GB848518A - Improvements in thermal electric switches - Google Patents

Abstract

848,518. Thermal switches. COTHERM S.A. Oct. 14, 1958 [Dec. 21, 1957 ; May 6, 1958], No. 32692/58. Class 38 (5). In a thermal switch of the differential-expansion rod-and-tube type, the rod 2 is screwed to a sleeve 4 passing through the insulating dustproof cover 13. Movement of the rod 2 is transmitted to a lever 7, pivoted on a knife 6, by a prism 8 whose upper face abuts the sleeve 4 and whose two knife edges engage a groove 7b on each side of the rod 2. A T-shaped rocking- lever 9 is urged by over-centre tension-springs 10 into a groove in the end 7c of the lever 7, so that normally the contacts 20, 21, are held closed by the resilience of blade 18, and an insulating-plate 12 on the rocking lever 9 abuts the contact 20. When the rod 2 is lowered on increase of temperature, lever 7 is rotated to raise the end 7c and move it over the line of centres, whereupon lever 9 snaps over and an insulating bar 22 secured to the plate 12 engages the blade 18 and moves it into the open position. The bar 22 may actuate up to three blades and the operating temperature is set by an adjustable knob 5. The switch operation may be reversed by interchanging the elements 1, 2, or by disposing the knife 6 on the other side of rod 2.