Patent GB-549495-A (GB)
Title: Improvements in or relating to electric elevator systems
IPC: B66B1/18
Filed: 1941-05-19
Abstract: 549,495. Push-button lifts. SHEPHERD, G. R. (Westinghouse Electric International Co.). May 19, 1941, No. 6410. [Class 40 (i)] Each car of the system has a continuously running scheduling selector ADP, BDP &c. Fig. 1, the position of which at any time indicates where the car ought to be, and it is arranged that calls are answered immediately only by cars that are ahead of schedule. Cars running to schedule answer only calls that have been waiting for at least (say) 15 seconds and cars that are behind schedule only calls that have been waiting for at least (say) 30 seconds. The cars are arranged to run in succession from the dispatching floor (preferably the first (i.e. ground) floor) to the top and back, the cars being started by their attendants in response to signal impulses from a device 37 which is continuously driven up and down and delivers a number of impulses in a cycle corresponding to the number of cars in service as determined by the position of a switch 52. The speed at which the scheduling selectors and the dispatching impulser are driven varies with the traffic conditions, the aim of the system as a whole being to give a waiting period which shall be as far as possible the same for all calls and as short as possible. Apart from these features, the system resembles that described in Specification 355,513, [Group XXX]. Dispatching arrangements.-Operation of the main switch 53, Fig. 6, by the dispatching attendant energizes Q which energizes the positive bus bars L + 4, L + 5, L + 6. The dispatching circuit comprises a relay AW, BW, CW &c. for each car in the system arranged on a chain under control of relays H, J, T. Whenever a car is available, its relay AY, BY &c. is energized by the car attendant's switch 56 &c. over a limit switch 55 &c. and a relay F is operated to open one of a number of parallel circuits for a relay T with a release period of (say) a quarter of a second. On the operation of Q, the first chain relay AW pulls up, locks and energizes QQ. If relay AY is operated, T will be held after the operation of F but if not, T falls back energizing H which re-energizes T and energizes J. By this means, BW is energized and AW released. If BY is operated, T will now be held but otherwise it falls when J comes up, releases H and then pulls up again releasing J. This energizes CW and releases BW. The chain is built up in this manner until the operated Y relay of an available car is found. Relay T is then held and the W relay remains operated. starting the scheduling selector by energizing its relay FU and lighting the landing lamps 5, 7 of and the "next" lamp 58 in the car concerned.. Impulses are being given at a constant rate depending on the position to which arm 52 is set in accordance with the number of cars in use by the impulses 37 to a relay V and at the next impulse the start relay AX, BX &c. corresponding to the selected car is operated, puts the "next" lamp 58 out and lights the "start" lamp 59 in the car. The X relay also releases T to initiate the building up of the chain to the point corresponding to the next available car. If there are no such cars, F falls and prevents the release of T. Keeping cars to schedule.-Corresponding terminals in the position and scheduling selectors are multipled as shown in Fig. 3. When the actual and the scheduled positions agree, relay M is operated and energizes relays KT, N, LT and P. If the car gets ahead, M falls and K operates releasing N and KT, the relapse of the latter being delayed for, say, five seconds by a dashpot. If the car falls behind, N and KT remain operated but L is operated to release P and LT. The floor pushes energize relays such as 11R, Fig. 5, to apply a stopping potential to the appropriate terminals of the position selector through two resistances such as 11r1, 11r2, Fig. 5, in series and at the same time couple a switch-operating cam-shaft to a timing motor to cause one of these resistances to be short-circuited after 15 and the other after 30 seconds. The stopping relays S, BS &c. Fig. 5, are operated over these resistances and two resistances such as Ar3, Ar4 of their own, one of which is short circuited if the car is running to time and both if the car is ahead of its schedule, and it is arranged that the relays cannot operate unless at least two of the four resistances in series with them are shortcircuited. As a result, a call can stop a car that is ahead of schedule immediately whereas a car running to schedule ignores calls until they are 15 seconds old and a car behind schedule ignores them until they are 30 seconds old. Varying speed of scheduling selectors and rate of dispatching impulses in accordance with traffic.-The motors 28, B28 &c. Fig. 5, for the scheduling selectors and the motor 40 for the dispatching impulser are fed for up and down motion respectively by generators 47, 48, the field circuits of which include two rheostats 85 driven as one by a motor 86, but capable of separate initial adjustments by arms 120, 121. The motor 86 has differential field coils in series with a number of resistances AR20, BR20 &c. and AR30, BR30 &c. The relays KT, LT respectively of each car are arranged to shortcircuit a resistance in each group so that if all cars are running to schedule or if there is an equal number ahead of and behind schedule the motor does not run. When, however, the cars are, on balance, behind schedule, the motor runs in such a direction as to reduce the generator outputs and so slow down the scheduling selectors and dispatching impulser. Conversely, if the cars are, on balance, ahead of schedule, the scheduling selectors &c. are speeded up. To give a quick reduction in the speed of the scheduling selectors when there is a rush of "down" calls the down generator field winding 48DF is shunted at 90 on the operation of a relay Z which is arranged as shown in Fig. 7 to operated when, say, six down call registering relays R are operated. A similar provision may be made for up calls if desired.