JP2606956B2 - Butterfly valve seat ring - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a seat ring for a butterfly valve, and more particularly to a seat ring having a chevron seat portion.

[Conventional technology]

Conventionally, it is interposed between the entire inner peripheral surface of a hollow cylindrical main body (valve main body) made of a rigid material and the peripheral edge of a disk-shaped valve body made of a rigid material rotatably supported in the main body. An annular seat ring made of an elastic material is formed in an arc shape with a circular cross section,
As a result, the rotation angle of the valve body from the position where the valve body closes from the open position and starts to contact the annular seat ring until the valve body rotates to 90 ° fully closed position is reduced, and when the so-called valve body closes, the annular seat is closed. Prevents dragging the ring,
When the valve element is closed by forming the valve element into a mountain shape to reduce the repulsion spring constant when the valve element bites into the seat ring to reduce the rotational torque, it has been previously developed by the present applicant. (See Japanese Utility Model Publication No. 52-30600) Further, the entire periphery of the valve body peripheral edge except for the vicinity of the boss portion is simultaneously brought into contact with the inner surface of the seat ring having a chevron cross section as described above, thereby providing a sealing effect. And rotation torque at the same time, and waste torque (rotation caused by the fact that all points except for the point farthest from the valve shaft in the peripheral portion of the valve body bite into the chevron seat portion earlier. The one that eliminates the torque) has already been developed by the present applicant (see Japanese Patent Publication No. 58-25911).

In this case, (i) the width of the chevron seat portion of the seat ring is set to a minimum width in the vicinity of the boss portion as long as the mechanical strength as a seal is not impaired. , The width of the curved shape represented by the cosine function with the center of the boss portion as a base point is increased.

[Problems to be solved by the invention]

As shown in FIG. 6, the seat ring of the butterfly valve having a curved shape represented by the cosine function, which has already been developed by the present applicant, has a valve body 1 with a valve opening α.
Of the elastic seat ring 2a at the same time comes into contact (contact) with the inner surface of the angled seat portion 2 of the elastic annular seat ring 2a. There was a problem.

In general, in the case of a butterfly valve, when the valve opening is 70 ° or more, the flow characteristics hardly change, and in order to extend the control range from fully closed to fully open, the closer the fully closed position is to 0 °, the better. It is advantageous.

Also, a 1 for penetrating the valve stem 3 supporting the valve element 1 is provided.
The boss portion of the seat ring 2a (not shown) corresponding to the vicinity of the periphery of the pair of through holes is constantly pressed against the periphery of the valve body 1, and therefore receives a torsional stress due to the rotation of the valve body 1 and is important in strength. It is a problem.

Further, as shown in the front view of the valve body of FIG. 5, the closing torque is the length of the arbitrary point P on the periphery of the valve body 1 with respect to the center point S when the point P rotates around the valve body center axis C. (Arm) ▲ ▼ = l = r
cos θ (where r is the radius of the valve body and θ is the phase angle), for example, the allowance of the angled seat 2 (FIG. 6) of the rubber seat ring 2a for closing the pressure of 10 kg / cm ² . Is 1 mm, crushing force of 1 mm at the boss B (θ = 90 °) and crushing 1 mm at the portion A (θ = 0 °) at the tip of the valve body corresponding to the center between the upper and lower bosses B, B With respect to the force, the latter increases the l (arm) and increases the closing torque, so that an actuator (not shown) for driving the valve element 1 needs to have a large load capacity and is uneconomical.
The above tendency was remarkable in a seat ring which has been developed and has a curved shape represented by a cosine function and widened toward the center between both bosses of the chevron seat.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a butterfly valve having high mechanical strength near a boss portion and having a chevron seat portion capable of controlling a flow rate.

Another object of the second invention is to allow the flow rate control to be performed in proportion to the valve opening.

[Means for solving the problem]

In order to achieve the above object, a first aspect of the present invention provides a hollow cylindrical main body made of a rigid material, and a valve made of a rigid material rotatably supported in the main body. An annular seat ring made of an elastic material is interposed between the outer peripheral portion of the body and the annular seat ring. A pair of bosses for forming a close contact with each other is formed.
In a butterfly valve provided with an annular seat ring formed between a pair of bosses and formed continuously along the circumferential direction with a chevron-shaped seat portion for press-contacting the peripheral edge portion of the valve body when the valve is closed, the chevron-shaped seat portion of the seat ring Is increased so as to increase the mechanical strength as approaching the vicinity of the boss portion, and the width of the angled seat portion is reduced toward the center between the two boss portions, and when the valve is closed, the valve body peripheral portion and the angled seat are reduced. The second invention is characterized in that an opening cross-sectional area between a valve body peripheral portion and a chevron seat portion of a seat ring is gradually increased from both boss portions toward a center portion. In order to increase or decrease in proportion to the valve opening, the peripheral portion of the valve body and the chevron seat portion are sequentially brought into close contact from both boss portions toward the center portion.

