US2759564A - Elevator dispatchers - Google Patents

Description

Aug. 21, 1956 J. H. BORDEN 2,759,564

ELEVATOR DISPATCHERS Filed Oct. 29, 1953 4 Sheets-Sheet l jiquf IN VEN TOR.

JOSEPH H BURDEN Aug. 21, 1956 J. H. BORDEN ELEVATOR DISPATCHERS Filed Oct. 29, 1955 4 Sheds-Sheet 2 I .Ilg.

Aug. 21, 1956 J. H. BORDEN 5 ELEVATOR DISPATCHERS Filed 001.. 29, 1953 I 4 Sheets-Sheet 5 -33 rMr-43, 45

JOSEPH H BURDEN El W United States Patent ELEVATOR DISPATCHERS Joseph H. Borden, Toledo, Ohio, assignor to Haughton Elevator Company, Toledo, Ohio, a corporation of Ohio Application October 29, 1953, Serial No. 389,101

8 Claims. (Cl. 187-29) This invention relates to automatic passenger elevators and in particular to dispatching mechanism for automatically keeping the cars on a balanced dispatching schedule.

Dispatching machines for giving signals for the departure of elevator cars from terminal floors are quite well known and widely used. The usual dispatching machine controlling an even number of cars usually gives signals simultaneously at the upper and lower terminal floors in order that cars may be dispatched from these floors simultaneously. As long as an even number of cars are in service such an arrangement tends to keep the cars uniformly spaced provided no unusual operating conditions occur. The dispatching machines are also arranged so that if an odd number of cars are in service the dispatching signals are given alternately at the terminals so as to maintain a uniform spacing of the cars in their respective trips. It occasionally happens with such dispatching machines that the system gets out of balance particularly if a car having received a signal to depart does not depart prior to the next signal. Thus for a given interval of time a certain number of cars may have been dispatched from one terminal and a different number from the other terminal. This results in assigning more cars to one trip than to the other, i. e. more cars may be conditioned for upward travel or waiting up dispatch than are conditioned for down trip or awaiting down dispatch. Several rather complicated arrangements have been devised for correcting or rebalancing the system when such a condition occurs. Other systems require the intervention of an attendant to rebalance the system.

The principal object of this invention is to provide a dispatching system Which not only allows manual dispatching or starter controlled dispatching at a terminal floor but which also maintains a balanced dispatching condition even though cars may fail to depart on schedule or may be unduly delayed during a trip.

Another object of the invention is to provide a dispatching system which automatically adjusts itself to ordinary variations in trafiic demand.

A still further object of the invention is to provide an automatic dispatching mechanism which may make corrections in dispatching intervals as required to maintain balance without materially changing the average dispatching time interval for the system.

A still further object of the invention is to provide a dispatching mechanism that automatically adapts itself to an odd number of cars or an even number of cars without attention on the part of a starter or other attendant.

More specific objects and advantages are apparent from the following description of a preferred form of the invention.

According to the invention a pair of motor driven timers, one for the upper terminal and one for the lower terminal, are employed with dispatching mechanism for I each terminal and other means responsive to the number Patented Aug. 21,

of cars at a terminal are employed to speed up the dispatcher timer motor at that terminal having more than a predetermined number of cars standing thereat and to simultaneously slow down the dispatcher timer motor for that terminal having a fewer number of cars awaiting dispatch. The amount of speeding up and slowing down of the dispatcher timing motors may be adjusted so as to maintain a generally constant average time interval. In a dispatching mechanism constructed according to the invention a set of sensitive relays one for each terminal are provided, the relays being operated as soon as a predetermined number of cars accumulate at the terminal. If such a predetermined number of cars accumulate at one terminal the dispatching machine for that particular terminal is speeded up to decrease the timing interval while the dispatching machine for the opposite terminal is slowed down a generally equal amount. The resulting speed change balances the system to get as many cars on the up travel and awaiting up dispatch as there are on the down travel and awaiting down dispatch. This balancing takes place even though one or the other of the timers may be detented as when there are no cars available for dispatching, and also rebalances the system should one of the cars be dispatched ahead of time by manual dispatching from one terminal or the other.

