JP2013083285A - Butterfly valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a butterfly valve, in which cavitation can be effectively suppressed on the orifice side up to an opening of a medium degree, and which is easily manufactured.SOLUTION: A semi-disc-like sub-valve element 5 having a large number of flow holes 16 is arranged on the downstream side on the orifice side of a valve element 4, and when the sub-valve element 5 integrally rotates with the valve element 4, a peripheral edge part of the sub-valve element 5 slidingly contacts with or approach an orifice side concave spherical surface part 11 of an inner surface of a valve casing body 2a, so that fluid is straightened when passing through the flow holes 16 of the sub-valve element 5 and the cavitation on the orifice side is restrained up to the opening of the medium degree, and the butterfly valve can be more easily and inexpensively manufactured than a conventional butterfly valve of using a plate member having a porous convex spherical surface.

Description

  The present invention relates to a butterfly valve that opens and closes a flow path in a valve box by rotating a valve body by operating a valve rod.

  A butterfly valve has a disc-shaped valve element fixed to a valve stem that is arranged so as to intersect the flow path in the cylindrical valve box, and the valve element is rotated around the axis of the valve stem by operating the valve stem. It opens and closes the flow path in the valve box, and since it has a simple structure and good flow characteristics, it is widely used as a flow control valve and on-off valve for piping in various facilities. However, when used under conditions where the differential pressure between the upstream side and the downstream side is large, when the opening of the valve body (hereinafter also simply referred to as “opening”) is small, the downstream side of the valve body (especially the orifice side) As a result, cavitation occurs, which not only causes vibration and noise, but also damages the valve body and piping. On the other hand, various butterfly valves have been developed that try to suppress cavitation by, for example, moderating the pressure change of the fluid passing through the orifice side of the valve body.

  For example, the butterfly valve proposed in Patent Document 1 is provided with a plate member having a large number of holes penetrating in the thickness direction at the peripheral edge of the downstream side on the orifice side of the valve body, the outer peripheral side being formed as a convex spherical surface, By causing the convex spherical surface portion of the plate member to slidably contact the valve seat (seal ring) of the valve box, the fluid is rectified when passing through the hole of the plate member, so that the medium opening degree (30 ° It is intended to suppress cavitation on the orifice side.

JP 2003-329169 A

  However, in the butterfly valve provided with the plate member having the porous convex spherical surface as described above, there is a problem that the production of the plate member is very troublesome and is expensive.

  Therefore, an object of the present invention is to provide a butterfly valve that can effectively suppress cavitation on the orifice side up to a medium opening degree and is easy to manufacture.

  In order to solve the above-described problems, the present invention provides a cylindrical valve box, a valve rod disposed so as to intersect a flow path in the valve box, and a disc-like valve body fixed to the valve rod. A butterfly valve that opens and closes a flow path in the valve box by rotating the valve body around an axis of the valve stem by operating the valve stem, and a predetermined downstream surface on the orifice side of the valve body. A semi-disc-shaped sub-valve body that rotates integrally with the valve body in a state of being opposed with a clearance in the rotation direction, and provided with a plurality of flow holes penetrating in the thickness direction in the sub-valve body, A configuration was adopted in which an inner surface of the valve box on the orifice side was provided with a concave spherical surface portion in which the peripheral edge portion of the auxiliary valve body slidably contacts or approaches when the auxiliary valve body rotates together with the valve body.

  That is, a semi-disc-shaped sub-valve body having a plurality of flow holes is provided on the downstream side of the orifice side of the valve body, and when the sub-valve body rotates integrally with the valve body, the peripheral portion of the sub-valve body Slidably contact with or close to the concave spherical surface of the inner surface of the valve box, the fluid is rectified to a moderate opening degree when the fluid passes through the flow hole of the sub-valve element, and cavitation on the orifice side is caused. In addition to being suppressed, it can be manufactured more easily and at a lower cost than the conventional one using a plate member having a porous convex spherical surface.

  In the above configuration, by providing a plurality of protrusions on the peripheral edge of the downstream side of the valve body on the orifice side, the fluid passing between the protrusions of the valve body is rectified when the opening is small. In this way, cavitation on the orifice side can be more effectively suppressed.

