Patent GB-700305-A (GB)
Title: Elevator car position indicator apparatus
IPC: B66B3/02
Filed: 1951-10-26
Abstract: 700,305. Electric selective signalling systems. OTIS ELEVATOR CO. Oct. 26, 1951 [Nov. 21, 1950], No. 25071/51. Class 40 (1). The invention relates to the car position indicators of a lift system associated with the call buttons at each floor, and to the indicator inside the lift car itself. The characters designating each floor, seen through a window in a face plate, are carried on the rim of a circular rotor on the inside of which is a number of permanent magnets spaced circumferentially and arranged alternatively in opposite directions, adapted to rotate the rotor step by step by two stator field windings energized through a distributer switch associated with the lift hoist mechanism. Construction.-The indicator, preferably combined with the push-buttons at the floor positions, is housed in a box 50 (Figs. 2 and 3), with a face plate 51 mounting the one or two call push-buttons 31, and a window 60 behind which is mounted on a non-magnetic frame 75, a drum 71 carrying a retainer band 67 of neoprene with slots 66 for carrying the floor designating characters 65. Around the inside of the rim of the drum is a series of permanent magnets 80 equally spaced circumferentially and pointing in opposite directions, each magnet being radially in line with one slot 66 on the outer rim. Motion of the rotor is effected by two field magnet coils 92, 93 mounted on frame 75, with cores 95 carrying forked pole-pieces 98, 101 an each side of the coils, each comprising three arms 103 extending over the ends of the rotor magnets 80 and spaced twice the rotor magnet pitch apart, each pair of pole-pieces 98, 101 being in line, but the pole-pieces of the one field magnet being displaced from the other by half a pole pitch. Rotor movement is damped by a friction brake 110 comprising a bent spring with a friction shoe 112 mounted on a bent arm 114 formed on the frame 75 and adjustable by a screw 115. The frame 75 is mounted on a bracket 117 which also carries a pin 121 which engages stops 123, 124 assembled on the rotor drum 71 to limit the arc of movement of the rotor. In a modification for particular use inside the lift car the floor indicating numerals are located on one face of the drum instead of on the rim, and are cut out on an opaque disc to be illuminated by a source of light. Operation.-The field coils 92, 93 in all the indicators are connected in parallel in two groups, and their energisation is controlled by two brushes 40, 41 (Fig. 9), driven by the hoist motor to move in synchronism with the lift over a series of fixed contacts SC1-SCT, corresponding to the floors 1-T. At the lowest position, as shown, the ends of the arms 103 of front pole-piece 98 are on three N poles of rotor magnets 80, and the coils 92 of each indicator, i.e. C, 1-T, are energised via a transformer TR, and rectifier RE, to produce S poles at the front ends of these arms. Coils 93, i.e. CX, 1X-TX, are unenergised, and the arms 103 of pole-pieces 100, 101 are resting between the rotor magnets. With movement of the lift car upwards brush 40 contacts contact SC2, and coils 93 are energised to produce N poles at the ends of the arms of front pole-piece 101, thereby causing the rotor to move clockwise one half-pitch. With further movement of the lift car brush 40 leaves SC2 which now contacts brush 41, whereupon coils 92 are energised in the opposite direction, i.e. with N poles at the front ends of arms 103, and causes the rotor to move clockwise a further half-pitch, whereupon the next floor position is indicated. These operations are repeated as the lift car reaches each successive floor, and counter-clockwise movement of the rotor is obtained when the sequence is reversed with downward movement of the lift car.