve body where the bending moment acts maximally due to the load of the fluid, so that the lateral bending rigidity of the central portion of the valve body can be improved, and the deflection amounts at the left and right ends of the valve disc can be suppressed to ensure the sealing performance.

[0025] In addition, the side wall surface on the central side of the valve body that is set as the boss portion and the side wall surface on the central side of the rib portion are continuous and single planes. Therefore, there are no stress concentration parts such as steps and linear boundary parts, and the stress at the connection part between the boss portion and the rib portion can be more effectively dispersed. It is difficult for cracks, fractures, etc. caused by stress concentration to occur, and a valve body with excellent durability can be obtained.

[0026] According to the invention of Technical Solution 6, a valve body is provided that is lightweight, has high rigidity, excellent sealing performance, and is difficult to generate cracks, fractures, etc. caused by stress concentration. Therefore, a butterfly valve with excellent operability, reliability, and durability and suitable for high-pressure fluids can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a perspective view showing a preferred embodiment of the valve body of the double-eccentric butterfly valve of the present invention.

[0028] Figure 2 is Figure 1 the front view.

[0029] Figure 3 is Figure 1 the top view.

[0030] Figure 4 is Figure 2 the sectional view taken along line A-A.

[0031] Figure 5 is the front view of the valve body of the double-eccentric butterfly valve of the comparative example.

[0032] Figure 6 is a perspective view showing an embodiment of the double-eccentric butterfly valve. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] Hereinafter, based on the drawings, preferred embodiments of the valve body of the double-eccentric butterfly valve of the present invention and the butterfly valve provided with the valve body will be described in detail. Figure 1 , Figure 2 , Figure 3 , Figure 4 In, a perspective view, a front view, a top view, and a sectional view of the valve body of the double-eccentric butterfly valve of the present invention are shown.

[0034] As Figure 1 , Figure 2 shown, the valve body 1 of the double-eccentric butterfly valve has a disk-shaped valve disc 2, and boss portions 3 and 4 are provided at the upper and lower parts of one surface 2a of the valve disc 2, and an annular rib portion 5 and rib portions 6 and 7 are provided on the surface 2a.

[0035] The boss portion is divided into a boss portion 3 on the upper side of the valve disc 2 and a boss portion 4 on the lower side, and is arranged in a state where the valve stem 8 is exposed. Hole portions 10 and 11 for mounting the valve stem 8 are formed in the boss portion 3 and the boss portion 4, and the valve stem 8 can be inserted therethrough.

[0036] As Figure 3 shown, the boss portion 3 is arranged on the surface 2a of the valve disc 2 in a state where the center S of the hole portion 10 is at a distance C (single eccentricity) from the sealing position 2b of the valve disc and is also at a distance D (double eccentricity) from the center line of the valve body main body 1 (valve body central axis 12). In addition, as Figure 2 shown, the boss portion 4 is arranged symmetrically with the boss portion 3 with the valve body horizontal axis 14 as the axis of symmetry, and the hole portion 10 and the hole portion 11 are formed coaxially.

[0037] When the valve stem 8 is inserted through the hole portion 10 of the boss portion 3 and the hole portion 11 of the boss 4, the centers S of the hole portion 10 and the hole portion 11 are the rotation centers of the valve stem 8. When the valve body 1 rotates the valve stem 8, the valve body 1 eccentrically rotates about the centers S of the hole portion 10 and the hole portion 11 to be able to close the valve. The valve body 1 is made of metal. For example, stainless steels such as SCS13A and SCS14A are used.

[0038] The annular rib portion 5 is concentric with the valve disc 2, that is, it protrudes and is formed in an annular shape shorter than the diameter of the valve disc 2 on the surface 2a of the valve disc 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. As Figure 2 shown, the annular rib portion 5 is connected to the side wall surfaces 3a, 3b of the boss portion 3 and the side wall surfaces 4a, 4b of the boss portion 4, and the cross-sectional shape is Figure 4 shown as trapezoidal. In this way, the annular annular rib portion 5 is protruded and formed on the surface 2a of the valve disc 2, thereby increasing the overall strength and bending rigidity of the valve disc 2.

[0039] The rib portion 6 is arranged in a substantially horizontal state at the side wall surface 3a near the valve body central side (valve body horizontal axis 14 side) of 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 valve body outer edge side are connected to the annular rib portion 5 to be integrated. Figure 2 shown, the rib portion 6 is arranged in a substantially horizontal state at the side wall surface 3a near the valve body central side (valve body horizontal axis 14 side) of 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 valve body outer edge side are connected to the annular rib portion 5 to be integrated.

