JPH0571649A - Double-seal type biplane valve - Google Patents

Abstract

PURPOSE:To prolong the service life of sheet packing as well as to reduce the capacity of a driver for a valve element. CONSTITUTION:Two identical valve plates 4, being attached with sheet packing 6b on the outer circumference and installed in parallel with each other in holding a valve stem 2 between, are engaged with respective valve seats 10a, 10b via the sheet packing 6b while two valve plates 4a, 4b of a double-seal type biplane valve, rotating with the valve stem 2 as the center and opening in one direction alone, are constituted in decentering them to linear symmetry centering on the valve stem 2 as making the opening side outward with each other together with respective these valve seats 10a, 10b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-seal type bileaflet valve which is applied when it is necessary to stop the flow from both directions such as a penstock having a branch.

[0002]

2. Description of the Related Art Conventionally, when it is necessary to stop the flow from both directions such as a penstock having a branch, a double seal type bileaflet valve is used. Generally, in a double-seal type bileaflet valve, a valve body formed of a bileaflet valve plate is integrally mounted on a valve shaft that penetrates a casing, and a seat packing is fixed to the outer periphery of the valve plate. Then, by rotating the valve shaft, the valve body rotates to open and close.

[0003]

In the conventional double-seal type bileaflet valve as described above, a rubber sheet is usually used for the seat packing, and a tightening margin of the seat packing of about 1 mm is required. When the valve body is opened and closed, the interference of the seat packing passes while contacting the valve seat of the other valve plate, so that the seat packing is easily damaged and its life is short. Further, the frictional resistance is increased to increase the capacity of the valve body drive device.

[0004]

SUMMARY OF THE INVENTION A double-seal type bileaflet valve according to the present invention is intended to solve the above-mentioned problems. The same two sheets are provided in parallel with each other with a seat packing mounted on the outer periphery and a valve shaft interposed therebetween. In a double-seal type bileaflet valve in which the valve plates engage with the respective valve seats via the seat packing and rotate about the valve shaft to open in only one direction, It is characterized in that the sides to be opened together with the valve seat are eccentric to each other outwardly in line symmetry about the valve shaft.

[0005]

That is, in the double-seal type bileaflet valve according to the present invention, the same two valve plates, which are provided with seat packings on the outer circumference and are arranged in parallel with each other with the valve shaft interposed therebetween, respectively act via the seat packings. Lines centering on the valve shaft outwardly on the sides that open the two valve plates of the double-seal type bileaflet valve that engages with the seat and rotates around the valve shaft and opens in only one direction with the valve seats. When they are opened and closed, when one valve plate passes the valve seat of the other valve plate, the center of the valve seat and the center of the passing valve plate are eccentric in opposite directions. Therefore, there is a gap between the two, and the tightening margin of the seat packing does not contact the valve seat.

[0006]

1 and 2 are structural explanatory views of a double seal type bileaflet valve according to an embodiment of the present invention. In the figure,
The double seal type bileaflet valve according to the present embodiment is used when it is necessary to stop the flow from both directions such as a penstock having a branch, and as shown in the figure, it penetrates the casing 1 having a two-split structure. The valve body 5 formed by the rib 3 and the bileaflet valve plates 4a, 4b is integrally mounted on the valve shaft 2 to be seated, and the seat packings 6a, 6b are attached to the outer peripheries of the valve plates 4a, 4b by the packing presser 7. It is fixed. The valve seats 10a and 10b of the casing 1 with which the seat packings 6a and 6b contact each other are made of stainless steel. Reference numerals 8 and 9
Is a penstock which is connected to the casing 1 via a flange.

When the valve shaft 2 is rotated, the valve body 5 is rotated to open and close. The solid line in FIG. 1 indicates the closed state, and the phantom line indicates the fully opened state. Seat packing 6a, 6
A rubber sheet is used for b, and the sheet packing 6
Approximately 1 mm is required as a tightening margin for a and 6b,
When the seat packings 6a, 6b of the one valve plate 4a, 4b are opened and closed, the valve seat 10 of the other valve plate 4a, 4b is opened and closed.
The center of the valve plate 4a is eccentric by the amount of eccentricity E downward with respect to the center of the valve shaft 2 together with the center of the valve seat 10a so as not to cause a trouble by passing through while contacting a.
Further, the center of the valve plate 4b is eccentric by the eccentric amount E in the upward direction together with the center of the valve seat 10b. Valve seat 10a and valve seat 1
Diagonal connecting the 0b length each R _1, R _2, valve seat 10a, 2G distance between 10b, when the valve bore and _{D, R 1 = [(D} / 2-E) 2 + G 2] 1 ^{/ 2} R ₂ = [(D / 2 + E) ² + G ² ] ^{1/2 From the} above equation, R ₁ <R ₂ , and the valve plate 4 a has the gap R _{2 −} R ₁ at the tip and the valve seat 4 b, and The valve plate 4b is the valve seat 1
0a respectively.