Means are also provided for adjusting, in the same direction, the respective speeds of the two timers and thus adjust the average timing interval according to traffic requirements. It is ordinarily considered good practice to arrange the dispatching interval such that it is equal or approximately equal to the round trip time of an elevator car divided by the number of cars in service. The average round trip time may be taken as the time required when there is a moderate to heavy amount of traffic. When the traffic is light, particularly in one direction, the cars tend to run ahead of schedule and accumulate at the terminal floor. With the dispatching machine according to the invention this accumulation occurs until more than a certain number of cars collect at the terminal. Then, during one or more dispatching intervals, one of the timers runs faster than the other, preferably twice as fast, until the cars are again evenly distributed.

A preferred form of the invention is illustrated in the accompanying drawings.

In the drawings:

Figure I is a generally schematic illustration of a plurality of elevators serving a plurality of floors.

Figure II is a simplified drawing of a dispatching machine suitable for timing the dispatching intervals.

Figure III is a detail view of a slip clutch for the dispatching machine timer.

Figures IV and V are timing diagrams illustrating the sequence of operation of the contacts that are periodically operated by the timing motors.

Figure VI is a schematic wiring diagram showing the means responsive to the departure of a car from a terminal floor for resetting the dispatching relays and for resetting the means signaling the number of cars standing at a terminal.

Figure VII is a schematic wiring diagram of the means employed to ascertain the number of cars awaiting dispatch at a terminal.

Figure VIII is a schematic wiring diagram showing the control circuits for the timing motors and the means for adjusting the speed of the timing motors.

Figure IX is a schematic wiring diagram of the dispatching relay system.

An elevator system including the dispatching mechanism according to the invention may comprise a bank of elevators having any practical number of cars. Figure I illustrates such a bank having five cars, 1a, 1b, 1c, 1d and 3 10 arranged to serve a plurality of floors. The cars are similar and each is suspended by a set of cables 2 passing over a drive sheave 3 and attached to a counterweight 4. The drive sheave 3 is mounted on a motor armature shaft 5 of an elevator drive motor 6. The shaft 5 is also arranged to drive a floor selector machine 7.

Although not shown in the drawing, common hall buttons for all of the elevators are provided at each of the floors for registering calls for service and corresponding control buttons in each of the cars are provided for registering destination calls. According to common practice the several selector machines 7 have certain of their contacts connected in parallel so that a floor call is answered by the first car to approach that floor in a direction corresponding to the call.

In order that the elevator cars may be kept in spaced relation in their travel up and down the shafts and thus provide the best service it is necessary that they be given dispatch signals at one or both terminals. The dispatching signals are ordinarily given at more or less regular intervals of time and these intervals may be determined either by timing relays or by motor driven timers. Ac cording to the invention variable speed motor driven timers are employed for timing the intervals. Such a motor driven timer is schematically illustrated in Figure II. This timer comprises a variable speed timing motor TM having an armature shaft 8 connected through reduction gearing 9 and output shaft 10 to a friction clutch 11 driving a pinion 12. The pinion 12 meshes with and drives a larger gear 13 mounted on a cam shaft 14. A plurality of earns 15, 16 and 17 of the cam shaft operate contacts TMB-A, TMB-B and TMB-C of the control system. These contacts appear at lines 54, 52 and 50 respectively, of Figure IX. A timer reset motor 18 is connected through a pinion 19 to the gear wheel 13.

The timing motor TM when driving through the gear reducer 9 drives the cam shaft 14 at a slow speed. When it is desired to reset the timer the reset motor 18 drives the gear at a much faster speed the difference in speed being accommodated by slippage of the pinion 12 of the friction clutch 11.

This friction clutch 11 is shown in greater detail in Figure III. It comprises a first washer or stop member 20 pinned to the output shaft 10 and frictionally engaging one side of the pinion 12. A washer 21 engaging the other side of the pinion 12 is held by a helical compression spring 22. The spring is compressed between the washer 21 and a nut 23 threaded onto the end of the output shaft. By adjustment of the tension of the spring 22 the friction may be adjusted so as to drive from the output shaft 10 to the cam shaft 14 when the reset motor 18 is de-energized and yet to permit the reset motor 18 to slip the clutch when it is necessary or desirable to reset the timer.

The sequence or timing of the operation of the contacts TMBA, B and C of the bottom terminal timer is illustrated in Figure IV. As shown therein as the cam shaft revolves from the initial starting position marked zero where the contacts A are momentarily closed, the contact operator 25 first momentarily opens contacts C at about thirty degrees of rotation and then continues around for another three hundred degrees before momentarily closing contacts B. While only a single is operator is shown in this figure it is to be understood that each cam has a high point for operating its associated contact and that those high points and the switches are oriented to give the above described timing.

