JPH0457912B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) This invention relates to a novel improvement of a seat ring for a butterfly valve.

(Prior Art) As is well known in the art, a butterfly valve has a hollow cylindrical valve body made of a rigid material such as metal, and a disc-shaped valve body made of a rigid material that is rotatable from the outside of the valve body. It has a structure in which an annular seat ring made of an elastic material is interposed between the inner peripheral surface of the valve body and the outer peripheral edge of the valve plate, and when the valve body rotates, the outer peripheral edge It is brought into contact with and separated from the seat ring to open and close the valve or adjust the flow rate. When the valve is closed, the outer periphery of the valve body is bitten into the annular seat ring, and the outer periphery of the valve body is brought into pressure contact with the inner periphery of the seat ring, thereby achieving a sealing effect.

Therefore, such butterfly valves have conventionally been required to have good sealing performance when the valve is closed, but to have a light load on opening and closing operations, that is, a light rotational torque of the valve body.

The present applicant proposed a proposal to solve these requirements in Japanese Utility Model Publication No. 30600/1983.
As shown in Figures 22 and 23, this is achieved by forming an arc-shaped chevron-shaped seat part along the radial direction on the inner circumferential surface of the seat ring, and pressing the outer peripheral edge of the valve body against this chevron-shaped seat part. This prevents the seat ring from being dragged by the valve body, lowers the repulsion spring constant, and ensures perfect sealing performance without increasing rotational torque.

However, in the technology disclosed in Japanese Utility Model Publication No. 52-30600, the seat ring is formed on the seat ring.
Since the arc-shaped chevron-shaped seat part is formed to have the same width in all parts in the circumferential direction, the valve body is attached to the seat ring in the vicinity of the valve stem (near the boss part) and in the part perpendicular to the valve stem. The contact angles of the valve stems are different, and the part near the valve shaft starts contacting at a larger angle than the orthogonal part, that is, the contact starts earlier, and the orthogonal part starts contacting later than this, and the contact with the seat ring at each part of the valve body is different. The contact start times are different. Such a difference in the timing of the start of contact results in the rotational torque until the orthogonal portions start contact being wasted and does not contribute to the generation of the sealing action.

Therefore, in order to solve these drawbacks, the present applicant further proposed a new proposal disclosed in Japanese Patent Publication No. 58-25911. As shown in Figs. 24 to 27, this is characterized in that the width of the chevron-shaped seat portion of the seat ring is formed by widening toward the orthogonal portion following a cosine curve starting from the center of the boss portion. It is. As a result, the valve body and the chevron-shaped seat portion start contacting simultaneously over the entire circumference in the circumferential direction, which eliminates the aforementioned wasted rotational torque, reducing rotational torque and improving sealing performance. I was able to obtain.

(Problems to be Solved by the Invention) However, even with such a seat ring as described above, the following drawbacks that have existed in the past have still not been solved.

As shown in Figures 28 and 29, the amount of movement of the valve body at the part perpendicular to the valve shaft is larger than that near the boss part, so near the part perpendicular to the valve shaft, the rubber bulges 1 during the valve opening operation, as shown in Figure 30. This increases the valve opening operating force.

At the part perpendicular to the valve shaft, the radius of rotation is larger than near the boss part, and therefore the rotational moment is also larger.
An increase in the operating force at the orthogonal portion of the valve shaft results in an increase in the rotational torque of the valve shaft.

At the part perpendicular to the valve shaft, the circumferential speed of the outer periphery is high, causing friction against the rubber at high speed, shortening the life of the seat ring.

Although such drawbacks are not so much of a problem with ON-OFF valves, when used as control valves, the following problems specifically occur.

The operating force that increases due to the swelling of the rubber during the valve opening operation drops rapidly when the valve body separates from the rubber, resulting in large load fluctuations that may cause the cylinder that drives the valve shaft to pop out. At the same time, it is impossible to minutely manipulate the valve opening in the vicinity of the closed state to control the flow rate, etc.

As shown by the solid line in FIG. 31, the flow rate characteristics of a typical butterfly valve have a very small rate of increase in flow rate in the vicinity of 0° to 20°, making controllability poor at low opening degrees. If this is set so that it is fully closed at 10 to 20 degrees, the flow rate characteristics become linear as shown by the dotted line in Figure 31, and a valve with good controllability can be obtained. The body or seat ring must have an elliptical shape extending in the direction of the valve axis, which has not been realized in the past because forming an elliptical shape is difficult and expensive.