  Further, if a concave spherical surface portion is provided on the inner surface of the valve box on the nozzle side so that the peripheral portion on the nozzle side is in sliding contact with or close to the valve body when it rotates, cavitation occurs on the nozzle side. Can also be prevented. At this time, it is desirable that the nozzle side concave spherical surface portion of the inner surface of the valve box is formed in the same spherical surface as the orifice side concave spherical surface portion. This is because the inner surface of the valve box can be easily processed. If a plurality of flow grooves extending along the flow path direction are provided in the nozzle side concave spherical surface portion of the inner surface of the valve box, the flow rate up to a medium degree of opening can be increased while suppressing cavitation on the nozzle side. can do.

  As described above, the butterfly valve of the present invention is provided with a semi-disc-shaped subvalve body having a plurality of flow holes on the downstream side of the orifice side of the valve body, and the subvalve body rotates integrally with the valve body. In this case, since the peripheral portion of the sub-valve element is configured to be in sliding contact with or close to the concave spherical portion of the inner surface of the valve box, it is possible to effectively suppress cavitation on the orifice side up to a moderate opening degree. It can be manufactured more easily and at a lower cost than the conventional one using a plate member having a porous convex spherical surface.

a is a partially cutaway front view of the butterfly valve of the first embodiment, b is a longitudinal sectional view of a Cross-sectional plan view of FIG. 1 is an external perspective view of the valve body of the butterfly valve of FIG. a to d are cross-sectional plan views for explaining the operation of the butterfly valve of FIG. a to d are cross-sectional plan views illustrating the structure and operation of the butterfly valve according to the second embodiment;

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 4 show a first embodiment. As shown in FIGS. 1 and 2, this butterfly valve includes a valve body 2 in which a cylindrical main body 2 a in which a flow path 1 is formed is attached to a cylindrical hooked neck 2 b that extends radially outward. , A valve stem 3 which is passed through the main body 2a and the neck 2b of the valve box 2 and arranged to be orthogonal to the flow path 1, a disc-like valve body 4 fixed to the valve stem 3, and a valve body 4 It is basically composed of a semi-disc-like subvalve element 5 formed integrally, and pipes (not shown) are connected to both ends of the main body 2a of the valve box 2. Then, the valve body 4 and the sub-valve body 5 are rotated around the axis of the valve stem 3 by gripping the base end portion of the valve stem 3 protruding from the neck 2b of the valve box 2 with a jig or the like and turning it. The flow path 1 is opened and closed by rotating integrally.

  The main body 2a of the valve box 2 has support holes 6 and 7 through which the valve rod 3 is inserted concentrically with the neck portion 2b, and an annular groove provided on the inner surface so as to intersect with the support holes 6 and 7 8, a valve seat (rubber sheet) 9 that is in sliding contact with the valve body 4 is fitted. The lower support hole 7 is closed by a lid 10 fitted from the outer peripheral side.

  Further, the inner surface of the valve body 2a on the orifice side is provided with a concave spherical surface portion 11 in which the peripheral portion of the sub valve body 5 is slidably contacted or close when the sub valve body 5 rotates integrally with the valve body 4. The inner surface on the nozzle side is provided with a concave spherical surface portion 12 in which the peripheral portion on the nozzle side slides or approaches when the valve body 4 rotates. The orifice-side concave spherical surface portion 11 and the nozzle-side concave spherical surface portion 12 are formed of the same spherical surface so that the inner surface of the valve box body 2a can be easily processed. The nozzle-side concave spherical surface portion 12 is provided with a plurality of flow grooves 13 extending along the flow path direction.

  The valve stem 3 has a base end protruding from the neck 2b of the valve box 2 with a square cross section, and the other part has a circular cross section. The valve stem 3 rotates at the support holes 6 and 7 of the valve box neck 2b and the valve box main body 2a. It is supported freely.

  The valve body 4 is integrally formed with a sub-valve body 5 so as to face the downstream side surface on the orifice side with a predetermined rotation direction gap, and two upper and lower reinforcing plates 14 are provided in the rotation direction gap. Is sandwiched. A plurality of protrusions 15 are provided on the peripheral edge of the downstream side of the valve body 4 on the orifice side, and the plurality of flow holes 16 penetrating in the thickness direction are provided in the sub-valve body 5.

