GB1452304A - Thermo-magnetically operated switches - Google Patents

Abstract

1452304 Thermo-magnetic switch TOHOKU METAL INDUSTRIES Ltd 30 Nov 1973 [30 Nov 1972] 55690/73 Heading H1N A curie point switch having a range of temperature at which the contacts are operated is arranged to be inoperative both above and below the temperature range and has a sealed magnetic reed contact unit whose reeds 12, 13 are influenced by two permanent magnets 2, 3 having curie points above the operative range and two ferromagnetic members 4, 5 having curie points at the lower and upper ends respectively of the temperature range. As shown in Figs 3A, 4A and 11A the flux distribution when the temperature is below the curie point of member 4 is such as to permit the contacts to remain open. When the temperature is above the curie point of member 4 but below that of 5 the magnet flux closes the contacts Figs. 3B, 4B, 11B (not shown), and when the temperature is above the curie point of the member 5 the flux does not pass through the contact points Figs. 3C, 4C, 11C, (not shown), and the contacts are permitted to open. The contacts may be arranged as in Fig. 12A which provides for contacts to be open between the two curie point temperatures and the magnets for arrangements such as that of Figs. 4A, 11A and 12A may be cylindrically disposed around the contact unit 1 with or without non- magnetic inserts, Fig. 14, (not shown) and a longitudinal grove Figs. 7A, 7B, 8A, 8B, and 15, (not shown), allowing contact connections to be made at one end of the switch.