The contacts C are used in the control circuit in connection with resetting the timer. At the upper terminal if resetting is not employed these contacts are omitted and only the contacts 'A and B and the associated cams used. The timing for this arrangement is shown in Figure V.

The actual dispatching of the cars or the giving of the dispatch signals is controlled by a pair of latch relays, one for the upper terminal and one for the lower terminal. The latch relays are reset when it is desired to dispatch a car and give a dispatch signal. The relays are tripped or returned to their non-reset or unlatched position as the next car leaves the corresponding terminal.

Relays the operating coils of which are shown:

Relay Diagram Function Symbol Line EDT-2 23 Bottom terminal minimum standing time.

Energized when no car is at bottom terminal.

DI) 43 Detent relay down dispatcher. Energized to interrupt down dispatching.

DU 52 Detent relay up dispatcher. Energized to interrupt up dispatching.

KD 4 Down dispatch relay trip coil. Operates when a car responds to down dispatch signal.

KD 45 Down dispatch reset coil operates from down dispatcher timer to give dispatch signal.

KU 9 Up dispatch relay trip coil. Operates when a car responds to up dispatch signal.

KU 54 Up dispatch reset coil operates from up dispatcher timer to give up dispatch signal.

KUT 12 Slow release timer relay for up dispatcher reset circuits.

MDT 48 Manual dispatch time relay. Slow release.

Resets up dispatcher to shorten interval.

NCB-Z 19 Car counting relaybottom terminal, operates when two or more cars are at terminal.

NCB- 21 Car counting relay bottom terminal, operates when three or more cars are at the terminal.

NCBR 7 Reset relay, bottom terminal. Resets car counting relays when a car leaves the terminal.

NOT-2 14 Upper terminal car counting relay, energized when two or more cars are at top terminal.

NOT-30-...-. 16 Upper terminal car counting relay, energized when three or more cars are at top terminal.

NOIR 2 Upper terminal car counting relay reset.

energized as a car leaves top terminal.

RF l. 49 Dispatch interval reset relay. Energized to operate reset motor 18.

SR 56 Starters release relay. Permits supervisor to hold car after expiration of dispatching time interval.

TMB 37 Dispatcher timing motor, bottom terminal.

TMI 33 Dispatcher timing motor. upper terminal.

Relays, the operating coils of which are not shown; that are individual to each car:

Symbol Function Bottom terminal relay. Indicates that the associated car is at the bottom terminal.

Down direction control relay.

In service relay.

Top terminal relay. Indicates that the associated car is at the top terminal.

Up direction control relay.

Bottom terminal minimum standing time relay.

Energized when no cars are at the terminal. I

Top terminal minimum standing time. Energized when no cars are at the terminal.

Up peak traflic program.

Heavy up trafiic program.

Night traffic program.

Dispatching interval program control.

Immediate down dispatch control.

Immediate up dispatch control.

Call controlled starting signal.

Special program. Two cars in service.

Figure VI illustrates the circuits for tripping the dispatch relays as the car leaves the terminal. As shown in this figure brushes 30, one for each car, are connected to direct current power lead L3 by way of in-service relay contacts IS, one set of such contacts for each elevator. These in-service relay contacts IS are closed as long as the corresponding elevator car is in service with its motor generator set running and the car ready to answer calls. The brushes 30A and 30C, for elevators A and C respectively, are shown in relation to selector machine con tacts 31A and 31C in the position that the brushes occupy when the corresponding cars are standing at the upper terminal. Selector brushes 30B and 30E are shown in the positions they occupy with respect to bottom terminal contacts 32B and 32B when the cars are standing at the lower terminal. The brush 30D for the fourth elevator is shown intermediate its contacts indicating that that car is on its trip between terminals. As a car starts down from the upper terminal whether it be the car A or the car Q it completes a circuit from the line L3 through its in-service relay contacts IS such as are illustrated in lines 1 or 3, then through its brush A or 30C to the corresponding selector machine terminal 31A or 31C, then through contacts DF of its down direction field relay to a lead 33 that is connected through a coil of a reset relay NCTR (line 2) to the return lead L4. At the same time a parallel circuit is completed through a lead 34 in line 4 and a trip coil KB of a down-dispatch relay KD (line 4). Reset relay NCTR has contacts in line 15 arranged to momentarily de-energize number relays NCT2 and NCT3 which indicates the number of cars at the top terminal. This reset relay NCTR is provided because the pull-in and release currents of sensitive relays are so widely different that it is not practical to depend upon a small enough difference so that the relay operates if one more than a prescribed number of cars is at the terminal and releases by itself as soon as one car leaves. However, by using the reset relay NCTR the car counting or number relays NCT2 or NCT3 of Figure VII are momentarily released as each car leaves and then re-energized if a sufiicient number of cars still remain at the terminal.

