JP7248286B2 - Disc of double eccentric butterfly valve and double eccentric butterfly valve - Google Patents

Description

TECHNICAL FIELD The present invention relates to a valve body of a double eccentric butterfly valve in which the center of the stem is doubly eccentrically mounted, and more particularly to a valve body suitable for a flow path of high-pressure fluid and a butterfly valve provided with the valve body.

In general, butterfly valves have a simple structure, are small and lightweight, and have the advantage of being able to reduce the face-to-face dimension compared to other valve types. Since it can be operated, it is suitable for automatic operation and has the functional merit of excellent flow control, so it is widely used in various forms in various situations such as water supply and drainage, air conditioning equipment, and factory processes. Therefore, there is a demand for a device that can handle higher-pressure fluids than ever before.

A double eccentric butterfly valve is conventionally known as a valve suitable for a flow path of high-pressure fluid. The double eccentric butterfly valve is mounted so that the stem is doubly eccentric with respect to the valve body. This double eccentricity ensures good sealing performance even at high pressures and reduces wear on the seat surface. can be prevented.

When a butterfly valve is used under high pressure, large fluid resistance acts on the valve body when the valve is open and intermediate opening. The load from the acting fluid is maximized. When a load is applied from the fluid, the valve body deforms, and the deflection of the tip of the valve body increases. When this tip moves from the seating position of the seat ring, the sealing performance is impaired. Therefore, it is necessary to ensure the strength of the valve body so that it does not easily flex, but if the thickness of the valve body is increased in order to secure the strength, the weight of the valve body increases, which increases the cost and impairs the operability of the valve. occurs. In order to avoid this, it is required to secure the strength while reducing the weight of the valve body, to reduce the deflection and stress concentration, and to reduce the fluid resistance at the valve opening and intermediate opening.

As a valve body of a butterfly valve with improved strength, for example, Patent Document 1 discloses a valve body of a butterfly valve. The valve body of this butterfly valve is for a center type butterfly valve, and is formed with a plurality of horizontal ribs extending in the X direction with the Y axis as the starting point. This is what we are trying to do.

Further, Patent Document 2 discloses a valve body of a center type butterfly valve in which a plurality of circular ribs that intersect with a boss portion are raised concentrically on the front and back surfaces of a substrate. In this valve body, the circular ribs provide a substantially uniform section modulus in any cross-section at any angle with respect to the center line of the valve body. I am trying to get.

Japanese Patent No. 3676785 Japanese Patent No. 4659927

However, in the valve body of the butterfly valve of Patent Document 1, ribs are provided on the valve body to reinforce the valve body to increase the rigidity of the valve body. If this occurs, cracks and breaks are likely to occur at that portion, and there is a risk that sufficient durability of the valve body cannot be obtained.

Further, in the valve body of the butterfly valve of Patent Document 2, the rigidity of the entire valve body is made substantially uniform to increase the rigidity of the valve body. The magnitude of the bending moment that causes the deflection of the valve body varies greatly depending on the part of the valve body. That is, while the central portion of the valve body in the vertical direction is supported by the stem, there are no supporting portions on the left and right ends of the valve body, so the maximum bending moment acts on the center line of the valve body in the horizontal direction. , and the amount of deflection at this portion is the largest. In order to provide the valve body of the butterfly valve of Patent Document 2 with a rigidity that does not impair the sealing performance when the valve is closed even if both the left and right ends are bent, the rigidity of the entire valve body is adjusted to the rigidity of the portion where the bending moment is the largest. As a result, the thickness of the entire valve body increases, which increases the manufacturing cost, and the increased weight of the valve body deteriorates the operability of the valve.

The present invention was developed in order to solve the above-mentioned problems, and the purpose thereof is to reduce the weight of the valve body and prevent the occurrence of deformation and deflection of the valve body when the valve is closed even for high-pressure fluid. A valve body of a double eccentric butterfly valve that can suppress stress to ensure sealing performance, prevent the occurrence of stress concentration due to the load acting from the fluid, and improve operability, reliability and durability. To provide a butterfly valve.

