JPH0241396Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention relates to the valve body of a butterfly valve, and in particular, the invention is a butterfly valve that prevents uneven pressure distribution applied to the valve body surface at intermediate opening degrees. Regarding the valve body.

(Prior art) A butterfly valve in which a disc-shaped valve body is rotatably supported in a substantially cylindrical main body, and the rotation of the valve body opens and closes the fluid flowing through the pipe and controls the flow rate. is conventionally known and has been put into practical use in a wide range of areas.

By the way, when such a butterfly valve is used as a flow control valve, the valve body is positioned in an inclined state with respect to the flow direction of the fluid at an intermediate opening degree, and acts as a resistance plate against the fluid. As a result, an unbalanced pressure distribution occurs on the surface of the valve body, causing a turning torque 2 in the closing direction to act on the valve body 1 and causing the valve body to vibrate as shown in FIG. Since the presence of rotational torque in the closing direction requires a driving means with a large force, this has been an extremely important issue regarding the selection and design of the driving means, especially for large-diameter butterfly valves. Further, vibration of the valve body may cause damage, loosening, leakage, etc. of the valve.

Therefore, in order to eliminate the occurrence of unbalanced pressure distribution at intermediate opening degrees, various proposals have been made in the past, such as Utility Model Application No. 60-62680, No. 6062681,
It is disclosed in Publication No. 60-64368.

The device disclosed in Japanese Utility Model Application Publication No. 60-62680 forms an air outlet that communicates with the atmosphere at approximately the center of the downstream surface of the valve body, so that the pressure on the downstream surface of the valve body is reduced at intermediate opening degrees. When the pressure drops, atmospheric pressure is introduced to offset the drop in pressure.
In such a structure, a communication hole must be formed in the valve body and the main body to communicate between the air outlet of the valve body and the atmosphere, and the structure is extremely complicated and the communication hole is closed when the valve is closed. Disadvantages included the need for valve means to prevent fluid from leaking through the valve.

The structure disclosed in Japanese Utility Model Application Publication No. 60-62681 has a communication hole that communicates the downstream side and the upstream side formed in the central part of the surface of the valve body, and when the valve is closed, the upstream opening of the communication hole is closed by a plate. However, the mounting structure of the caul plate becomes complicated, and it is difficult to perfect the closing ability of the caul plate, making it impossible to create a completely closed valve.

Utility Model Application Publication No. 60-64368 was previously proposed by the present applicant, in which small holes are opened on both sides of the rotation center axis of the valve body, and these small holes are communicated with each other to form a surface of the valve body. This is intended to offset the unbalanced pressure that occurs in the valve body, but the pressure loss in the communication path that communicates the small holes is larger than that in the flow path that flows on the surface of the valve body.
The effect of pressure offset by the communication passage was small, and it could hardly be expected to eliminate the pressure imbalance.

(Problems to be solved by this invention) This invention aims to solve the above-mentioned drawbacks seen in the conventional ones.It has a simple structure and reliably eliminates unbalanced pressure, and also completely eliminates pressure when the valve is closed. The purpose is to provide a structure that can be closed.

(Means for Solving the Problems) In order to solve the above problems, the means adopted by this invention is to install at least a pair of introduction ports opening at the outer peripheral edge of the valve body 1 at radially symmetrical positions perpendicular to the valve shaft. The other end of the introduction passage 5 facing the upstream side is opened on the downstream surface of the valve body 1, and the other end of the introduction passage 5' facing the downstream side is opened on the upstream surface of the valve body 1. It is characterized by what it did.

(Function) At an intermediate opening degree of the valve body, fluid is guided to the center of the downstream surface of the valve body where the pressure decreases through a communication passage opened at the outer periphery of the valve body where the pressure is high, thereby reducing the pressure drop on the surface of the valve body. prevent. As a result, the pressures on the valve body surfaces on the upstream and downstream sides are substantially balanced. When the valve is closed, one end of the communication passage that opens to the outer periphery of the valve body is closed by a seat ring that is in close contact with the outer periphery of the valve body.

(Effects of the invention) According to this invention, since the pressures on the upstream and downstream surfaces of the valve body are balanced, it is possible to suppress the occurrence of rotational torque and vibration caused by imbalance in the pressure on the valve body surface. I can do it. Furthermore, when the valve is closed, the communication path is closed by the seat ring, so it can be completely closed.

Furthermore, according to this invention, the structure is simple, and there is almost no pressure loss in the pressure introduction path.
This makes it possible to reliably prevent pressure imbalance from being eliminated.

(Embodiment) A preferred embodiment of this invention will be described below with reference to the drawings. In the figure, 1 is a valve body of a butterfly valve, which is rotatably supported within a cylindrical main body 2 by a valve stem 3. A seat ring 4 made of an elastic material such as rubber is attached to the inner peripheral surface of the main body 2, and as shown in FIG. 2, the outer peripheral edge of the valve body 1 is brought into close contact with the seat ring 4 to close the valve. At an intermediate opening degree between the fully closed position and the fully open position in which the valve body 1 is rotated together with the valve stem 3 and positioned parallel to the axial direction of the main body 2, the valve body 1 is As shown in Fig. 1, the valve body 1 is inclined with respect to the axial direction of the body 2, and acts as a resistance plate against the fluid flowing through the body 2. The collision produces an unbalanced pressure distribution as shown in FIG.

Reference numerals 5 and 5' denote pressure introduction passages, and at least one pair is formed at radially symmetrical positions perpendicular to the valve shaft. One ends of the introduction passages 5, 5' are both opened at the outer peripheral edge of the valve body 1, while the other ends of the two introduction passages are opened in a symmetrical direction. That is, when the valve body 1 rotates, the other end of the introduction path 5 toward the upstream side is connected to the valve body 1.
is opened approximately at the center of the downstream surface of the
The other end of the introduction path 5' toward the downstream side is opened at approximately the center of the upstream surface of the valve body 1.

Thus, when the valve body 1 is at the intermediate opening degree, the pressure fluid is guided to the downstream surface via the introduction path 5 toward the upstream side of the valve body 1, thereby preventing a pressure drop on the downstream surface. Similarly, pressure fluid is guided to the upstream surface of the valve body 1 via the introduction path 5' toward the downstream side, thereby preventing a drop in pressure on the surface. As a result, the pressure is almost balanced over the entire surface of the valve body 1, and the generation of rotational torque and vibration is suppressed.

When the valve is closed, the outer periphery of the valve body 1 and the seat ring 4
Since the openings on the outer peripheral edge side of the introduction passages 5 and 5' are closed by the close contact with the introduction passages 5 and 5', complete closure is achieved and there is no risk of fluid leakage.

In the illustrated embodiment, one introduction passage 5, 5' is formed at symmetrical positions, but it goes without saying that a plurality of introduction passages 5, 5' may be formed.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the valve body according to this invention in an intermediate opening state, and FIG. 2 is a cross-sectional view showing the valve body in a fully closed state.
FIG. 3 is a sectional view showing the pressure distribution state in a conventional valve body. 1... Valve body, 2... Main body, 3... Valve stem, 4...
Seat ring, 5...Introduction path.

Claims (1)

[Scope of utility model registration request] At least a pair of introduction passages 5, 5' opening at the outer peripheral edge of the valve body 1 are formed at radially symmetrical positions perpendicular to the valve shaft, and the other end of the introduction passage 5 facing the upstream side is connected to the valve body 1.
A valve body for a butterfly valve, characterized in that the other end of an introduction path 5' directed toward the downstream side is opened at the upstream surface of the valve body 1.