Offset butterfly valve

Details Offset butterfly valve Offset butterfly valve

2000-04-19

2001-09-04

Shaver, Kevin (Department: 3754)

Valves and valve actuation

Rotary valves

Butterfly

C251S074000, C251S313000

Reexamination Certificate

active

06283448

ABSTRACT:

TECHNICAL FIELD
The present invention relates to butterfly valves and more particularly to a butterfly valve with a valve body air flow conduit there through with no interruptions to impede or disrupt air flow. Any cross section of the conduit is about equal in diameter and essentially round. A valve plate is dimensioned as an oblique cross section of the conduit at a location in the conduit where the valve plate will seal. The valve plate has first and second coplanar sections extending on respective sides of its axis of rotation while the axis of rotation is offset with respect to the center of the valve plate and offset with respect to a center of the conduit. Rotation of the offset oblique shaped valve plate within the round conduit is accomplished by two opposing indentations on the interior surface of the conduit which accommodate a maximum diameter of an opened valve plate. The peripheral edge of the valve plate is easily machined to seal with an interior surface of the conduit which is continuous with the conduit interior surface providing a smooth unobstructed efficient air flow path.
BACKGROUND ART
Butterfly valves have been around a long time. One can find butterfly valves in numerous applications such as sewer vent stack checks, turbine checks, exhaust brakes, throttle valves, and air intake shut-off devices. Simplicity of operation make the butterfly valve the choice in these and many other applications. The offset butterfly valve was developed to satisfy the need for self closure which works nicely for check valves of all sort. One of the problems with the offset butterfly, is that rotating a round or oblique valve plate in a cylindrical conduit about a rotational axis offset from the center of the valve plate and offset from the center of the conduit is impossible because the maximum diameter of the valve plate will not be accommodated by the dimensional cross section within the conduit along the plane parallel with the rotation axis of the valve plate and parallel with the center of the conduit. An assortment of solutions to this problem have been described in the prior art, such as:
Biddle, U.S. Pat. No. 3,941,151 which describes and claims a vent pipe check valve with offset valve plate that provides an example of placing semi-annular seat means for sealing at upper and lower surfaces of the valve plate on respective opposite sides of the valve plate pivot axis.
Meneely, U.S. Pat. No. 5,676,110 which describes and claims an exhaust brake with offset butterfly valve plate that provides an example of enlarging an upstream section of the conduit to accommodate the maximum diameter of the valve plate rotating into the enlarged area.
Herron, U.S. Pat. No. 5,392,812 which describes an offset hinged flapper valve useful as a turbine inlet check valve providing an example of altering the valve plate dimensions with side planar surfaces, which decrease the maximum diameter of the valve plate, while also providing accompanying planar surfaces on the interior of the conduit to accommodate the valve plate.
While the prior art has satisfied numerous problems associated with offset butterfly valves there is always a need to improve air flow efficiency through the valve air flow conduit which, as those skilled in the art know, is accomplished by reducing air flow disruption caused by interruptions in the air flow path. The present invention accomplishes this by providing a butterfly valve with no interruptions extending into the air flow conduit, besides the valve plate, while also providing an air flow conduit with an essentially round cross section with a diameter which may be maintained throughout the length of the valve and while the valve plate is dimensioned as an oblique cross section of the conduit. The axis of rotation of the valve plate is offset from the center of the valve plate and further offset from the center of the conduit while rotation of the valve plate within the conduit to an open position where the valve plate is aligned with a plane parallel with the axis of rotation of the valve plate and the center of the conduit is accomplished by providing two opposing indentations on the interior surface of the conduit which accommodate the maximum diameter of the valve plate when rotated to an open position.
GENERAL SUMMARY DISCUSSION OF INVENTION
It is thus an object of the invention to provide an offset butterfly valve with improved air flow efficiency with no interruptions extending into the valve air flow conduit while a cross section of the conduit is essentially round and a consistent diameter for the length of the valve and the valve plate rotatably positioned and offset therein is an oblique cross section of the conduit.
It is a further object of the invention to provide an offset butterfly valve with an offset valve plate with a rotation axis offset from the center of the valve plate and offset from the center of the air flow conduit which is dimensioned as an oblique cross section of the air flow conduit and includes a sealing periphery which mates with a sealing surface in the interior of the air flow conduit wherein the sealing surface on the interior of the conduit includes no interruptions or disruptions of air flow there through.
Accordingly, an offset butterfly valve is provided that includes a valve body with an air flow conduit extending there through wherein any cross section of the conduit is about equal in diameter and essentially round with no interruptions to impede or disrupt air flow there through. A valve plate is dimensioned as an oblique cross section of the conduit at a location in the conduit where the valve plate will seal with an interior surface of the conduit. The valve plate is rotatable mounted within the conduit with an axis of rotation offset from the center of the valve plate and further offset from the center of the conduit while rotation of the valve plate within the conduit to an open position, where the valve plate is aligned with a plane parallel with the axis of rotation of the valve plate and the center of the conduit is accomplished by providing two opposing indentations on the interior surface of the conduit which accommodate the maximum diameter of the valve plate when rotated to an open position. The peripheral edge of the valve plate is easily machined to seal with an interior surface of the conduit which is continuous with the conduit interior surface providing a smooth unobstructed efficient air flow path. The valve plate shaft ends may be contained within the material forming the valve body or exit one or opposing sides on the valve body providing attachment locations for latching, biasing, tripping, closing or opening means. The valve may be adapted for numerous applications which will dictate inclusion of and a type of valve tripping or shaft rotation biasing means attached thereto. The shaft rotation may be allow to freely rotate when the valve is used as a check, while a spring biasing the shaft to rotate closed may be used for other applications such as a diesel exhaust brake, or air flow intake shut-off device. Tripping the shaft to rotate to a closed position may also be accomplished by any number of suitable means beyond the scope of this application.


REFERENCES:
patent: 3809361 (1974-05-01), Pfundstien et al.
patent: 3941151 (1976-03-01), Biddle
patent: 4533114 (1985-08-01), Cory et al.
patent: 4659064 (1987-04-01), Scobie et al.
patent: 5048552 (1991-09-01), Bourne
patent: 5103858 (1992-04-01), Hunt
patent: 5392812 (1995-02-01), Herron
patent: 5464696 (1995-11-01), Gmelin
patent: 5673895 (1997-10-01), Kaneko
patent: 5676110 (1997-10-01), Meneely
patent: 5762044 (1998-06-01), Hollister et al.

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