JPH01112084A - Butterfly valve having regulating function - Google Patents

Abstract

PURPOSE:To improve controllability of the low opening, by a method wherein the chevron seat part of a seat ring is formed with first and second chevron sheet parts. CONSTITUTION:The chevron part of a seal ring 4 is formed with first and second chevron sheet parts 8 and 9. The radius, the width, and the inner size of the first chevron sheet part 8 are changed so that a cut-through amount and a cut-through moving amount of the outer peripheral part of s valve body are uniformized, and the radius of the second chevron sheet part 9 is set so that the tip edge surface of the valve body is brought into pressure contact. This constitution uniformizes an amount of cut-through made on the sheet ring throughout a whole periphery, and eliminates unnecessary cut-through, resulting in the possibility to provide stable sealing ability for a long time. Further, since valve stem torque during opening of a valve is decreased and flow rate characteristics shown approximately in a linear line are provided, controllability of the low opening is improved.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a butterfly valve having an adjustment function, particularly a butterfly valve with a thin toothed valve body that can exhibit an improved adjustment function at a low opening degree. Regarding valves.

(Prior Art) Conventionally, a butterfly valve for controlling the opening and closing of a steam pipeline for a steam turbine is required to have a high degree of control performance, and a butterfly valve having a comb-shaped valve body as shown in FIG. 1 has been used.

In a butterfly valve having such a comb-shaped valve body, the fluid becomes a fine jet flow due to the action of the comb teeth, so it suppresses the occurrence of cavitation, suppresses noise generation at intermediate opening degrees, and reduces dynamic torque and maintains stability. It has excellent advantages such as good controllability.

However, even with a butterfly valve having such a comb-like valve body, at low opening degrees, fluctuations in valve shaft torque affect the range from 0 to 30 degrees, as shown by the dotted line in FIG. 22, resulting in poor controllability. Ta.

This is due to the following reasons. In other words, since the amount of movement of the valve body at the part perpendicular to the valve shaft is larger than the amount of movement of the valve body near the boss part, a bulge of rubber (A>) is formed at the part perpendicular to the valve shaft during the valve opening operation, as shown in FIG. In addition to increasing the valve opening operating force, the rotation radius and rotational moment at the part perpendicular to the valve shaft are larger than those near the boss, so the increase in the operating force at the part perpendicular to the valve shaft is due to the rotation of the valve shaft. This results in an increase in dynamic torque. Therefore, the operating force that increases due to the swelling of the rubber during the valve opening operation suddenly decreases when the valve body separates from the rubber, increasing load fluctuations and driving the valve stem. This may cause the cylinder to pop out, and it also makes it impossible to control the flow rate by performing minute valve operations at low opening degrees.

(Problem to be solved by the invention) In order to improve controllability at low opening degrees of 50 degrees or less, if the valve opening degree is set so that it is fully closed at 10 to 20 degrees, the valve opening as shown in Fig. 24 can be improved. As shown by the dotted line, it is possible to obtain a valve with linear flow characteristics and good controllability, but for this purpose, the valve body and seat ring must have an elliptical shape extending in the direction of the valve axis. Conventionally, this was difficult to realize because molding 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, has flow characteristics close to linear, and can improve controllability at low openings. It is an object of the present invention to provide a butterfly valve having an adjustment function.

(Means for Solving the Problems) In order to solve the above problems, the means taken by the present invention include a hollow cylindrical body made of a rigid material, and a body rotatably supported within the body. a disc-shaped valve body made of a rigid material;
An annular seat ring made of an elastic material is interposed between the inner peripheral surface of the main body and the outer peripheral edge of the valve body, and the seat ring is provided with a pair of valve stem holes 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 boss portion is formed in which the base of the valve stem of the valve body is always in pressure contact, 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. are formed continuously along the circumferential direction, and the valve body has comb teeth extending toward the primary side and the secondary side at symmetrical positions around the valve axis. In the valve, the chevron-shaped seat portion of the seat ring is composed of first and second chevron-shaped seat portions, and the first chevron-shaped seat portion has a radius (R).
, the width (W) and the inner diameter (x4) are changed so that the injection Ji (t) and the biting movement amount (E) of the outer periphery of the valve element to the seat ring are the same at any outer periphery of the valve element. The second chevron-shaped seat part exists between the part of the first chevron-shaped seat part where the mechanical strength and sealing function as a seal are impaired and the boss part, and the tip edge surface of the valve body is It is set to the radius (R″) of pressure contact, and
It is characterized by being set smaller than the amount of biting movement of the valve body and the width (Ka) of the edge surface of the valve body.

(Operation and Effects of the Invention) The injection ji(t) to 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. At the same time, the amount of biting movement (E) is uniform and set smaller than the valve body work and nozzle width (Ka), so the protrusion of the gore 11 as shown in Fig. 23, which is seen in conventional butterfly valves, is eliminated. As a result, the valve shaft torque when opening the valve becomes smaller. In addition, since the amount of biting movement is minute, the range in which the valve stem torque increases due to biting is limited to a minute range of 1 m degree, and as shown in Figure 22, a wide opening range with no torque fluctuation can be adopted. I can do it.

