JP3090587B2 - Seal structure of butterfly valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seal structure for a butterfly valve, and more particularly to a seal structure for a seat ring mounted on an inner surface of a main body (valve main body).

[0002]

Conventional butterfly valves (centered butterfly valve), as shown in FIG. 5 (a) showing a right-angled cross-section to the flow, the inner peripheral surface of the main body 1, the elastic seat ring 2 such as an elastomer The two side edges 2a shown in FIG. 3B are bent outward at right angles, and the bent portions are fitted into annular grooves (not shown) formed on both side surfaces of the main body. in the contact pressure on the inner surface of the seat ring 2, the valve element 3 is mounted is supported by the valve rod 4. In FIG. 3A, the valve element 3 shows a fully closed state, and the two-dot chain line shows a fully opened state.

The outer peripheral surface of the seat ring 2 which is in contact with the inner peripheral surface of the main body 1 in the vicinity of the portion where the valve stem 4 penetrates the elastic seat ring 2 is arranged so as to surround the valve stem 4. A secondary seal ring 5 made of a hard material such as metal or resin is fitted and mounted in a groove 2 b formed concentrically with the peripheral surface of the valve body 3, and is constantly pressed by the peripheral surface of the valve body 3. The seat ring 2 near the fitting portion with the valve stem peripheral surface is pressed radially inward from the outside to prevent leakage of fluid from the fitting portion with the valve stem 4. I have. The secondary seat ring 5 is normally formed in an annular shape as shown in FIG. 6, but may be a regular square or the like that surrounds the valve stem concentrically.

[0004]

In the seat ring 2 of the conventional butterfly valve described above, the seat ring 2 fitted into the groove 2b on the outer peripheral surface of the seat ring 2 near the through portion of the valve rod 4 is provided.
By: a seal ring 5 presses the seat ring portion (corresponding to portion B of FIG. 2 (a).) Located radially inwardly of the second seal ring 5.

[0005] FIG. 2 (a), shows the compression ratio distribution of the seat ring 2 based on a press of the second seal ring 5, the left half for the line Z-Z, shows a conventional example.
In the left half of the figure, A shows two parts (area) of the seat ring excluding the vicinity of the valve stem penetrating part in the valve body fully closed state,
X indicates a fitting portion (area) of the secondary seal ring 5 and B
Is a radially inner portion (region) of the secondary seal ring X.
E indicates a gap (region) between the secondary seal ring X and the valve stem 4.

FIG. 4 shows the above-mentioned A, B, and X by taking the compression ratio (%) on the vertical axis and the distance from the valve stem peripheral surface on the horizontal axis.
FIGS. 4A and 4B show changes in the compression ratio of the seat ring in each of the regions E and E. As can be seen from these figures (FIGS. 2 and 4 ), in the conventional secondary seal ring X, the portion B is excessively compressed. It had been. This is because a leak (leakage) when the butterfly valve is fully closed occurred on the seat surface by 90% or more. Conventionally, the compression ratio of the portion B is 20% to 40%,
The compression ratio of the portion A is about 10%, and the poor balance of the compression ratios of these two portions causes a reduced portion of the compression ratio as shown in the portion A in the figure, thereby lowering the sealing pressure on the seat surface. Figure 4
However, there is a problem that the life is shortened due to excessive compression of the portion B.

Further, at present, the durability test of the butterfly valve is specified in JIS B 2032 as 10,000 times, but at the end of the durability test, only the B portion of the seat ring is greatly worn, and the durability is deteriorated. It was the first element to make. This is one of the causes of the fact that the portion B is always in contact even when the valve element is opened and closed, but it has been found that the largest cause is due to excessive compression of the portion B.

[0008] On the other hand, the shape of a conventional secondary seal ring 5 (X) is, since a circular shape or a positive square symmetrical shape, such as shown in FIG. 6, to eliminate mounting errors to the seat ring 2 However, there is a problem that it has to be dealt with by casting or bonding to a seat ring.

The present invention solves the above-mentioned problems of the prior art and improves the sealing pressure of the seating surface of the seat ring near the valve stem penetration portion when the valve element is fully closed, and also improves the durability of the seat ring. It is an object of the present invention to provide a butterfly valve seal structure that does not cause mounting errors.

[0010]

In order to achieve the above object, according to the first aspect of the present invention, a secondary seal ring is fitted from the inner peripheral surface side of the main body to the vicinity of a valve rod penetration portion of a seat ring of a butterfly valve. In the seal structure of the butterfly valve, the cross-sectional shape including the center line of the valve stem of the secondary seal ring has a constant compression ratio at a portion near the valve stem peripheral surface.
And a part connected to the shape of the valve
It has a laterally extending portion whose thickness is gradually reduced so as to gradually change the compression ratio.

Further, the invention of claim 2 is characterized in that the sectional shape of the secondary seal ring including the center line of the valve stem has an outer surface conforming to the shape of the inner peripheral surface of the main body.

