JP2003028312A - Valve element for butterfly valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provided a valve element for a butterfly valve capable of minimizing the damage of piping in a downstream side, even when bubbles by cavitationis generated at the time of passing of fluid. SOLUTION: A platy swirl flow inducing means 15 (15a to 15d) generating swirl flow in a downstream side at the time of passing of fluid is formed on at least a nozzle side upstream surface 11a of a valve body 11. The swirl flowinducing means 15 is protrusively formed so as to make a main surface thereof extend from a valve shaft side to a valve casing inner wall side while tilting to an orthogonal plane to a valve shaft 2 and extend from an upstream surface 11a of the valve body 11 to an upstream side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve body of a butterfly valve, and more particularly, to a valve body of a butterfly valve for minimizing the effect of bubbles caused by cavitation.

[0002]

2. Description of the Related Art Conventionally, in various valve bodies for adjusting the flow velocity and passage amount of fluid, noise and vibration are caused by the generation of bubbles due to cavitation during passage of fluid, and further, the downstream side of the valve body. It is an important technical issue to suppress the influence of bubbles due to cavitation (hereinafter referred to as cavitation bubbles) because it may cause damage to the piping.

In order to solve this problem, conventionally, various valve bodies of butterfly valves have been provided with a plurality of comb-teeth-shaped protrusions near the outer periphery of the valve body so that cavitation bubbles are decomposed at each protrusion. Proposed.

For example, in Japanese Unexamined Patent Publication No. 57-157866, a plurality of comb-teeth shaped projections are provided along the outer periphery of the valve body, and the projection length increases as the projections on the valve shaft side increase. There is disclosed a valve body having a shorter length.

According to the valve body having such a structure, the cavitation bubbles are finely decomposed by the respective protrusions when the fluid moves when the valve is opened, so that the valve body has no comb-shaped protrusions as compared with the conventional valve body. Then, it is surely possible to obtain the effect of suppressing the occurrence of noise and damage to the downstream piping.

[0006]

However, in the valve body having such a structure, each small bubble decomposed by the protrusions moves to a certain position on the downstream side regardless of the variation of the valve opening and pressure. Since it passes in a streak shape, the streak-like damage may occur on the downstream side of the pipe because the shock is always applied to the same position on the downstream side pipe. Therefore, there is still room for improvement in terms of minimizing damage to the downstream piping.

Further, in the above-described conventional valve body, the air bubbles decomposed by the rib-shaped member flow near the inner wall of the pipe on the downstream side, so that there is still room for improvement in noise reduction. It was

The object of the present invention is to minimize the damage to the piping on the downstream side even if cavitation bubbles are generated at the time of passage of the fluid, and to obtain a further improvement effect on noise reduction. It is to provide a valve body of a butterfly valve.

[0009]

The main structure of the valve element of the butterfly valve according to the present invention is a butterfly valve valve element which is rotatable about a valve shaft in a valve box, and which is located downstream of a fluid passage. The plate-like swirl flow inducing means for generating swirl flow at
The swirl flow inducing means is formed on at least the nozzle side upstream surface of the valve body, and extends from the valve shaft side to the valve box inner wall side so that its main surface is inclined with respect to a plane orthogonal to the valve shaft, and
It is characterized in that it is formed so as to extend from the upstream surface of the valve body toward the upstream side.

The swirl flow inducing means extends from the valve shaft side to the valve box inner wall side so that its main surface is inclined with respect to the plane orthogonal to the valve shaft, unlike the comb-teeth-shaped protrusion of the conventional example, and ,
Since the valve body is configured to have a plate-shaped main surface with a large area that is formed so as to extend from the upstream surface toward the upstream side, when the valve body is opened, the fluid passes through the swirl flow inducing means. A swirl flow (spiral) is generated on the downstream side. Also,
Even when cavitation bubbles are generated, the bubbles collide with the ends of the swirl flow inducing means, so that the bubbles are finely decomposed.

That is, when the valve body is opened from the closed state, a gap is created between the inner wall of the valve box and the nozzle side and the orifice side of the valve body, and the fluid moves downstream from this gap.
At this time, even if cavitation bubbles are generated,
The bubbles are finely decomposed by hitting the swirl flow inducing means,
Further, the fluid passing through the nozzle side of the valve body causes a swirl flow (vortex) on the downstream side while being guided to the swirl flow inducing means.

Therefore, in the valve body of the present invention, not only the conventional action and effect of reducing damage to the downstream pipe and noise resulting from the decomposition of the cavitation bubbles, but also the decomposed bubbles are By being put on the swirling flow generated on the downstream side, each bubble is guided to the center of the pipe, and the bubbles colliding with the inner wall of the pipe are reduced, so that the damage and noise of the pipe are reduced more effectively. .

