US Patent 7140593 Bi-directional air flow damper having uni-directional synchronous motor

A damper assembly that produces bi-directional damper door movement from a single-direction motor is provided. Bi-directional rotation of the damper door is enabled by a cam slot on an end of the damper door that is engaged by a motor-driven drive cam having a drive pin extending into the cam slot. As the single-direction motor collectively rotates the drive cam and the drive pin, the drive pin reciprocates within the cam slot. This causes sealing flanges and the damper from the damper door to alternatively engage under a positive pressure and disengage from one another as the damper door is rotated bi-directionally.