LOCKING MECHANISMS

摘要

The release mechanism of an electronic timelock employs two bistable electromagnetic actuators to control the ''onguard'' and ''off-guard'' conditions of the lock, each actuator comprising an element of ferro-magnetic material whose magnetic polarity serves as the ''memory'' of whether the lock is in an on- or off-guard period and which polarity is reversed by single magnetising pulses through associated coils when each successive on- and off-guard period is programmed to commence. More particularly, when on-guard the coils are pulsed in one direction to magnetise the actuating elements so that they are attracted by specified poles of associated field magnets. In this condition the actuating elements block a beam which is pivotted centrally to a bolt which in turn blocks a bar which is attached to the door's boltwork. When off-guard the coils are pulsed in the opposite direction to reverse the magnetisation of the actuating elements so that they are attracted by the other poles of the associated magnets. This enables the beam to be lifted with the bolt as a spring snib on the bolt rides up a notch in the aforesaid bar when the latter is retracted. If the bar is forced when the mechanism is locked the snib is turned until a face on the bar is blocked by the bolt, thus limiting the force which can be applied through the beam to the actuating elements. If one actuator should for any reason fail in the on-guard position the lock can still be released when the other actuator switches to the off-guard position, by pivotal movement of the beam.