(Operation)

Since the present invention is configured as described above, in the first invention, when the valve element is closed from the open state, the valve element peripheral portion is constantly pressed into contact when the set valve opening degree is reached. From the boss portion of the seat ring, which comes into contact with the central portion, the flow rate is gradually and gradually controlled in accordance with the valve opening degree.

According to the second aspect of the present invention, the opening cross-sectional area between the peripheral portion of the valve body and the chevron seat portion of the seat ring increases or decreases in proportion to the valve opening. Various control characteristics can be realized by the butterfly valve.

〔Example〕

 Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a drawing of a seat ring showing an embodiment of the present invention. FIG. 1 (a) is a development view of a portion corresponding to a substantially semicircular length, and FIG. 1 (b) is a drawing of FIG. FIG. 6A is a cross-sectional view at each of 10 divided positions of 0 ° to 90 ° in FIG. 6A, in which the same reference numerals as those shown in FIG. 6 indicate the same or similar parts.

In the figure, an annular seat ring 12a attached to the inner surface of a main body (valve main body), not shown, has a pair of bosses 4, 4 around a valve stem through hole 3a, as shown in a developed view of FIG.
4 is formed, and between the pair of bosses 4, 4, when the valve is closed,
The cross-sectional chevron seat portion 12 for pressing against the peripheral portion of the valve body,
It is formed continuously along the circumferential direction.

3 (a) and 3 (b), when the valve opening degree is α and the phase angle of an arbitrary point P on the periphery of the valve element 1 is θ. , Α = θ, and as shown in FIG.
FIG. 1B shows the cross-sectional shape of the chevron sheet portion 12 at each of the divided phase angle θ positions.

In this embodiment, the opening cross-sectional area (flow path cross-sectional area) formed by the gap between the valve element 1 and the annular seat ring 12a is:
The peripheral portion of the valve body and the chevron seat portion 12 are formed so as to be in contact with each other so as to increase and decrease with an equal cross-sectional area for each valve opening α, that is, to increase and decrease in proportion.

3 (a) and 3 (b) are drawings for explaining the above-mentioned relationship, wherein FIG. 3 (a) is a top view of FIG. 3 (b), and FIG. 3 (b) is a front view showing the open / closed state of the valve element 1. In the drawing, O is the center of the valve element 1, A is the tip position when the valve element 1 is in the fully closed state, B is the intersection between the valve stem centerline C and the valve element 1, and P is the peripheral part of the valve element. And R is a point symmetrical to P with respect to B, the tip position of the valve element 1 when the valve element 1 is opened from the fully closed position (α = O in FIG. Is A ', and the valve element 1 at this time has an elliptical shape in which the major axis is 2b and the minor axis is 2a in the same figure (b), and a = r cosα b = r (where r is the valve element Radius).

In addition, the area of the circle S ₀ = πr ² The area of the ellipse S ₂ = πab = πr ² cosα On the other hand, the fluid passage, that is, the cross section of the opening when the valve element 1 is opened corresponds to the area difference S ₃ between the circle and the ellipse. to _{order, S 3 = S 0 -S 2} = πr 2 -πr 2 cosα = πr 2 (1-cosα) area difference S ₃ corresponding to the above-described fluid passage, equally divided has been increased or decreased in accordance with the valve opening α In order to obtain a cross-sectional area such that the P-shaped portion at the phase angle θ position equal to the valve opening α is in contact with the chevron seat portion 12, the P-shaped portion is The curve of the chevron sheet portion 12, that is, the cross-sectional shape at each phase angle position, is obtained by keeping the parallel oblique line portion D with the portion B in a closed state.

FIGS. 2 (a) and 2 (b) show that the valve element 1 in the fully open position with the valve opening α = 90 °, the P portion of θ = 80 ° abuts the chevron seat portion 22 when α = 80 °. FIGS. 1 (a) and 1 (b) show an embodiment in which, when α = 0 °, θ = 0 ° and a fully-closed state is formed to form a chevron curve.

