Fail-safe fire door release mechanism having automatic reset
DCFirst Claim
1. An improved motor-operator unit for a fire door of the type having a high speed shaft rotatably driveable in a first direction, reversibly driveable speed reduction means for rotatably connecting said high speed shaft with a low speed shaft, means for connecting said low speed shaft to driving means for a fire door, said fire door opening responsive to said high speed shaft rotating in said first direction, a brake movable between a disengaged position and an engaged position, said brake in said disengaged position allowing free rotation of said high speed shaft, said brake in said engaged position preventing rotation of said high speed shaft, wherein the improvement, a fail-safe door release mechanism comprises:
- (a) a solenoid having an open state in the absence of an applied electric current and a closed state in the presence of an applied electric current; and
(b) means for communicating said states of said solenoid with said brake, said means switching said brake to said disengaged position in response to said open state of said solenoid, said means switching said brake to said engaged position in response to said closed state of said solenoid.
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Abstract
A resettable fail-safe fire door release mechanism which allows normal powered operation of a fire door is disclosed. A solenoid having a first open state in the absence of an applied electric current and a second closed state in the presence of an applied electric current is incorporated into the motor-operator unit of an overhead door. Brake actuator utilizes the spring force of a normally disengaged brake to keep the brake actuator in a first position. The plunger of the solenoid acts through the brake actuator in opposition to the spring so that energizing the solenoid overcomes the force of the spring, moving the brake actuator, and engaging the brake; deenergizing the solenoid causes the spring to again disengage the brake. A normally closed switch having a mechanical actuator is wired in series with the solenoid. The melting of a fusible link releases a spring loaded plunger which depresses the actuator opening the switch. A cable having one end connected to the actuator of the switch and the other end external to the case of the motor-operator allows manual opening of the switch and hence closing of the door.
149 Citations
5 Claims
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1. An improved motor-operator unit for a fire door of the type having a high speed shaft rotatably driveable in a first direction, reversibly driveable speed reduction means for rotatably connecting said high speed shaft with a low speed shaft, means for connecting said low speed shaft to driving means for a fire door, said fire door opening responsive to said high speed shaft rotating in said first direction, a brake movable between a disengaged position and an engaged position, said brake in said disengaged position allowing free rotation of said high speed shaft, said brake in said engaged position preventing rotation of said high speed shaft, wherein the improvement, a fail-safe door release mechanism comprises:
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(a) a solenoid having an open state in the absence of an applied electric current and a closed state in the presence of an applied electric current; and (b) means for communicating said states of said solenoid with said brake, said means switching said brake to said disengaged position in response to said open state of said solenoid, said means switching said brake to said engaged position in response to said closed state of said solenoid. - View Dependent Claims (2, 3, 4, 5)
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Specification