In order to achieve the above object, the invention according to claim 1 provides a valve body for a double eccentric butterfly valve having a circular outer shape, wherein one side surface of the disc has a boss portion for accommodating a stem. and a rib portion extending from the boss portion toward both outer edge portions of the valve body in a direction intersecting with the stem. In addition, the rib portion is provided on each of the divided boss portions, and the rib portion and the boss portion have a continuous smooth surface so that there is no step in the height direction when viewed from the surface of the disc. A smooth surface is continuously formed and connected to the side wall surface of the boss portion so as not to form a linear boundary portion , and the boss portion is connected to the valve body. It is divided into two so that the stem is exposed near the center, the rib portion is formed near the center side of the valve disc in the boss portion, and the boss portion is located on the center side of the valve disc. The valve body of the double eccentric butterfly valve is characterized in that the side wall face and the side wall face of the rib portion on the center side of the valve body are provided so as to form a continuous single plane.

In the invention according to claim 2 , a stem is mounted on the upper and lower shaft mounting parts of a short cylindrical body, and a valve body is provided in the body so that the valve body can be freely opened and closed through the stem. It is an eccentric butterfly valve.

According to the first aspect of the invention, since the rib portion extending from the boss portion toward both outer edge portions of the valve body in the direction that intersects the stem is provided, the load that acts in the direction that intersects the stem of the valve body is reduced. This rib part can receive and directly transmit to and support the boss part, and by improving the rigidity in the direction intersecting with the stem of the valve body, the deflection amount of the left and right ends of the disc due to the bending moment acting by the fluid load can be suppressed to ensure sealing performance, the thickness of the entire disk can be suppressed and the weight of the disk can be reduced.

Further, a smooth R surface is formed so that the rib portion and the boss portion do not form a step in the height direction as viewed from the disk surface, and the side wall surface of the boss portion does not form a linear boundary portion. Therefore, when fluid load acts on the valve body, there are areas where stress concentration occurs such as steps and linear boundaries in the connecting parts of the bosses and ribs that support the load. As a result of the fact that the stress is moderately dispersed, cracks and breakage caused by stress concentration are less likely to occur, and the durability of the valve body can be improved.

Moreover , the boss part is divided into two so that the stem is exposed near the center of the valve body, and the rib part is formed closer to the center side of the valve body in the boss part, so the bending moment acts most due to the load of the fluid. Since a rib is provided near the center of the valve disc to ensure the maximum length, the bending rigidity in the lateral direction of the center of the disc is increased, and the amount of deflection of the left and right ends of the disc is suppressed, resulting in excellent sealing performance. can be ensured.

In addition, since the side wall surface of the boss portion on the center side of the valve element and the side wall surface of the rib portion on the center side of the valve element are provided so as to form a continuous single plane, there is no step or linear boundary portion. Since there is no such stress concentration portion, the stress at the connecting portion between the boss portion and the rib portion can be more effectively dispersed, and cracks and breakage caused by stress concentration are less likely to occur. A valve body having excellent durability can be obtained.

According to the second aspect of the invention, the valve body is lightweight, has high rigidity, and is excellent in sealing performance. It is possible to obtain a butterfly valve that is suitable for high-pressure fluids and is excellent in durability and durability.

FIG. 4 is a perspective view showing a preferred embodiment of the valve body of the double eccentric butterfly valve of the present invention; FIG. 2 is a front view of FIG. 1; FIG. 2 is a plan view of FIG. 1; FIG. 3 is a sectional view taken along the line AA of FIG. 2; FIG. 4 is a front view of a valve body of a double eccentric butterfly valve of a comparative example; FIG. 11 is a perspective view showing an embodiment of a double eccentric butterfly valve;

EMBODIMENT OF THE INVENTION Below, preferable embodiment of the butterfly valve which provided the valve body of the double eccentric butterfly valve and the valve body in this invention is described in detail based on drawing. 1, 2, 3, and 4 show a perspective view, a front view, a plan view, and a cross-sectional view of the valve body of the double eccentric butterfly valve of the present invention.

As shown in FIGS. 1 and 2, the valve body 1 of the double eccentric butterfly valve has a disc-shaped disc 2, and bosses 3 and 4 are formed on the top and bottom of the surface 2a on one side of the disc 2. , an annular rib portion 5 and rib portions 6 and 7 are provided on the surface 2a.

