JP3567111B2 - Butterfly valve seat ring - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention is an industrial butterfly valve used by being attached to a pipe flange for completely closing a fluid such as water, air and steam of 0 to 2 MPa, wherein the inner surface of the valve body and the flange connection surface are made of rubber. The rubber covered is a butterfly valve fitted with a sealing seat ring which also serves as a flange seal and a valve seat seal.
[0002]
[Prior art]
The conventional butterfly valve described above has a structure in which a rotating disk-shaped valve element cuts into a rubber sheet and seals the valve element. The force which stops the rotation of the body works.
[0003]
In order to mitigate the above-mentioned phenomenon, a device described in Japanese Utility Model Publication No. 52-30600 developed by the present applicant is mounted on the inner surface of a main body (valve main body) 1 as shown in FIG. A seat ring having a bulged peak with a radius r on the inner diameter side of the seat ring 2 was devised. This is to inflate only the portion where the valve element 3 comes into contact and seal, and when the valve element 3 is opened, it comes off quickly to reduce torque and at the same time improve durability.
[0004]
Here, the inner diameter φD0, the peak radius r, the peak height e, and the flat portion inner diameter φD1 at the base are always constant. For this reason, die machining can be performed with a general-purpose lathe, and the workability is good, but the peak height e is constant and the rubber rigidity is the same, so the contact area between the valve element and the seat ring is large, and the valve stem that increases the friction force In the vicinity of the (valve stem hole 5), the rubber tends to move, so that there is a problem that the sealing performance is reduced in this portion.
[0005]
FIG. 3A is a front view of the above, and the valve element is omitted. Both of the inner diameters φD0 and φD1 indicate a perfect circular shape.
FIG. 2B is a cross-sectional view of the vicinity of the valve blade. In this vicinity, since the turning radius of the valve body is the largest and the moment is long, the friction between the seat ring and the valve body has the greatest influence on the valve stem torque. (Valve torque = frictional force between seat ring and valve body × rotation radius) FIG. 3C is a cross-sectional view nearer to the valve stem than FIG. In this vicinity, the radius of rotation of the valve element is smaller than that in FIG.
FIG. 4D is a diagram in which an annular seat ring is developed on a straight line.
[0006]
Similarly, in the invention described in Japanese Patent Publication No. 58-25911 according to the present applicant's invention, the above features are further advanced, and as shown in FIG. The contact and detachment with the valve body 3 are simultaneously generated over the entire circumference to improve torque and durability.
[0007]
Here, there is a bulge on the inner diameter side, and the radius r of the ridge changes, and the radius r of the ridge becomes smaller as the ridge is closer to the valve stem. As a result, the contact between the valve body and the seat ring is intended to occur simultaneously in the vicinity of the valve stem and in the circumferential direction, but since the peak radius r cannot be made zero, simultaneous contact cannot be realized in the vicinity of the valve stem. There are also sites.
[0008]
Since the peak radius r changes, die machining of the seat ring cannot be performed by a general-purpose lathe or a numerically controlled lathe. Since manual work is required, it is difficult to maintain accuracy and the processing cost is also increased.
[0009]
In addition, since the peak height e is constant and the rubber rigidity is the same, the contact area between the valve body 3 and the seat ring 2 is large, and the rubber is easily moved in the vicinity of the valve stem where the frictional force increases, and the sealing property is obtained in this portion. However, there is a problem in that
[0010]
FIG. 3A is a front view of the above, and the valve element is omitted. This shows that both the inner diameters φD0 and φD1 are perfectly circular.
FIG. 2B is a cross-sectional view of the vicinity of the valve blade. In this vicinity, since the turning radius of the valve body is the largest and the moment is long, the friction between the seat ring and the valve body has the greatest influence on the valve stem torque. (Valve torque = frictional force between seat ring and valve body × rotation radius) FIG. 3C is a cross-sectional view nearer to the valve stem than FIG. In this vicinity, the radius of rotation of the valve element is smaller than that in FIG.
Further, since the peak radius r is smaller and the height e is the same as in FIG. 6B, the rigidity against the movement of rubber due to the rotation of the valve body is smaller.
FIG. 4D is a diagram in which an annular seat ring is developed on a straight line.
[0011]
[Problems to be solved by the invention]
The above-mentioned conventional ones (FIGS. 2 and 3) reduce the torque and improve the durability, and the butterfly valve has been widely used in the industrial world. With the change in (requirement), the following drawbacks have become problematic.
[0012]
1) Since the valve element seals when fully closed, the valve element operates while rubbing against the seat ring. However, the rubber movement of the seat ring made of an elastic body such as rubber occurs as the valve element moves.
[0013]
2) The movement of the rubber is necessary to suppress the torque, but it is necessary to suppress the movement amount to a certain amount in order to reduce the sealing performance.
