GB844051A - Improvements in or relating to magnetic position indicating devices - Google Patents

Abstract

844,051. Controlled non-linear inductors. ENGLISH ELECTRIC CO. Ltd. Sept. 25, 1956 [Sept. 27, 1955], No. 27466/55. Class 40 (9). [Also in Groups XXXV and XXXVI] A fixed magnetic circuit including air gaps and a constant source of magneto-motive force (eg. permanent magnets) is unbalanced when an armature on a lift cage approaches the gaps. A flux detector comprising saturable reactors responds to the flux change and operates an indicator. In one arrangement, Fig. 1, the fluxes from two permanent magnets 12, 13 normally circulate in the air gaps between a central member 14a and wing-like members 11a, the fluxes being in opposition in limb 11. When the lift approaches from above, an armature 16 unbalances the circuit and the flux detector 10 gives an indication of one polarity. When the two armatures 15, 16 produce similar conditions in the two gaps, the detector gives a zero indication and as armature 16 leaves the gap the detector gives an indication of the opposite polarity. The flux detector 22, Fig. 2, may be arranged in the central limb of a three-limbed core, the permanent magnets 23, 24 producing fluxes in opposition in the central limb. In another arrangement, Fig. 3, a detector 34 forms a junction between two parallel magnetic circuits identified with the magnets 30, 31 and limbs 33a, 33b. The member 32 is common to the two circuits. Only one armature 35 is used in this arrangement. The flux from both magnets tends to flow through the air gap with the least reluctance.