The boss portion is divided into an upper boss portion 3 and a lower boss portion 4 of the disk 2, and is provided with a stem 8 exposed. Mounting holes 10 and 11 are formed so that the stem 8 can be inserted therethrough.

As shown in FIG. 3, the boss portion 3 separates the center S of the hole portion 10 from the seal position 2b of the disc by a distance C (single eccentricity), and also separates it from the center line of the valve body 1 (valve center axis 12). It is provided on the surface 2a of the disk 2 in a state separated by a distance D (double eccentricity). Further, as shown in FIG. 2, the boss portion 4 is provided line-symmetrically with respect to the boss portion 3 with respect to the valve body horizontal axis 14, and the hole portion 10 and the hole portion 11 are formed coaxially. .

When the stem 8 is inserted through the hole 10 of the boss 3 and the hole 11 of the boss 4, the center S of the hole 10 and the hole 11 becomes the rotation center of the stem 8, and the valve body 1 rotates the stem 8. In some cases, the valve can be closed by rotating eccentrically around the center S of the holes 10 and 11 . The valve body 1 is made of metal, for example, stainless steel such as SCS13A or SCS14A is used.

The annular rib portion 5 is concentric with the disk 2, i.e., centered on the intersection O of the valve body center axis 12 of the disk 2 and the valve body horizontal axis 14, and has a ring shape with a shorter diameter than the diameter of the disk 2. 2a is formed to protrude. The annular rib portion 5 is connected to side wall surfaces 3a and 3b of the boss portion 3 and side wall surfaces 4a and 4b of the boss portion 4 as shown in FIG. 2, and has a trapezoidal cross-sectional shape as shown in FIG. . By forming the ring-shaped annular rib portion 5 protruding from the surface 2a of the disk 2 in this manner, the strength and bending rigidity of the disk 2 as a whole are increased.

As shown in FIG. 2, the rib portion 6 is provided in a substantially horizontal state near the side wall surface 3a of the boss portion 3 on the center side of the valve body (on the valve body horizontal shaft 14 side). and a short rib 16 connected to the side wall surface 3 c of the boss portion 3 . Further, the ends of the long rib 15 and the short rib 16 on the outer edge side of the valve body are connected to the annular rib portion 5 and integrated.

Similarly, the rib portion 7 is provided in a substantially horizontal state near the side wall surface 4a of the boss portion 4 on the valve body center side (valve horizontal shaft 14 side), and is connected to the side wall surface 4b of the boss portion 4. It is composed of a long rib 17 and a short rib 18 connected to the side wall surface 4 c of the boss portion 4 . Further, the ends of the long rib 17 and the short rib 18 on the outer edge side of the valve body are connected to the annular rib portion 5 so as to be integrated.

In FIG. 2, in order to clarify the positional relationship between the rib portions 6 and 7 and the annular rib portion 5, the long rib 15 and short rib 16, and the long rib 17 and short rib 18 are shown at their ends on the outer edge side of the valve body. and the annular rib portion 5 are represented by lines, but in reality, these boundaries are also continuously connected by forming a smooth R surface so that no step or linear boundary portion occurs, and stress It is configured so that concentration does not occur. (The same applies to Figures 1, 3, and 4.)

As shown in FIG. 2, the boss portion 3 and the boss portion 4, and the rib portion 6 and the rib portion 7 are constructed in the same manner except that they are symmetrical with respect to the valve body horizontal axis 14. Therefore, details of the rib portions 6 and 7 will be described below with reference to the rib portion 6 .

As shown in FIG. 2 , the rib portion 6 has long ribs 15 and short ribs 16 extending from the side wall surfaces 3 b and 3 c of the boss portion 3 toward both outer edge sides of the valve body 1 to the annular rib portion 5 . However, the annular rib portion 5 is formed concentrically with the disc 2 with the center point O of the disc 2 as the center, while the stem center axis 20 which is the center of the boss portion 3 extends from the valve body center axis 12. Since they are shifted by the distance D, the length of the long rib 15 is longer than the length of the short rib 16 by 2D even with the same side wall surfaces 3b and 3c of the boss portion 3 as starting points.

