JPS6212425B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a valve body for a butterfly-shaped valve, particularly a valve disc for a butterfly-shaped valve having two valve plates, when the butterfly-shaped valve is opened to a small opening. The present invention relates to a valve body for a fold-away valve that is designed to alleviate the fluid ejection that occurs in the valve and prevent damage to the seat ring.

Conventionally, when a valve body with two parallel valve plates is opened to a small opening degree (5 to 10 degrees), both valve plates have the same opening degree, so a flow path is created between them and the seat ring. is formed, and the fluid passes through this channel. At this time, the fluid passes through a narrow channel, so the flow rate increases rapidly and the pressure drops, causing a so-called flushing phenomenon (self-evaporation phenomenon), which can damage the seat ring made of elastic material such as rubber. be. In order to prevent such damage, it is possible to use a rigid seat ring made of tetrafluoroethylene or metal, which is relatively hard to damage, but it is said that this would not be able to obtain the perfect shutoff force due to lack of elasticity. There was a problem.

This is due to the fact that both valve plates simultaneously form a small opening with the same area and that the characteristics of the seat ring material cannot be utilized.

This invention was made in order to solve the problems seen in such conventional ones, and when the valve body consisting of two valve plates is opened to a small opening, the fluid is not ejected. The technical challenge is to prevent damage to the seat ring by making the most of the properties of the seat ring material.

The technical means of the present invention, designed to solve such technical problems, consists of two
The valve body is composed of two valve plates, and the upstream valve plate is slightly inclined with respect to the downstream valve plate, the upstream valve seat is a rigid seat ring, and the downstream valve plate is made of elastic material. It was decided to use a seat ring.

The above technical means works as follows. When the downstream valve plate is in the closed state, the upstream valve plate is slightly inclined with respect to the downstream valve plate, so a slight flow path is formed between it and the rigid seat ring, and from this flow path Fluid is allowed to enter in a downstream direction. However, since the downstream valve plate is in the closed state as described above, the fluid that has entered is stopped almost simultaneously and no jet flow is generated.

Next, the valve stem rotates and the downstream valve plate moves by, for example, 5%.
When in the open position (opening area ratio: 100% fully open, 0% fully closed), the upstream valve plate is fully closed, so no fluid flows and no jet phenomenon occurs.

Further, when the valve body is rotated by the valve stem, a portion of the periphery of the upstream and downstream valve plates is largely separated from the seat ring, and the main flow of fluid flows through the inside of the valve body, so there is no risk of a jet phenomenon. In addition, while the downstream valve plate shifts from the closed position to the 5% open position, there is a period when both the upstream and downstream valve plates are open, but in this state, the degree of opening is small, and Since the flow of fluid is restricted by the upstream valve plate, the flow rate is small and there is no risk of causing a flushing phenomenon.

The present invention has the following unique effects.

When the downstream valve plate is in the closed position, the upstream valve plate is tilted open to a small opening, so when the valve body begins to rotate in the opening direction, the upstream valve plate will open slightly. becomes the closed position, that is, the cross point of the opening curve, but after passing the cross point, the downstream valve plate opening becomes larger by the inclination angle than the upstream valve plate opening (see FIG. 4). Therefore, after the cross point, regardless of the valve body opening, the downstream valve plate opening relative to the upstream valve plate opening always forms a flow path that widens by the inclination angle (for example, in Fig. 4, When the downstream valve plate opening is 45°, the upstream valve plate opening is 40°.)
Therefore, the jet phenomenon can be reliably prevented.

Next, a specific example of the above technical means will be explained with reference to the drawings. FIG. 1 shows the fully closed state of the chimney-shaped valve of the present invention, in which the valve plate 1 includes a downstream valve plate 10, an upstream valve plate 11, and support members 12, 13, 14 that support both valve plates 10, 11. A valve stem 15 is fixed to a central support member 13. The downstream valve plate 10 is in pressure contact with an elastic seat ring 4 made of rubber or the like that is fitted into the main body 2 and fixed with a seat retainer 3.

The upstream valve plate 11 is slightly inclined with respect to the downstream valve plate 10, for example, by 3 to 5 degrees. The drawing shows the upstream valve plate 11 inclined at 5°. The upstream valve plate 11 is in pressure contact with a rigid seat ring 6 that is fixed by a seat retainer 5 fitted into the main body 2 and has a lower elasticity than rubber such as tetrafluoroethylene or metal.

In the fully closed state, the entire circumference of the downstream valve plate 10 is in pressure contact with the elastic seat ring 4;
The upstream valve plate 11 forms a slight flow path between it and the rigid seat ring 6 at a part of its periphery. Therefore, fluid from upstream passes through the channel and heads downstream, but since the downstream valve plate 10 is in a fully closed state, the fluid in the pipeline is blocked and the fluid energy disappears. No jet phenomenon occurs.

Next, as shown in FIG.
When the valve plate 11 is rotated clockwise by 5 degrees, the upstream valve plate 11 comes into pressure contact with the rigid seat ring 6 on its entire circumferential surface, and the downstream valve plate 10 forms a small flow path in a portion thereof. Since the pressurized state of the upstream valve plate 11 is a rigid seat ring when the fluid is at high temperature and high pressure, a small amount of fluid may leak, but since no flow path is formed, a jet state will not occur. do not have.

When the valve body 1 is further rotated clockwise to open 30 degrees as shown in Fig. 3, the fluid flows through the upstream valve plate 1.
1 and the downstream valve plate 10 to freely pass through the valve body space 16 and flow downstream. The valve body space 16 is the fourth
As shown in the figure, since a flow path is formed that widens by the angle of inclination of the upstream valve plate 11, there is no risk of a jet phenomenon occurring.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a partial cross section of a butterfly valve according to the present invention, and FIG.
Figure 3 is a diagram similar to the one shown in Figure 1, showing the 30° open position.
FIG. 4, which is similar to the figure, is a diagram showing the relationship between the opening area ratio of the downstream valve plate and the upstream valve plate and the valve body angle. 1... Valve plate, 2... Main body, 3... Seat retainer, 4
...Elastic seat ring, 5... Seat retainer, 6...
Rigid seat ring, 10...downstream valve plate, 11...upstream valve plate, 12, 13, 14...support member, 15...
Valve stem, 16...valve body space.

Claims (1)

[Claims] 1 The valve body is composed of two valve plates located on the upstream side and the downstream side, and the upstream valve plate is slightly inclined with respect to the downstream valve plate, and the upstream valve seat is made of a rigid sheet. What is claimed is: 1. A valve body for a chimney-shaped valve, characterized in that the downstream valve seat is an elastic seat ring.