JPH1130340A - Butterfly valve provided with air intake function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent cavitation even if a butterfly valve is used in the throttled operation with a valve element slightly opened or half opened. SOLUTION: This butterfly valve is provided with a plurality of first air intake passages 7 with their outlets 7A, which face the valve box 2 interior, opened on the valve element 1 surface and the passages 7 extending from the outlets 7A to inlets 7B opened on a valve stem fitting part 8, while a valve stem 3 is provided with a second air intake passage composed of a blind pipe hole 10A and cutouts 10B, 10B. As pressure in a contraction part 6 lowers, when the valve element 1 is held at a slightly opened or a half opened mode, and a well known air valve composing an air intake means opens, air is sucked into the valve box 2 through a route of the second air intake passage inlet →the blind pipe hole 10A → cutouts 10B, 10B → the outlet → respective inlets 7B of a plurality of first air intake passages 7 → the outlet 7A, and cavitation is restrained from occurring by preventing pressure from dropping below the vapor pressure of the water temperature at that time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a butterfly valve having an intake function.

[0002]

2. Description of the Related Art As shown in FIGS. 9 and 10, a butterfly valve has an axis C which intersects an axis C1 of a valve box 2 with an axis C1.
The valve body 3 is attached to the valve box 2 so as to be rotatable around its axis together with the valve rod 3, and the rotation of the valve body 1 causes the valve body sheet 4 on the outer peripheral portion of the valve body 1 to rotate. It is configured to open and close by contacting with and separating from the inner valve box sheet 5. The inner surface of the valve box 1 has a uniform circular shape with a uniform inner diameter and extends in the direction of the axis C1.

[0003] In the butterfly valve configured as described above,
When the valve element 1 is rotated in the direction indicated by the solid line arrow from the valve closed position shown by the solid line in FIG.
With the increase of the rotation angle, the distance between the inner surface of the valve box 2 and the rotation trajectory of the outer peripheral portion of the valve body 1, more specifically, the space between the inner surface of the valve box 2 and the rotation trajectory of the valve body sheet 4 increases, The passage cross-sectional area of a fluid (a liquid such as water) is enlarged, and the flow rate can be increased. In addition, when the valve body 1 is rotated in the direction indicated by the broken line from the fully open position indicated by the imaginary line to the valve closed position indicated by the solid line, the inner surface of the valve box 2 and the outer peripheral portion of the valve body 1 (the valve body) The distance between the seat 4) and the rotation trajectory becomes smaller,
The flow cross section of the fluid is reduced to reduce the flow rate, and the flow rate can be set to “0” in the fully closed position. Therefore,
Rotation of the valve element within the range of the flow rate "0" in which the valve element 1 is positioned at the valve closing position indicated by the solid line with the rotation angle of 0 ° and the maximum flow rate positioned at the fully open position indicated by the imaginary line with the rotation angle of 90 ° The flow rate through the pipe can be adjusted according to the angle.

However, as shown in FIG. 11, when the fluid (water) F is passed while the valve body 1 is held at a small opening degree,
In the contraction section 6 in which the cross-sectional area of the passage is reduced, the pressure is reduced by increasing the flow velocity of the water. When the pressure falls below the vapor pressure at the water temperature at that time, the water evaporates or the dissolved air in the water separates to generate bubbles (cavitation), and the bubbles are crushed and disappear on the downstream side where the pressure recovers In addition to generating noise and vibration, cavitation erosion peculiar to the cavitation-exposed portion (the inner surface of the tube wall) occurs when such a state is continued. This applies not only to the use in the throttle operation in which the valve element 1 is held at a small opening degree, but also to the operation in which the valve element 1 is held at an intermediate degree.

[0005]

That is, in the conventional butterfly valve, since noise, vibration or cavitation erosion occurs due to the occurrence of cavitation, the valve body is held at a small opening degree and the throttle is operated at an intermediate degree. Limited use in driving.

Accordingly, the present invention provides a butterfly valve having an intake function capable of preventing cavitation even when used in a throttle operation in which the valve body is held at a small opening or an operation in which the valve body is held at an intermediate degree. It is an object.

[0007]

In order to achieve the above object, the present invention provides a valve element which is fitted and mounted on a valve stem having an axis intersecting the axis of a valve box, and the valve stem and the valve stem are rotated around the axis. A butterfly valve configured to be rotatably housed in a valve box and configured to open and close by rotating so that an outer peripheral portion thereof comes into contact with and separate from an inner surface of the valve box, wherein the valve body has an opening on the surface of the valve body. A first intake passage extending from an outlet facing the inside to an inlet opening to the valve stem fitting portion is provided, and the valve stem has an outlet that communicates with an inlet of the first intake passage when fitted to the valve body. A second intake passage is provided,
An intake unit communicating with the entrance of the second intake passage is provided.

