GB1172258A - Elevator System - Google Patents

Abstract

1,172,258. Measuring weight electrically. OTIS ELEVATOR CO. May 30, 1967, No.24956/67. Heading G1N. [Also in Division G4] The load carried by a lift car is measured by the change in permeability of a magnetostrictive nickel rod subjected to the load. The lift car 29 Fig. 1 and a counterweight 31 are supported by cables 27, 28 passing over sheaves 24, 25 attached to a horizontal bedplate 21 with limited rotation about a central fulcrum 32. The basic parts of the lift system are mechanically balanced so that the rotational moment is due to the load in the lift car only. One end of the bed plate 21 is rigidly attached to the bottom of a magnetostrictive nickel rod 121 Fig. 3, which is itself clamped between a plate 117 and a fixed beam 71. The rod forms part of the magnetic circuit of a transformer 125 whose output is therefore reduced when the permeability of the rod 121 is reduced by stress caused by the movement of the load about the fulcrum 32. A similar but unstressed transformer 136 is mounted above the plate 117. The two secondary windings are connected in series opposition giving a resultant output signal indicative of the lift load. This signal is rectified and fed to a relay circuit which gives indications at different values of load. A further relay, which is only energized when the car is moving, causes the measuring relays to hold their readings during movement, and permits further measurement when the lift car stops at a landing.