[0040] Similarly, the rib portion 7 is arranged in a horizontal state at the side wall surface 4a near the valve body central side (valve body horizontal axis 14 side) of 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 portion 5 to be integrated.

[0041] In addition, Figure 2In order to clarify the positional relationship between the ribs 6, 7 and the annular rib 5, the boundaries between the ends of the long ribs 15 and the short ribs 16, and the long ribs 17 and the short ribs 18 on the outer edge side of the valve body and the annular rib 5 are represented by lines. However, in fact, these boundaries are also formed as smooth R surfaces without steps and linear boundary parts and are continuously connected, so as not to cause stress concentration.( Figure 1 , Figure 3 , Figure 4 It is the same in

[0042] As Figure 2 shown, the boss part 3 and the boss part 4, and the rib 6 and the rib 7 are similarly formed in terms of line symmetry about the axis symmetric to the horizontal axis 14 of the valve body. Therefore, the following details about the ribs 6, 7 will be described with the help of the rib 6.

[0043] As Figure 2 shown, the rib 6 forms the long ribs 15 and the short ribs 16 from the side wall surfaces 3b, 3c of the boss part 3 to the two outer edge sides of the valve body 1 to the annular rib 5. However, the annular rib 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 central axis 20 as the center of the boss part 3 deviates from the valve body central axis 12 by a distance D. Therefore, even starting from the same side wall surfaces 3b, 3c of the boss part 3, the length of the long rib 15 is 2D longer than the length of the short rib 16.

[0044] In addition, as Figure 3 shown, the shapes of the long rib 15 and the short rib 16 observed from the end face 3d side on the outer peripheral side of the valve body of the boss part 3 are approximately right-angled triangles. The inclined upper surfaces 15c of the long rib 1 corresponding to the hypotenuse of the approximately right-angled triangle and the inclined upper surfaces 16c of the short rib 16 are set such that the height from the surface 2a of the valve disc 2 gradually decreases from the side wall surfaces 3b, 3c of the boss part 3 toward the two outer edge directions of the valve body 1.

[0045] The side wall surface 3a on the valve body central side of the boss part 3, the side wall surface 15a on the valve body central side of the long rib 15, and the side wall surface 16a on the valve body central side of the short rib 16 are connected in such a way as to form a single plane, that is, in a so-called coplanar manner. Therefore, the length of the rib 6 can be ensured to the maximum extent, and the stress at the connection part between the boss part 3 and the rib 6 can be more effectively dispersed.

[0046] As Figure 2 and Figure 3As shown, the side wall surface 15b on the opposite side of the side wall surface 15a of the long rib 15 is formed as a smooth R surface so as not to have a linear boundary portion with the side wall surface 3b of the boss portion 3 and is continuously connected. The inclined upper surface 15c of the long rib 15 is formed as a smooth R surface so as not to have a step in the height direction as observed from the surface 2a of the valve disc 2 with respect to the side wall surface 3c of the boss portion 3 and is continuously connected.

[0047] Similarly, the side wall surface 16b on the opposite side of the side wall surface 16a of the short rib 16 is formed as a smooth R surface so as not to have a linear boundary portion with the side wall surface 4b of the boss portion 4 and is continuously connected. The inclined upper surface 16c of the short rib 16 is formed as a smooth R surface so as not to have a step in the height direction as observed from the surface 2a of the valve disc 2 with respect to the side wall surface 4c of the boss portion 4 and is continuously connected.

[0048] In this way, the long rib 15 and the short rib 16 of the rib portion 6 are continuously connected to the boss portion 3 by forming a smooth R surface so as not to have a step or a linear boundary portion, and are integrally formed with the boss portion 3. Therefore, there is no portion where stress concentration occurs such as a step or a linear boundary portion at the connection portion between the boss portion 3 that supports the load of the fluid and the rib portion 6. As a result, stress concentration does not occur, the stress is moderately dispersed, and cracks and fractures caused by stress concentration are difficult to occur at the boss portion 3 and the rib portion 6, and the durability of the valve body 1 can be improved.

[0049] Furthermore, the long rib 15 and the short rib 16 are directly connected to the boss portion 3 with extremely high rigidity, and the long rib 15, the short rib 16, and the boss portion 3 are integrally formed to form the rib portion 6. Therefore, the bending rigidity of the entire rib portion 6 can be greatly improved.

[0050] Generally, in a butterfly valve, when the load of the fluid acts on the valve body during valve closure, the central portion in the longitudinal direction of the valve body is supported by the valve stem. On the other hand, there is no support portion at the left and right ends in the lateral direction of the valve body. Therefore, particularly, the maximum bending moment acts in the lateral direction at the central portion of the valve body, and the deflection amounts at the left and right ends of the central portion of the valve body are the largest.

