Eccentric butterfly valve

Abstract

To provide an eccentric butterfly valve which can distribute the stress applied on a valve even if a diameter of the valve is enlarged to secure the strength of the whole valve body while mitigating the stress, can be reduced in weight, and can surely seal a high-pressure fluid therein.SOLUTION: A valve body 4 is attached into a body 2 so as to be openable and closable in an eccentric state by a stem 3. The valve body has: a vertical rib 20 in which one stem is inserted into the vicinity of a center of a one-side face of the valve body, and held therein; and a horizontal rib 40 which is formed so as to extend up to the vicinity of a valve blade end part 33 from the vertical rib in a direction in which the horizontal rib intersects with the vertical rib. The vertical rib has an upper boss part 20a, a lower boss part 20b, and a sidewall part 24 for connecting both end parts of the upper / lower boss parts in a vertical direction so that the stem is exposed between the upper / lower boss parts.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an eccentric butterfly valve that is particularly suitable for passing high-pressure fluids. [Background technology]

[0002] Conventionally, as butterfly valves suitable for high-pressure fluids, for example, eccentric butterfly valves such as double eccentric type are known. As an example of this type of eccentric butterfly valve, the applicant has filed a butterfly valve in Patent Document 1. In this butterfly valve, two boss portions are provided separately on the upper and lower sides of one surface of the disk in the mounting direction, and the disk is attached to the body by a stem through these upper and lower boss portions so as to be freely opened and closed.

[0003] The stem consists of a single stem with integral attachment portions for attaching to the upper and lower mounting portions of the body, and this stem is inserted through the upper and lower bosses and fixed to the upper and lower bosses with the central portion between the upper and lower bosses exposed to the flow passage. In this way, by attaching the valve disc to the body through the upper and lower bosses with a single stem, the axial strength of the disc is improved by this stem, and it is possible to suppress deflection of the disc mainly in the direction crossing the axial direction when high-pressure fluid flows through the valve.

[0004] The butterfly valve further includes ribs extending from the boss of the disk toward both outer edges in a direction intersecting with the stem. These ribs increase the strength of the disk on the valve blade side and primarily suppress deflection of the disk on the valve blade side when high-pressure fluid flows through the valve.

[0005] As described above, in the eccentric butterfly valve of Patent Document 1, the strength of the entire valve body can be improved, mainly around the stem axial direction and the valve wing side of the disk, and deformation and bending of the valve body due to the fluid pressure of the high-pressure fluid when the valve is closed is suppressed, thereby ensuring sealing performance. Furthermore, by providing the rib portion, the thickness of the entire disk can be reduced while improving its strength, thereby making the disk lighter. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2020-139583 A Summary of the Invention [Problem to be solved by the invention]

[0007] In general, when the flow passage diameter of a butterfly valve is increased, the valve disc also becomes larger, and in addition to the increase in weight due to the increase in the valve disc diameter, the weight is likely to increase further if reinforcement parts are provided to ensure strength. In addition, when the diameter is increased, the pressure-receiving area that receives the fluid increases, which increases the rotation torque and tends to lead to reduced operability. In addition, there is also the problem that the amount of material used during manufacturing increases due to the increase in the size and thickness of the valve disc. Therefore, when increasing the diameter of the valve body (enlarging the valve), it is becoming difficult to reduce the amount of material that constitutes the valve body while ensuring strength against fluid pressure.

[0008] The above-mentioned issues are also common to eccentric butterfly valves such as that described in Patent Document 1. In particular, in eccentric butterfly valves designed to provide high sealing performance, even when the valve disc is made larger in diameter, it is necessary to ensure the strength of the entire valve disc and reliably prevent leakage when the valve is closed.

[0009] Therefore, the applicant discovered that in an eccentric butterfly valve, the strength of the entire valve disc can be improved by increasing the strength of the area between the upper and lower bosses of the valve disc that supports the stem while preventing stress concentration. That is, the applicant came up with the idea that in a double eccentric butterfly valve, by providing a reinforcing structure on one side of the valve disc, which is the surface on which the boss is formed, that further improves the strength in the valve axis direction and the valve wing direction, it is possible to make the valve disc even larger in a case where the valve disc is provided with a large diameter, while utilizing the structure in which a single stem is inserted into the boss to ensure the strength of the valve disc in the stem axis direction, while avoiding an increase in the thickness of the entire valve disc, and dispersing stress mainly in the valve axis direction and the valve wing direction, and further improving the strength of the entire valve disc and reducing its weight.