A plurality of swirl flow inducing means are preferably formed on the nozzle side upstream surface of the valve body. In this case, the main surface of each swirl flow inducing means extends from the upstream surface of the valve body toward the upstream side. It is configured to be formed so as to extend in substantially the same direction as each other.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail with reference to the drawings. In each of the following embodiments, an example in which the present invention is applied to a butterfly valve for a pipe diameter of 100 mm will be described. The half side of the valve body that moves downstream when the valve is opened is called the nozzle side, and the other half side that moves upstream when the valve is opened is called the orifice side.

(First Embodiment) First, with reference to FIG. 1, a first embodiment of a valve body of a butterfly valve to which the present invention is applied will be described. In FIG. 1, (a) shows a plan view showing the valve body from above, and (b) shows a rear view showing the valve body as seen through from the downstream side of the pipe.

The valve body 10 of the first embodiment is shown in FIG.
As shown in (a) and (b), the valve body 1 has a substantially disk-like plane.
1, a hub 12 formed on both end sides (upper and lower sides of FIG. 1B) of the valve body 11 and having a hole portion to be fitted with the valve shaft 2 of the valve box (not shown), and the valve body 11 Nozzle side upstream surface 11a
A plate-like projection 15 formed as a swirl flow inducing means
(15a to 15d).

The valve body 10 is rotatably housed in a valve box (not shown) around a valve shaft, and is opened when the valve is opened.
It rotates in the counterclockwise direction in (a), and when the valve is closed, as shown in FIG.
By rotating in the clockwise direction of (a), the flow of fluid is controlled. FIG. 1A shows a state in which the valve body 10 is slightly open.

In the valve body 10 of the present embodiment, FIG.
As shown in (b) and (b), a plurality of (four in this example) plate-shaped protrusions 15 a to 15 d each having a flat plate shape and having the same shape are provided on the nozzle side upstream surface 1 of the valve body 11.
It is provided only in 1a.

In the first embodiment, each plate-shaped protrusion 15
The main surfaces of a, 15b, 15c and 15d are formed so as to be parallel to each other. Further, as shown in FIG. 1B, the main surface of each of the plate-shaped protrusions 15 a to 15 d is formed so as to be inclined at a predetermined angle with respect to the plane orthogonal to the valve shaft 2.

Here, if the inclination angle of the plate-like projection 15 is too small, a swirling flow, which will be described later, is less likely to occur,
If it is too large, the resistance at the time of opening the valve (when the fluid moves) becomes high, and it becomes difficult for the fluid to flow especially when the valve is at a high opening degree. According to experiments conducted by the present inventor, when the plate-like protrusions 15 are formed in parallel with each other, good results were obtained when the inclination angle was in the range of 10 to 40 degrees.

As shown in FIG. 1 (a), each plate-shaped projection 15 has a circular outer side (outer edge facing the inner wall) in order to avoid interference with the inner wall of the valve body when the valve body 11 rotates. It has an arc shape. The thickness of each plate-shaped protrusion 15 is the same in the central portion and the outer peripheral portion.

The shape and the like of the plate-like protrusion 15 can be modified variously as described later.

In the valve body 10 having such a structure, when the valve body 11 is rotated in the counterclockwise direction in FIG. 1A from the closed state to open the valve, the inner wall of the valve box and the nozzle of the valve body 11 are opened. Side and the orifice side, a gap is created, and the fluid to which a predetermined pressure is applied from the upstream side moves from the gap to the downstream side.

At this time, even if cavitation bubbles are generated, they collide with the plate-like projections 15 when passing through the valve body 10, and the bubbles are finely decomposed. Further, the fluid passing through the nozzle side of the valve body 11 is directed to the respective plate-shaped projections 15 and the traveling direction thereof is directed upward in FIG. 1B, so that a swirling flow (vortex) is generated on the downstream side. Give rise to. Then, the cavitation bubbles finely decomposed by each plate-like protrusion 15 move on the downstream side while being carried on this swirling flow.

According to the results of experiments conducted by the inventor of the present invention, a swirling flow occurs when the valve opening degree is around 10 degrees, and the swirling flow occurs between 15 degrees and 5 degrees.
The swirl flow appeared most clearly at the valve opening of 0 degree.