Further, the invention of claim 3 is characterized in that the upper, lower, left and right shapes of the secondary seal ring are different from each other.

[0013]

The present invention is configured as described above.
According to the first aspect of the invention, the following operation is provided. That is, all
Seat phosphorus in the vicinity of the valve stem through hole when closed
The compression ratio of the tag can be kept constant.
Since the excessive compression occurring in the part is eliminated,
Wear can be prevented, durability is increased, and the compression ratio from the vicinity of the valve stem through hole gradually changes as the distance from the valve stem peripheral surface increases, so that the sealing pressure on the seat surface is improved. As a result, the compression ratio is reduced as in the case of the conventional example (FIG. 4).
Does not occur to parts, because the sealing force of the seat surface be lowered compression ratio of the valve stem circumference vicinity is maintained, the durability is increased, it is possible to extend the life.

[0014] According to the second aspect of the invention, since the outer surface of the secondary seal ring is formed in accordance with the shape of the inner circumferential surface body, the valve body in the valve stem through hole near the vicinity of the fully closed Can stabilize the compression ratio of the seat ring, and further promote the operation of the above-described claim 1.

According to the third aspect of the present invention, since the secondary seal ring has an asymmetric shape in which the upper, lower, left and right shapes are different from each other, mounting errors during valve assembly can be eliminated.

[0016]

Next, an embodiment of the present invention will be described with reference to the drawings. 1, the secondary seal ring of the present invention showing one embodiment of mounting the seat ring, a fragmentary cross-sectional view of a right angle to the flow, in the figure, the same reference numerals as described in Figure 5 are the same Or similar parts.

In the figure, an elastic seat ring 2 is fixed to an inner peripheral surface of a main body 1 by bending both side edges 2a outward at right angles to fit into annular grooves (not shown) formed on both side surfaces of the main body 1. 5 is the same as that of the conventional example (FIG. 5 ), but in the present embodiment (the present invention), the secondary ring is attached to the outer peripheral surface of the seat ring 2 which is in contact with the inner peripheral surface of the main body 1. The shape of the seal ring 15 is
5 , 6 ). That is, the secondary seal ring 15 in the present embodiment is made of a hard material such as metal or resin, and has a cross-sectional shape including the center line of the valve stem 4 (the shape shown in FIG. 1A). In order to keep the compression ratio of the surface constant, a portion 15a close to the valve rod peripheral surface formed in accordance with the peripheral surface shape of the valve body 3, and connected to the portion 15a, gradually reduce the compression ratio of the seat surface. In order to change, a radially inner surface composed of an inclined sideways extending portion 15b and a radially outer surface 15c adapted to the shape of the inner peripheral surface of the valve body 1 to stabilize the compressibility. Is formed.

As shown in FIG. 1B when the seat ring 2 is viewed from the outer peripheral surface, the secondary seal ring 15 is
The direction of flow, that is, the direction of the pipe axis (vertical direction in Fig. (B))
The width is gradually reduced.

According to this embodiment, as shown in the right half of the ZZ line in FIG. 2 showing the compression ratio distribution of the seat ring, the Y portion (region) corresponding to the above-mentioned secondary seal ring 15
A seat ring portion (region) C which comes into contact with a portion 15a (FIG. 1A) of the inner surface of the inner surface close to the valve stem peripheral surface;
inclined against the a contact with the seat ring portion (region) D in the portion 15b extending laterally, subject to gradual change in the compression ratio as shown in FIG. In FIG. 3 , E
Part (region) and part A (region), E portion in FIG. 4 and A
No change from the part, each secondary seal ring Y (15)
3 shows a gap between the valve stem 4 and a peripheral surface of the valve stem 4 and a seat ring 2 part separated from the valve stem.

As shown in FIG. 3 , the compression ratio of the seat ring in the vicinity of the valve stem penetrating portion increases sharply by approximately 10% from the portion E, which maintains a substantially constant value (10%), to the portion C, and at the portion C, After maintaining a substantially constant value (20%), the value gradually decreases in the portion D, and the portion A keeps the constant value (10%) again, whereby the portion B in the conventional example (FIG. 4 ) is obtained. Is avoided, the sealing pressure on the seat surface is improved, and the compression ratio from the portion C to the portion A gradually changes. Therefore, even if the compression ratio of the portion C is reduced, the sealing force of the seat surface is maintained, the durability is increased, and the life is prolonged.

In the embodiment shown in FIG. 1, the secondary seal ring of the present invention has an asymmetrical shape on the upper and lower surfaces, which are the inner surface and the outer surface, at the time of mounting. A mistake in mounting the secondary seal ring upside down can be prevented, and the shape of the secondary seal ring shown in the plan view (FIG. 1B) is asymmetrical on the horizontal axis and the vertical axis. Therefore, when assembling the valve, when attaching the secondary seal ring to the seat ring with the same direction as the peripheral surface of the valve body in the fully closed state (work), the left and right directions are rotated 90 ° to open. It is also possible to prevent mistakes such as mounting by mistake in the direction.

