Patent ID: 7179054

Claim:
A ventilating device comprising: a drive shaft that rotates about a longitudinal axis thereof; a blade support wheel coupled at a central portion thereof to the drive shaft for rotation of said blade support wheel with said drive shaft; a plurality of fan blades joined to said blade support wheel capable of producing an airflow when said blade support wheel rotates; a means for reversing pitch joined to each of said plurality of fan blades comprising a disk positioned about the drive shaft adjacent said blade support wheel; at least one torsion spring coupled to said blade support wheel and to said disk wherein, when said at least one torsion spring is in tension, said disk is poised for a relative rotation about the drive shaft, said relative rotation being relative to said blade support wheel; a locking means positioned between said disk and said blade support wheel for coupling said disk to said blade support wheel when said at least one torsion spring is in tension, wherein rotation of said blade support wheel causes corresponding rotation of said disk; each of said plurality of fan blades having a stem rotationally supported by said blade support wheel wherein a rotational position of said stem sets blade pitch for a corresponding one of said plurality of fan blades; a means for coupling each said stem to said disk wherein rotation of the drive shaft causes rotation of said plurality of fan blades about the drive shaft, said means for coupling each said stem to said disk positioning said plurality of fan blades to generate a flow therethrough when the drive shaft rotates with said locking means coupling said disk to said blade support wheel while said at least one torsion spring is in tension; a release means coupled to said locking means for uncoupling said locking means from said disk and said blade support wheel when said release means is activated, wherein said disk experiences said relative rotation about the drive shaft as said tension in said at least one torsion spring is released, and wherein said relative rotation of said disk causes rotation of each said stem to re-position said plurality of fan blades to reverse said flow therethrough as the drive shaft rotates; a sensor capable of sensing an event that will require reversing the air flow; and a controller joined to said sensor capable of actuating said means for reversing pitch in order to initiate the reversal of airflow upon the occurrence of said event.