WO1983004430A1

WO1983004430A1 - Butterfly valve

Info

Publication number: WO1983004430A1
Application number: PCT/US1983/000754
Authority: WO
Inventors: Robert L. Widdows
Original assignee: Cashco, Inc.
Priority date: 1982-06-07
Filing date: 1983-05-18
Publication date: 1983-12-22
Also published as: EP0110957A1

Abstract

A butterfly valve (10) adapted for precision control of fluid flow includes a novel annular seating ring (22) of resilient material which reduces seating forces required and enables the valve to open to a selected position more smoothly in response to an input command signal without a sudden or excessive disk reaction as sealing pressure on the seat is relaxed during initial opening. The resilient seating ring (22) includes a first seating surface (124) on one side of a valve disk pivot axis (30) dimensioned for confronting a peripheral edge portion on one face of the valve disk (26) on one side of the pivot axis (30) when the disk is closed and a second seating surface (126) on an opposite side of the pivot axis (30) dimensioned for confronting another peripheral edge portion on an opposite face of the disk (26) on the opposite side of the pivot axis (30).

Description

BUTTERFLY VALVE BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a new and improved butterfly valve and more particularly a but- terfly valve employing a novel, annular seating ring and valve disk designed to provide for more precise control of fluid flow through the valve in response to input command signals.

2. Description of the Prior Art The following United States Patents illus¬ trate and describe valves which are typical of the prior art:

U.S. Patent No. 3,122,353 Killian U.S. Patent No. 3,143,132 Pangburn U.S. Patent No. 3,173,.650 Cotterman

U.S. Patent No. 3,306,573 Trefil U.S. Patent No. 3,338,551 Black U.S. Patent No. 3,346,005 Hanssen OBJECTS OF THE INVENTION it is an object of the present invention to provide a new and improved butterfly valve and more particularly, a butterfly valve having an improved valve seating ring design adapted to reduce the seating pressure required to obtain a fluid tight seal when the valve is closed.

Another object of the invention is to provide a butterfly control valve specially adapted to open to a selected position in response to an input command signal without sudden and excessive disk force reactions as the valve disk initially clears the seat¬ ing ring.

Another object of the present invention is to provide a butterfly valve of the character described having a resilient annular seating ring which provides an increased life yet tight sealing effectiveness thorughout the life of the seating ring.

Still another object of the present inven¬ tion is to provide a new and improved butterfly valve of the character described which employs an annular seating ring of resilient material of novel design which reduces the amount of torque applied to a valve stem supporting the valve disk that is necessary for effecting a fluid tight seal or closure of the valve. Still another object of the present inven¬ tion is to provide a new and improved butterfly valve in which distortion of the resilient seating ring when the valve disk is closed is minimized yet which provides effective fluid tight sealing while the valve is closed.

Still another object of the present inven¬ tion is to provide a new and improved butterfly valve of the character described in which built up co pres- sive forces in the resilient seating ring while the valve is a closed condition do not result in sudden and excessive forces reacting upon opening of the disk from the closed position so as to cause the disk to open beyond a selected position as set forth or programmed by a control instrument signal utilized for precision control of the open position of the valve disk.

Yet another object of the present invention is to provide a new and improved butterfly control valve which reduces excessive valve swing or oscil- lations during initial valve opening which would otherwise resit from pent up compressive sealing forces in the valve seating ring being suddenly relaxed during initial stages of valve opening. BRIEF SUMMARY OF THE INVENTION The foregoing and other objects and advan¬ tages of the present invention are accomplished in a new and improved butterfly control valve useful for precision control of fluid flow. The valve includes a body with an annular valve seating ring of resilient material mounted in the body and defining an internal flow passage through the body between opposite upstream and downstream faces of the seating ring. A valve disk is mounted for pivotal movement about a pivot axis extending across the seating ring between opposite faces thereof and the pivot axis divides a cross-section of the flow passage into a pair of flow segments on opposite sides of the axis. Stem(s) or pivots are provided for supporting the valve disk to pivot between a sealed or closed position, generally transverse to the axis of the flow passage and an open position angularly disposed thereto for permit¬ ting a controlled rate of fluid flow through the pas- sage.