Therefore, the opening range in which there is no torque fluctuation in the minute opening range is increased compared to the conventional butterfly valve.

Furthermore, the fully closed seal angle of the valve is not 0° as in the past, but
Since the angle can be set to about 10 to 20', it is possible to cut out the low opening portion of the valve with poor flow characteristics and use only the portion with good flow characteristics. As a result, it is possible to obtain a butterfly valve whose opening degree-flow rate characteristic approaches a linear characteristic as shown by the dotted line in FIG. 24, and which is easy to control as a control valve.

(Embodiments) Preferred embodiments of the present invention will be described below with reference to the drawings.

In Figures 1 to 3, (1) is the main body of the butterfly valve made of a rigid material such as metal and formed into a substantially cylindrical shape, and the valve body (1) made of a rigid material such as metal formed into a disc shape inside. A seat ring (4) made of an elastic sealing material such as rubber is attached to the inner circumferential surface of the main body (1), which is rotatably supported by a valve stem (3). The butterfly valve is opened and closed by the outer peripheral edge of the valve body (2) coming into contact with and separating from the inner peripheral surface of the valve body (2), and the flow x? Section A is performed. The outer peripheral edge of the valve body (2) has comb teeth 5 extending toward the primary side and the secondary side at symmetrical positions around the valve shaft.
) is formed, and is further bent in a dogleg shape about the valve shaft toward the negative side.

Due to the shape of the valve body (2) with comb teeth, the fluid becomes a fine jet flow, which produces a low noise effect at intermediate opening degrees, and also reduces dynamic torque and provides stable valve control.6 In addition, it exhibits a high initial cavitation differential pressure and a high pressure recovery coefficient, suppressing the occurrence of cavitation. The valve stem (3) extends outward from the main body and is connected to a valve drive m tM, 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. As shown in FIGS. 4 to 6, the seat ring (4) has a valve shaft hole (
6), and the periphery of the valve stem hole (6) is formed into a boss portion (7) having a spherical seat with which the periphery of the valve stem of the valve body (2) is constantly pressed. A first chevron-shaped seat portion (8) is formed between the boss portions (7) and extends in the circumferential direction on the inner circumferential surface of the seat ring (4). The first chevron-shaped seat portion (8) has an arc-shaped cross section that projects inward of the seat ring, and the outer peripheral edge (2a) of the valve body (2) bites into the side surface of the first chevron-shaped seat portion (8), as shown in FIG. The valve is closed by pressure contact. In the closed state, the valve body (2) has a slight inclination angle with respect to the center line.

The first chevron-shaped seat part (8) is configured to adjust the amount of bite (t) of the outer peripheral edge of the valve disc into the first chevron-shaped seat part (8) and the injection movement fi (E ) are the same (see Fig. 16), change the radius (R), width (W>, and inner diameter (X4) of the first chevron-shaped seat part (8) (see Fig. 18.21) ), the radius (R) and width (W>) of this first chevron-shaped seat portion (8) are related to the closing angle of the valve body (2), and the closing angle can be set by increasing R and W. Since this can be done arbitrarily, it is easy to design the fully closed angle at a position that is easy to control as a control valve.

Figures 18 to 20 show O-V a, 〇-Vb,
It is a cross-sectional view showing the shape of the first chevron-shaped sheet portion (8) in the 0-Ve portion, and it shows the shape of the first chevron-shaped sheet portion (8).
If the radius (R), radius (W>) and inner diameter (X4) are set so that E) is uniform, the portion near the boss (7) will have a chevron-shaped sheet as shown by the dotted line in Figure 20. Part (8)
If the radius (R) and width (W> of the valve body become too small and the valve body digs in, there is a risk that the chevron-shaped seat portion will be damaged or broken due to the strength of the rubber.

Therefore, from the part where the radius (R) and width (W) become small to a certain extent to the boss part, instead of the first chevron seat part (8) described above, the radius (R'
) is formed as a backup second chevron-shaped seat part (9) so that it comes into pressure contact with the edge surface of the valve body (2) rather than the side surface of the tip end thereof. In this case, the amount of biting movement (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, we will discuss the theory for changing the radius (R), width (W), and inner diameter (X1) in order to make the biting amount (t) and the injection movement 1it (E) the same, and the second chevron seat part (9 ) radius (Ro
) will be explained with reference to FIG. 21st
The figure is a sectional view taken along a plane that passes through the center of FIG. 3 and forms an angle S2 with the axis perpendicular to the valve shaft. In FIG. Predetermined injection movement! Find the strength of point B with (E). Similarly, a point C with a predetermined injection Jlt(t) is determined. By finding a circle that passes through points B and C and has its center point on the center line, the desired R and X can be found.

Furthermore, if the inner diameter B3 of the cylindrical plane of the sheet is kept constant, the width (W) of one circle is determined. In this way, change s2 from 0° to 9
Find R, X, and W for each opening degree up to 0°. In reality, dimensions were obtained for each degree of opening by changing s2 by 1°, and processing was performed based on the dimensions.