[0010] The present invention was developed to solve the above-mentioned problems, and has as its object to provide an eccentric type butterfly valve which can ensure the strength of the valve body as a whole while dispersing and mitigating the stress applied to the valve body, even when the valve diameter is increased, and which can be made lighter and can reliably seal in high-pressure fluid. [Means for solving the problem]

[0011] In order to achieve the above object, the invention of claim 1 is an eccentric butterfly valve in which a valve disc is eccentrically attached within a body by a stem so as to be able to be opened and closed freely, the eccentric butterfly valve having a vertical rib through which one stem is inserted and held near the center of one side of the valve disc, and a horizontal rib formed so as to extend from the vertical rib to near the end of the valve wing in a direction intersecting the vertical rib, the vertical rib having an upper boss portion, a lower boss portion, and side wall portions connecting both vertical sides of the upper and lower boss portions so that the stem is exposed between the upper and lower boss portions.

[0012] The invention according to claim 2 is an eccentric butterfly valve in which the valve body has a gap surrounded on all four sides by the opposing surfaces of the upper and lower boss portions and the left and right side wall portions, and the four corners of this gap are formed with rounded surfaces.

[0013] The invention according to claim 3 is an eccentric butterfly valve in which the rounded surfaces at the four corners are arc-shaped curved surfaces, and the gap is provided in a substantially elliptical shape.

[0014] The invention according to claim 4 is an eccentric butterfly valve in which the horizontal ribs are integrally formed with the vertical ribs with a portion of their end face side reaching into the gap portion in the formation direction from the vertical ribs.

[0015] The invention of claim 5 is an eccentric butterfly valve in which the cross rib is formed from the side wall portion, and the base end of the cross rib on the side wall portion side is integrally formed with the side wall portion while being slightly shifted inward from at least one or both of the end faces of the side wall portion in the length direction and height direction.

[0016] The invention according to claim 6 is an eccentric butterfly valve in which the width between the left and right side wall portions is formed wider than the width of each of the upper and lower boss portions that house the stem. Effect of the Invention

[0017] According to the invention of claim 1, the valve body has a vertical rib near the center of one side surface through which a stem is inserted and held, and a horizontal rib formed to extend from the vertical rib to the end of the wing in a direction intersecting the vertical rib, and the vertical rib has an upper boss portion, a lower boss portion, and a side wall portion connecting both vertical sides of the upper and lower boss portions so that the stem is exposed between the upper and lower boss portions, so that even if the valve diameter is increased, the strength of the entire valve body can be ensured while dispersing the stress applied to the valve body through the side wall portion to alleviate the stress, and the amount of material used in manufacturing the valve body can be reduced while preventing a decrease in operability due to the light weight. In this case, the strength of the entire valve body is ensured by reinforcing the side wall portion in the stem axial direction and the horizontal rib in the wing direction, respectively, so that the valve body is prevented from bending due to high-pressure fluid, reliably preventing fluid leakage, and exhibiting excellent sealing performance. Since the valve body is attached eccentrically within the body via a single stem so that it can be opened and closed freely, this single stem improves the axial strength of the valve body and suppresses the occurrence of rattle at the attachment point of the stem and movement in the direction of the flow path, making it possible to accommodate both types of flow without having to give the seat a special shape.

[0018] According to the invention of claim 2, the valve body has a gap surrounded by four sides by the opposing surfaces of the upper and lower bosses and the left and right side walls, and this gap makes it possible to reduce the weight of the valve body. Moreover, by forming rounded surfaces at the four corners of the gap, stress concentration at the four corners of the gap is prevented, and the strength of the entire valve body, centered on the axial direction of the stem and the valve wing direction, is improved, stress acting on the valve body is alleviated, and deformation of the valve body can be reliably suppressed even when a high-pressure fluid flows.

[0019] According to the invention of claim 3, the rounded surfaces at the four corners are formed into arc-shaped rounded surfaces and the gap is formed in a substantially elliptical shape. Therefore, when a load due to bending of the valve body or the like is applied near the gap, the load is appropriately dispersed through the side wall and the horizontal ribs, preventing localized stress concentration and thus deformation or damage.

[0020] According to the invention of claim 4, the horizontal ribs are formed integrally with the vertical ribs with a portion of their end faces reaching into the gap in the formation direction from the vertical ribs. This ensures the strength of the entire valve while making the length of the gap in the shaft mounting direction of the valve body as large as possible, thereby significantly reducing the weight of the valve body. Furthermore, when a bending force is applied from the horizontal ribs, this force can be reliably distributed to suppress deformation of the valve body.

[0021] According to the invention of claim 5, the horizontal rib is formed from the side wall portion, and the base end portion of the horizontal rib on the side wall portion side is integrally formed with the side wall portion, shifted slightly inward from at least one or both of the end faces of the side wall portion in the longitudinal and vertical directions. This prevents the force from the horizontal rib from being concentrated on the end face side of the vertical rib, and distributes the stress acting on the vertical rib to prevent bending.

