Safety circuit for cigar lighter - short circuits power supply to blow protecting fuse in case of overheating

摘要

The object of the proposed circuit interruption system is to prevent overheating of the cigar lighter body. When pushed into its socket (2) against the action of a spring (7') the heating element (8) of the lighter engages with the hooked ends (9') of two bimetal strips (9) connected to the supply (11). At the set temperature the strips expand and release the latch and the lighter springs clear of the electrical contacts. Should the spring fail, the bimetal strips fail, or the lighter be otherwise prevented from moving then current is fed to it by a second set of bimetal strips (15, 15'). Their mechanical action is to grip the element (8) tighter as they heat up. This improves the heat transfer from element to strip. This heat is conducted by the electrical connection (10) past the ceramic base insulator (12) to a fusible insulator (13). Should the fusible insulator melt a spring contact (14) is released to connect the supply (11) to earth on the socket (2). The associated fuse then operates to clear the circuit and prevent any further heating.