Valve structure adapted to be arranged in a flue bend

Claim 1

IN COMBINATION WITH A DUCT ALONG WHICH FLUID IS ADAPTED TO FLOW, VALVE STRUCTURE FOR CONTROLLING FLOW OF FLUID ALONG SAID DUCT, SAID VALVE STRUCTURE REQUIRING SUBSTANTIALLY SMALL FORCES FOR ACTUATION TO OPEN AND CLOSED POSITIONS AND WHEN IN ITS OPEN POSITION PRODUCING NEGLIGIBLE RESISTANCE TO FLOW OF FLUID ALONG SAID DUCT, SAID VALVE STRUCTURE COMPRISING: (A) MEANS DEFINING AN ABRUPT BEND IN THE DUCT, SUBSTANTIALLY STRAIGHT PORTIONS OF THE DUCT BEING UPSTREAM AND DOWNSTREAM FROM SAID BEND DEFINING MEANS AND A PORTION OF THE BEND DEFINING MEANS INTERMEDIATE ITS CONNECTIONS WITH SAID SUBSTANTIALLY STRAIGHT PORTIONS HAVING A CROSS SECTION AREA GREATER THAN THAT OF SAID UPSTREAM AND DOWNSTREAM STRAIGHT PORTIONS OF THE DUCT; (B) A PLURALITY OF ELONGATED VANES, EACH HAVING A CONCAVE SURFACE AND A GENERALLY OPPOSITE CONVEX SURFACE, THE RADIUS OF CURVATURE OF SAID CONCAVE SURFACE BEING ON THE ORDER OF TWICE THAT OF THE CONVEX SURFACE SO THAT EACH VANE HAS SUBSTANTIAL THICKNESS, AND SAID SURFACES OF EACH VANE BEING CONVERGENT TOWARDS PARALLEL LENGTHWISE EXTENDING LEADING AND TRAILING EDGES OF THE VANE, THE PORTION OF THE CONVEX SURFACE THAT IS NEAR THE LEADING EDGE OF THE VANE HAVING A SUBSTANTIALLY SMALLER RADIUS OF CURVATURE THAN THE REMAINDER THEREOF; AND (C) MEANS MOUNTING SAID VANES IN SPACED APART PARALLEL RELATION IN SAID BEND DEFINING MEANS AND PROVIDING FOR ROTATION OF CERTAIN OF THE VANES ABOUT AXES WHICH ARE PARALLEL TO THEIR LEADING AND TRAILING EDGES AND INTERMEDIATE THEM AND WHICH ARE LOCATED IN SAID BEND DEFINING MEANS SLIGHTLY DONWSTREAM FROM THE PORTION THEREOF OF LARGEST CROSS SECTIONAL AREA, SAID MOUNTING MEANS DISPOSING THE VANES, WHEN THE VALVE STRUCTURE IS OPEN, WITH THEIR CONCAVE SURFACES FACING THE BEND AND THEIR LEADING EDGES UPSTREAM RELATIVE TO THE DIRECTION OF FLUID FLOW THROUGH THE DUCT, AND PROVIDING FOR ROTATION OF SAID VANES TOWARD THEIR CLOSED POSITIONS IN THE DIRECTION TO DISPOSE THEIR CONVEX SURFACES UPSTREAM.