[0022] According to the invention of claim 6, the width between the left and right side wall portions is formed wider than the width of each of the upper and lower boss portions that house the stem, thereby suppressing a decrease in the strength of the entire valve body due to gaps, and even when the valve body is installed with a large diameter, its deflection is suppressed, thereby ensuring sealing performance. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 is a perspective view showing an embodiment of an eccentric butterfly valve of the present invention. [Diagram 2] FIG. 2(a) is a front view showing the valve body in FIG. 1, and FIG. 2(b) is a cross-sectional view taken along line AA in FIG. [Diagram 3] FIG. [Figure 4] FIG. 4 is an enlarged perspective view showing the valve body from the valve wing direction. [Diagram 5] FIG. 11 is a perspective view showing another example of a valve body. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] An embodiment of an eccentric butterfly valve according to the present invention will be described in detail below with reference to the drawings. Fig. 1 is a perspective view of an embodiment of a butterfly valve according to the present invention, and Figs. 2 to 4 show the valve body in Fig. 1.

[0025] In the figure, an eccentric butterfly valve (hereinafter referred to as valve body 1) in an embodiment of the present invention comprises a body 2, a stem 3, and a valve element 4, and is provided with a large diameter of, for example, about 350A to 600A. It is a valve that can be used even if the flow path direction is reversed, so it is compatible with both flows.

[0026] The body 2 is formed in a short cylindrical shape and has a flow passage 10 provided therein. The upper and lower parts of the body 2 are provided with mounting portions 11 for mounting the stem 3, and these mounting portions 11 are provided with a stem insertion hole 12. The valve element 4 is provided in the body 2 in an eccentric state so as to be able to be opened and closed freely by the single stem 3 inserted into the stem insertion hole 12.

[0027] 2 to 4, the valve element 4 is formed in a substantially circular disk shape, and a vertical rib 20 for mounting a stem is provided near the center of one side of the valve element 4. In this embodiment, the vertical rib 20 is provided at a position relative to the valve element 4 that allows the stem 3 to be held in a state offset from the center of the valve element 4 by double eccentricity, and thus the valve body 1 is provided as a double eccentric butterfly valve.

[0028] The vertical rib 20 has an upper boss portion 20a, a lower boss portion 20b, and a side wall portion 24, and is arranged in an upper and lower divided structure so that the stem 3 is exposed near the center in the longitudinal direction (the direction in which the stem 3 is attached to the valve body 4). An upper boss portion 20a and a lower boss portion 20b are provided near the top and bottom of the valve body 4, i.e., on the upper and lower mounting portions 11 side of the body 2, and an insertion hole 21 through which the stem 3 can be inserted is provided at a position opposite the body-side stem insertion hole 12 of each boss portion 20a, 20b. The stem 3 is inserted into this insertion hole 21, and the valve body 4 is rotatably held relative to the stem insertion hole 12 by the single stem 3 through each boss portion 20a, 20b.

[0029] In this example, the upper and lower boss portions 20a, 20b are formed integrally with the valve body 4 in a boss shape having a substantially rectangular parallelepiped shape, and each of the upper and lower boss portions 20a, 20b is provided with a through hole into which a tapered pin (not shown) can be inserted so as to penetrate the stem 3 from the side. The valve body 4 and the stem 3 are connected at the upper and lower parts by the tapered pin, so that the valve body 4 rotates integrally with the stem 3 with vibration suppressed.

[0030] The side wall portions 24 connect both sides of the upper and lower boss portions 20a, 20b in the vertical direction, i.e., in the direction in which the stem 3 is attached, and are integral with both sides of the upper and lower boss portions 20a, 20b, each having an appropriate width dimension and thickness, and these side wall portions 24, 24 reinforce the space between the upper and lower boss portions 20a, 20b, with the stem 3 exposed between the upper boss portion 20a and the lower boss portion 20b.

[0031] The side wall portion 24 is preferably formed in a thin plate shape that can ensure bending strength and can be made lightweight. In other words, the vertical rib 20 is composed of at least the upper and lower boss portions 20a, 20b and the side wall portions 24, 24 connecting them, and in this example, a frame portion 25 having a substantially rectangular shape in plan view is provided near the center in the vertical direction, and the frame portion 25 has a structure in which the upper and lower block-shaped boss portions 20a, 20b through which the stem 3 passes are continuously provided above and below.