However, when the valve body 5 is fully opened from the fully closed state shown in FIG. 1, the points a, b, c of the valve plates 4a, 4b,
2 is moved on the arc of radius R3 by 90 degrees to reach the state shown in FIG. 2. For example, since the valve plate 4b is eccentric to the center of the valve shaft 2 in the upward direction by the eccentric amount E, it is fully opened. At times, the valve seat 10b is eccentric in the horizontal direction. That is, when the horizontal distances of points a and b in FIG. 2 are L ₁ and L ₂ , respectively, L ₁ = [(D / 2) ² − (GE) ² ] ^1/2 L ₂ = [(D / 2) ² − (G + E) ² ] ^{1/2 From the} above formula, L ₁ > L ₂ , and even if the tightening margin of the seat packing 6b is zero, the tightening margin for the valve seat 10b is L ₁ when fully opened.
-Increase by L ₂ . The same applies to the valve plate 4a.
Therefore, if the valve body 5 has a normal size, the eccentricity E of the respective valve plates 4a and 4b is 0.3 regardless of the valve diameter D.
By restricting the range of mm to 1.5 mm, the valve body 5 can be smoothly fully opened by eliminating the contact of the seat packings 6a and 6b with excessive tightening margins when fully opened. It was possible to confirm it as a result of manufacturing and examining. 1 shows the case where the valve body 5 rotates to the right and fully opens, but when the valve body 5 rotates to the left and fully opens, the valve plates 4a, 4b and the valve seat 10a, 1
The eccentricity amounts E of 0b are reversed.

As described above, the present valve causes the valve plates 4a, 4b together with the respective valve seats 10a, 10b to be eccentric to the center of the valve shaft 2 in the vertical direction by the same eccentric amount E, and the eccentric amount is eccentric. E is 0.3 to 1. regardless of the valve diameter D.
The range is 5 mm, and when the valve body 5 is opened and closed, the valve plates 4a, 4
When the seat packings 6a and 6b of b pass through the valve seats 10a and 10b on the opposite sides, respectively, there is a gap between them and they do not come into contact with each other. Further, when the valve bodies 4a, 4b are fully opened, the seat packings 6a, 6b are tightened by the respective valve seats 10.
Although there are points that increase with respect to a and 10b, the amount of contact of the seat packings 6a and 6b with the valve seats 10a and 10b is minimized when the contact of the excessive tightening margin is eliminated and the valve body 5 is fully opened. It is limited. As a result, the life of the seat packings 6a and 6b can be extended and the capacity of the drive device of the valve body 5 can be reduced, but the sealing effect of the seat packings 6a and 6b when the valve body 5 is fully closed is the same as the conventional one. does not change.

[0010]

The double-seal type bileaflet valve according to the present invention is configured as described above, and the tightening margin of the seat packing of one valve plate does not contact the valve seat of the other valve plate when the valve body is opened and closed. Therefore, the life of each seat packing is extended and the capacity of the valve element driving device is reduced.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a double-seal type bileaflet valve according to an embodiment of the present invention.

FIG. 2 is a view taken along the line II-II in FIG.

[Explanation of symbols]

 1 casing 2 valve shaft 4a, 4b valve plate 5 valve body 6a, 6b seat packing 10a, 10b valve seat E eccentric amount

Claims (1)

[Claims] 1. A seat packing is mounted on the outer periphery, and two identical valve plates, which are provided in parallel with each other with a valve shaft interposed therebetween, engage with respective valve seats through the seat packing and center around the valve shaft. In a double-seal type bileaflet valve that rotates in one direction and opens only in one direction, the two valve plates are opened together with their respective valve seats so that the sides of the two valve plates are eccentrically outwardly oriented in line symmetry about the valve shaft. Double-seal type bileaflet valve characterized by.