Patent GB-1495392-A (GB)
Title: Elevator system with object detection means
IPC: E05F15/00
Filed: 1974-12-09
Abstract: 1495392 Control of D.C. motors WESTING- HOUSE ELECTRIC CORP 9 Dec 1974 [18 Dec 1973] 53091/74 Heading H2J [Also in Divisions E1-E2] An object detection door control mechanism (particularly suitable for lift car doors) comprises a radiant energy source 98 which radiates through horizontally spaced apertures 94 in a sill portion 92 of the door entranceway to provide a number of vertical beams 100, a detector mounted to move with the door, and a detector mounted stationary with respect to the door; interruption of the energy to either detector by an object in the entranceway or adjacent the door edge causing the door to be prevented from closing. As shown centreopening sliding lift car doors 5, A5 are moved by an electric motor 25 via a lever-and-link assembly and detector devices 110, 112 mounted on each door-each device comprising two detectors (e.g. 114, 116, Fig. 3). Two stationary detectors 102, 104 are mounted above the entranceway and these are rendered inoperative by the action of a cam 106 on a limit switch 108 as the doors near closure. The source 98 is preferably an electric lamp and visible light is used in the embodiment shown to highlight the sill. Glass or plastics lenses 96 are disposed in the apertures. A further detector 118 is disposed beneath the source 98 and, should the source fail, operates to isolate the detectors 102, 104 and bring additional sources 120, 122 on the doors into operation. The doors are controlled in addition by a system of cams driven off the motor which act on control contacts and limit switches at predetermined points in the door travel to stop the motor and to vary the motor armature resistance, accelerating the doors from rest and slowing them down progressively as they approach rest. The circuit shown in Fig. 4 causes the door closing movement to be stopped when an object is detected and then causes the doors to be opened. Additional detectors may be provided to either count passengers, or to define a central zone in which the doors are stopped and an edge zone in which the doors are both stopped and reversed. The doors are operated by a reversible D.C. motor fed from a D.C. supply L +, L- and having a shunt field winding 25F and an armature 25A connectible with variable resistors to accelerate and decelerate the motor. Closure of main contacts SW1, SW2 (manually or relay controlled) respectively energize a door opening or closing relay OP, OL also controlled by limit switches 37, 39. The relay contacts OP1 ... OP4, CL1 ... CL4 control the resistors RAC, RDC for acceleration and deceleration during door closing and the resistors RAO, RDO for acceleration and deceleration during door opening, these resistors being switched in and out by contacts AC, DC1 ... DC4; AO, DO1 ... DO4 sequentially actuated by cams keyed to gearing associated with the motor, so that acceleration or deceleration is dependent on the distance moved by the doors. Further resistor control contacts ASC, ASO are controlled by a relay AS and limit switches 43, 45 to increase the motor torque after a predetermined time delay (set by circuit 47, 49, 51, 53) to fully close or open the doors against a restraining force (e.g. wind pressure). Safety relay DR is controlled by contacts C102, C104; C114, C116 and C112 C112<SP>1</SP> of the detectors 102, 104; 110 and 112, by a limit switch 108 which closes to shunt C102, C104 just before the closing doors inter. rupt the radiant energy to detectors 102, 104, and by contacts M1 of a relay M energized by contacts C118 of detector 118 so long as source 98 is operative. Hence if radiant energy to one of the detectors 102, 104, 110, 112 is interrupted, relay DR is de-energized and its contacts DR1, DR2 open and close to de-energize and energize relays CL, OP to reverse the door closing movement. If source 98 fails contacts M1 close to cut out detectors 102, 104 and contacts M2 close to energize sources 120, 122 to retain the door edge object detection function. A timer may be added to the circuit to hold the doors open for a predetermined time in response to object detection, after which the protective devices are overriden and the doors closed at a slow speed.