GB220584A - Improvements in thermally-actuated electric switches - Google Patents

Abstract

220,584. Svensson, I. V. March 27, 1924. Electrically - released switches. - In a thermally-actuated switch, of the kind having contacts normally engaging one another and at least one of which is adapted to become released and be movable at a certain temperature so that they will be disengaged by spring action or the like, the contact adapted to be released is so arranged that, when released, it is moved aside by the other contact, which owing to spring action, moves out of engagement. The invention, as applied to a sad-iron, comprises an insulating body 21 having holes in which sleeves 22, 23, which form the supply terminals, are fitted, that 22 communicating with a lead 26. The sleeve 23 is secured by a screw to a strip from which projects a stud 30 surrounded by a contact spring 31, one leg 32 of which bears on a flange 33 of the strip, while the other 34 bears on a contact 35, mounted on a stud 36 projecting from a plate 37 which is connected by means of a screw 38 and bar 39 to a lead 40. The contact 35 is controlled by a spiral spring 41 urging it against a stop 42 formed as a flange or plate 37, and is secured bv fusible solder to stud 36 or to stop 42 or by friction around the stud 36. When the solder melts or the contact 35 expands sufficiently around the stud, the contact 35 becomes loose, so that the spring 31 will overcome the spring 41 to move aside the contact 35 and so break circuit, the spring 41 then restoring the contact 35 which is again secured when the device cools off. A re-setting button 44 urges the contact 34 until it snaps behind the contact 35. The spring 31 is bent around the stud 30 so that when under tension it will grip the stud and make firm contact, and the leg 32 will also be pressed against the flange 33 to reinforce the contact.