  Next, the operation of this butterfly valve will be described. First, when the opening degree of the valve body 4 is 0 °, as shown in FIG. 2, the entire periphery of the valve body 4 is in close contact with the valve seat 9 provided on the inner surface of the valve box body 2a. Is maintained, and the upstream fluid does not flow downstream. At this time, the peripheral edge portion of the sub-valve body 5 is in sliding contact with or close to the downstream end portion of the orifice-side concave spherical surface portion 11 on the inner surface of the valve box body 2a, as in the second embodiment to be described later. In the fully closed state, the auxiliary valve body 5 and the concave spherical surface portion 11 may be separated from each other.

  When the valve body 4 and the sub-valve body 5 are integrally rotated counterclockwise from the fully closed state of FIG. 2 and the opening degree is about 15 °, the orifice of the valve body 4 is shown in FIG. The peripheral edge on the side is separated from the valve seat 9, and the peripheral edge on the nozzle side comes into sliding contact with or close to the nozzle-side concave spherical surface portion 12. At this time, on the orifice side, the fluid is rectified by the flow hole 16 of the sub-valve body 5, so that cavitation can be effectively suppressed. Furthermore, in this embodiment, the fluid that has flowed into the gap between the peripheral edge of the valve body 4 and the valve seat 9 where the area through which the fluid can pass is the narrowest is between the protrusions 15 provided on the downstream side surface of the valve body 4. Since the air is rectified and flows downstream as it passes through, the cavitation can be more effectively suppressed. Further, on the nozzle side, the fluid hardly flows between the valve body 4 and the concave spherical surface portion 12, so that there is no possibility that cavitation occurs.

  Further, even if the valve body 4 and the sub-valve body 5 are further rotated from the state of FIG. 4A and the opening degree is about 25 °, as shown in FIG. Since rectification is performed at the flow hole 16 of the body 5, cavitation can be effectively suppressed. At this time, since the fluid passage area in the gap between the peripheral edge of the valve body 4 and the valve seat 9 is larger than the flow hole 16 of the sub-valve body 5, the rectifying effect at the protrusion 15 of the valve body 4 is reduced. The region between the valve body 4 and the sub-valve body 5 has an intermediate pressure between the upstream side and the downstream side, and the differential pressure between the downstream side and the downstream side becomes small. .

  If the opening is further increased to about 45 °, as shown in FIG. 4C, the sub-valve body 5 comes into sliding contact with or close to the valve seat 9 on the orifice side, but the flow rate increases, and the nozzle side However, the fluid flows through the flow groove 13 provided in the concave spherical surface portion 12. At this time, since the fluid passing through the flow groove 13 is rectified at that time, a relatively large flow rate can be secured while suppressing cavitation on the nozzle side.

  When the opening is set to 90 ° (fully open state), as shown in FIG. 4 (d), the sub-valve element 5 can flow smoothly without causing a major obstacle.

  As described above, when the butterfly valve rotates integrally with the valve body 4 as the porous semi-disc-shaped sub-valve body 5 provided on the downstream side of the orifice side of the valve body 4, Since the concave spherical portion 11 on the inner surface of the valve box main body 2a is slidably contacted or brought close to, the cavitation on the orifice side can be effectively suppressed to an intermediate opening degree. Moreover, since the concave spherical surface portion 11 is provided on the inner surface of the valve box body 2a that is easier to process than the sub-valve body 5, it is easier and less expensive to manufacture than the conventional one using a plate member having a porous convex spherical surface. be able to.

  Next, a second embodiment will be described based on FIG. In addition, about the member which has the same function as 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 5A, the butterfly valve according to the second embodiment has an eccentricity that causes the valve body 4 to slide in contact with the inner surface of the valve box body 2a on the upstream side of the flow path 1 with respect to the installation position of the valve stem 3. Of the type. The valve box body 2a is divided into two in the flow path direction, and an annular member 17 constituting a part of the orifice-side concave spherical part 11 and a part of the nozzle-side concave spherical part 12 is provided inside the upstream side main body 2c. It is fitted and the remainder of each concave spherical surface part 11 and 12 is provided in the inner surface of the downstream main body 2d.