[0032] With this structure, the valve body 4 is provided with a gap 26 surrounded on all four sides by the opposing surfaces 20c, 20d of the upper and lower boss portions 20a, 20b and the left and right side wall portions 24, 24. The width W1 between the left and right side walls 24, 24 is formed wider than the width W2 of each of the upper boss portion 20a and the lower boss portion 20b that accommodate the stem 3. As a result, the upper and lower boss portions 20a, 20b are of the minimum size that allows the stem 3 to pass through, while the side walls 24 can prevent the side surface of the tip of the machining tool from interfering with the inner surface of the gap portion 26 when machining the stem insertion hole 21, and this also improves the strength of the valve body 4 near the center in the direction in which the stem 3 is attached.

[0033] A rounded surface 30 is formed at each of the four corners of the gap 26, and these rounded surfaces 30 prevent stress from concentrating at the four corners of the gap 26. These rounded surfaces 30 at the four corners are provided so as to smoothly connect to the opposing surfaces 20c, 20d of the upper and lower boss portions 20a, 20b constituting the gap 26 and the left and right side wall portions 24, 24. These rounded surfaces 30 are particularly in the form of an arc with a longer bottom toward the left and right side wall portions 24, 24 than toward the upper and lower opposing surfaces 20c, 20d, and in the most preferable case, the rounded surface 30 extends to the center of the side wall portion 24, so that the entire side wall portion 24 becomes an arc-shaped rounded surface without a flat portion.

[0034] The upper and lower opposing surfaces 20c, 20d can also be made into arc-shaped curved surfaces so that the gap 26 as a whole has a generally elliptical shape in a plan view, which is preferable in terms of strength, but the upper and lower boss portions 20a, 20b are provided with the stem insertion holes 21 by drilling holes from above and below toward the gap 26. In that case, it is advantageous for the upper and lower opposing surfaces 20c, 20d at the penetration end to be as close to flat as possible, so from the viewpoint of machining, it is preferable that the upper and lower opposing surfaces 20c, 20d are not made into curved surfaces overall, but that at least a part (for example, near the center) remains flat.

[0035] In addition, it is preferable that the opening edge 31 of the gap 26 (the edge of the boundary between the gap 26 and the upper surfaces 27 (surfaces parallel to the valve wing direction) of the upper and lower boss portions 20a, 20b) in the vertical rib 20 is also rounded. Since stress caused by the deflection of the valve body 4 tends to concentrate particularly in the corners, connecting this opening edge 31 in a rounded shape makes it easier to disperse the stress.

[0036] A transverse rib 40 is formed in a direction intersecting with the upper and lower bosses 20a, 20b, so as to extend from the side wall 24 to the vicinity of the end (valve wing end) 33 of the valve wing 32. The transverse rib 40 is formed in a substantially right-angled triangle shape with both sides of the valve wing 32 as bases, one of the bases being provided on the side wall 24 side, and the part forming the oblique side from the side wall 24 side is gently formed in the valve wing direction, and the part located on the tip side of the oblique side is provided at a position slightly away from the end face side of the valve wing 32. The transverse rib 40 should have an appropriate thickness to ensure its rigidity, and should have an external shape that does not concentrate stress on the side wall 24 side when bending stress acts on the valve wing 32 side.

[0037] When fluid pressure is applied to the valve disc 4, the central area is not easily displaced because it is supported by the stem 3, and the valve wing 32 side is deformed so as to bend toward the secondary side, with the degree of bending increasing toward the valve wing end 33 side. From the viewpoint of suppressing such bending, it is advantageous for the transverse rib 40 to be taller and thicker, but this increases the weight of the valve disc 4 accordingly, so it is preferable to keep the height and thickness of the transverse rib 40 to the minimum necessary. Since the stress caused by the bending of the valve disc 4 increases closer to the stem 3 side, the transverse rib 40 can be made into a right-angled triangular shape as described above accordingly.

[0038] The lateral ribs 40 are formed integrally with the side wall 24 at four locations in total, approximately toward the valve wing 32, from the top and bottom on the left and right sides of the side wall 24, and these four lateral ribs 40 reinforce the valve body 4 in the direction of the valve wing 32. In this case, the lateral ribs 40 should be provided near the outside of the four curved surfaces 30 provided in the gap 26, so as to be as far away as possible from the gap 26 in the up-down direction (the direction in which the stem 3 is attached), thereby making it possible to widen the gap 26 in the up-down direction.

[0039] Furthermore, the lateral ribs 40 are provided in a state where a part of their end face side in the formation direction from the side wall portion 24 abuts on the gap portion 26. In this example, the lateral ribs 40 are formed on the side wall portions 24 in a state where 1 / 3t to 1 / 2t of the plate thickness t abuts on the end side of the gap portion 26.