The resilient valve seating ring includes a first seating surface on one side of the pivot axis dimensioned for sealing confrontation with a peripheral edge portion on one face of the closed valve disk on one side of the pivot axis, and a second seating sur¬ face on an opposite side of the pivot axis dimensioned for sealing confrontation of an opposite peripheral edge portion formed on an opposite face of the valve disk on an opposite side of the pivot axis. The first and second seating surfaces of the annular seating ring extend into a pair of planar surface areas gener¬ ally normal to the pivot axis adjacent opposite edges of the valve disk. The novel seating surface design permits fluid tight sealing of the valve disk in a closed position with a minimum of seating pressure being required. Moreover, the seating surface design eliminates or greatly reduces the possibility of sudden and excessive reactive forces on the valve disk as it is initially opened from the sealed or closed position in response to a precise amount of input torque applied to the valve disk as prescribed by an input command signal from a controller. BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the present invention, reference should be had to the following detailed description taken in conjunction with the drawings, in which:

FIG. 1 is a longitudinal cross-sectional view of a typical prior art butterfly valve; FIG. 2 is a longitudinal cross-sectional view of a new and improved butterfly control valve constructed in accordance with the features of the present invention;

FIG. 3 is an elevational view of an end face of a new and improved annular valve seating ring constructed in accordance with the features of the present invention and looking in the direction of arrows 3-3 of FIG. 2;

FIG. 4 is a transverse, cross-sectional view of the annular valve seating ring taken substan¬ tially along lines 4-4 of FIG. 3;

FIG. 5 is a transverse, cross-sectional view of the annular valve seating ring taken substan¬ tially along lines 5-5 of FIG. 3; and FIG. 6 is a transverse, cross-sectional view of another embodiment of a valve seating ring in accordance with the present invention similar to that shown in FIG. 5 but with a valve disk pivot axis spaced eccentrically of a longitudinal central axis through the flow passage of the valve seating ring. DESCRIPTION OFTHE PREFERRED EMBODIMENTS Referring now more particularly to the drawings, in FIG. 1 is illustrated a typical prior art butterfly control valve 10 having a valve body 12 formed of upstream and downstream sections 14 and 16 defining a flow path 18 therethrough for containing fluid under pressure in a static or a flowing condi¬ tion. Typically, the upstream and downstream segments of the valve body are formed with shouldered recesses 14a and 16a respectively, in which recesses is seated a collar or ring 20 adapted to contain and support an annular valve seating ring 22 formed of resilient material and provided with a stiffening ring 24 of metal or the like. The valve 10 includes a butterfly valve disk 26 supported for pivotal movement on a stem or pivot axle 28 extending transversely across the flow passage within the interior bore of the seating ring 22. The stem 28 is pivotable about a longitudinal axis 30 thereof which transversely intersects a longi¬ tudinal, centrally disposed flow axis 32 in the fluid passage 18 extending between the upstream and down¬ stream portions 14 and 16 of the valve body.

The pivot axis 30 is preferably positioned to lie on a central plane 34 midway between opposite faces 22a of the valve seating ring 22. The valve disk 26 is pivotable about the axis 30 between a closed position (as shown extended transversely across the flow axis 32) in a counterclockwise direction toward an open position as indicated by the arrow "A".

For the purpose of providing precise and accurate control of fluid flow, the precise angular position of the valve disk 26 relative to the flow axis 32 is controlled and selected at a particular angle with respect to the fully closed or sealed posi- tion as shown, and for the purpose of effecting such control, input torque of a corresponding value is applied to the valve disk supporting stem 28 to rotate the disk to a selected angle of an open position as desired.

Typically, the valve disk 26 of the prior art valve in FIG. 1 is formed with a rounded outer peripheral edge 26a and the disk has an outer diameter which is slightly greater than a minimum inside diameter or bore 22b (dotted lines) of the resilient valve ring 22 on the plane 34. Consequently, when the valve is closed to effect a seal between the upstream and downstream portions 14 and 16 of the valve body, the rounded outer peripheral edge portion 26a of the valve disk 26 causes inward deflection and compression of the resilient material of the seating ring 22 in an area contacted by the rounded edge (designated by the numeral 23) in order to establish a fluid tight seal. Because of the interference between the minimum diameter central portion of the seating ring 22 and the outer diameter of the valve disk 26, when the valve is closed, the compression forces in the valve seat tend to exert sudden and excessive disk reaction forces on the valve disk as it is initially cracked open or moved out of the closed or sealed position.

Often times these forces are difficult to control and result in excessive swing of the valve disk beyond the desired position which is sought by the opening command or control signal applied as opening torque to the valve stem 28.