  The valve body 4 is sandwiched between a valve plate 18 fixed to the valve stem 3, a seat press 19 screwed to the upstream side surface of the valve plate 18, and an outer peripheral portion of the valve plate 18 and an outer peripheral portion of the seat press 19. And an annular rubber sheet 20. In the fully closed state, the rubber sheet 20 is in close contact with an annular valve seat portion 21 protruding from the inner surface of the upstream main body 2c of the valve box 2 as shown in FIG. The sub-valve body 5 is formed separately from the valve body 4 and is attached to the valve shaft 3 so as to rotate integrally with the valve body 4. is seperated. In addition, the protrusion as in the first embodiment is not provided on the downstream side surface of the valve body 4 on the orifice side.

  The basic operation of this butterfly valve is the same as that of the first embodiment. That is, when the opening degree of the valve body 4 is about 15 °, the rubber sheet 20 on the orifice side of the valve body 4 is separated from the valve seat portion 21 of the valve box 2 as shown in FIG. The rubber sheet 20 is in sliding contact with or close to the nozzle side concave spherical surface portion 12 and the sub valve body 5 is in contact with or close to the orifice side concave spherical surface portion 11. Therefore, there is no possibility that cavitation occurs on the nozzle side, and on the orifice side, the fluid that has flowed into the gap between the rubber sheet 20 of the valve body 4 and the valve seat portion 21 passes through the flow hole 16 of the sub-valve body 5. Since it is rectified and flows downstream, cavitation is less likely to occur.

  Further, when the opening is about 45 °, as shown in FIG. 5C, the sub-valve body 5 is in sliding contact with or close to the valve seat portion 21 of the valve box 2, but the flow rate on the orifice side increases. A fluid flows on the nozzle side, and a relatively large flow rate can be secured. Then, when the opening degree is 90 ° (fully opened state), as shown in FIG. 5 (d), the fluid can flow without the sub-valve element 5 becoming a major obstacle.

  In addition, in this invention, it is desirable that the angle which a subvalve makes with a valve body shall be 30-40 degrees from a viewpoint of a cavitation suppression effect and flow volume ensuring.

  Further, in order to enhance the cavitation suppressing effect of the present invention, it is preferable that the nozzle side has a structure in which no fluid flows at a small opening degree as in the first and second embodiments. The structure is not limited to that of the embodiment, and for example, a convex spherical surface portion that is in sliding contact with the valve seat of the valve box may be provided on the nozzle side of the valve body.

  In each of the above-described embodiments, a large number of flow holes are provided in the sub-valve body. However, the flow holes may be open to the outer periphery of the sub-valve body, that is, may be groove-shaped.

DESCRIPTION OF SYMBOLS 1 Flow path 2 Valve box 2a Main body 3 Valve rod 4 Valve body 5 Subvalve body 9 Valve seat 11 Orifice side concave spherical surface part 12 Nozzle side concave spherical surface part 13 Flow groove 15 Protrusion part 16 Flow hole

Claims (5)

  A cylindrical valve box, a valve rod disposed so as to intersect with a flow path in the valve box, and a disc-shaped valve body fixed to the valve rod, and the valve body is operated by operating the valve rod. In the butterfly valve that opens and closes the flow path in the valve box by rotating the valve shaft about the axis of the valve stem, the valve is opposed to the downstream side surface on the orifice side of the valve body with a predetermined rotation direction gap. A semi-disc-shaped sub-valve body that rotates integrally with the body, and a plurality of flow holes that penetrate the sub-valve body in the thickness direction thereof, and the sub-valve on the inner surface of the valve box on the orifice side A butterfly valve comprising a concave spherical surface portion in which a peripheral edge portion of a sub-valve body is slidably contacted or approached when the body rotates integrally with the valve body.   2. The butterfly valve according to claim 1, wherein a plurality of protrusions are provided on a peripheral edge of a downstream side surface of the valve body on an orifice side.   3. The concave spherical surface portion in which the peripheral portion on the nozzle side is slidably contacted or close to the inner surface of the valve box on the nozzle side when the valve body rotates is provided. Butterfly valve.   The butterfly valve according to claim 3, wherein the nozzle side concave spherical surface portion of the inner surface of the valve box is formed of the same spherical surface as the orifice side concave spherical surface portion.   5. The butterfly valve according to claim 3, wherein a plurality of flow grooves extending along a flow path direction are provided in the nozzle side concave spherical surface portion of the inner surface of the valve box.

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