According to the present invention, by holding the valve at a small opening or an intermediate opening and allowing the liquid to pass through, the flow velocity in the contraction section is increased and the pressure is reduced. Means are taken into the valve box through the paths of the second intake passage and the first intake passage, and the pressure can be prevented from becoming lower than the vapor pressure at the water temperature at that time, and the occurrence of cavitation can be suppressed. Since the air bubbles generated by the intake do not disappear on the downstream side, there is no occurrence of noise, vibration, erosion of the inner surface of the tube wall, or the like. On the other hand, when the valve body is held at the fully opened position or at a large opening near the fully opened position, the intake operation of the intake means is stopped, so that the intake into the valve box through the second intake passage and the first intake passage. At the same time, it is possible to prevent the liquid passing through the valve box from leaking from the first intake passage to the outside through the second intake passage.

[0009]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view showing an embodiment of a butterfly valve according to the present invention, and FIG.
It is a line sectional view. The same or corresponding parts as those in the conventional example shown in FIGS. 9 to 11 are denoted by the same reference numerals and described. 1 and 2, a valve rod 3 having an axis C2 intersecting with an axis C1 of the valve box 2 is fitted to and attached to the valve body 1, and the valve rod 2 is rotatable about the axis together with the valve rod 3. The valve body 1 rotates so that the valve body sheet 4 on the outer periphery of the valve body 1 comes into contact with and separates from the valve box sheet 5 on the inner surface of the valve box 2 to open and close. The inner surface of the valve box 1 has a uniform circular shape with a uniform inner diameter and extends in the direction of the axis C1.

As shown in FIGS. 2 and 3, the valve element 1 has an outlet 7A facing the inside of the valve box 2 on its surface.
A plurality of first air intake passages 7, 7,... Extending from the outlet 7A to an inlet 7B opening to the valve rod fitting portion 8 are provided. It is provided in. Therefore, the valve stem fitting portion 8 communicates with the inside of the valve box 2 through the plurality of first intake passages 7, 7,....

One axial end of the valve stem 3 is liquid-tight and has an axis C
The output shaft of the opening and closing device (both not shown) is rotatably connected to the protruding portion 3X via a coupling 9 so as to freely rotate around one side of the valve box 2. The other end of the valve stem 3 in the axial direction protrudes outside the other side of the valve box 2 so as to be liquid-tight and rotatable around the axis C2, and an intake means described later is attached to the protruding portion 3Y.

On the other hand, as is apparent from FIGS.
The valve stem 3 is formed with a blind through-hole 10A extending on the axis C2 from the outer end surface of the other-side protrusion 3Y toward one end in the axial direction, and from the blind through-hole 10A toward the outer periphery of the valve stem 3. Notches 10B, 10B extending radially on both sides are provided, and the blind intake hole 10A and the notches 10B, 10B define the second intake passage 10B.
When the valve stem 3 is fitted into the valve stem fitting portion 8 of the valve body 1, the notches 10 </ b> B, 10 </ b> B are provided with a plurality of first intake passages 7, 7 provided in the valve body 1. It leads to the entrance 7B of .... That is, the notches 10B, 10B function as the outlet 10b of the second intake passage 10.

On the other hand, as shown in FIG.
An intake means 11 formed by an air valve is provided in communication with the inlet 10a.

In the above configuration, when the valve element 1 is rotated in the direction indicated by the solid line arrow from the valve closed position shown by the solid line to the fully open position shown by the imaginary line in FIG. The spacing between the inner surface of the valve body 1 and the rotation trajectory of the outer peripheral portion of the valve body 1, more specifically, the spacing between the inner surface of the valve box 2 and the rotation trajectory of the valve body sheet 4 is increased, and the cross-sectional area of water passage is increased to reduce the flow rate. Can be increased. In addition, when the valve body 1 is rotated in the direction indicated by the broken line from the fully open position indicated by the imaginary line to the valve closed position indicated by the solid line, the inner surface of the valve box 2 and the outer peripheral portion of the valve body 1 (the valve body) The space between the seat and the rotation locus of the seat 4) is reduced, the cross-sectional area of the passage of the fluid is reduced, the flow rate is reduced, and the flow rate can be set to "0" in the fully closed position. Therefore, the valve body 1 is moved from the state of the flow rate “0” where the valve body 1 is positioned at the valve closed position indicated by the solid line with the rotation angle of 0 ° to the maximum flow rate positioned at the fully open position indicated by the virtual line with the rotation angle of 90 °. Can be adjusted according to the rotation angle of the pipe.

