Thermosensitive fuse

Claim 1

A thermosensitive fuse, comprising: a casing made of an electrically conductive material, said casing having an axially elongated configuration with its one end opened and the other end closed; a first conductor connected to said casing; a meltable substance located in said casing and extending from said closed end of said casing to a position between said closed and opened ends, said meltable substance being in a solid state when it is under a predetermined temperature and in a liquid state when it is above said predetermined temperature; a bushing made of an electrically non-conductive material and fixedly attached to said open end of said casing; a second conductor supported by said bushing such that one end of said second conductor projects into said casing in alignment with an axis of said elongated casing and the other end of said second conductor extends outwardly from said casing; a solid contact member made of, or coated with, an electrically conductive material and having first and second end faces located at opposite ends of said contact member, said end faces being parallel to one another, an angle defined between said end faces and an axis of said contact member extending between the centers of said first and second end faces being other than 90°, said contact member being movably housed in said casing with said first end face facing said meltable substance and said second end face facing said bushing; a first coil spring housed in said casing between said meltable substance and said first end face of the contact member for pushing said contact member against said one end of said second conductor; and a second coil spring, which is weaker than said first coil spring, housed in said casing between said bushing and said second end face of said contact member for biasing said contact member away from said one end of said second conductor, said first and second springs acting on said contact member to produce a moment about said one end of said second conductor such that said contact member contacts said casing and establishes an electrical path between said first and second conductors through said casing and said contact member, said meltable substance being melted above said predetermined temperature to release said first coil spring from pushing said contact member against said one end of said second conductor to effect the separation of said contact member away from said one end of said second conductor by the biasing force of the second coil spring.