[0051] However, in the valve body 1, near the center of the valve body where the maximum bending moment acts due to the fluid pressure during valve closure, the rib portion 6 and the rib portion 7 that ensure the maximum length across the horizontal axis 14 of the valve body are provided in parallel. Thereby, the lateral bending rigidity of the central portion of the valve disc 2 is improved, so that the deflection amounts at the left and right ends of the valve disc 2 caused by the bending moment acting due to the fluid load during valve closure can be suppressed to ensure the sealing performance. Reinforcement of other parts of the valve disc 2 is not very necessary, and an increase in the weight of the valve disc 2 can be suppressed.

[0052] As described above, in the valve body 1, an annular rib portion 5 is provided to improve the overall strength and rigidity of the valve disc 2. Near the center of the valve body where the maximum bending moment acts due to the fluid pressure during valve closure, ribs 6 and 7 are provided in parallel while maximizing the length across the horizontal axis 14 of the valve body, thereby improving the lateral bending rigidity of the central portion of the valve disc 2 and suppressing the deflection amount at both left and right ends of the valve disc 2 during valve closure.

[0053] Furthermore, the annular rib portion 5 is connected to the boss portions 3 and 4, the rib 6 is connected to the boss portion 3, and the rib 7 is connected to the boss portion 4. The annular rib portion 5 is connected to the ribs 6 and 7. The boss portions 3 and 4, the annular rib portion 5, and the ribs 6 and 7 are integrally formed, so they can be integrated to bear the load and bending moment acting on the valve body 1. Thus, compared with the case where the annular rib portion 5 and the ribs 6 and 7 are not connected to the boss portions 3 and 4, and the case where the annular rib portion 5 is not connected to the ribs 6 and 7, the occurrence of deformation and deflection of the valve body 1 can be more effectively suppressed, and the sealing performance can be ensured.

[0054] Next, as Figure 3 shown, the side shapes of the long rib 15 and the short rib 16 of the rib 6 observed from the end face 3d side of the boss portion 3 are substantially right-angled triangles. The reasons for setting the long rib 15 and the short rib 16 as substantially right-angled triangles and setting the side shape of the long rib 15 to be larger than that of the short rib 16 will be described below.

[0055] In a butterfly valve, the outer edge portion of the disc-shaped valve disc is sealed by closely contacting the valve seat of the valve body. However, if the deflection amount of the outer edge portion of the valve disc becomes large, the surface pressure for close contact with the valve seat of the valve body becomes insufficient, which causes a decrease in sealing performance. Therefore, it is necessary to keep the deflection amount of the outer edge portion of the valve disc during valve closure within a range where sufficient sealing performance can be obtained.

[0056] In addition, in the case of a double-eccentric butterfly valve, the position relationship is such that the center axis of the valve stem is inconsistent with the center axis of the valve body and is eccentric. Therefore, the distances from the center axis of the valve stem to both left and right ends of the valve disc are different. Thus, when receiving a load from the fluid, a larger bending moment is generated on the side with a longer distance from the center axis of the valve stem (hereinafter referred to as the long side) than on the side with a shorter distance from the center axis of the valve stem (hereinafter referred to as the short side), and the deflection amount of the outer edge portion on the long side is larger than that on the short side. In a double-eccentric butterfly valve, if the deflection amounts at both left and right ends of the valve disc are different during valve closure, the surface pressure for close contact with one-sided valve seat becomes insufficient, which causes a decrease in sealing performance.

[0057] Therefore, in a double-eccentric butterfly valve, it is necessary to suppress the deflection amounts at both left and right ends of the valve disc during valve closure, and make the difference in the deflection amounts at both left and right ends of the valve disc caused by the eccentricity of the valve stem as small as possible. If possible, there should be no difference in the deflection amounts at both left and right ends.

[0058] 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. Thus, that is, the rigidity of the long side that can be bent more greatly can be made higher than that of the short side with less bending, and thus the equalization of the amount of bending at the left and right ends of the valve disc 2 can be achieved.

[0059] 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 section modulus, and there is an effect of making it difficult for the valve disc 2 to bend. Therefore, the height of the long rib 15 provided on the long side is set to be overall higher than the height of the short rib 16 provided on the short side, and thus, the long side provided with the long rib 15 can be made difficult to bend.

[0060] That is, as Figure 4 shown, when comparing at positions at an equal distance L from the center axis 20 of the valve stem, the heights of the long rib 15 and the short rib 16 are set such that, except for the boss portion 3, the height Hl of the long rib 15 provided on the long side from the surface 2a of the valve disc 2 is higher than the height Hs of the short rib 16 provided on the short side from the surface 2a of the valve disc 2.