According to this embodiment, the flow rate control can be performed over a wide angle range of the valve opening.

FIG. 4 is a cross-sectional view of a main part showing another embodiment showing a seat ring portion having the narrowest width at the center between both boss portions 4. In order to increase the mechanical strength of the portion, the boss portion is shown. One peak (radius R ₀ ) is formed at the root width (W ₀ ) of the root of _No. 4, and the above-mentioned peak-shaped sheet portion 12 (radius R ₁ ) having the above-mentioned predetermined width is further provided thereon. Note that the radius R ₁ <R ₀ is satisfied.

In both embodiments described above, the structure in which the flow rate can be controlled in proportion to the valve opening degree has been described, but the valve opening degree and the control flow rate can be arbitrarily set other than the proportional relation. .

〔The invention's effect〕

As described above, according to the present invention, the angled seat portion of the annular seat ring is made wider as approaching the vicinity of the boss portion, and the angled seat portion is reduced in width toward the center between both bus portions, At the time of closing the valve, the following effects can be achieved by making the peripheral portion of the valve body and the chevron seat portion come into close contact with each other in a stepwise manner from the boss portions toward the center portion.

(I) When the fully-closed position simultaneously contacting the chevron seat portion over the entire circumference of the valve body is set to 30 ° or less in the valve opening degree in the conventional device already developed by the present applicant, the seat near the boss is set. While the difference between the width and the center sheet width almost disappears, in the present invention,
Even when the valve opening degree is 30 ° or less, not only can the center part be narrowed to a width slightly larger than the edge thickness of the peripheral part of the valve body, but also the mechanical strength near the boss can be increased.

(Ii) Since the flow control can be performed in a range smaller than the set valve opening, the butterfly valve can be used as a flow control valve.

According to the second aspect, the opening cross-sectional area between the peripheral portion of the valve body and the chevron seat portion of the seat ring is increased or decreased in proportion to the valve opening, thereby achieving control characteristics such as a globe valve. Can be realized by a butterfly valve. Therefore, the valve drive unit may be of a general proportional control type, so that the cost can be reduced.

[Brief description of the drawings]

1 (a) and 1 (b) are a development view of an annular seat ring showing one embodiment of the present invention, a cross-sectional view at each position divided at every 10 °, and FIGS. 2 (a) and 2 (b). FIGS. 3A and 3B are views similar to FIGS. 1A and 1B showing another embodiment, and FIGS. 3A and 3B are views for explaining the action of a valve body with respect to FIGS. FIG. 4 is a sectional view of an essential part showing another embodiment of the present invention, and FIGS. 5 and 6 are explanatory views showing a contact relationship between a valve body and a chevron seat portion of a seat ring. 1 ... Valve, 2,12,22 ... Gantt seat, 2a, 12a, 22a ...
... Seat ring, 3 ... Valve stem, 3a ... Valve stem hole, 4 ... Boss, α ... Valve opening, θ ... Phase angle.

Claims (2)

(57) [Claims] An annular seat made of an elastic material is provided between the entire inner peripheral surface of a hollow cylindrical main body made of a rigid material and a peripheral portion of a valve body made of a rigid material rotatably supported in the main body. A ring is interposed, and a pair of boss portions are formed in the annular seat ring around the pair of through holes for allowing the valve stem to pass therethrough, so as to constantly press the valve body near the base of the valve stem, In a butterfly valve provided with an annular seat ring formed continuously along the circumferential direction between the pair of bosses and formed along the circumferential direction with a chevron-shaped seat portion for press-contacting the peripheral portion of the valve body when the valve is closed, The seat portion is widened so as to increase the mechanical strength as approaching the vicinity of the boss portion, and the width of the chevron seat portion is reduced toward the center between both boss portions, and when the valve is closed,
A butterfly valve seat ring in which a valve body peripheral portion and said chevron seat portion are sequentially and closely contacted from both boss portions toward a central portion. 2. The valve body peripheral portion and the chevron seat portion are separated from both boss portions so that the opening cross-sectional area between the valve body peripheral edge portion and the chevron seat portion of the seat ring is increased / decreased in proportion to the valve opening. 2. A seat ring for a butterfly valve according to claim 1, wherein the seat ring is arranged to be closely contacted sequentially toward a center portion.