JP2003161374A - Eccentric butterfly valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a smooth separation of valve seat section without causing flow rate loss at the time of full open and also without diminishing the sealing performance of a valve seat, while enabling easy of the fluid in the low opening range of a triple eccentric butterfly valve to be controlled. <P>SOLUTION: In the eccentric butterfly valve having triple eccentric structure of a first eccentricity which it makes the center of a valve body eccentric from the center of a valve spindle, a second eccentricity which makes the center of a valve spindle eccentric from the center of a valve body and a third eccentricity which makes the center line of the cone constituting the sealing surface of a valve body incline to the center line of a valve body, the thickness of a oval-shaped long spindle forming the periphery edge of a valve body is made more thickly than that of a short spindle, and it is characterized by decreasing the thickness from a long-spindle side to a short spindle side gradually with a smooth curve. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an eccentric butterfly valve having a structure in which the center of a valve body is eccentric with respect to the center of a valve rod that axially supports the valve body, and more particularly to fluid control in a low opening range. An eccentric butterfly valve that facilitates

[0002]

2. Description of the Related Art Conventionally, the center of a valve rod, which serves as a rotating shaft, is eccentric (primary eccentricity) from the center of a valve body, and is eccentric (secondary eccentricity) from the center of a valve body, and the valve body is sealed. An eccentric butterfly valve having a triple eccentric structure in which a center line of a cone forming a surface is inclined (positioned as a third eccentricity) from a center line of a valve body is known, and, for example, JP-A-11-1
It is disclosed in Japanese Patent Laid-Open No. 48563 and Japanese Patent Laid-Open No. 62-83563. Such a triple eccentric valve has the advantage that when opening the valve from fully closed, the valve body smoothly separates from the seat ring with less sliding, and the seat ring is less likely to be damaged. Since the valve element comes off almost all over the contact surface of the valve seat at the same time, and the gap between the valve element and the seat ring becomes large, it is easy for the fluid to flow from the low opening degree and the fluid can be controlled in the low opening degree area. There was a difficult problem. If the outer peripheral sealing surface of the valve body is formed thick over the entire circumference, the gap between the valve body and the seat ring at a low opening can be lengthened to increase the resistance due to the contraction of the fluid. It is considered that the flow rate can be controlled by suppressing the change in the flow rate in the opening range, but this may damage the seal surface of the valve seat when opening and closing the valve body, and at the time of fully opening the outer peripheral surface of the valve body. There is a risk that the thickness of the will cause fluid resistance and a sufficient flow rate cannot be secured.

[0003]

SUMMARY OF THE INVENTION The present invention makes it possible to easily control a fluid in a low opening region of a triple eccentric butterfly valve, and to prevent a flow loss at the time of full opening. An object of the present invention is to enable a smooth disengagement of the valve seat portion without impairing the sealability of the valve seat.

[0004]

Means for Solving the Problems The means adopted by the present invention for solving the above-mentioned problems are a primary eccentricity for eccentricizing the center of the valve body from the center of the valve shaft and a center of the valve shaft for the valve body. In an eccentric butterfly valve having a triple eccentric structure, a secondary eccentricity that is eccentric from the center and a third eccentricity that makes the center line of the cone that constitutes the sealing surface of the valve body inclined with respect to the center line of the valve body. The thickness of the elliptical shape that defines the outer peripheral edge of the valve disc is made thicker on the major axis side than on the minor axis side, and the change in thickness from the major axis side to the minor axis side continues in a smooth curve and gradually increases. It is characterized in that it is reduced to.

The thickness on the minor axis side is partially constituted by a parallel portion, and the parallel portion is continuous from the maximum thickness portion on the major axis side in a smooth curve, and the thickness is gradually reduced. And

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described in detail below. As shown in FIG. 1, the present invention makes the center (O) of the valve rod (3), which is the rotating shaft, eccentric (primary eccentricity) from the center (P) of the valve body (2), and 1) The position is eccentric (secondary eccentricity) from the center (Q), and the center line (R) of the cone that constitutes the sealing surface of the valve body is inclined from the center (Q) of the valve body (third order). An eccentric type eccentric butterfly valve having a triple eccentric structure is characterized in that the thickness of the outer peripheral portion of the valve body is changed in the major axis direction and the minor axis direction of the ellipse. The valve body seal portion and the seat ring inner diameter of the triple eccentric butterfly valve have an elliptical shape in which a cone is obliquely cut by primary eccentricity, secondary eccentricity, and tertiary eccentricity. Therefore, the inner circumference of the seat ring has an elliptical minor axis in the direction parallel to the valve axis and an elliptic major axis in the direction perpendicular to the valve axis. With such a structure, the valve body seal portion can be smoothly separated from the seat ring inner diameter portion when the valve body rotates.