Therefore, according to the present embodiment, when cavitation bubbles are generated, not only the conventional effects such as damage to the downstream pipe and noise that are obtained by the decomposition of the bubbles are reduced, The decomposed bubbles are placed on the swirling flow (vortex) generated on the downstream side, so that the bubbles are guided to the center of the pipe, and the bubbles that collide with the inner wall of the pipe are reduced. Is reduced even more effectively.

That is, in the above-mentioned conventional butterfly valve, since the decomposed bubbles flow at a fixed position near the inner wall of the downstream pipe, the downstream pipe should always be impacted at the same place. However, according to the present embodiment, since the decomposed bubbles are guided to the center of the pipe by the swirling flow on the downstream side, the impact on the inner wall of the pipe is reduced. This makes it possible to more effectively reduce the occurrence of damage to the downstream piping.

Further, according to the conventional butterfly valve, since each decomposed bubble flows near the inner wall of the pipe on the downstream side, there is room for improvement in reducing noise transmitted to the outside of the pipe. However, according to the present embodiment, since the decomposed bubbles are guided to the center of the pipe by the swirling flow on the downstream side, the noise transmitted to the outside of the pipe can be more effectively reduced.

Further, according to the present embodiment, the valve body 1
Since the position where the cavitation bubbles pass changes depending on the opening degree of 0 and the flow velocity of the fluid, impact is not applied to a certain position of the pipe, and damage to the downstream pipe can be minimized. Becomes

(Second Embodiment) Next, the second embodiment of the present invention will be described.
The embodiment will be described with reference to FIG. In addition, valve bodies 10A to 10E of the following respective embodiments are different from the valve body 10 of the above-described first embodiment only in the configuration of the plate-shaped protrusions, and the above-mentioned first embodiment is described. The same parts as those of the embodiment are designated by the same reference numerals, and the description thereof will be omitted as appropriate.

The valve body 10A of the second embodiment shown in FIG.
Then, as can be seen by comparing with FIG. 1, in addition to the configuration of the above-described first embodiment, the plate-like protrusions 15 (15e, 15f, 15) are also formed on the orifice side downstream surface 11b of the valve body 11.
g, 15h).

For convenience of description, the plate-like projections formed on the nozzle side upstream surface 11a of the valve body 11 will be generically referred to as a first group of projections, and will be referred to as the orifice side downstream of the valve body 11. The plate-like protrusions formed on the surface 11b are collectively referred to as the second
It is called a group of protrusions.

In the second embodiment, as can be seen from FIG. 2 (b), the second group of protrusions (15e to 15h) is a perspective plane with respect to the first group of protrusions (15a to 15d). It is configured to be formed on the orifice side downstream surface 11b of the valve body 11 so as to be bilaterally symmetrical with respect to the axis of the valve shaft 2 as a reference.

According to the second embodiment having such a structure, the swirl flow is clearly formed also from the orifice side, so that the fluid passing through the orifice side is quickly put on the swirl flow. It is guided to the center of the pipe, and particularly at a high opening degree of the valve, the noise reduction effect can be obtained more than that of the valve body 10 of the first embodiment.

The inventor of the present invention has made the valve body 10 of the second embodiment.
The noise was measured for each of A and the valve body having no plate-like protrusion. The result of this measurement is shown in FIG. In FIG. 7, the vertical axis represents the flow rate characteristic value, the horizontal axis represents the noise level, the characteristics of the valve element 10A are shown by the solid line, and the characteristics of the valve element without the plate-like protrusion are shown by the dotted line.

As shown in FIG. 7, it can be seen that in the valve body 10A having the plate-like protrusions 15, the noise level around the noise peak value is significantly reduced.

(Third Embodiment) FIG. 3 shows a third embodiment of the present invention.

The valve body 10B of the third embodiment shown in FIG.
Then, as can be seen by comparison with FIG. 2, the second projection group (15i to 15i) is formed on the orifice-side downstream surface 11b of the valve body 11.
k) is provided in the same manner as in the second embodiment described above, but as shown in FIG. 3B, the second group of projections is transparent to the first group of projections. A configuration in which the center of the valve body 11 is arranged in a point-symmetrical position on the plane, that is, when the center of the valve body 11 is rotated by 180 degrees, the second group of protrusions (15i
.About.15k) are arranged so that they are located at the same position on the perspective plane as the first group of protrusions (15a to 15d). Even when such an arrangement is adopted, it is the same as the second embodiment. Equivalent effect is expected.

Next, with reference to FIGS. 4 to 6, fourth to sixth embodiments of the valve body will be described. In the following embodiments, an example in which the valve element of a butterfly valve for low opening or low flow rate is mainly described.

