Failsafe door closing device of a fire proof rolling door

A power-off door closing device 20 of fire proof rolling door, which is provided on one side face of the cover plate 11 of the rolling machine 1 for rotating the rolling shaft, a receiving chamber 10a being formed on this side face by a tail cover 10;

• a inherent brake device 30 being fixed on the other side face of said cover plate 11, a braking pin 34 included in this brake device 30 being extended into said receiving chamber 10a, characterized in that said device comprises:
• a brake actuation rod 21, one end 21a of which being fixed on said braking pin 34, the other end being formed as a free end 21b;
• a clamp member 22, one end 22a of which guides a sliding block 23, the other end being formed as a pivot end 22b, wherein one end 23a of said sliding block 23 abuts against the free end 21b of said brake actuation rod 21, and the other end being a connecting end 23b;
• a bent arm 24 having a first end 24a and a second end 24b, said first end 24a being supported on the pivot end 22b of said clamp member 22, and said first end 24a including an extension end 241 which moves together with the connecting end 23b of the sliding block 23 by a support arm 25;
• a solenoid 26, having a sliding lever 261 provided at the center and stored with potential energy of a spring 262, said sliding lever 261 having a first end 261a and a second end 261b in which said first end 261a moves together with the second end 24b of the bent arm 24, and said second end 261b resisting the potential energy of the spring 262 to be pushed outwardly in axial direction under energized condition of said solenoid;
• a control circuit used to control the solenoid 26 for brake-releasing under energized condition or for brake-applying under power-off condition, thus, said brake is brought into brake applied state under abnormal power-off condition, if fire is detected and confirmed by a fire detection device, electric current being supplied temporarily to the solenoid from a reserved power supply to maintain a temporary brake releasing so as to cause the rolling door sliding down by its own weight to close.