This invention eliminates the above-mentioned drawbacks without forming the valve body and seat ring into an elliptical shape that is difficult to mold.The present invention provides a butterfly valve that has near-linear flow characteristics and improves controllability at low opening degrees. The purpose is to provide a valve.

(Means for Solving the Problems) The means adopted by the present invention to solve the above-mentioned problems is that the inner peripheral surface of a hollow cylindrical main body made of a rigid material and the inner peripheral surface of the main body are rotatably supported within the main body. An annular seat ring made of an elastic material is interposed between the outer circumferential edge of a disk-shaped valve body made of a rigid material, and has a pair of valve stem holes formed at diametrically opposed positions through which the valve stem passes. A boss portion is formed around each of the pair of valve stem holes, and a base portion of the valve stem of the valve body is in pressure contact with the valve body at all times, and a chevron-shaped seat portion is formed between the pair of boss portions, with which the outer periphery of the valve body is in pressure contact when the valve is closed. In the seat ring of a butterfly valve that is formed continuously along the circumferential direction, the chevron-shaped seat part consists of a first and a second chevron-shaped seat part, and the first chevron-shaped seat part has a radius R, a width W, and an inner diameter. By _changing exists between the part where the mechanical strength and sealing function as a seal of the first chevron-shaped seat part are impaired and the boss part, and is set to a radius R' where the tip edge surface of the valve body comes into pressure contact, and The amount of biting movement of the valve body is determined by the width of the edge surface of the valve body.
It is characterized by being set smaller than Ka.

(Operation and Effects of the Invention) The amount of biting t into the seat ring becomes uniform over the entire circumference, eliminating unnecessary biting, so it is possible to exhibit stable sealing performance over a long period of time, and the biting The travel amount E is uniform and the valve body edge width is
Since it is set smaller than Ka, the rubber bulge as shown in FIG. 30, which is seen in conventional butterfly valves, is eliminated, and the valve shaft torque when the valve is opened is reduced. In addition, since the amount of biting movement is minute, the range in which the valve shaft torque increases due to biting remains within a minute opening range, and as shown in Figure 21, a wide opening range with no torque fluctuation is adopted. I can do it. Therefore, the opening range in which there is no torque fluctuation in the minute opening range becomes larger than that of the conventional butterfly valve.

Furthermore, since the fully closed seal angle of the valve can be set at an angle of about 10 to 20 degrees instead of 0 degrees as in the conventional case, the low opening part of the valve with poor flow characteristics can be cut out, and only the part with good flow characteristics can be set. It becomes possible to use it.
As a result, it is possible to obtain a butterfly valve whose opening-flow rate characteristic approaches a linear characteristic as shown by the dotted line in FIG. 31 and is easy to control as a control valve.

(Embodiments) Preferred embodiments of the present invention will be described below with reference to the drawings. Figures 1 and 2 show the seat ring and valve body of the butterfly valve according to the present invention.
11 is a seat ring fixed to the inner peripheral surface of a substantially cylindrical main body made of a rigid material such as metal, and 11 is a disc-shaped seat ring rotatably supported within the main body by valve stems 12 and 13. It is a valve body, and its outer periphery is covered with a seat ring 10.
Opens and closes the valve by bringing it into contact with and separating from the inner peripheral surface of the valve. As is conventionally known, the seat ring 10 is made of a rubber-like elastic material such as vulcanized rubber, and the valve body 11 is made of the same rigid material as the main body. One of the valve rods 12 extends outward from the main body and is connected to a valve drive mechanism, so that the valve body can be driven and rotated from the outside to open/close or adjust the opening degree of the butterfly valve. seat ring 10
As shown in FIGS. 3 to 5, there is a valve stem hole 14 through which the valve stems 12 and 13 of the valve body 11 pass through at positions facing each other in the diametrical direction.
The periphery of the valve stem hole 14 is formed into a flat boss portion 15 with which the periphery of the valve stem of the valve body 11 is constantly pressed. A first chevron-shaped seat portion 16 is formed between the boss portions 15 and extends in the circumferential direction on the inner circumferential surface of the seat ring 10. The first chevron-shaped seat portion 16 has an arcuate cross-section projecting inwardly from the seat ring, and as shown in FIG. Closure takes place. In the closed state, the valve body 11 has a slight inclination angle with respect to the valve shaft.