[0061] By setting the heights of the long rib 15 and the short rib 16 in this way, the long side that is more likely to bend is reinforced and made difficult to bend compared to the short side. Therefore, as a result, the difference in the amount of bending between the outer edge portion of the long side and the outer edge portion of the short side can be made smaller.

[0062] In addition, the relationship between the heights of the long rib 15 provided on the long side and the short rib 16 provided on the short side from the surface 2a does not necessarily need to hold at all rib positions, and the height relationship can also be partially reversed according to design conditions, etc. For example, when comparing the average heights, it is sufficient that the long rib 15 is higher than the short rib 16.

[0063] Such ribs for reinforcing the valve body are often set such that the height gradually decreases from the boss portion toward the outer edge side of the valve disc from the viewpoint of manufacturability, etc., and the upper surface of the rib is inclined at a substantially constant angle except near the connecting portion with the boss portion and near the connecting portion with the outer edge of the valve body. In this case, the shape of the rib can be approximated as a right triangle surrounded by a side (bottom side) corresponding to the position of the surface of the valve disc, a side (hypotenuse) corresponding to the inclined portion of the constant angle of the upper surface of the rib, and a side (height) on the center axis of the valve stem when viewed from the side.

[0064] Regarding the strength of the rib having such a side shape of a hypothetical right triangle, there is a case where the idea of applying a beam with uniform strength in material mechanics (a cantilever beam with an equal distributed load on the bottom side of the right triangle) is used. According to the formula of this beam with uniform strength, the amount of bending of the approximate rib cantilever beam can be calculated. Therefore, based on this formula, the heights (the heights Ha and Hb of the hypothetical right triangles on the valve stem center axis 20) of the hypothetical right triangles on the long side and the short side can be set such that the difference in the amount of bending at the ends of the ribs on the long side and the short side becomes smaller.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] Thus, in the valve body 1, the rib triangle ( Figure 4 The 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.

[0069] 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).

[0070] Figure 1 The embodiment is structured as described above, but Figure 5The valve body 31 of the comparative example shown has a disk-shaped valve disk 32, and is configured such that boss portions 33 and 34 are provided at the upper and lower portions of one surface 32a of the valve disk 32, a ring-shaped rib portion 35 for reinforcement is provided on the surface 32a, rib portions 36, 37, 38, 39 for reinforcement are provided, and missing wall portions 40a, 40b, 40c, 40d, 40e, 40f are provided.

[0071] In the valve body 31 of the double-eccentric butterfly valve of the comparative example, the ring-shaped rib portion 35 is connected to the rib portions 36, 37, 38, 39, but the boss portions 33 and 34 provided at the upper and lower portions of the valve disk 2 are not connected to the rib portions 36, 37, 38, 39. The non-connection between the boss portion and the rib portion is a significant difference from the embodiment. In addition, the valve body of the double-eccentric butterfly valve of this comparative example has a usage record in a butterfly valve with a maximum allowable pressure of 2 Mpa and has excellent sealing performance.

[0072] During analysis, for each dimension of the valve body shown in Table 1, for the embodiment and the comparative example, the displacement amounts (flexure amounts) at the left and right ends on the horizontal axis of the valve body and the weight of the valve body in the case of a fluid pressure of 5.11 MPa of load are obtained. Based on this result, the reduction rate (flexure improvement rate) of the difference in the flexure amounts at the left and right ends of the valve body, which is reduced in the embodiment compared to the comparative example, is calculated.

[0073] Table 1 shows the flexure improvement rate and the increase rate of the valve body weight for each dimension obtained by analysis. In addition, in Table 1, the positive direction means the case where fluid pressure is applied from the primary side, and the reverse direction means the case where fluid pressure is applied from the secondary side.

[0074] [Table 1]

[0075]

[0076] As shown in Table 1, according to the structure of the valve body of the embodiment, it is confirmed that a flexure improvement effect of reducing the difference in the flexure amounts at the left and right ends of the valve body without significantly increasing the weight of the valve body compared to the comparative example is significantly obtained.

[0077] Next, an example of installing the valve body 1 of the present invention in a double-eccentric butterfly valve will be described. Figure 6 A perspective view of a double-eccentric butterfly valve 51 showing a state where the valve body 1 of the present invention is assembled to the valve body 52 to fully close the valve.