On the other hand, with the valve element 1 held at a small opening indicated by a solid line or an intermediate opening indicated by an imaginary line in FIG.
When F passes through, the flow velocity of the water in the contraction section 6 having a reduced passage cross-sectional area increases, and the pressure decreases. Along with this pressure drop, a well-known air valve constituting the intake means 11 is opened, and the inlet 10a of the second intake passage 10 → the blind hole 10A → the notches 10B, 10B → the outlets 10b → the plurality of outlets. 1 intake passage 7, 7, ... each inlet 7B → outlet 7A
The intake path is sucked into the valve box 2 through the path, and the pressure can be prevented from becoming lower than the vapor pressure at the water temperature at that time, and the occurrence of cavitation can be suppressed. In addition, since the air bubbles generated by the intake air do not disappear on the downstream side, there is no occurrence of noise, vibration, erosion of the inner surface of the tube wall, or the like. When the valve body 1 is held at the fully open position indicated by the imaginary line in FIG.
Since the well-known air valve constituting the valve 1 is closed, the suction operation of the suction means 11 can be stopped and the water passing through the valve box 1 can be prevented from leaking to the outside.

In the above embodiment, the solid valve body 1 is provided with a plurality of first intake passages 7, 7,... Extending from the outlet 7A to the inlet 7B opened to the valve rod fitting portion 8. The rod 3 is provided with a second intake passage 10 composed of a blind through hole 10A and cutouts 10B, 10B. As shown in FIG. 8, a hollow valve body 1 having a hollow portion 1A is used. A plurality of communication holes 1B, 1B,... Which penetrate the hollow portion 1A and the outer peripheral portion of the hollow valve body 1 and communicate the hollow portion 1A and the inside of the valve box 2 constitute a first intake passage 7. Even if the valve stem 3 is divided into one valve stem 3A and the other valve stem 3B, the second intake passage 10 is constituted by an intake passage provided through the other valve stem 3B in the direction of the axis C2. Operation and effect similar to those of the above-described embodiment.
The effect can be achieved. Function as

[0017]

As described above, the present invention can suppress the occurrence of cavitation even when used in a throttle operation in which the valve body is maintained at a small opening degree or an operation in which the valve body is maintained at an intermediate degree. Therefore, noise, vibration, erosion of the inner surface of the tube wall, and the like do not occur. That is, even if the valve body is used in an operation in which the valve body is held at a small opening degree or an intermediate opening degree, no inconvenience occurs.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of a butterfly valve according to the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a front view showing an embodiment of a valve body and a valve stem.

FIG. 4 is a view taken in the direction of arrows BB in FIG. 3;

FIG. 5 is a sectional view taken along line CC of FIG. 3;

FIG. 6 is a partial cross-sectional view showing a relationship between a second intake passage and intake means.

FIG. 7 is an explanatory diagram showing a state in which the butterfly valve of the present invention is held at a small opening and an intermediate opening.

FIG. 8 is a cross-sectional view showing another embodiment of the present invention.

FIG. 9 is a front view of a conventional example.

FIG. 10 is a sectional view taken along line DD of FIG. 9;

FIG. 11 is an explanatory view showing a state in which a conventional butterfly valve is held at a small opening.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 valve body 2 valve box 3 valve stem 7 first intake passage 7A exit of first intake passage 7B entrance of first intake passage 8 valve stem fitting portion 10 second intake passage 10a entrance of second intake passage 10b second intake Exit of passage 11 Air valve (intake means) C1 Axis of valve box C2 Axis of valve stem

Claims (1)

[Claims] A valve body is fitted and mounted on a valve stem having an axis intersecting with the axis of the valve box, and is housed in the valve box so as to be rotatable around the axis together with the valve stem. In a butterfly valve configured to open and close by contacting and separating from an inner surface of a valve box, from an outlet facing the inside of a valve box opened to a surface of the valve body to the valve body, to an inlet opening to the valve rod fitting portion. A first intake passage extending is provided, and the valve stem is provided with a second intake passage having an outlet that communicates with an inlet of the first intake passage when fitted to the valve body.
A butterfly valve having an intake function, wherein an intake means communicating with an inlet of the second intake passage is provided.