[0040] The transverse rib 40 is formed on the side wall 24 with its base end 41 on the side wall 24 side offset slightly inward by an appropriate offset width from both the end faces in the length direction and height direction of the side wall 24. It is preferable that the base end 41 on the side wall 24 side of the transverse rib 40 is also connected to the side wall 24 in an arc shape on both the top surface 42 and the side surface 43 of the transverse rib 40.

[0041] As described above, the valve body 1 is reinforced as a whole by the vertical rib 20 having the upper and lower boss portions 20a, 20b and the side wall portion 24, and the horizontal rib 40, to suppress deflection due to high-pressure fluid. In this case, as described above, the side wall portion 24 is provided so as to connect the upper boss portion 20a and the lower boss portion 20b to each other, thereby improving the rigidity of the entire valve body.

[0042] In the above valve body 50, the base end 41 of the cross rib 40 on the side wall portion 24 side only needs to be slightly shifted inward from at least one or both of the end faces in the length direction and height direction of the side wall portion 24, and the magnitude of the shift can be set arbitrarily depending on the size of the valve body aperture, etc.

[0043] In the above embodiment, an example of a double eccentric butterfly valve has been described as the eccentric butterfly valve constituting the valve body, but a triple eccentric butterfly valve can also be configured in a similar manner to the above.

[0044] In this embodiment, the valve body 4 is reinforced by providing the side walls 24 on both sides of the upper and lower boss portions 20a, 20b. However, the valve body 4 can also be reinforced by something other than the side walls 24.

[0045] For example, another example of the valve body is shown in Fig. 5. In this valve body, the same parts as those of the above-mentioned valve body are denoted by the same reference numerals, and the description thereof will be omitted. In this valve body 50, a plate-like member 51 is provided to connect the front surfaces of the upper and lower boss portions 20a, 20b, and the upper and lower boss portions 20a, 20b are reinforced by a so-called bridging structure using this plate-like member 51. In this case, as in the case of the configuration in which the side wall portion 24 is provided, the weight of the valve body 50 can be reduced and the overall strength can be improved.

[0046] In the bridging structure of Figure 5, the upper and lower boss portions 20a, 20b of the vertical rib 20 are separated from each other, and a gap portion 52 is formed near the center. In this gap portion 52, the stem 3 is exposed, but on the surface side of the vertical rib 20, the upper and lower portions are connected to each other by a plate-shaped bridging portion (plate-shaped member 51).

[0047] The bridging portion (plate-like member 51) is formed with an appropriate cross-sectional shape, and in this example, it is provided with a cross-sectional shape shown by the dashed-dotted line in the figure. In this structure, the stem 3 is passed through each of the insertion holes 21 of the upper and lower bosses 20a and 20b, and is arranged below the bridging portion in the central gap 52, and is exposed to the side at this portion. The plate-like member 51 has the same width as the upper and lower bosses 20a and 20b, and a groove 51a having a cross-sectional arc shape is provided on the back surface located on the stem 3 side along the direction along the stem 3 so as not to interfere with the rotational movement of the stem 3 and to avoid contact with the cross-sectional shape of the stem 3 shown by the dashed line. The thickness of the plate-like member 51 is not particularly limited, but if the thickness of the portion above the height position of the base end 41 of the transverse rib 40 is as if it were extended directly to the bridging portion, and the transverse rib 40 is formed integrally with the plate-like member 51, an excellent stress dispersion effect tends to be obtained.

[0048] Next, the operation of the eccentric butterfly valve of the present invention in the above embodiment will be described. 1 to 4, the valve body 1 has a vertical rib 20 and a horizontal rib 40, and the vertical rib 20 has upper and lower bosses 20a, 20b and a side wall 24. The upper and lower bosses 20a, 20b are not provided continuously over the entire top and bottom sides of the valve body 4, but the upper boss 20a, the lower boss 20b, and the stem 3 are exposed between the upper boss 20a, the lower boss 20b, and the upper and lower bosses 20a, 20b. This is advantageous when the valve body 1 is made large in diameter, when the valve body 4 is manufactured by casting, and the valve body 4 can be made lighter by reducing the material of the valve body 4. Furthermore, the lighter weight can suppress an increase in the rotational torque during operation via the stem 3 of the valve body 4, thereby suppressing a decrease in operability.

[0049] In this case, the side wall portion 24 is formed in a thin plate shape while ensuring bending strength, thereby making it possible to maintain the light weight of the valve body 4 while supplementing the strength of the portions of the upper and lower boss portions 20a, 20b where the stem 3 is exposed.

[0050] Here, in the valve body 4 of this embodiment, the vicinity of the center thereof is held by the stem 3 and is fixed to the body 2 via this stem 3 . However, in the present embodiment, when the upper and lower boss portions 20a, 20b are separated, the valve body 4 is not supported by the stem 3 in the gap 26 between the upper and lower boss portions 20a, 20b, and therefore the rigidity of this portion is inferior.