The first chevron-shaped seat portion 16 is arranged so that the amount of bite t and the amount of biting movement E of the outer circumferential edge of the valve body into the first chevron-shaped seat portion 16 are the same at any outer peripheral edge of the valve body ( (see FIG. 15), and the radius R, width W, and inner diameter _X4 of the first chevron-shaped seat portion 16 are changed (see FIG. 17). The radius R and width W of the first chevron-shaped seat portion 16 are related to the closing angle of the valve body 11, and by increasing R and W, the closing angle can be arbitrarily set. It becomes easy to design the closing angle at a position that is easy to control as a control valve.

Figures 17 to 19 show Va, Vb, Vc in Figure 16.
It is a cross-sectional view showing the shape of the first chevron-shaped seat portion 16 in a portion, and the radius R, width W, and inner diameter X ₄ are set so that the biting amount t and the biting movement amount E are uniform. And, in the part near the boss part 15, the first
As shown by the dotted line in FIG. 9, if the radius R and width W of the chevron-shaped seat portion 16 become too small, the chevron-shaped seat portion may be damaged or broken due to the strength of the rubber when the valve body bites into it.

Therefore, from the part where the radius R and the width W become small to a certain extent to the boss part, a second chevron for backup with a radius R' is used instead of the first chevron sheet part 16 described above, as shown in FIG. A seat portion 18 is formed so as to come into pressure contact with the edge surface of the valve body 11 rather than the side surface of the tip. In this case, the biting movement amount E of the valve body is set smaller than the width Ka of the edge surface of the valve body to prevent the rubber from swelling when the valve body is opened.

Next, the theory for changing the radius R, width W, and inner _diameter
This will be explained according to Figure 0. FIG. 20 is a sectional view taken along a plane forming an angle S ₂ with the axis orthogonal to the valve shaft, and in FIG. 20, the seal point A of the valve body is
The coordinates of the point are determined, and the coordinates of point B, which has a predetermined biting movement amount E from point A, are determined. Similarly, a point C having a predetermined biting amount t is found. Passing through these points B and C,
And if we find a circle with center point D on the center line, we can find R and _X4 .

Furthermore, if the inner diameter _B3 of the cylindrical plane of the sheet is kept constant, the width W of the circle is determined. In this way S ₂
R, X ₄ and W are determined for each opening degree from 0° to 90°. In reality, we varied S ₂ by 1° to obtain dimensions for each opening degree, and performed processing based on the dimensions.

If we calculate as above, R will become too small in a range where S ₂ is large to a certain extent, and it will no longer be possible to give constant E and t, so we will find a new circle with larger E' and t. is the mountain R′.

The upper part of the chevron does not contribute to the sealing action of the valve because the side surface of the tip of the valve element bites into the side surface of the first chevron-shaped seat part 16. Therefore, as shown in FIGS. 6 and 7, the upper surface of the first chevron-shaped sheet portion 16 is cut off to form a flat surface. This makes it possible to suppress the reduction in the valve inner diameter due to the protrusion of the chevron-shaped seat portion and increase the valve inner diameter, which has the advantage of increasing the flow rate. However, such cutting of the upper surface of the first chevron-shaped sheet portion 16 is not necessarily essential.

Thus, according to the present invention, the biting amount t into the seat ring becomes uniform over the entire circumference and unnecessary biting is eliminated, so that stable sealing performance can be exhibited over a long period of time, and the biting Since the displacement E is uniform and set smaller than the valve body edge width Ka, the rubber bulge shown in Figure 30, which is seen in conventional butterfly valves, is eliminated, and the valve stem torque when the valve opens is small. Become. In addition, since the amount of biting movement is minute, the range in which the valve shaft torque increases due to biting remains within a minute opening range, and as shown in Figure 21, a wide opening range with no torque fluctuation is adopted. I can do it. In Fig. 21, the dotted line indicates the opening-torque characteristic of the conventional butterfly valve,
While the fluctuation of the valve stem torque is large when the opening degree is 30 degrees or less, in the case of the butterfly valve of the present invention, the fluctuation in the valve stem torque disappears from around the opening degree of 7 degrees, as shown by the solid line. The inner opening range of torque fluctuation in the minute opening range is larger than that of conventional butterfly valves.