Referring now to FIGS. 2-5, in accordance with the present invention, a valve 10 includes a new and improved, annular valve seating ring 122 formed of resilient material and provided with opposite side faces 122a and a metal stiffening element 24 similar to the prior art seating ring 22. The valve seating ring 122 includes a first seating surface 124 adapted to directly face and confront a narrow peripheral edge portion on the rounded edge 26a of the valve disk 26 when the disk is in a closed or sealed posi¬ tion as shown in FIG. 2. The seating surface 124 is positioned above the pivot axis 30 and the longitudinal, centrally disposed flow axis 32 of the flow passage and is on the upstream side of the transverse plane 34.

The seating ring includes a second con¬ fronting valve seating surface 126 on the downstream side of the transverse plane 34 and located below the pivot axis 30 and the longitudinal flow axis 32 as illustrated in FIG. 2. The seating surfaces 124 and 126 directly confront opposite upper and lower narrow strips along the peripheral edge of the valve disk 26, but on opposite sides of the transverse plane 34 to provide a fluid tight seal when the valve is closed (as shown in FIG. 2) . This directly confronting rela¬ tionship provides a fluid tight seal with a minimum of distortion or seating pressure being required so. that excessive and sudden releases of pent up force from compressed or deformed resilient material of the seating ring is eliminated or reduced. As the valve disk 26 is initially cracked open and begins to move from the fully closed or sealed condition (as shown) toward an open position for permitting fluid flow through the passage 18, the forces exerted thereon from the seating ring 122 are minimal.

Adjacent a mid-portion of the seating ring 122, both above and below the pivot axis 30, the seating ring is formed with a pair of planar, circular shaped seating surfaces 128, spaced parallel ana on opposite sides of the central flow axis 32 in concen-

WIP tric relation to the pivot axis 30. These planar surfaces (as shown in FIG. 5) are adapted to directly confront, adjacent facing opposite side edges of the valve disk 26 as the disk rotates from an open to a closed position and vice versa.

The seating ring 122 and its metal stiffener 24 are formed with respective circular stem openings 122c and 24a in concentric alignment with the pivot axis 30 in order to accommodate pivot axles or stems 28 supporting the valve disk 26. As shown in FIG. 5, these openings for the stems are in concentric centered alignment with respect to the circular planar surfaces 128 on opposite inside faces of the resilient seating ring. In accordance with the present invention, the internal bore of the valve seating ring 122 is provided with an arcuate first passage surface 130 defining an upper portion- or segment of an upstream flow passage above the central flow axis 32 and on the upstream side of the transverse plane 34 as viewed in FIG. 2. The first passage surface 130 is dimen¬ sioned with a radius or diameter less than the radius or outer diameter of the valve disk 26 and is joined to the inner periphery of the arcuately shaped first seat- ing surface 124. Similarly, the valve seating ring includes a second passage surface 132, but on the down¬ stream side of the transverse plane 34 and below the central flow axis 32. The surfaces 130 and 132 are of substantially equal diameter and neither surface extends beyond the central flow axis 32 toward the other. The second flow passage surface 132 is joined to the inner peripheral edge of the arcuate, second seating surface 126 and an outer edge of the seating surface is in turn joined with a second, clearance passage surface 134 positioned on an opposite or up- stream side of the transverse plane 34 below the flow axis 32 as shown in FIG. 2. Similarly, the outer edge of the first seating surface 124 is joined with a first clearance passage surface 136 on the down- stream side of the transverse plane 34 and above the central axis 32 as shown in FIG. 2.

The first seating surface 124, the first passage surface 130 and the first clearance surface 136 define a wall surface of an upper half segment or portion of the whole flow passage 18 above the central flow axis 32 and the second seating surface 126, the second passage surface 132 and the second clearance surface 134 define a similar wall surface of a lower half of the flow passage below the central flow axis 32. The surfaces 134 and 136 have a radius is equal to or just slightly greater than the maximum radius of the circular valve disk 26 around the outer peri¬ phery thereof so that no interference is encountered with the seating ring 122 when the valve disk 26 is pivoted to open in a counterclockwise direction from the closed position as shown in FIG. 2. Because no interference between the disk 26 and the surfaces 134 and 136 is encountered during unseating of the value disk, there is little possibility for any displaced resilient material in the annular valve seat ring to expand as seating pressure is released to exert exces¬ sive or undue sudden opening torque on the valve disk as it is initially cracked open. Adjacent the central portion of the flow passage, both above and below the flow axis 32 and the pivot axis 30, the surfaces 130, 132, 134 and 136 blend into the respective, circular side planar surfaces 126 through a pair of crescent shaped, frustroconical transition surfaces 138 which form elliptically shaped patterns concentrically around the pivot axis 30 as best shown in FIGS. 2 and 5. Referring now to FIG. 6, therein is illus¬ trated another embodiment of an annular valve seating ring 222 which is similar to the ring 122 except that a pivot axis 30A of the valve disk 26 is eccentrically positioned with respect to the central flow axis 32 of the passage 18 in the valve body. The valve seating ring 222 is similar in function and operation to the previously described seating ring 122 except for the eccentric position of the pivot axis of the valve disk with respect to the longitudinal flow axis 32 of the valve body. The pivot axis 30A divides the flow passage into segments or cross-sectional areas of unequal valve rather than the substantially equal area flow passage segments above and below the flow axis 32 in the embodiment of FIGS. 2-5.

