THERMOSENSITIVE PELLET TYPE THERMAL FUSE

PROBLEM TO BE SOLVED: To provide a thermosensitive pellet type thermal fuse which properly prevents breaking at an early stage before reaching an operating temperature. SOLUTION: The thermosensitive pellet type thermal fuse 1 has a movable electrode 8 movably housed in a metal case 2 and connected to a B lead wire 12. The movable electrode 8 is urged by a B spring 7 held by a thermosensitive pellet 3 that melts and softens at an operating temperature, so that the movable electrode 8 is brought into contact with an A lead wire 13 to establish conduction. As the thermosensitive pellet 3 melts and softens at the operating temperature, an A spring 10 urges and moves the movable electrode 8 to interrupt the contact between the movable electrode 8 and the A lead wire 13. The thermal fuse 1 is provided with a pre-operating-temperature breaking prevention mechanism 20 that maintains the contact between the movable electrode 8 and the A lead wire 13 by preventing movement of the movable electrodes 8 caused by an urging force of the A spring 10 resulting from softening of the pellet 3, before melting, which occurs at temperatures in the region of the operating temperature and lower than the operating temperature. COPYRIGHT: (C)2004,JPO