Further, as shown in FIG. 3, the shape of the long rib 15 and the short rib 16 seen from the end face 3d on the outer peripheral side of the valve body of the boss portion 3 is a substantially right-angled triangle, and corresponds to the oblique side of the substantially right-angled triangle. The inclined upper surface 15c of the long rib 1 and the inclined upper surface 16c of the short lube 16 gradually increase in height from the surface 2a of the disc 2 from the side wall surfaces 3b and 3c of the boss portion 3 toward both outer edges of the valve body 1. designed to be reduced.

The side wall surface 3a of the boss portion 3 on the center side of the valve disc, the side wall surface 15a of the long rib 15 on the center side of the valve disc, and the side wall surface 16a of the short rib 16 on the center side of the valve disc form a single plane. are connected so as to be flush with each other. Therefore, the length of the rib portion 6 can be maximized, and the stress at the connecting portion between the boss portion 3 and the rib portion 6 can be dispersed more effectively.

As shown in FIGS. 2 and 3, the side wall surface 15b of the long rib 15 opposite to the side wall surface 15a has a smooth rounded surface so as not to form a linear boundary with the side wall surface 3b of the boss portion 3. The inclined upper surface 15c of the long rib 15 is formed so as to be continuously connected, and the inclined upper surface 15c of the long rib 15 has a smooth R so as not to cause a step in the height direction viewed from the surface 2a of the disk 2 with respect to the side wall surface 3c of the boss portion 3. It forms a surface and is continuously connected.

Similarly, the side wall surface 16b of the short rib 16 opposite to the side wall surface 16a is continuously connected to the side wall surface 4b of the boss portion 4 forming a smooth R surface so as not to form a linear boundary portion. , the inclined upper surface 16c of the end rib 16 forms a smooth R surface with respect to the side wall surface 4c of the boss portion 4 in the height direction as seen from the surface 2a of the disk 2 so as to form a smooth R surface so as to form a continuous surface. It is connected.

In this way, the long ribs 15 and the short ribs 16 of the rib portion 6 are continuously connected to the boss portion 3 while forming a smooth R surface so as not to generate a step or a linear boundary portion. Therefore, there are no steps or straight boundary portions where stress concentration occurs in the connecting portions of the boss portion 3 and the rib portion 6 that support the load of the fluid, so stress concentration occurs. As a result of the stress being moderately dispersed without the existence of a portion where the stress is applied, the occurrence of cracks or breakage caused by stress concentration in the boss portion 3 or the rib portion 6 is unlikely to occur, and the durability of the valve body 1 is improved. can be done.

Furthermore, the long rib 15 and the short rib 16 are directly connected to the boss portion 3 having extremely high rigidity, and the long rib 15, the short rib 16, and the boss portion 3 are integrally configured to form the rib portion 6. Therefore, the bending rigidity of the rib portion 6 as a whole can be greatly improved.

Generally, in a butterfly valve, when a fluid load acts on the valve body when the valve is closed, the center part of the valve body in the vertical direction is supported by the stem, while the left and right ends of the valve body in the horizontal direction are supported by the stem. Since it does not exist, the maximum bending moment acts especially in the lateral direction of the central portion of the valve body, and the amount of bending of the left and right ends of the central portion of the valve body becomes the largest.

However, in the valve body 1, the rib portion 6 and the rib portion 7 which secure the maximum length with the valve body horizontal shaft 14 therebetween are located near the center of the valve body where the maximum bending moment acts due to the pressure of the fluid when the valve is closed. and are arranged in parallel to increase the lateral bending rigidity of the central portion of the disk 2, thereby suppressing the bending amount of the left and right ends of the disk 2 due to the bending moment acting due to the load of the fluid when the valve is closed, thereby improving the sealing performance. can be ensured, and reinforcement of other portions of the disc 2 is not required so much, and an increase in the weight of the disc 2 can be suppressed.

As described above, in the valve body 1, the annular rib portion 5 is provided to enhance the strength and rigidity of the entire disk 2, and the valve body 1 is provided near the center of the valve body where the maximum bending moment acts due to the pressure of the fluid when the valve is closed. The lateral bending rigidity of the center portion of the disc 2 is increased by providing the rib portion 6 and the rib portion 7 in parallel with each other to secure the maximum length across the body horizontal axis 14, thereby increasing the lateral bending rigidity of the disc 2 when the valve is closed. He is trying to suppress the bending amount of both right-and-left ends.

