JPS5825911B2 - Chiyo-shaped valve seat ring - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in seat rings for butterfly valves.

In general, a valve called a butterfly valve is a general-purpose valve mainly used for opening pipelines through which water flows.

As is well known, the basic structure of a butterfly valve, as shown in Fig. 1, is a hollow cylindrical valve body 2 made of a rigid material (for example, cast metal), and a rotatably supported shaft within the valve body 2. and a circular seat ring made of an elastic material (for example, vulcanized rubber) interposed between the entire inner peripheral surface of the valve body 2 and the peripheral edge of the valve plate 3. 1, and when the butterfly valve is closed, as shown in FIG. 1, when the valve plate 3 is rotated to the valve closing position,
The tip of the peripheral edge of the valve plate 3 is pressed into contact with the inner circumferential surface of the annular seat ring 1 (microscopically, the tip of the peripheral edge of the valve plate 3 is bitten into the inner circumferential surface of the annular seat ring 1 to form a seal. It is a structure that causes an action to take place.

A pair of valve plate rotation shaft through holes S1. are located at diametrically opposed positions on the inner peripheral surface of the annular seat ring 1. A portion near the periphery of S2 (hereinafter referred to as the boss portion) is always in pressure contact with the vicinity of the root of the valve plate rotating shaft, regardless of whether it is opened or closed.

The butterfly valve with the above structure has good sealing performance when the valve is closed, and the load (hereinafter referred to as "rotation torque") for opening and closing operations.

) is required to be lightweight.

Utility Model Application Publication No. 52-30600 is one of the answers to this demand.

That is, as shown in FIG. 5, by forming the seat portion of the conventionally flat inner peripheral surface of the annular seat ring that contacts the valve plate into an arcuate mountain shape, the valve plate closes from the open position and becomes annular. The rotation angle of the valve at 1, which rotates from the position where it starts contacting the seat ring to the fully closed position of 90 degrees, is reduced to prevent the valve plate from dragging the annular seat ring when the so-called valve plate closes. By forming the valve body into the seat ring, the repulsion spring constant of the seat ring is lowered and the rotational torque is reduced. By preventing this from occurring, complete sealing performance can be ensured without increasing the rotational torque.

However, this conventional technology has the following problems.

In the above-mentioned prior art, the width of the chevron-shaped sheet portion was the same in all parts.

For this reason, in Fig. 1, if we focus on point B at the tip of the valve plate and arbitrary point A, we can see that the arbitrary point A is OA, and the OB of point B is
Since the valve rotates with a shorter arm, when the valve goes from opening to closing, point A comes into contact with the chevron gating part earlier than point B, as shown in Fig. 6.

In other words, point A contacts point A at a larger angle αA than point B.
In the figure, 20 is the trajectory due to valve rotation at point B, and 21 is point A.
, αB is the angle at which point B starts contacting the chevron-shaped sheet portion, and αA is a similar angle at point A.

The above phenomenon becomes more noticeable as point A approaches the valve stem.

That is, the angle αAii: becomes larger. Unless all points on the peripheral edge of the valve plate come into contact with the annular seat ring, the pressure of the fluid flowing inside the valve will not begin to seal. Therefore, as long as point B does not come into contact with the chevron root, there will be no sealing action. Only the rotational torque increases.

The sealable pressure (the maximum pressure of the fluid that can be completely sealed) after point B comes into contact with the chevron-shaped seat and the sealing action starts - the rotational torque characteristic, that is, the entire periphery of the valve plate is the annular belt. As the valve plate comes into contact with the valve plate and digs into the slope of the chevron-shaped groove, the sealable pressure increases and the rotational torque also increases. FIG. 7 shows the relationship between the two.

As shown in FIG. 7, rotational torque E is required from the time when the sealable pressure is Okq/cm2.

This is referred to as "waste torque" below the rotational torque C caused by all points on the peripheral edge of the valve plate, except for the point farthest from the valve stem, biting into the chevron root part earlier. ).

On the other hand, commercially available butterfly valves are often sold uniformly as 10 to 97-seal valves, but in reality they are used at pressures far lower than the maximum 7-degree pressure. The majority are.

When turning a butterfly valve manually, there is no problem even if the turning torque is a little large, but when turning a butterfly valve with an automatic actuator, if the turning torque is large, the actuator with a large load capacity may be necessary, expensive and uneconomical.

For this reason, as shown in Figure 8, automatic actuators for Gomunt butterfly valves are generally equipped with a stopper for adjusting the closed position. After adjusting the position and stopping it, one thing is done.

In Figure 1, for example, the pressure to be sealed is 5Icg/c.
In the case of rtt, adjust the closed position using the stopper,
It is used by adjusting the rotating torque to F, which is about 60 times the maximum torque value G.

However, since there is the above-mentioned wasted torque E, it has not been possible to reduce the rotational torque significantly below F.

Eliminating wasteful torque E, sealing action and rotational torque are
If it is possible to make them occur simultaneously, the characteristics will be as shown by the two-dot chain line in FIG.