The change in thickness of the outer peripheral portion of the valve disc in the major axis direction and the minor axis direction of the valve body, which is a feature of the present invention, is achieved as follows. Referring to FIG. 10, the thickness in the major axis direction of the outer circumference of the valve element is made thicker on the valve rod side, and the thickness in the minor axis direction of the valve element is made thinner than that on the major axis side. The thickness (c) on the minor axis side of the valve body partially becomes the parallel portion (d), and a curve is drawn from the maximum thickness portion on the major axis side of the valve body so that the thickness gradually decreases continuously to the parallel portion. The valve body surface on the side opposite to the valve rod mounting seat shall be a flat surface.
The thicknesses (a) and (b) of the long-diameter portion of the valve body are the thickness (b) on the side close to perpendicular to the surface on the side opposite to the valve rod mounting seat and the thickness (a) on the taper side in the cross section of the valve body. ) Are preferably the same, but do not necessarily have to be the same. The distance from the thickness of the valve body sealing surface on the side close to perpendicular to the surface opposite to the seat for valve stem installation to the thickness parallel part (d) of the minor diameter part is shorter than the distance to the center of the valve stem. It is set, and is limited by the distance from the major diameter portion on the taper side to the minor diameter parallel portion (d) as well as the eccentric amount and the positional relationship with the inner diameter portion of the seat ring.

[0008]

EXAMPLE Referring to FIGS. 2 to 15, (1) is a valve body having a substantially cylindrical flow passage extending therethrough, and the flow passage in the valve body is valved by a valve rod mounting seat (4). Wafer that is opened and closed by contact and separation between a disc-shaped valve body (2) rotatably supported by a rod (3) and a seat ring (5) arranged on the inner circumferential surface of the flow path of the valve body. This type of butterfly valve is, as mentioned above, the valve body (1),
The valve body (2) and the valve rod (3) have triple eccentric structures which are eccentric to each other. That is, the valve body (2) of the butterfly valve has the center (O) of the valve rod (3), which is the rotating shaft, as the valve body (2).
The eccentricity (primary eccentricity) from the center (P) of (2) and the eccentricity (secondary eccentricity) from the center (Q) of the valve body (1), and the conical surface forming the sealing surface of the valve body Center line (R)
Has a triple eccentric structure in which the valve is tilted from the center (Q) of the valve body to be positioned (third eccentricity).

FIG. 2 and FIG. 6 showing a cross section taken along line XX.
Referring to, the sealing surface of the valve body (2) has an elliptical shape, and when the valve is closed, the sealing surface is in close contact with the inner peripheral surface of the seat ring (5) to close the flow path. Seat ring (5) is tightening bolt (7)
And the seat retainer (8) is attached to the valve body (1) in an exchangeable manner. (9) is a seat ring (5) and a valve body (1)
It is a gasket that seals between and. The valve element seal portion and seat ring inner diameter of the triple eccentric butterfly valve are
As shown in the figure, the eccentric shape of the cone is cut diagonally by the primary eccentricity, the secondary eccentricity and the tertiary eccentricity. Is the shortest diameter, and is the longest diameter of the ellipse in the direction perpendicular to the valve axis.

Referring to FIGS. 9-12, seat ring (5)
The thicknesses (a) and (b) in the major axis direction of the outer peripheral portion of the valve element (2) which is in close contact with the inner peripheral surface of the are formed thicker than the thickness (c) in the minor axis direction. The thickness on the minor axis side of the valve body partially becomes a parallel portion (d), and the maximum thickness portion (a) (b) on the major axis side of the valve body.
To (Rt1) and (Rt2), the thickness is gradually reduced to the parallel portion (d). The surface (6) of the valve body opposite the valve rod mounting seat (4) is formed into a flat surface. The thicknesses (a) and (b) of the long-diameter portion of the valve body are the thickness of the side (a) that is nearly perpendicular to the surface on the side opposite to the valve rod mounting seat in the cross section of the valve body (b) and the side that is tapered (a). In the illustrated embodiment, they are almost the same, but they do not necessarily have to have the same thickness. The distance from the thickness (b) to the parallel part (d) of the valve body sealing surface on the side close to perpendicular to the surface (6) on the side opposite to the valve stem mounting seat (4) is the distance to the center of the valve stem. It is set shorter than the above, and is limited by the distance from the taper side major axis portion (a) to the minor axis parallel portion (d), the eccentric amount, and the positional relationship with the seat ring inner diameter portion.

