| 摘要 |
In a safe (102) having thermal re-lockers (108), each thermal re-locker (108) comprises two opposing springs which both act on a plunger (122) attached to a re-locking bolt (116) mounted within a tubular container (110). One spring is a memory metal spring (134) and the other is a non-memory metal spring (136). At room temperature the strength of the non-memory metal spring (136) is sufficient to hold the re-locking bolt (116) within the container (110). If a safe (102) comes under thermal attack, the temperature rises causing the re-locker (108) to be activated. The memory metal spring (134) becomes stiffer compressing the non-memory metal spring (136) and pushing out the re-locking bolt (116) so that it protrudes out of the container (110), and thereby prevents either a safe door (104) from being opened, or a safe boltwork mechanism (106) from being unlocked. Once the re-locker (108) has cooled down to room temperature, the memory metal spring (134) returns to its normal less stiff state thus bringing about retraction of the bolt (116). <IMAGE> |