In this case, in the case of a seal for a fluid pressure of 5/C9/crA, the rotational torque is H, which can be greatly reduced by 1 to the extent of G.

In order to eliminate this wasteful torque E, the width of the chevron-shaped groove can be uniformly made extremely thin as shown in Fig. 9, so that the valve plate does not come into contact even near the valve stem from before the closed position. In addition to the drawback of insufficient mechanical strength as a seal, there is also the problem that it becomes difficult to adjust the position of the valve plate using the stopper in response to the necessary sealing pressure.

In other words, when the width of the chevron seat part is narrowed, the part where the valve plate and the chevron seat part come into contact and are away from the valve stem during sliding at 90 degrees fully closed 1 (i.e., point B in the third figure) also becomes narrower. , as shown in Figure 10, the change in seal pressure with changes in the position of the valve plate becomes significant, and if the position of the valve plate shifts even slightly, the seal pressure changes greatly. It is not possible to increase the opening degree of the valve (hereinafter referred to as "valve closing angle") at any valve closing position (O) corresponding to the valve closing position (O).

The technical problem of the present invention is to make the valve plate have a relatively large valve closing angle so that the boss part and the entire circumference of the valve plate except for the vicinity simultaneously contact the chevron-shaped note part of the nott ring. .

The technical measures taken to solve the above technical problems are as follows.

In other words, ■ Make the width of the chevron-shaped part of the belt ring the minimum width as a seal in the vicinity of the boss part without impairing the mechanical strength @ towards the center between both boss parts of the chevron-shaped seat part The purpose is to widen the width along a curved shape expressed by a cosine function whose starting point is the center of the boss.

The above technical means works as follows.

When the valve plate closes from the "open" state, the valve plate approaches the chevron-shaped seat portion before reaching the closed position, and eventually comes into contact with the chevron-shaped seat portion.

At this time, points on each portion of the peripheral edge of the valve plate pass through the apex of the chevron-shaped seat portion.

Surface C perpendicular to the flow path (hereinafter referred to as the "plane at the 90° closed position")
Describe how far away it is in the vertical direction.

(Hereinafter referred to as "separation distance t."

) In Fig. 1, any point A on the peripheral edge of the valve plate is rotated with a radius shorter than point B around point 01.

Fig. 3A is a more geometrically easy-to-understand drawing, where 3 is the valve plate, C is the central axis of the valve plate, r is the valve plate radius O is the center of the valve plate.

If the angle formed by OA and OB is θ, the λ point rotates around 0' with a radius of r rO8θ.

In FIG. 3B, assuming that the valve plate abuts against the chevron-shaped seat portion at an angle α, the above-mentioned separation distance t is expressed as follows.

t=(r cos θ)

That is, each point on the peripheral edge of the valve plate is distributed at a distance proportional to cos θ from the plane where the valve plate is at the 900° closed position.

On the other hand, in the chevron-shaped seat part, the distance at the point l where the valve plate separates from the surface of the 900 closed position is distributed along a curve expressed by the same cosine function, so the curved part of the chevron-shaped seat covers all of its parts. It comes into contact with the valve plate at the same time.

Also, the width of the chevron-shaped seat at the farthest point from the valve stem is the above-mentioned separation distance t = r sin αXc applied to this point above.
os 00=r sin α(CO800:1),
By using the design values r and a, it is possible to obtain a chevron-shaped groove width sufficient to freely select and easily adjust the closing position of the valve plate.

By widening the minimum width of the chevron-shaped sheet portion within a range that does not impair mechanical strength, the strength of the chevron-shaped sheet portion can be ensured over the entire circumference.

Examples illustrating specific examples of the technical means of the present invention will be described below.

FIG. 2 is a developed view of the inner circumferential surface of the annular seat ring 1 of the embodiment, showing about half of it symmetrical with respect to the valve shaft.

Valve stem hole S1. The area around S2 is a boss that the valve plate comes into contact with regardless of whether it is opened or closed, so the valve stem hole S1. It protrudes from the inner peripheral surface of the seat ring 1 in a disc shape with the same name as s2.

A chevron-shaped seat portion 11 is formed by smoothly connecting to the boss portion, and the width of the chevron-shaped seat portion 11 is such that the width of the chevron-shaped seat portion 11 is such that cosoo is the point B farthest from the valve stem in Fig. 1, and c is the center of the valve stem hole S1.
os900, center of valve stem hole S2 cos (-90°)
A curve expressed by a cosine function (hereinafter referred to as a "cosine curve").

) is changing.

As the width of the chevron sheet gets closer to the boss part than point B, the width becomes narrower and the mechanical strength necessary for a seal begins to deteriorate, but just before the width begins to deteriorate, stop changing it using a cosine curve and change it to a straight line. Then go to the boss department.

Therefore, in Fig. 2, the width of the chevron sheet portion at point B is the maximum,
It becomes the minimum width near the boss part, and is connected to the boss part while maintaining the minimum width.