[0014]
3) Also, when the contact with the valve body is close to the valve stem and that of the valve blade portion farthest from the valve stem, the valve blade portion has a higher peripheral speed of the valve body but a smaller contact area (fully closed). From 3 to 10 degrees open, and the edge of the valve element is narrow), but as it approaches the vicinity of the valve stem, the peripheral speed decreases and the contact area increases. Always in contact.
[0015]
4) Here, in the case of the mountain-height structure as shown in FIG. 2, if the torque and the seating property are designed to be balanced at the valve blade portion with a small contact amount, the increase in the contact area near the valve stem with the large contact amount causes friction. Therefore, there is a risk that the moving amount becomes large and the sealing performance is impaired.
[0016]
5) Also, in FIG. 3, the contact opening between the valve body and the seat ring is intended to be simultaneously generated in the circumferential direction and the valve stem direction, and the contact amount should be the same over the entire circumference. To achieve true simultaneous contact, the peak width near the valve stem is close to zero, but this cannot be achieved, so the peak width is maintained to some extent. For this reason, simultaneous contact cannot be realized in a certain portion, and a portion having a large amount of contact still occurs. Furthermore, the width of the mountain becomes narrower (the radius of the mountain r becomes smaller) as it approaches the valve stem, which creates a situation in which rubber movement is likely to occur.
[0017]
In other words, in each case, there is a disadvantage that the movement of the rubber is large in the vicinity of the valve stem (FIGS. 2 (c) and 3 (c)), and this portion tends to leak under high pressure. Further, in order to compensate for this defect, the amount of crushing of this portion must be increased, resulting in a decrease in durability.
[0018]
In the structure of FIG. 3, the radius r of the mountain continuously changes along the cosine curve, so that the die cannot be processed by a general-purpose processing machine, and manual processing is required. It has become.
[0019]
An object of the present invention is to improve the following points in view of the above-mentioned problems of the related art.
[0020]
1) A mountain height structure that is quickly separated and effective for suppressing torque and improving durability.
[0021]
2) In addition, the height of the rubber near the valve stem is lowered and the rigidity of the rubber is increased, so that the amount of movement of the rubber is made smaller than that of the valve blade, thereby preventing the sealing ability from being lowered.
[0022]
3) The amount of bite between the valve body and the seat ring is optimized over the entire circumference, and the structure is simple with no abrupt shape change or change in the amount of bite to provide the above-mentioned structures 1) and 2). The structure is such that excessive stress is not applied.
[0023]
4) In addition, the design is such that the processing of the seat ring can be performed by a general-purpose processing machine, such as means capable of realizing the manufacturing cost at a minimum, for example, to keep the inner diameter constant, to keep the radius r of the mountain constant, and the like. .
[0024]
[Means for Solving the Problems]
Means taken by the present invention to solve the above-mentioned problem is that the center type butterfly valve has a structure having a seat ring that covers all of the main body wetted portion and the flange connection portion with rubber, and the seat ring is radially moved. section cut in the has a mountain shape bulging to an inner diameter side, and Ri a lower as the peak height approaches the valve stem, and the cross section obtained by cutting the sheet ring radially swelled radially inward bowler shape, It is characterized in that it has a cylindrical flat portion at the base, and the cylindrical shape of the flat portion has an elliptical shape having a short diameter in the valve stem direction and a long diameter in the valve stem orthogonal direction.
[0026]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described with reference to examples shown in the drawings.
FIG. 1 shows an embodiment of a seat ring of a butterfly valve according to the present invention. FIG. 1 (a) is a front view and a valve body is omitted. Inner diameter φD0 indicates a perfect circle, and φD1 indicates an elliptical shape. (B) is a sectional view near the valve blade. In this vicinity, since the turning radius of the valve body is the largest and the moment is long, the friction between the seat ring and the valve body has the greatest influence on the valve stem torque. (Valve torque = frictional force between seat ring and valve x radius of rotation). (C) is a sectional view in the vicinity of the valve stem as compared with (b). In this vicinity, the radius of rotation of the valve element is smaller than that in FIG. Also, as compared with FIG. (B), the peak r is the same and the height e is lower. (D) is a view in which an annular seat ring is developed on a straight line.
[0027]
In FIG. 1, as shown in the cross section A (FIG. 1B) of the seat ring 12, the seat ring 12 has an arc peak height of a radius r bulging to the inner diameter side, and the inner diameter φD0 formed by the peak height is always The inner diameter of the valve body 3 is smaller than the outer diameter of the valve body 3 by a certain amount, and the crush amount (deformation amount) for proper sealing is secured over the entire circumference. Here, the radius r can be constant over the entire circumference.
[0028]
Further, the flat portion (inner diameter φD1) forming the foot of the mountain has an elliptical shape when viewed from the direction of FIG. For this reason, the height e of the peak is high in the section A in the valve blade direction, but the height e decreases as approaching the valve stem as in the section B, and in the vicinity of the valve stem where the valve element and the seat ring are in contact with each other in the surface, The height e of the peak is configured to be zero.