The radius of the above-mentioned secondary seal ring is
The inner peripheral surface is formed approximately as a flat surface, and the outer peripheral surface is
Secondary seal ring
1 has an approximate shape that is easy to process, and
Approximate actions similar to the examples can be performed.

[0023]

As described above, according to the present invention,
According to the first aspect of the present invention, in the seal structure of a butterfly valve, a secondary seal ring is fitted near the valve stem penetration portion of the seat ring of the butterfly valve from the inner peripheral surface side of the main body. The cross-sectional shape including the center line of the valve stem of the ring keeps the compression ratio constant near the valve stem peripheral surface.
Connected to the valve body shape so that
It is With the arrangements so as to have a portion extending laterally to gradually decrease the thickness so as to gradually change the compression ratio, fully closed
Ring near the periphery of the valve stem through hole during operation
Can be kept constant, and also prevents excessive compression of the seat ring by the valve element in the vicinity of the valve stem through hole when fully closed, and reduces the compression ratio from around the valve stem through hole. Since it can be gradually changed as the distance from the valve stem peripheral surface increases, the compression as shown in FIG.
No decrease in the rate occurs, and the sealing pressure on the seating surface can be improved, so even if the compression ratio near the valve stem peripheral surface is reduced, the sealing force on the seating surface is maintained, increasing durability. ,
Life can be extended.

Further, in the invention of claim 2 , the above-mentioned 2
Since the cross-sectional shape including the center line of the valve stem of the next seal ring is configured to have an outer surface adapted to the shape of the inner peripheral surface of the main body, the seat by the valve element in the vicinity of the valve stem through hole when fully closed. Since the compression ratio of the ring can be stabilized, the effect of the above-mentioned claim 1 can be further promoted, and the compression ratio can be made completely the same from a portion close to a portion close to the valve stem peripheral surface. Become.

Further, in the invention of claim 3 , the above-mentioned 2
Since the upper and lower, left and right shapes of the next seal ring are formed differently, it is possible to eliminate troubles caused by improper assembly during valve assembly.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view of an essential part perpendicular to the flow of a butterfly valve having a secondary seal ring mounted on a seat ring according to an embodiment of the present invention, and FIG. It is the principal part top view seen from the side (back surface).

FIG. 2 is a diagram showing a compression ratio distribution of a seat ring, and (a)
Is a cross-sectional view at right angles to the flow, (b) is a plan view of a main part viewed from the back surface of the seat ring, and the left half of the ZZ line shows the conventional shape and the right half shows the present shape.

FIG. 3 is an explanatory diagram showing a change in compression ratio of the seat ring of the present invention.

FIG. 4 is an explanatory diagram showing a change in compression ratio of a seat ring in a conventional example.

FIG. 5A is a cross-sectional view of a main part perpendicular to the flow of a butterfly valve having a secondary seal ring mounted on a seat ring, showing a conventional example, and FIG. 5B is a plan view of the main part viewed from the back surface of the seat ring part. is there.

6 (a) of the secondary seal ring in the prior art is a plan view, (b) is _X 7 -X ₇ line cross-sectional view of (a), (c)
Is _Y 7 -Y ₇ line cross-sectional view of (a).

[Explanation of symbols]

1 body 2 seat ring 3 the valve body 4 stem 1 5 secondary seal ring

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-50-74817 (JP, A) JP-A-57-164359 (JP, U) JP-A-57-179658 (JP, U) 18296 (JP, B2) (58) Field surveyed (Int. Cl. ⁷ , DB name) F16K 1/16-1/226

Claims (3)

(57) [Claims] 1. A butterfly valve seal structure in which a secondary seal ring is fitted and mounted from the inner peripheral surface side of a main body in the vicinity of a valve stem penetrating portion of a seat ring of a butterfly valve. The cross-sectional shape including the centerline of the rod should maintain a constant compression ratio near the valve rod peripheral surface.
A butterfly valve seal structure , comprising: a portion adapted to the shape of a valve body; and a portion extending to the side connected to the portion and having a thickness gradually reduced so as to gradually change a compression ratio. 2. A butterfly valve seal structure in which a secondary seal ring is fitted and mounted in the vicinity of a valve stem penetrating portion of a seat ring of a butterfly valve from an inner peripheral surface side of a main body. seal structure of claim 1 Symbol placement butterfly valve, characterized in that the cross section including the center line of the rod has an outer surface matching the shape of the inner circumferential surface body. 3. A butterfly valve seal structure in which a secondary seal ring is fitted and mounted from the inner peripheral surface side of the main body in the vicinity of a valve stem penetrating portion of a seat ring of the butterfly valve. The butterfly valve seal structure according to claim 1 or 2, wherein the left and right shapes are different from each other.