Further, the annular rib portion 5 and the boss portions 3 and 4 are connected, the rib portion 6 and the boss portion 3 are connected, the rib portion 7 and the boss portion 4 are connected, and the annular rib portion 5 and the rib portions 6 and 7 are connected. , the boss portions 3, 4, the annular rib portion 5, and the rib portions 6, 7 are integrally formed, so that the load and bending moment acting on the valve body 1 can be borne by these integrally. . As a result, it is more effective than when the annular rib portion 5 and the rib portions 6 and 7 are not connected to the boss portions 3 and 4 and the annular rib portion 5 and the rib portions 6 and 7 are not connected. It is possible to suppress the occurrence of deformation and bending of the valve body 1 and to ensure sealing performance.

Next, as shown in FIG. 3, the long rib 15 and the short rib 16 of the rib portion 6 viewed from the end face 3d side of the boss portion 3 have a substantially right-angled triangular shape. The reason why the long ribs 15 and the short ribs 16 are substantially right-angled triangles and the side surface shape of the long ribs 15 is set larger than the side surface shape of the short ribs 16 will be described below.

In a butterfly valve, the outer edge of the disk-shaped disc is in close contact with the valve seat of the body to seal. Therefore, it is necessary to keep the amount of deflection of the outer edge of the disc when the valve is closed within a range in which sufficient sealing performance can be obtained.

Also, in the case of a double eccentric butterfly valve, the stem center axis and the valve body center axis do not coincide and are in an eccentric positional relationship, so the distances from the stem center axis to the left and right ends of the disc are different. Therefore, when a load is applied from the fluid, the side with a longer distance from the stem center axis (hereinafter referred to as the long side) has a larger load than the side with a shorter distance from the stem center axis (hereinafter referred to as the short side). A bending moment is generated, and the amount of deflection of the outer edge on the long side is greater than the amount of deflection on the outer edge on the short side. In a double eccentric butterfly valve, if the amount of deflection differs between the right and left ends of the disc when the valve is closed, the pressure on the valve seat on one side is insufficient, resulting in a decrease in sealing performance.

Therefore, in the double eccentric butterfly valve, the amount of deflection at the left and right ends of the disc when the valve is closed is suppressed, and the difference in the amount of deflection at the left and right ends of the disc caused by the eccentricity of the stem is minimized. It is required that there is no difference in the bending amount of the ends.

In the valve body of the double eccentric butterfly valve of the present invention, the degree of reinforcement of the disc 2 by the ribs 6 and 7 is differentiated, namely, the rigidity of the long side that flexes greatly and the rigidity of the short side that flexes less. By increasing the height of the disc 2, the amount of deflection at the left and right ends of the disc 2 is made uniform.

The ribs 6 and 7 provided on the surface 2a of the disk 2 have a larger section modulus as the height from the surface 2a increases, and have the effect of making the disk 2 less likely to bend. Therefore, by making the height of the long ribs 15 provided on the long side higher than the height of the short ribs 16 provided on the short side as a whole, the long side on which the long ribs 15 are provided can be made difficult to bend.

That is, as shown in FIG. 4, when compared at a position equidistant L from the stem center axis 20, the height of the long rib 15 provided on the long side from the surface 2a of the disc 2 except for the boss portion 3 is The heights of the long ribs 15 and the short ribs 16 are set so that the height Hl is higher than the height Hs of the short ribs 16 provided on the short side from the surface 2a of the disc 2 .

By setting the heights of the long ribs 15 and the short ribs 16 in this way, the longer side, which is more flexible, is reinforced more than the short side, making it more difficult to bend. It is possible to reduce the difference in the amount of bending of the outer edges on the short side.

It should be noted that the relationship between the heights of the long ribs 15 provided on the long side and the short ribs 16 provided on the short side from the surface 2a does not necessarily have to be established at all positions of the ribs. The height relationship may be partially reversed. For example, the long ribs 15 should be higher than the short ribs 16 in terms of average height.

