GB806289A - Improvements in or relating to thermal magnetic relays - Google Patents

Abstract

806,289. Magnetic relays. BAIER, O., BAIER, L., BAIER, W., BAIER, W., and SCHLUMPRECHR, E., (trading as BAIER KOMM-GES WEBASTO-WERK, W.]. March 21, 1956 [Aug. 16, 1955; Sept. 22, 1955], No. 8815/56. Class 38 (5). A relay operated by the effect of radiant heat upon a magnetic member having a permeability variable with temperature comprises, Fig. 1, a casing 70 with a window 71 and supporting a thermomagnetic bar 78 extending across a vertically movable permanent magnet 77 mounted in a conducting cup 84. Normally, the magnet is held against the bar 78 so that contacts 85, 86 on the cup 84 bridge-fixed contacts 75, 76; however, radiant heat reaching the bar through the window 71 causes the magnet 77 to be released and attracted towards a fixed magnetic plate 91, thereby opening the contacts. In a modification (Fig. 3, not shown), a lens in the casing concentrates the heat rays and the thermomagnetic member is movable with the contact-carrying cup which is biased to the " off " position by a spring, the permanent magnet being adjustably mounted in the casing. In another modification of Fig. 1 (Fig. 5, not shown), the contacts are closed when the permanent magnet is released by the thermomagnetic bar. According to a further construction, Fig. 7, an evacuated or inert gas-filled bulb 135 with a lens portion 135<SP>1</SP> contains a disc 139 of thermomagnetic material carried by a lead wire 145 and normally held against a permanent magnet 142 carried by connecting wire 140 so that a contact point 196 on the end of the wire 145 engages the end of the magnet to complete the circuit between wires 140, 145. On receipt of radiant heat through the lens 135<SP>1</SP> the disc 139 is released and the point 196 is moved to the open position by the bias of the wire 145. In a modification of Fig. 7 (Fig. 9, not shown), the permanent magnet is replaced by an electromagnet situated outside the bulb, a rheostat in the electromagnet circuit permitting adjustment of the operating temperature. In another arrangement, Fig. 10, a lens 170 with alternative diaphragms 182 ... 184 directs heat rays on to a thermomagnetic member 177 biased by a spring 209 and co-operating with a fixed annular magnet 178. A rod 179 fixed to the member 177 controls a lever 180 pivoted at 205 to rock a mercury switch 181 and control the circuit between wires 207, 208. According to a further construction, Fig. 11, thermal radiation 211 is directed on to a plate 187 of thermomagnetic material through a prism 195, the plate being connected to a bellows 190 through a rod 189. On heating of the plate 187 the resiliency of the bellows moves the plate away from an annular magnet 188 and a member 191 on the rod rises causing the level of mercury 192 in the bellows to fall and the circuit between leads 193, 194 to be broken.