[0051] Therefore, when fluid pressure is applied to the valve body 4, a force (a force trying to bend the stem 3) is applied in a direction that tries to bend the axis-attached side (upper and lower sides) of the valve body 4 symmetrically around a line L perpendicular to the center line P of the stem 3, as described below, and there is a risk of bending in the region of this gap portion 26, which has low rigidity, causing it to bend. In other words, in a structure in which the upper and lower boss portions 20a, 20b are separated as in this embodiment, the strength against forces tending to bend the stem 3 is likely to be weaker than in a case in which the vertical ribs are provided continuously in the vertical direction.

[0052] In contrast, in the present embodiment, the upper and lower boss portions 20a, 20b of the valve body 1 are connected and integrated by the side wall portion 24, thereby improving the strength of the valve body 4 mainly in the axial direction (the direction in which the stem 3 is attached). Combined with the strength provided by the single stem 3 inserted into the insertion holes 21 of the upper and lower boss portions 20a, 20b, it is possible to suppress bending of the valve body 4 in a direction perpendicular to the axial direction caused by the high-pressure fluid.

[0053] If the stem is divided into upper and lower parts, rattles are likely to occur at the mounting points of the upper and lower stems. In other words, if the upper stem and the upper boss hole of the valve body, and the lower stem and the lower boss hole of the valve body are mounted with a loose fit, clearances will be generated between the mounting positions, and the valve body will be easily moved significantly by the fluid pressure, especially when a high-pressure fluid flows. In this case, it becomes difficult to design the seat on the valve seat side, and if the seat is designed to accommodate both fluid flows, it becomes difficult to prevent leakage when the valve is closed using the seat.

[0054] In contrast, in the valve body 1 of this embodiment, as described above, the valve element 4 is attached to a single stem 3, which prevents rattling near the upper and lower mounting positions of the stem 3 and also prevents movement of the valve element 4 due to the fluid. This simplifies the design of the valve seat and makes it easy to accommodate both types of flow.

[0055] Furthermore, by providing the upper and lower boss portions 20a, 20b in an upper and lower divided structure, when forming the insertion hole 21 for the stem 3 in the valve body 4, the processing can be easily performed by drilling from the upper and lower sides of the upper and lower boss portions 20a, 20b toward the divided portions near the center of the valve body 4, and the insertion hole 21 can be formed in a short time. Moreover, since the distance from the upper and lower sides of the upper and lower boss portions 20a, 20b to the divided portions is shorter than when the stem insertion hole is formed over the entire valve body, there is less runout of the drill during the hole drilling process, and the insertion hole 21 can be formed by highly accurate hole drilling.

[0056] In addition to the vertical ribs 20 described above, the valve body 4 is formed with transverse ribs 40 extending from the side wall portion 24 to the vicinity of the valve wing end portion 33 in a direction intersecting with the upper and lower boss portions 20a, 20b. The transverse ribs 40 improve the strength of the valve body 4 mainly in the valve wing direction, and suppress bending of the valve body 4 in the valve wing direction due to high-pressure fluid, thereby preventing bending. The vertical ribs 20 and the horizontal ribs 40 provide reinforcement in two directions, thereby minimizing the displacement of the valve body 4 when high-pressure fluid flows, and reducing the stress acting on the valve body 4, thereby providing excellent durability.

[0057] The action of the force when fluid pressure is applied to the valve disc will now be specifically described. In Figure 4, when fluid pressure such as a high-pressure fluid is applied to the valve element 4 from the upstream side of the flow path 10 while the valve body 1 is fully closed, the valve element 4 is primarily subjected to a force F in a direction that attempts to bend the valve wings 32 symmetrically around the center line P of the stem 3, and a force F' (a force that attempts to bend the stem 3) in a direction that attempts to bend the attachment sides (upper and lower sides) of the valve element 4 symmetrically around a line L that passes through the center of the valve element 4 in Figure 2 and is perpendicular to the center line P of the stem.

[0058] In response to these problems, as described above, the horizontal ribs 40 ensure strength against the force F in the direction that tries to bend the valve wings 32 symmetrically with respect to the center line P of the stem 3, and the vertical ribs 20 ensure strength against the force F' in the direction that tries to bend the stem 3. The upper and lower bosses 20a, 20b are provided with side walls 24 that connect them and run continuously in the mounting direction of the stem 3, thereby increasing the section modulus against the force F' in the direction that tries to bend the stem 3. This significantly improves the strength against bending forces compared to a valve body that has a flat shape and no side walls.