From the standpoint of manufacturability, such ribs that reinforce the valve body are often provided so that the height gradually decreases from the boss toward the outer edge of the disc. It is inclined at a substantially constant angle except for the vicinity of the connecting portion and the vicinity of the connecting portion of the outer edge of the valve body. In this case, the shape of the rib consists of a side (bottom side) corresponding to the surface of the disc when viewed from the side, a side (hypotenuse) of the inclined portion of the upper surface of the rib with a certain angle, and a side (height) on the center axis of the stem. ) can be approximated by a right-angled triangle.

For the strength of such a rib having a side shape of a virtual right triangle, the concept of a beam of uniform strength (a cantilever beam that receives a uniformly distributed load on the base of a right triangle) in material mechanics may be applied. . Since the amount of deflection of a cantilever approximating a rib can be calculated from this formula for a beam of uniform strength, based on this formula, the difference in the amount of deflection between the ends of the ribs on the long and short sides should be small. , the heights of the imaginary right-angled triangles on the long and short sides (heights Ha and Hb of imaginary right-angled triangles on the stem central axis 20) can be set.

If the side surface shape of the rib portion is obtained by this method, the height of the rib provided to increase the lateral bending rigidity of the disc can be minimized, and an increase in the weight of the valve body can be suppressed.

However, in reality, when the valve is closed, the load of the fluid is received not only on the rib portion but also on the entire valve body including the disc and boss, and the amount of deflection is also affected by the thickness and size of the disc. , In many cases, the concept of a beam of equal strength cannot be applied as it is, but the difference between the heights of the imaginary right triangle on the long side and the short side is at least the height derived based on this concept of a beam of equal strength is preferably set to be equal to or greater than the difference between .

As shown in FIG. 4, the long rib 15 and the short rib 16 have substantially constant inclined upper surfaces 15c and 16c that gradually rise from the outer edge side end of the valve body toward the boss portions 3 and 4. A rib center line 24 passing through an intersection point P of virtual lines 22 and 23 obtained by virtually extending the inclined upper surfaces 15 c and 16 c toward the center of the valve body is aligned with the valve body center axis 12 . It is located on the opposite side of the central axis 20 .

Thus, in the valve body 1, a rib triangle formed by the long rib 15, the short rib 16, and the surface 2a of the disc 2 (in FIG. A rib center line 24 passing through the apex P of a triangle formed by an imaginary line 23 extending the inclined upper surface 16C of the short rib 16 and a line 25 indicating the surface of the disk 2 is aligned with the stem center axis 20 with respect to the valve body center axis 12. By offsetting to the opposite side, the section modulus of the flexible side is made larger than the section modulus of the hard-to-bend side to increase the rigidity and equalize the amount of bending of the left and right ends of the disc.

1 and the comparative example shown in FIG. was analyzed by FEM (Finite Element Method) for the valve body of the double eccentric butterfly valve.

The embodiment of FIG. 1 has the structure described above, but the valve body 31 of the comparative example shown in FIG. 33 and 34 are provided, and the surface 32a is provided with an annular rib portion 35 for reinforcement, rib portions 36, 37, 38 and 39 for reinforcement and lightening portions 40a, 40b, 40c, 40d, 40e and 40f. It is configured.

In the valve body 31 of the double eccentric butterfly valve of the comparative example, the annular rib portion 35 and the rib portions 36, 37, 38, 39 are connected, but the boss portions 33, 34 provided on the upper and lower portions of the disc 2 are connected to each other. and ribs 36, 37, 38, 39 are not connected. The major difference from the embodiment is that the boss portion and the rib portion are not connected. The valve body of the double eccentric butterfly valve of this comparative example has been used in a butterfly valve with a maximum allowable pressure of 2 MPa, and has excellent sealing properties.

In the analysis, for each valve body size shown in Table 1, the displacement amount (deflection amount) at the left and right ends of the valve body horizontal axis when a fluid pressure of 5.11 MPa is loaded and the valve body asked for weight. Based on this result, the reduction rate (deflection improvement rate) at which the difference in the amount of deflection between the left and right ends of the valve body decreased in the example compared to the comparative example was calculated.
Table 1 shows the deflection improvement rate and valve weight increase rate for each size obtained by the analysis. In Table 1, the positive direction means that the fluid pressure is applied from the primary side, and the reverse direction means that the fluid pressure is applied from the secondary side.

