GB397557A - Improvements in and relating to elevator installations - Google Patents

Abstract

397,557. Lifts. WAYGOOD-OTIS, Ltd., 54, Fetter Lane, London. Jan. 20, 1933, No. 1968. Convention date, Feb. 29, 1932. [Class 78 (ii).] Electric plant.-The tape 50 by which the movement of the cage 57 is transmitted to the floor selector device 78 is coiled spirally in a circumferential groove on a reel 47 upon which a substantially constant torque is exerted by an electric motor 38 regardless of the speed or direction of movement of the cage. The lower end of the tape is gripped by a clamp 52 mounted on the weighted end 53 of an arm 51 pivoted in a bracket on the top of the cage. The other end of the arm 51 is cam shaped, and if the tape becomes unduly slack or breaks it engages with an actuating roller of a mechanically operated switch 54 and separates its contacts. The shaft 44 on which the reel 47 is mounted is acted on by a spring-applied, electrically-releasable brake 31, and is connected by reduction gearing 72 to a reel 66. A flexible transmission member 64 is attached to the reel 66 and to the vertically movable cross-head 62 of the selector device. A taohometer generator 36 is arranged to be driven in accordance with the speed of rotation of the cage hoisting sheave 46. The armature 40, Fig. 2, of the motor 38 and the armature 37 of the generator 36 are connected in series across the direct current constant supply line controlled by switch 20. The energization of the armatures is controlled by a pair of contacts S41 of an electromagnetic relay S45, the actuating coil of which is connected across the supply terminals through the contacts 54. Consequently, if switch 20 is closed, and if the contacts 54 are engaged, and normal full voltage is supplied by the mains, the contacts 841, S30 and S22 are closed. The closing of switch 20 also energizes the separately excited fields 32, 34 of the generator 36 and motor 38, respectively. The torque exerted by the motor 38 is such that the reel 47 tends to rotate to wind up the tape, and since the motor brake 31 has been released consequent on the energization of the coil 27 due to the closing of the contacts S30, the tape is maintained taut. Contacts S22 are inserted in the same circuit as the emergency stopping switch, the over speed governor switch and the potential switch for the cage hoisting motor 23. If the cage 67 is raised, the motor 38 winds the tape on the reel 47, and a voltage is induced in its armature 40 which is, in polarity, in opposing relation to the supply line, and, in magnitude, variable in accordance with the speed of the cage. By appropriate design of the mechanical and electrical parts, and by appropriate adjustment of the field resistances 33, 35, the magnitude of the voltage generated at the same time in the generator 36 may be made to equal the magnitude of the induced voltage generated in the armature 40 for all speeds of the cage from zero to the maximum, and since these voltages are of opposite polarity, the induced voltage in the armature 40 is neutralized, and the motor 38 exerts a constant torque. A similar compensation occurs when the cage descends.