[0078] The valve body 52 has a valve body 53 in the shape of a short cylinder, and shaft mounting parts 54 for shaft 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 disposed within the valve body 53. In this state, the valve stem 8 is shaft mounted in the hole 10 of the boss part 3 of the valve body 1, and the valve body 1 is integrally fixed to the valve stem 8 by a taper 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 vertical direction, and the valve body 1 is disposed at a predetermined position within the valve body 53. By rotating the valve stem 8, the valve body 1 can be rotated to open and close freely via the valve stem 8.

[0079] The double eccentric butterfly valve 51 can correspond to either the case where fluid pressure is applied from the side of the surface of the valve body 1 provided with the boss part 3 or the case where fluid pressure is applied from the side opposite to the surface provided with the boss part 3, and can be reliably sealed in the closed valve state in both flow directions.

[0080] In addition, at the upper end of the valve stem 8, a handle for manual operation can be installed to manually open and close the valve, or an actuator can be mounted to automatically open and close the valve.

[0081] As described above, the valve body of the double eccentric butterfly valve of the present invention is provided by connecting the transverse ribs that maximize the length near the center of the valve disc, which is subjected to a large bending moment due to the fluid pressure during valve closure, to the boss part, thereby improving the bending rigidity of the valve disc. Therefore, compared with the conventional valve body, it is possible to suppress the occurrence of deflection at the left and right ends of the valve disc during valve closure without significantly increasing the weight.

[0082] In addition, when ribs are provided to improve the bending rigidity of the valve disc, the rigidity is improved by increasing the section modulus of the ribs provided on the side where deflection is more likely to occur, and the equalization of the deflection amounts at the left and right ends of the valve disc is achieved. Therefore, sufficient sealing performance can be obtained during valve closure.

[0083] Furthermore, when connecting the boss part and the rib part, a smooth R surface is formed in such a way that there is no stress concentration part such as a stepped and linear boundary part, so as to continuously connect. Therefore, the stress at the connection part between the boss part and the rib part can be more effectively dispersed, and thus the occurrence of cracks, fractures, etc. caused by stress concentration is difficult to occur, and it has excellent durability.

[0084] The double eccentric butterfly valve of the present invention is provided with the following valve body. The aforementioned valve body is lightweight, has high rigidity, excellent sealing performance, and it is difficult for cracks, fractures, etc. caused by stress concentration to occur. Therefore, its operability, reliability, and durability are excellent, and it can be more suitable for application to high-pressure fluids than before.

[0085] Explanation of reference numerals

[0086] 1 Valve body

[0087] 2 Valve disc

[0088] The surface of the 2a valve disc

[0089] 3, 4 boss parts

[0090] 5 annular rib parts

[0091] 6, 7 rib parts

[0092] 8 valve stem

[0093] 51 double eccentric butterfly valve

[0094] 52 valve body

[0095] C The distance between the sealing position of the valve disc and the center of the hole of the boss part

[0096] D The distance between the center axis of the valve body and the center of the hole of the boss part

[0097] Ha The height of the right triangle formed by the imaginary long rib on the center axis of the valve stem

[0098] Hb The height of the right triangle formed by the imaginary short rib on the center axis of the valve stem

[0099] Hl The height from the long rib at the position with a distance L from the center axis of the valve stem to the surface of the valve disc

[0100] Hs The height from the short rib at the position with a distance L from the center axis of the valve stem to the surface of the valve disc

[0101] O The intersection point of the center axis of the valve body and the horizontal axis of the valve body

[0102] P The vertex of the rib triangle formed by the long rib, short rib and the surface of the valve disc

[0103] S The center of the hole of the boss part.

Claims

1. A double eccentric butterfly valve body, which is a double eccentric butterfly valve body with a circular shape. It is 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 upper surface of the rib is inclined at a substantially constant angle downward from the boss toward the outer edge 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.

2. The valve body of the double eccentric butterfly valve according to claim 1, It is characterized in that The rib portion is provided so as to gradually become higher from the end portion on the outer edge side of the valve body toward the boss portion.

3. The valve body of the double eccentric butterfly valve according to claim 1 or 2, It is characterized in that The aforementioned boss portion is divided into a plurality of parts in such a manner that the valve stem is partially exposed, and the aforementioned rib portion is arranged on each of the divided boss portions, and is continuously connected in such a manner that the aforementioned rib portion and the aforementioned boss portion do not produce a step in the height direction observed from the surface of the aforementioned valve disc, and do not produce a linear boundary portion on the side wall surface of the aforementioned boss portion.

4. A double eccentric butterfly valve, It is characterized in that A valve stem is axially mounted on upper and lower axial mounting portions of a short cylindrical valve body, and the valve body according to any one of claims 1 to 3 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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