Abstract:
AN ELECTRICALLY ACTUATED DOOR HOLDER APPLIED TO A HINGED DOOR HAVING A CLOSER. THE DOOR HOLDER MAY BE MANUALLY OVERRIDDEN AND ALSO AUTOMATICALLY RELEASED. FUNCTIONALLY, THE DOOR IS HELD OPEN AT ANY DESIRED ANGULAR POSITION WHEN A SOLENOID IS ENERGIZED TO CAUSE A HELICAL SPRING TORQUE CLUTCH TO LOCK IN ENGAGEMENT TWO RELATIVELY ROTATABLE CLUTCH SHAFTS ENVELOPED BY THE SPRING. EACH CLUTCH SHAFT IS MECHANICALLY COUPLED TO A DIFFERENT HINGE LEAF. IN THE DOOR OPENING DIRECTION, THE SPRING IS UNWOUND RELATIVE THE CLUTCH SHAFTS TO PERMIT MANUAL ENLARGEMENT OF THE DOOR OPENING. A SECOND CONE OR TORQUE LIMITING CLUTCH IS MECHANICALLY CONNECTED IN SERIES WITH THE HELICAL SPRING CLUTCH TO ENABLE MANUAL CLOSING OF THE DOOR WHEN SUFFICIENT DOOR CLOSING TORQUE IS APPLIED TO DISENGAGE THE CONE CLUTCH, EVEN THOUGH THIS CLOSING TORQUE IS INSUFFICIENT TO DISENGAGE THE HELICAL SPRING CLUTCH IN THE DOOR CLOSING DIRECTION. DEENERGIZATION OF THE SOLENOID BY THE MANUAL OPERATION OF A SWITCH, OR BY AN AUTOMATIC FIRE DETECTOR, FOR EXAMPLE, DISENGAGES THE HELICAL CLUTCH AND PERMITS CLOSER TO CLOSE THE DOOR AUTOMATICALLY.