With reference to FIGS. 13 to 15 showing a state in which a small opening valve is opened from the fully closed position, the flow path gaps (S1), (S1), in both the long diameter portions of the taper side (a) and the vertical side (b). S
2) and the lengths (L1) and (L2), the clearance (S3) of the conventional triple eccentric butterfly valve shown in FIGS.
Compared with (S4), length (L3), and (L4), the gap is narrower and the length is longer. As described above, in the butterfly valve of the present invention, since the width of the flow path is narrow and long at a low valve opening degree, the fluid flows as a contracted flow over a long distance, which causes resistance. Therefore, FIGS.
As shown in 0, the change in the flow rate when the valve body opens from the fully closed state can be suppressed to a small level, the flow rate can be controlled in a wide opening range, and the controllability can be improved.
Further, the thickness of the outer peripheral portion of the valve body can be made lower than that of the valve rod mounting seat, and the thickness of the outer peripheral portion (c) on the minor axis side located within the flow rate is also small. It is possible to suppress the flow loss of.

[0012]

According to the present invention, it is possible to easily control the fluid in the low opening region of the triple eccentric butterfly valve, and it is possible to suppress the flow loss at the time of full opening. Further, it is possible to smoothly disengage the valve seat portion without impairing the sealability of the valve seat.

[Brief description of drawings]

FIG. 1 is a diagram conceptually showing the structure of a triple eccentric valve.

FIG. 2 is a front view of an eccentric butterfly valve according to the present invention.

FIG. 3 is a side view of the same.

[Figure 4] Rear view of the same

FIG. 5 is a plan view of the same.

FIG. 6 is a sectional view taken along the line XX in FIG.

FIG. 7 is an enlarged view of the taper side.

FIG. 8 is an enlarged view of the same vertical side.

FIG. 9 is a front view of the valve body.

FIG. 10 is a plan view of the same.

FIG. 11 is a left side view of the same.

FIG. 12 is a right side view of the same.

FIG. 13 is a sectional view at a small opening.

FIG. 14 is an enlarged view of the taper side.

FIG. 15 is an enlarged view of the same vertical side.

FIG. 16 is a sectional view of a conventional butterfly valve at a small opening degree.

FIG. 17 is an enlarged view of the taper side.

FIG. 18 is an enlarged view of the same vertical side.

FIG. 19 is a graph showing the relationship between flow rate and opening.

FIG. 20 is a graph showing the relationship between flow rate and opening at low opening.

[Explanation of symbols]

(1) Valve body (2) Disc (3) Valve stem (4) Valve rod seat (5) Seat ring (6) Surface opposite the valve stem mounting seat (7) Fastening bolt (8) Sheet presser (9) Gasket (A) Thickness on major axis side (taper side) (B) Thickness on major axis side (vertical side) (C) Thickness on the minor axis side (D) Parallel part (S1) to (S4) Gap between valve body and valve body (L1) to (L4) Gap length

Claims (2)

[Claims] 1. A primary eccentric for eccentricizing the center of a valve element from the center of a valve shaft, a secondary eccentric for eccentricizing the center of a valve shaft from the center of a valve body, and a cone forming a sealing surface of the valve body. In an eccentric butterfly valve having a triple eccentric structure with a third eccentricity that inclines the center line of the valve body to the center line of the valve body, the thickness on the major axis side of the elliptical shape that defines the outer peripheral edge of the valve body is short. An eccentric butterfly valve characterized in that it is formed thicker than the diameter side, and the change in thickness from the long diameter side to the short diameter side is continuous in a smooth curve, and the thickness is gradually reduced. 2. The thickness on the minor axis side is partially formed by a parallel portion, and the parallel portion is continuous from the maximum thickness portion on the major diameter side in a smooth curve, and the thickness is gradually reduced. The eccentric butterfly valve according to claim 1.