If you calculate as above, R will become too small in a range where 82 is large to a certain extent, and it will no longer be possible to give constant E and t, so a new circle with larger E' and t will be calculated as the second one. It is a mountain (Ro).

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 body bites into the side surface of the first chevron-shaped seat part (8). Therefore, Fig. 7.8 The upper surface of the first chevron-shaped sheet portion (8) is cut off to form a flat surface as shown in FIG. 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, cutting off the upper surface of the first chevron-shaped sheet portion (8) to be bent is not necessarily essential.

Thus, according to the invention, injection into the seat ring 1
Since i(t) is uniform around the entire circumference and unnecessary biting is eliminated, it is possible to exhibit stable sealing performance over a long period of time, and the injection movement Ji(E) is uniform and Since it is set smaller than the valve body edge width (Ka),
The rubber bulge (A) shown in FIG. 23, which was seen in the conventional butterfly valve, 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 stem torque increases due to biting remains within a minute opening range, and as shown in Figure 22, a wide opening range with no torque fluctuation is adopted. I can do it. In Fig. 22, the dotted line indicates the opening-torque characteristic of the conventional butterfly valve, and the rm degree 3
While the valve stem torque fluctuates significantly below 0°, in the butterfly valve of the present invention, as shown by the solid line, the valve stem torque does not fluctuate from around 7°, and even at minute openings. The inward opening range of torque fluctuation is larger than that of conventional butterfly valves.

Furthermore, the fully closed seal angle of the valve is not 0° as in the past, but
Since the angle can be set to about 10 to 20', it is possible to cut the low opening portion of the valve with poor flow characteristics and use only the portion with good flow characteristics. 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. 24 and is easy to control as a control valve.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional perspective view of a butterfly valve according to the present invention, FIG. 2 is a vertical sectional view thereof, FIG. 3 is a front view, and FIG.
5 is a developed view of the seat ring, FIG. 6 is a perspective view of the seat ring, FIG. 7 is a sectional view taken along line 11ra-nl- of FIG. 9 is a sectional view taken along line b-1b, FIG. 9 is a sectional view taken along line mc-111c in FIG. 5, FIG. 10 is a sectional view taken along line md-#d in FIG. A partial front view showing the injection state of the ring and the valve body, Fig. 12 is a sectional view taken along the line 111■b-■a, and Fig. 13 is a sectional view taken along the line 111■b-IVb. Figure, 1st
Figure 4 is a sectional view taken along the line fVc-IVc in Figure 11.
Figure 5 is a sectional view taken along the line d-IVd in Figure 11, and Figure 16.
The figure is a cross-sectional view showing the relationship between the amount of injection of the valve body into the seat ring and the amount of biting movement, and shows Va-Va and v of FIG.
It is a representation in which parts along the b-vb line are overlapped. Figure 17 is a front view of the valve body, Figure 18 is Figure 17 0-Va.
19 and 20 are cross-sectional views showing the injection state of the seat ring and the valve body at the line portion, and the cross-sectional views shown in FIG.
Figure 21, which is similar to Figure 18 in the Vc line section, shows the radius (R) and width (
W), a conceptual diagram for determining the inner diameter (X1), Fig. 22 is a graph showing the relationship between valve opening degree and valve shaft torque, Fig. 23 is a cross-sectional view showing the state of rubber swelling due to the valve body, Fig. 24
The figure is a graph showing the valve opening versus flow rate characteristics of the conventional butterfly valve and the present invention. (1)...Body (2)...Valve body (3)
... Valve stem (4) ... Seat ring (5)
...Comb teeth (6)...Valve stem hole (7)...
Boss part (8)...First chevron seat part)...Second chevron seat part Patent applicant Tomoe Technology Research Institute Co., Ltd.
o.

Claims (1)

[Claims] (1) A hollow cylindrical main body made of a rigid material, a disc-shaped valve body made of a rigid material rotatably supported within the main body, and a space between the inner peripheral surface of the main body and the outer peripheral edge of the valve body. An annular seat ring made of an elastic material is interposed therebetween, and the seat ring has a pair of valve stem holes formed at diametrically opposed positions through which the valve stem passes, and a ring around each of the pair of valve stem holes. A boss portion is formed in which the base of the valve stem of the valve body is in pressure contact at all times, and a chevron-shaped seat portion in which the outer peripheral edge of the valve body is in pressure contact when the valve is closed is formed continuously along the circumferential direction between the pair of boss portions. In a butterfly valve with an adjustment function, the valve body has comb teeth extending toward the primary side and the secondary side at symmetrical positions about the valve shaft, and the chevron-shaped seat portion of the seat ring is the first and second
The first chevron seat has a radius (
R), width (W), and inner diameter (X_1) so that 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 the same at any outer periphery of the valve body. The second chevron-shaped seat part exists between the part of the first chevron-shaped seat part where the mechanical strength and sealing function as a seal are impaired and the boss part, and the second chevron-shaped seat part is set to A butterfly valve having an adjustment function, characterized in that the radius (R') is set at which the surfaces come into pressure contact, and the amount of biting movement of the valve body is set smaller than the width (Ka) of the edge surface of the valve body. .