[0029]
As a result, even if the radius r of the peak and the inner diameter φD0 are kept constant, the height e of the peak can be increased in the direction of the valve blade of the cross section A, and can be decreased toward the valve stem. In the section A where the radius is large and the contact area with the seat ring is small, the rubber of the seat ring is appropriately moved, and a torque reduction effect can be achieved. Also, in the vicinity of the valve stem (section B) where the rotation radius of the valve body is small and the torque is little affected (cross section B), the contact area is large, and the rubber is likely to be displaced. Can be prevented from decreasing.
[0030]
FIG. 1 shows a typical embodiment, in which the inside diameter φD0 and the peak radius r are constant regardless of the portion.
[0031]
The inner diameter φD1 of the flat portion at the foot of the mountain is elliptical with the center of the seat ring center, and is shorter in the valve stem direction and longer in the valve blade direction. As a result, the peak height e is highest in the section A, becomes lower as approaching the valve stem, and e = 0 in the valve stem portion.
[0032]
【The invention's effect】
As described above, according to the present invention, in the center type butterfly valve, a structure having a seat ring that entirely covers the main body liquid contact portion and the flange connection portion with rubber is provided, and a cross section obtained by cutting the seat ring in a radial direction is formed. , The peak shape that bulges to the inner diameter side, and the hill height decreases as it approaches the valve stem, and the cross-section obtained by cutting the seat ring in the radial direction bulges to the inner diameter side is a cylindrical shape at the base. Having the flat portion, the cylindrical shape of the flat portion is short in the valve stem direction and has an elliptical shape having a long diameter in the valve stem orthogonal direction, so that the following effects can be obtained. .
[0033]
(I) It is possible to suppress the movement of rubber by lowering the peak height and increasing the rubber rigidity near the valve stem having a large contact amount. As a result, the surface pressure (crushing amount) in the vicinity of the valve stem that is in constant contact can be made equal to the direction of the valve blade, and the sealing performance can be obtained without a large amount of crushing, and the sealing performance and durability can be improved simultaneously. is there.
That is, since the rubber stiffness against the movement of the rubber accompanying the rotation of the valve body near the valve stem where the sealing property is apt to decrease is increased, a high sealing property can be obtained with a small crushing amount.
[0035]
( Ii ) Even if the diameter r of the peak and the inner diameter φD0 are kept constant, the height e of the peak is high in the direction of the valve blade of the section A and can be reduced as the position approaches the valve stem. In the section A where the radius is large and the contact area with the seat ring is small, the rubber of the seat ring is appropriately moved, and a torque reduction effect can be achieved. Also, in the vicinity of the valve stem (section B) where the rotation radius of the valve body is small and the torque is little affected (cross section B), the contact area is large, and the rubber is likely to be displaced. Can be prevented from decreasing.
[0036]
( Iii ) Further , since the inner diameter and the radius r of the peak are constant and the inner diameter of the ellipse is determined by a constant function value, the processing of the molding die for the rubber seat ring is performed by general numerical control (NC) last night or the like. It is possible, and the mold can obtain high precision at low cost.
[0037]
( Iv ) Further, the inner diameter φD0 and the peak radius r are the most important factors for determining the sealing and torque performance. However, since this portion has a perfect circular shape and a constant r, it can be performed by a general-purpose lathe. Since the precision of the elliptical shape of φD1, which is difficult to process with a general-purpose lathe, has almost no effect on the sealing and torque performance, rough precision is sufficient, and the processing man-hour is not significantly impaired. Machining is not difficult with a numerically controlled (NC) lathe.
[Brief description of the drawings]
1A and 1B show an embodiment of a seat ring of a butterfly valve according to the present invention, wherein FIG. 1A is a front view, FIG. 1B is a sectional view near a valve blade (section A), and FIG. Sectional views (cross section B) in the vicinity and (d) are views in which an annular seat ring is developed on a straight line.
2A and 2B show an example of a conventional seat ring structure, in which FIG. 2A is a front view, FIG. 2B is a sectional view near a valve blade (section A), and FIG. 2C is a section near a valve stem. Figures (section B) and (d) are views in which an annular seat ring is developed on a straight line.
3A and 3B show another example of a conventional seat ring structure, in which FIG. 3A is a front view, FIG. 3B is a sectional view near a valve blade (section A), and FIG. 3C is near a valve stem. Are cross-sectional views (cross-section B) and (d) of the annular seat ring developed on a straight line.
[Explanation of symbols]
1 body (valve body)
3 valve body 5 stem hole 12 seat ring

Claims (1)

In the center type butterfly valve, a structure having a seat ring that covers all the main body liquid contact portion and the flange connection portion with rubber is provided, and a cross-section obtained by cutting the seat ring in a radial direction has a mountain shape bulging toward the inside diameter, and mountain Ri height is lower toward the valve stem, and the cross section obtained by cutting the sheet ring radially swelled radially inward bowler shape has a flat portion of the cylindrical foot that, cylindrical its flat portion A butterfly ring having a diameter shorter in the valve stem direction and longer in a direction perpendicular to the valve stem .

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