In the above-described first to third embodiments,
Each plate-shaped protrusion 15a to 15 constituting one protrusion group
Regarding d, 15e to 15f, and 15g to 15l, the main surfaces on one side are arranged so as to be parallel to each other. However, in the fourth to sixth embodiments, FIG.
As shown in FIG. 6, the main surfaces of the respective plate-like protrusions are arranged so that the distance between them becomes narrower toward the center side (the valve shaft 2 side).

(Fourth Embodiment) That is, the valve body 10C of the fourth embodiment shown in FIG. 4 is similar to the first embodiment, as can be seen by comparison with FIG. 1 (b). Although only the first group of protrusions is provided in the above, the distance between the main surfaces of the plate-like protrusions (15m, 15n, 15o, 15p) becomes narrower toward the center side (as the outer side becomes closer). It becomes wide).

More specifically, in the fourth embodiment, the lowermost plate-like projection 15p has the gentlest inclination angle with respect to the plane orthogonal to the above-mentioned valve shaft (rotating shaft). None, they are arranged so that the inclination angle becomes steeper as the plate-shaped protrusions on the upper side.

With such a structure, the same effects as those of the above-described first structure can be obtained, and it is expected that the swirling flow will be clearly generated even when a low opening is used.

(Fifth Embodiment) FIG. 5 shows a fifth embodiment of the present invention.

A valve body 10D of the fifth embodiment shown in FIG.
Then, as can be seen by comparing with FIG. 4, in addition to the configuration of the above-described fourth embodiment, the plate-like protrusions 15 (15q, 15r, 15) are also formed on the orifice-side downstream surface 11b of the valve body 11.
s, 15t). That is, in the fifth embodiment, as can be seen from FIG. 5B, the second group of protrusions 15q to 15t is the first group of protrusions (15).
(m to 15p), it is formed on the orifice side downstream surface 11b of the valve body 11 so as to be bilaterally symmetrical with respect to the valve shaft 2 (rotating shaft) on a perspective plane.

According to the fifth embodiment having such a structure, the same effect as that of the valve body 10A of the second embodiment described above can be obtained.

(Sixth Embodiment) FIG. 6 shows a sixth embodiment of the present invention.

A valve body 10E of the sixth embodiment shown in FIG.
Then, as in the fifth embodiment described above, the valve body 11
This is similar in that a second group of protrusions is provided on the orifice-side downstream surface 11b, but as can be seen from FIG. 6 (b),
A configuration in which the second group of protrusions (15u, 15v, 15w, 15x) is arranged point-symmetrically with respect to the first group of protrusions (15m to 15p) on the perspective plane, that is, of the valve body 11. The second projection group (15u to 15x) is arranged so as to be at the same position on the perspective plane as the first projection group (15m to 15p) when rotated by 180 degrees with the center as the rotation center. It is composed.

According to the sixth embodiment having such a configuration, the same effect as that of the above-described third embodiment can be obtained.

In each of the above-described embodiments, an example in which the number of plate-like protrusions 15 formed on one surface is four has been described, but the number of plate-like protrusions is not limited to this. However, it can be appropriately changed depending on the pipe diameter, the type of fluid, and the like.

Further, the plate-like protrusions may be arranged so that they are oriented in substantially the same direction so as to generate a swirling flow on the downstream side, and therefore, in addition to the structure in each of the above-described embodiments, Also, for example, the following various modifications are included.

That is, in each of the above-described embodiments, as shown in FIGS. 1 to 6, each plate-like protrusion 15 has a flat plate shape, and its cross-sectional shape extends linearly.
The same effect can be expected when each plate-shaped protrusion 15 is formed in a curved plate shape having a curved cross-sectional shape.

In each of the above-described embodiments, as shown in FIGS. 1 to 6A, the plate-like protrusion 1 is used.
Regarding the outer shape of 5, the central portion is low and the outer peripheral portion is high (there is a depth in the upstream and downstream directions when the valve is closed), but the reverse shape, that is, the central portion is high (there is a depth) The same effect can be expected even with a configuration in which the depth decreases toward the outer peripheral side (no depth).

Furthermore, in each of the above-described embodiments, the thickness of the plate-like protrusion 15 is the same in the central portion and the outer peripheral portion, but the central portion is thickened to the outer peripheral portion. A tapered cross-sectional shape in which the wall thickness gradually decreases as

Further, for example, the plate-like protrusion 15 (15a, 15b, 15c, 15d) of any of the first to third embodiments is provided on the nozzle side upstream surface 11a of the valve body 11 to provide the orifice side. The downstream surface 11b may be configured by appropriately combining the above-described various plate-shaped protrusions such as the configuration in which the plate-shaped protrusions according to any one of the fourth to sixth embodiments are provided, or the reverse configuration. good.

