| 摘要 |
699,183. Electrically-released switches. BESCOCCA, L. July 21, 1950, No. 18241/50. Class 38 (v) An automatic device for controlling an electric circuit, a fluid valve or an alarm in response to a predetermined condition, e.g. temperature, fluid pressure, or overload in an electric circuit, comprises a control member frictionally held in one position against the action of a biasing force, the frictional effect being reduced by the condition so that the member is moved by the biasing force to effect a control function. As-shown, the member is a U-shaped wire spring 15 fixed to a terminal 13 and having a forked projection 17 which is normally held frictionally between fixed and movable plates, 22, 26 respectively by means of a "hot wire" 25 stretched between plate 26 and an adjusting screw 31, which forms one terminal of the switch, the other being formed by a metal ferrule 10 welded to the terminal 13. An increase of current through wire 25, causes it to stretch and reduce the pull on plate 26 so that the bias of the spring 15 overcomes the frictional effect so as to open the circuit, the spring moving to the dotted position. The switch is reset by moving knob 20 to the left, and the tripping movement of the knob may control a toggle switch. |