Furthermore, since the fully closed seal angle of the valve can be set at an angle of about 10 to 20 degrees instead of 0 degrees as in the conventional case, the low opening part of the valve with poor flow characteristics can be cut out, and only the part with good flow characteristics can be set. It becomes possible to use it.
As a result, it is possible to obtain a butterfly valve whose opening degree-flow rate characteristic approaches linearity as shown by the dotted line in FIG. 31 and is easy to control as a control valve.

[Brief explanation of the drawing]

FIG. 1 is a front view of the seat ring and valve body according to the present invention, FIG. 2 is a sectional view taken along the line shown in FIG. 1, FIG. 3 is a sectional view of the seat ring, and FIG. 4 is an exploded view of the same. Figure 5 is the same inclined view, Figure 6 is Figure 4a.
- A cross-sectional view along line a, Figure 7 is Figure 4 b-
A cross-sectional view along line b, Figure 8 is Figure 4 c-
A cross-sectional view along line c, Figure 9 is Figure 4 d-d.
10 is a partial front view showing the state of engagement between the seat ring and the valve body, FIG. 11 is a sectional view taken along line a-a in FIG. 10, and FIG. Figure 10 is a cross-sectional view taken along line b-b, Figure 13 is a cross-sectional view taken along line c-c in Figure 10, and Figure 14 is a cross-sectional view taken along line c-c in Figure 10.
The figure is a sectional view taken along the line dd in Figure 10.
Fig. 5 is a sectional view showing the relationship between the amount of biting of the valve body into the seat ring and the amount of biting movement, and Va in Fig. 16.
The parts along the -Va and Vb-Vb lines are shown superimposed. Fig. 16 is a front view of the valve body, and Fig. 17 is the state of the seat ring and the valve disc being bitten together at the Va-Va line in Fig. 16. 18 and 19.
The figure is the same as Figure 17 in the Vb-Vb and Vc-Vc line portions in Figure 16, and Figure 20 shows the radius R, width W, and inner diameter to make the biting amount and the biting movement the same.
A conceptual diagram for determining X ₄ , Fig. 21 is a graph showing the relationship between valve opening degree and valve shaft torque, Fig. 22 is a front view of a conventional butterfly valve, and Fig. 23 is a graph taken along the line shown in Fig. 22. Fig. 24 is a cross-sectional view of the seat ring of another conventional butterfly valve.
Figure 5 is a perspective view of the same, Figure 26 is Figure 24 a-a.
A sectional view along the line, Fig. 27 is Fig. 24b-
28 is a sectional view taken along the line b, and FIG. 28 is a sectional view showing the amount of biting and the amount of biting movement of the valve body into the seat ring in a conventional butterfly valve;
The portions along lines -a and bb are shown overlapping each other. FIG. 29 is a front view of the valve body, and the third
Fig. 0 is a cross-sectional view showing the state of the rubber bulging due to the valve body at the line a-a and b-b in Fig. 29, and Fig. 31 is a graph showing the valve opening degree-flow rate characteristics of the conventional butterfly valve and the butterfly valve of the present invention. . 10... Seat ring, 11... Valve body, 12...
... Valve stem, 13... Valve stem, 14... Valve stem hole, 15,
17... Outer periphery, 16... First chevron sheet portion,
18...Second chevron sheet portion.

Claims (1)

[Claims] 1. An annular valve made of an elastic material interposed between the inner peripheral surface of a hollow cylindrical main body made of a rigid material and the outer peripheral edge of a disc-shaped valve body made of a rigid material rotatably supported within the main body. The seat ring has a pair of valve stem holes formed at diametrically opposed positions through which the valve stem passes, and a boss portion around each of the pair of valve stem holes that is in constant pressure contact with the base of the valve stem of the valve body. In the seat ring of a butterfly valve, in which a chevron-shaped seat portion is continuously formed along the circumferential direction between the pair of boss portions and the outer peripheral edge of the valve body comes into pressure contact with the valve body when the valve is closed, the chevron-shaped seat portion is the first. 1 and a second chevron-shaped seat part, and the first chevron-shaped seat part has a radius R, a width W, and _an inner diameter
The amount of biting t and the amount of biting movement E of the outer periphery of the valve body into the seat ring are set to be the same, and the second chevron seat has the same mechanical strength as the seal of the first chevron seat. It exists between the part where the sealing function is impaired and the boss part, and is set to a radius R' where the tip edge surface of the valve body comes into pressure contact, and the amount of biting movement of the valve body is determined by the width Ka A seat ring characterized by being set smaller.