[0056]

As described above, according to the valve body of the butterfly valve of the present invention, the plate-like swirling flow inducing means for generating the swirling flow on the downstream side when the fluid passes is provided. Even when cavitation bubbles are generated when the fluid passes, damage to the downstream pipe can be minimized, and a further improvement effect regarding noise reduction can be obtained.

[Brief description of drawings]

FIG. 1 is a view for explaining a first embodiment of a valve body of a butterfly valve to which the present invention is applied, and is a plan view of the valve body (a).
2B is a rear view of the valve body as seen through from the downstream side of the pipe.

FIG. 2 is a diagram for explaining the second embodiment of the valve body of the butterfly valve, in which FIG. 2 (a) is a plan view of the valve body and FIG. A side view of the valve body is shown in (b) and (c), respectively.

FIG. 3 is a view for explaining the third embodiment of the valve body of the butterfly valve, in which FIG. 3 (a) is a plan view of the valve body and FIG. Each is shown in b).

FIG. 4 is a diagram for explaining a fourth embodiment of the valve body of the butterfly valve, in which FIG. 4 (a) is a plan view of the valve body and FIG. Each is shown in b).

FIG. 5 is a view for explaining the fifth embodiment of the valve body of the butterfly valve, in which FIG. 5 (a) is a plan view of the valve body and FIG. Each is shown in b).

FIG. 6 is a view for explaining the sixth embodiment of the valve body of the butterfly valve, in which FIG. 6 (a) is a plan view of the valve body and FIG. Each is shown in b).

FIG. 7 is a diagram showing an actual measurement result of a difference in noise reduction effect depending on the presence or absence of a plate-like protrusion, and regarding the relationship between a flow rate and noise, the butterfly valve and the plate-like protrusion of the second embodiment are not provided. It is a figure which compares and shows the characteristic with a butterfly valve.

[Explanation of Codes] 2 valve shaft 10 valve bodies 10A to 10E valve body 11 valve body 11a nozzle side upstream surface 11b orifice side downstream surface 12 hub 15 (15a to 15x) plate-like protrusion (swirl flow inducing means)

Claims (7)

[Claims] 1. A valve body of a butterfly valve, which is rotatable about a valve shaft in a valve box, wherein a plate-like swirling flow inducing means for generating a swirling flow on the downstream side when a fluid passes through the valve. It is formed on at least the nozzle side upstream surface of the main body, the swirl flow inducing means extends from the valve shaft side to the valve box inner wall side so that its main surface is inclined with respect to a plane orthogonal to the valve shaft, and A valve body of a butterfly valve, wherein the valve body is formed so as to project from the upstream surface of the valve body toward the upstream side. 2. A plurality of the swirl flow inducing means are formed on a nozzle side upstream surface of the valve body, and main surfaces of the swirl flow inducing means are mutually arranged from the upstream surface to the upstream side of the valve body. The valve element of the butterfly valve according to claim 1, wherein the valve element is formed so as to extend in substantially the same direction. 3. The valve body for a butterfly valve according to claim 2, wherein the swirl flow inducing means are arranged such that their main surfaces are parallel to each other. 4. The swirl flow inducing means is arranged so that an inclination angle of each main surface with respect to a plane orthogonal to the valve axis gradually increases from one end side. The valve body of the butterfly valve. 5. A plurality of the swirl flow inducing means are formed also on the orifice side downstream surface of the valve body, and the main surface of each of the swirl flow inducing means on the orifice side downstream surface is in a plane orthogonal to the valve shaft. The valve element of the butterfly valve according to any one of claims 2 to 4, wherein the valve element is formed so as to be inclined with respect to one another and to extend from the downstream surface toward the downstream side in substantially the same direction as each other. . 6. A swirl flow inducing means on the upstream side of the nozzle,
Each swirl flow inducing means on the downstream surface on the orifice side has a valve shaft (rotating shaft) on a perspective plane with respect to the main surface of the valve body.
The valve element of the butterfly valve according to claim 5, wherein the valve element is arranged so as to be bilaterally symmetric with respect to. 7. Each swirl flow inducing means on the nozzle side upstream surface,
The swirling flow inducing means on the downstream surface on the orifice side is arranged in a point-symmetrical position with the center of the main surface of the valve body as a center of rotation on a perspective plane with respect to the main surface of the valve body. The valve body of the butterfly valve according to item 5.