[0059] In this case, when a force F acting in a direction tending to bend the valve wing 32 is applied to the valve wing 32 in a bending direction, a force f tending to tilt the side wall 24 towards the stem 3 is applied strongly, particularly to the base end 41 where the transverse rib 40 is attached to the side wall 24. This force f is transmitted through the side wall 24 and concentrated in the vicinity of the boundary between the upper and lower boss portions 20a, 20b of the vertical rib 20 and the side wall 24. At this time, the aforementioned force F is also applied to the cross rib 40 in the direction of bending the valve wing 32 side, and particularly, as a result of a large stress being applied to the upper surface 42 side, the force f near the boundary with the side wall portion 24 at the upper and lower boss portions 20a, 20b becomes larger.

[0060] On the other hand, when a force F' attempting to bend the stem 3 is applied to the vertical rib 20 in a direction that causes the vertical rib 20 to fall around a line L perpendicular to the center line P of the stem, a force f' attempting to bend the side wall portion 24 in its length direction due to force F' acts mainly near the boundary between the upper and lower boss portions 20a, 20b of the vertical rib 20 and the side wall portion 24. For these reasons, stress concentration is likely to occur, particularly on the upper surface side, near the four corners of the gap 26 surrounded on all four sides by the opposing surfaces 20c, 20d of the upper and lower boss portions 20a, 20b and the left and right side wall portions 24, 24.

[0061] As described above, in this embodiment, the vertical ribs 20 and the horizontal ribs 40 are provided on the valve body 4 to increase the rigidity of the valve body 4, thereby suppressing deflection of the valve body 4 when fluid pressure is applied and improving its strength. However, according to studies by the inventors, it was found that while the provision of these vertical ribs 20 and horizontal ribs 40 increases the overall rigidity, it also creates areas where stress concentration is more likely to occur.

[0062] Even if the rigidity of the valve body 4 can be increased, if there is a large difference between areas where stress is likely to concentrate and areas where it is not, cracks and breaks will easily occur in the areas where stress is likely to concentrate, and sufficient durability may not be obtained. In this embodiment, in order to alleviate such stress concentration and further enhance the effect of improving the strength of the valve body 4 by providing the vertical ribs 20 and the horizontal ribs 40, the following structural features are devised.

[0063] That is, first, the upper and lower bosses 20a, 20b are connected to each other by the side wall 24, a frame 25 having a generally rectangular shape in plan view is formed near the center of the valve body 4, the upper boss 20a and the lower boss 20b are formed vertically from the frame 25, and the stem 3 is arranged so as to pass vertically through the center of the frame 25 while penetrating the upper and lower bosses 20a, 20b, thereby making it possible to easily resist forces in any of the directions that deflect the valve body 4, and furthermore, the four corners of the gap 26 surrounded by the frame 25 are made into rounded surfaces 30, which makes it possible to effectively alleviate the effect that tends to concentrate near the corners of the gap 26. In particular, by forming the rounded surfaces 30 so that the arcs on the upper and lower opposing surfaces are short and the arcs on the left and right side wall portions are long, it becomes possible to ease the formation of the insertion holes 21 of the upper and lower bosses 20a, 20b while alleviating stress.

[0064] In addition, when fluid pressure is applied from the stem 3 holding side, for example, the force of this fluid pressure acts in a direction that stretches the upper surfaces 27, 42 of the vertical ribs 20 and the horizontal ribs 40, and when fluid pressure is applied from the opposite side, the force acts in a direction that compresses the upper surfaces 27, 42 of the vertical ribs 20 and the horizontal ribs 40, so that in either case, the stress tends to be concentrated on the upper surfaces 27, 42 of the vertical ribs 20 and the horizontal ribs 40. In contrast, in this embodiment, the vicinity of the upper opening of the gap 26 is also rounded, so that it is possible to disperse and alleviate the stress concentrated on the upper surface 27 of the vertical rib 20 in the direction of the side wall portion 24.

[0065] In addition, the horizontal ribs 40 are provided in the intersecting direction of the vertical ribs 20, and it is advantageous in terms of strength that the horizontal ribs 40 are connected to the vertical ribs 20 at positions that do not overlap the gaps 26, i.e., connected to the block-shaped portions of the upper and lower bosses 20a, 20b. However, in that case, it is necessary to move the horizontal ribs 40 as close as possible to the top and bottom, or to make the gaps 26 as small as possible, and in the former case, the horizontal ribs 40 cannot be formed long enough in the direction of the valve wing 32, so that the strength against bending is insufficient, and in the latter case, it is necessary to form long insertion holes 21 for passing the stem 3 in the upper and lower bosses 20a, 20b, which is disadvantageous in terms of processing.