As shown in Table 1, according to the configuration of the valve body of the example, compared with the comparative example, the deflection improvement effect of reducing the difference in the amount of deflection between the left and right ends of the valve body is remarkable without significantly increasing the weight of the valve body. It was confirmed that

Next, an example in which the valve body 1 according to the present invention is attached to a secondary eccentric butterfly valve will be described. FIG. 6 shows a perspective view of a secondary eccentric butterfly valve 51 in which the valve body 1 according to the present invention is attached to the valve body 52 and the valve is fully closed.

The valve main body 52 has a short cylindrical body 53 , and upper and lower portions of the body 53 are provided with shaft mounting portions 54 for mounting the stem 8 of the valve body 1 thereon. The valve body 1 is arranged in the body 53. In this state, the stem 8 is axially mounted in the hole 10 of the boss 3 of the valve body 1, and the valve body 1 is integrally fixed to the stem 8 with a taper pin (not shown). As a result, the stem 8 is rotatable with respect to the body 53 and cannot be vertically moved, and the valve body 1 is disposed within the body 53 at a predetermined position, allowing the stem 8 to rotate. , the valve body 1 can be rotated to freely open and close via the stem 8 .

In the double eccentric butterfly valve 51, the fluid pressure is applied from the side of the valve body 1 on which the boss portion 3 is provided, or the fluid pressure is applied from the side opposite to the surface on which the boss portion 3 is provided. , and can reliably seal in the valve closed state in both flow directions.

A handle for manual operation can be attached to the upper end of the stem 8 to manually open and close the valve, or an actuator can be mounted to automatically open and close the valve.

As described above, the valve body of the double eccentric butterfly valve of the present invention has a lateral rib that secures the maximum length near the center of the disc where a large bending moment acts due to the pressure of the fluid when the valve is closed. Since the flexural rigidity of the disc is increased by connecting it to the part, the deflection of the left and right ends of the disc that occurs when the valve is closed is suppressed without significantly increasing the weight compared to the conventional valve body. be able to.

In addition, since the boss and ribs are continuously connected by forming a smooth R surface so that there are no steps or linear boundaries where stress concentration occurs, the bosses and ribs are Since the stress at the connecting portion can be more effectively dispersed, cracks and breakage caused by stress concentration are less likely to occur, and excellent durability is achieved.

The double eccentric butterfly valve of the present invention is lightweight, has high rigidity, and is excellent in sealing performance. , excellent in reliability and durability, and can be applied to fluids of higher pressure than conventional ones.

1 Valve body 2 Disc 2a Surface 3, 4 Boss 5 Annular rib 6, 7 Rib 8 Stem 51 Secondary eccentric butterfly valve 52 Valve body C Distance between disc sealing position and center of boss hole D Distance between the center axis of the valve body and the center of the hole in the boss Ha Height of the right triangle formed by the imaginary long rib on the stem center axis Hb Height of the right triangle formed by the imaginary short rib on the stem center axis Hl Height of long rib from disk surface at distance L from stem center axis Hs Height from disk surface of short rib at distance L from stem center axis O Valve body center axis and valve body horizontal Point of intersection of axes P Vertex of rib triangle composed of long rib, short rib and disc surface S Center of boss hole

Claims (2)

A valve body for a double eccentric butterfly valve having a circular outer shape, wherein a boss portion for accommodating a stem and a valve body extending from the boss portion in a direction intersecting with the stem are provided on one side surface of the disc. The boss portion is divided into a plurality of portions so that the stem is partially exposed, and the rib portion is attached to each of the divided boss portions. The rib portion and the boss portion are connected by continuously forming a smooth surface so that there is no step in the height direction when viewed from the surface of the disk. A smooth surface is continuously formed and connected so that a straight boundary does not occur on the wall surface ,
The boss part is divided into two parts so that the stem is exposed near the center of the valve body, the rib part is formed near the center side of the valve body in the boss part, and A double eccentric butterfly characterized in that the side wall surface of the boss portion on the center side of the valve body and the side wall surface of the rib portion on the center side of the valve body are provided so as to form a continuous single plane. valve disc. The stem is mounted on the upper and lower shaft mounting portions of a short cylindrical body, and the valve body according to claim 1 is provided in the body so that the valve body can be freely opened and closed via the stem. Heavy eccentric butterfly valve.

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