Patent ID: 8484897

Claim:
A door operator of a fireproof door for releasing a reel of a door curtain in an event of a fire accident, said door operator comprising: a housing defining an interior space; a central shaft pivoted in said housing; a torsion spring brake mechanism arranged around a circumference of a left end on said central shaft, said torsion spring brake mechanism including at least one torsion spring for controlling said central shaft to be either in brake-actuated state or in brake-release state; a drive mechanism disposed on said central shaft for applying an external force; a first external shaft mounted on and rotatable relative to said central shaft; a clutch mechanism disposed on a right end of the first external shaft and fixed on said central shaft for engaging or disengaging said central shaft and said first external shaft in a control manner; a second external shaft disposed on a left end of said first external shaft and rotatably mounted on said central shaft, an output pulley being fixed on the second external shaft for operating the reel of the door curtain; a reduction mechanism being coupled to said first external shaft and said second external shaft by means of a plurality of gears for reducing the rotation speed transferred from said first external shaft to said second external shaft; wherein in the presence of a power supply, the clutch mechanism is coupled to the central shaft and the first external shaft, and when the external force is applied by the drive mechanism, the central shaft actuates the torsion spring brake mechanism to radially expand the at least one torsion spring and the external force transfers through the central shaft, first external shaft, and second external shaft to roll the door curtain, and in the event of a power failure, said clutch mechanism disconnects said central shaft from said first external shaft to thereby release the reel such that the door curtain drops by gravity to close the fireproof door.