[0066] Therefore, in this embodiment, the horizontal rib 40 is formed integrally with the side wall portion 24 in a state where 1 / 3t to 1 / 2t of the plate thickness t of the horizontal rib 40 abuts on the end side of the gap portion 26. In this way, the horizontal rib 40 can be formed so as to overlap with the block-shaped portions of the upper and lower boss portions 20a, 20b as much as possible, and can be provided within the width of the rounded surface 30 even at the position where it overlaps with the gap portion 26. Therefore, even if the bending stress on the horizontal rib 40 is applied to the vertical rib 20, it can be effectively alleviated, and sufficient strength is obtained.

[0067] Furthermore, the transverse rib 40 is formed integrally with the side wall portion 24 with its base end 41 on the side wall portion 24 side shifted slightly inward by an appropriate offset width from both the longitudinal and vertical end faces of the side wall portion 24. Therefore, when a force is applied to the side wall portion 24 from the transverse rib 40 by the fluid, the stress that is maximum at the end face side of the transverse rib 40 is absorbed by the opposing surface side with the side wall portion 24, thereby reducing the maximum stress value applied from the transverse rib 40 to the end face side of the side wall portion 24 and the overall stress applied from the transverse rib 40 to the vertical rib 20.

[0068] In particular, when bending stress is applied to the transverse rib 40, the stress tends to be applied to its upper surface 42, so if this upper surface 42 is connected to the upper surface of the side wall portion 24 at the same height and the boundary between them becomes angular, the stress tends to concentrate at the corner, which is likely to cause damage, etc. In contrast, by connecting the transverse rib 40 to a position midway along the side wall where its upper surface 42 is lower than the upper surface of the side wall portion 24, the bending stress applied to the transverse rib upper surface 42 can be distributed and received by the surface of the side wall portion 24, which is extremely advantageous for alleviating the stress. Furthermore, by connecting both the side surface 43 and the top surface 42 of the horizontal rib 40 with the side wall portion 24 by a rounded surface portion, it is possible to obtain an even more excellent stress relaxation effect.

[0069] 2(b), it is preferable that the upper surface of each horizontal rib 40 extending on both sides of the vertical rib 20 is formed at an angle such that its extension line in the stem direction intersects near the center of the stem 3 as shown by the dashed line. In this way, when a force is applied in a direction that bends the horizontal rib 40, the stress can be supported by the virtual triangle formed on the upper surface of the horizontal rib 40, and high strength against bending can be exhibited.

[0070] Although the embodiment of the present invention has been described in detail above, the present invention is not limited to the description of the embodiment, and various modifications can be made without departing from the spirit of the invention described in the claims of the present invention. [Explanation of symbols]

[0071] 1 Valve body 2 Body 3. Stem 4 Valve body 20 Vertical ribs 20a Upper boss part 20b Lower boss part 20c, 20d Opposite surface 24 Side wall 25 Cavity 30 R-surface 32 Valve blades 33 Valve blade end 40 Horizontal ribs 41 Proximal end W1 Width between left and right side walls W2 Width of upper boss and lower boss

Claims

1. An eccentric butterfly valve in which a valve disc is eccentrically attached within a body by a stem so as to be able to open and close freely, the valve disc having a vertical rib through which one stem is inserted and held near the center of one side of the valve disc, and a horizontal rib formed so as to extend from the vertical rib to near the end of a valve wing in a direction intersecting the vertical rib, the vertical rib having an upper boss portion, a lower boss portion, and side wall portions connecting both vertical sides of the upper and lower boss portions so that the stem is exposed between the upper and lower boss portions.

2. 2. The eccentric butterfly valve according to claim 1, wherein the valve body has a gap surrounded on all four sides by the opposing surfaces of the upper and lower boss portions and the left and right side wall portions, and rounded surfaces are formed at the four corners of this gap.

3. 3. The eccentric butterfly valve according to claim 2, wherein the rounded surfaces at the four corners are arcuate rounded surfaces, and the gap is provided in a substantially elliptical shape.

4. 4. The eccentric butterfly valve according to claim 2 or 3, wherein the horizontal ribs are integrally formed with the vertical ribs in a state in which a portion of an end face side of each of the horizontal ribs extends into the gap in a formation direction from the vertical ribs.

5. 2. The eccentric butterfly valve according to claim 1, wherein the transverse rib is formed from the side wall portion, and a base end portion of the transverse rib on the side wall portion side is integrally formed with the side wall portion in a state slightly shifted inward from at least one or both of the end faces in the length direction and the height direction of the side wall portion.

6. 3. The eccentric butterfly valve according to claim 2, wherein a width between the left and right side wall portions is formed wider than a width of each of the upper and lower boss portions that accommodate the stem.

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