In the case of a butterfly valve with a large diameter, the interpolation dimension of the valve is large, so the maximum diameter of the chevron seat at point B can be made large, and the diameter of the boss is also large, so that the diameter of the chevron seat near the boss can be increased. The width of the cosine curve also increases.

Therefore, as shown in Figure 2, the straight portion of the chevron seat width is extremely small, but in the case of a butterfly valve with a small diameter, the 4th
As shown in the figure, the straight portion of the chevron-shaped sheet width is longer than that in FIG.

Note that the rotational torque of the valve is the product of the resistance force that each portion of the peripheral edge of the valve plate receives from the chevron-shaped note portion multiplied by the distance from the valve stem.

Therefore, a large torque is generated at a location far from the valve stem, but only a small torque is generated at a location close to the valve shaft, so the degree of influence on torque differs depending on the location of the peripheral edge of the valve plate.

Therefore, it is not necessary to change the width of the chevron sheet over the entire area.

According to a calculation example, the torque T generated in the range from 00 of θ to an arbitrary angle θ in the third person figure is expressed as follows.

However, f: Frictional force received from the annular seat ring per unit length of the valve plate periphery r: When the valve plate radius θ=900 T.

. = fr2θ=45° T45°= 0.7 f
r2=0.7T9o.

As a result, since f is constant, θ is O ~
45° range In other words, O to 1 on one side with respect to the valve shaft of the valve plate
It can be seen that in the 80° range, the valve plate periphery in the range of 45° to 135° produces 70% of the total torque.

From this, it can be seen that in Fig. 4, the width of the arcuate chevron-shaped groove becomes a straight line near the boss, but this range is narrower than 45 degrees and does not have a large effect on torque. .

The present invention has the following unique effects.

The problem of the present invention can also be solved by changing the width of the chevron-shaped groove along the entire circumference along a curve expressed by a cosine function (see Fig. 11); An inconvenience occurs in the valve.

In other words, as the diameter becomes smaller, the face-to-face dimension of the valve (distance between the two flange faces of the valve) becomes smaller due to restrictions based on standards, etc., so the allowable width of the chevron seat part also becomes narrower. If the width is reduced using a cosine function, the area near the boss will become extremely thin, impairing the sealing performance near the boss.

In the present invention, the shape of the chevron-shaped root portion near the boss portion is deviated from the cosine curve and is thickened to a width that maintains mechanical strength, so that sealing performance is not impaired.

[Brief explanation of the drawing]

Fig. 1 is an end view of a butterfly valve, Fig. 2 is an exploded view of a portion of a seat ring according to an embodiment of the present invention, which corresponds to the semicircular length of the seat ring, and Figs. FIG. 3 is an explanatory diagram showing the contact relationship between the valve plate and the chevron-shaped seat portion of the seat ring for explaining the action of the technical means. FIG. 4 is a developed view similar to FIG. 2 showing another embodiment of the present invention. Fig. 5 is a sectional view showing the IJ song shape of the prior art, Fig. 6 is an explanatory diagram showing a comparison of the contact situation of two points A-B on the peripheral edge of the valve plate with the chevron-shaped seat portion of the prior art; Fig. 7 is a sealable pressure-rotational torque characteristic diagram of a butterfly valve with a chevron-shaped groove, Fig. 8 is a sectional view of a commercially available pneumatic rotary actuator for a butterfly-shaped valve, and Fig. 9 shows the width of the chevron-shaped groove. An explanatory diagram showing the contact situation with the peripheral edge of the valve plate when the valve plate is made extremely thin, Figure 10 shows the valve opening vs. seal pressure characteristics when shown in Figure 9, and Figure 11 explains the unique effects of the present invention. This is a reference diagram for Symbols in the figure, 1... annular seat ring, 2...
... Valve body, 3... Valve plate, S, , S2.
... Valve shaft through hole, 11 ... Chevron root part, 20 ... Locus of point B in Figure 1, 21 ...
・Figure 1 Locus of point A, 30...stopper 31
...Piston, 32...Output shaft, 33
...Tube, 34 ...Arm, 35
... Torque bin.

Claims (1)

[Scope of Claims] 1. Between the entire inner peripheral surface of a hollow cylindrical valve body made of a rigid material and the peripheral edge of a disc-shaped valve plate made of a rigid material that is rotatably supported within the valve body. An annular seat ring made of an elastic material is interposed, and a pair of through holes for passing the rotation axis of the valve plate are provided at diametrically opposed positions on the inner peripheral surface of the ring. A pair of bosses are formed around each of the through holes so as to be in pressure contact with the base of the rotating shaft of the valve plate at all times, regardless of whether the valve is open or closed. In an annular seat ring in which a chevron-shaped seat part is continuously formed along the circumferential direction to press against the peripheral edge of the valve plate, the width of the chevron-shaped seat part of the IJ song is set near the boss part. The width should be the minimum width within the range that does not impair the mechanical strength of the seal. Seat ring of a wide butterfly-shaped valve.