The annular valve seating rings 122 and 222 of the present invention provide a minimum of seating pressure necessary to establish a fluid tight seal with the valve disk 26 in a closed position centered on the plane 34 because of unique seat design which eliminates interference between the disk and seat. Upon initial application of torque to the stem 28 of the valve disk during an opening cycle, little if any uncontrolled excessive or sudden force is encountered because of compressive stresses in the resilient material of the valve seat being released and conse¬ quently, the valve seating rings 122 and 222 provide for accurate flow control characteristics permitting precision control of fluid flow in direct response to input torque of valve opening command signals applied to the control valve stem 28.

Although the present invention has been described with reference to several illustrated embodi¬ ments thereof, it should be understood that numerous other modifications and embodiments can be made by those skilled in the art that will fall within the spirit and scope of the principles of this invention. What is claimed as new and is desired to be secured by Letters Patent is:

Claims

1. A butterfly valve including a body, an annular valve seating ring of resilient material mounted in said body and defining an internal flow passage through said body between opposite, upstream and downstream faces of said seating ring, a valve disk mounted for pivotal movement in said ring about a pivot axis extending across said ring and between said opposite faces, said pivot axis dividing a cross- section of said flow passage into a pair of segments on opposite sides of said axis, and stem means for supporting said valve disk to pivot between a closed position angularly disposed thereto, said seating ring having a first seating surface on one side of said pivot axis dimensioned for sealing confrontation with a peripheral edge portion on one face of said vavle disk on one side of said pivot axis when said valve disk is in said closed position and a second seating surface on an opposite side of said one side of said pivot axis dimensioned for sealing confronta¬ tion with another peripheral edge portion on an oppo¬ site face of said valve disk on an opposite side of said pivot axis when said disk is in said closed posi¬ tion.

2. The butterfly valve of claim 1 wherein said seating ring is formed with one pair of parallel, planar surfaces on the inside thereof normal to said pivot axis confronting opposite edges of said valve disk.

3. The butterfly valve of claim 2 wherein said planar surfaces are spaced inwardly of adjacent portions of said first and second seating surfaces toward a center point on said pivot axis.

4. The butterfly valve of claim 1 wherein said valve seating ring includes a first inside passage surface joining said first seating surface on an up- strea portion of said ring and a second inside passage surface joining said second surface on a downstream portion of said ring, said inside passage surfaces having portions spaced inwardly of respective first and second inside clearance surfaces of said ring toward a center point on said pivot axis.

5.^' The butterfly valve of claim 4 wherein said respective first and second inside clearance surfaces of said ring are spaced outwardly of adjacent edge portions of said valve disk from said center point. β . . The butterfly valve of claim 5 wherein said respective first and second inside passage sur¬ faces are spaced inwardly of adjacent edge surfaces of said valve disk toward siad center point when said valve disk is in said closed position.

7. The butterfly valve of claim 6 wherein said first inside passage surface and said first inside clearance surface define a first wall surface of said flow passage on said one side of said pivot axis and wherein said second inside passage surface and said second inside clearance surface define a second wall surface of said flow passage on said opposite side of said pivot axis.

8. The butterfly valve of claim 7 wherein said seating ring is formed with one pair of parallel, planar surfaces on the inside thereof normal to said pivot axis and confronting opposite edges of said valve disk, and a pair of annular transition surfaces around said planar surfaces joining said inside sur¬ faces of said passage along outer edge portions.

9. The butterfly valve of claim 8 wherein said flow passage has a generally circular transverse cross-section bisected by said pivot axis of said valve disk and wherein said planar surfaces are gener¬ ally circular shaped.

10. The butterfly valve of claim 9 wherein said pivot axis is offset from a center of said flow passage and said planar surf ces* are generally ellip¬ tical in shape.