Method and apparatus for forced air balancing of damper blades

Abstract

The present invention encompasses a method and apparatus for assisting in the operation of air control dampers. An air deflector is positioned downstream from a rotatable damper in an air conduit. The deflector is positioned to direct air moving over one side of the damper against the damper during opening to assist in the opening movement and thereby reduce the amount of weight which would otherwise be required. The same deflector is positioned so that upon closing of the damper air will be deflected against the opposite side of the damper blade to augment the torque forces tending to close the damper while also reducing the pressure drop from one side of the damper to the other. In another embodiment of the invention a sail blade is provided upstream from the control damper to assist in closing the damper at low flow conditions. The sail blade is of relatively lightweight construction so that it will close at a higher pressure than the main control damper thereby partially blocking the flow of air across the damper. This results in increasing the static pressure upstream on the pneumatic pressure sensitive taps to effect actuation of the closing mechanism. During normal operation of the damper the sail blade is moved to an out of the way position because of its relatively lightweight construction which causes it to open at a lower pressure than the main control damper.