As the cars leave the bottom terminal corresponding circuits are completed from the supply lead L3 through the in-service relay contacts IS, the brushes 30, to the corresponding bottom contacts 32, then through the up-field relay contacts UF that are closed only when a car is conditioned for upward travel, and then through the up dispatch relay trip coil KU to the return lead L4. A bottom terminal reset relay NCBR, for resetting number relays NCBZ and NCB3 indicating the number of cars at the bottom terminals, is connected in parallel with the up dispatch trip coil KU so as to be momentarily energized as the car leaves the bottom terminal.

FigureVII illustrates the circuits employed for determining the number of cars standing at a terminal and available for dispatching. As long as the car is in service its in-service relay contacts IS appearing at the left in Figure VII are closed. Likewise when a car arrives at a terminal either top or bottom the corresponding terminal relay is energized so as to close its contacts TT if it be an upper or top terminal relay or contacts BT if it be a bottom terminal relay. There are a pair of such terminal relays for each car. Each car standing at the top terminal with its motor generator set running (so that it is in service) operates its terminal relay so that current may flow from the supply lead L3 through the corresponding in-service contacts IS, the top terminal relay contacts TT for the corresponding car, then through corresponding resistors 35, 36, 37, 38 or 39. From the resistors the current divides and flows through the coils of number relays NCT2 and NCT3 which are connected in parallel and then through normally closed contacts NCTR of the reset relay NCTR. The resistors to 39 are selected according to the current sensitivity of the relays so that one car alone at a terminal floor is insufiicient to energize either relay. However, if two cars arrive at the top terminal simultaneously thus placing two of the resistors 35 to 39 in parallel enough current flows through the relay coils to energize or operate the relay NCT2. If a third car arrives at that floor before either of the other two leaves enough additional current is supplied by the third resistor connected in parallel so that the other number relay NCT3 is also energized. These number relays NCT2 and NCT3, control various circuits of the dispatching mechanism to maintain generally balanced operation of the system. The first of these, the relays NCT2 and NCB2 are only used during certain periods of the day when perhaps only two cars are operating and serve to dispatch a car from a terminal floor as soon as the other car arrives at that floor. The other number relay NCT3 is employed in connection with the dispatching mechanism during the time when all cars are operating and serves to speed up the dispatching machine at the top terminal and slow down the machine at the bottom terminal whenever three or more cars are standing at the top terminal. As was mentioned previously the normally closed contacts NCTR in line 15 are included to momentarily de-energize the relays NCT2 and NCT3 whenever a car leaves the upper terminal. Thus whether one or both of these relays are energized depends upon the number of cars remaining at the terminal. It is not necessary that these relays be closely adjusted for drop-out current, i. e. the current flow which will just fail to sustain the relay in operated condition, since the relays are both de-energized and re-energized each time a car leaves. Therefore a relay is energized only if enough current is flowing to cause it to pull in.

Similar circuits using resistors 40 to 44 inclusive are employed to energize bottom terminal number relays NCBZ and NCB3. The first of these is energized as long as two or more cars are standing at the lower terminal while the second of these relays is energized if three or more cars are at the terminal. Likewise these relays are momentarily de-energized as a car in leaving the bottom terminal operates its reset relay NCBR of Figure VI thereby momentarily breaking the circuit at the contacts NCBR in line 20. Also included in Figure VII is an up dispatch timer relay KUT shown in line 12. This relay takes part in the resetting of the up dispatch timer.

Another relay BDTZ shown at the bottom of Figure VII (line 23) is used in controlling the resetting operation during periods of heavy up traffic when there are no cars at the bottom terminal. This relay BDT2 has contacts in line 49 of Figure IX which cooperate with other contacts in controlling the timer reset motor 18. As shown in Figure VII, up-peak program contacts H1 in line 23 are closed during periods of up-peak passenger traflic while heavy-up program contacts H4 are closed when the tralfic is predominantly up. The other set of contacts in line 23, the contacts BDT, are contacts of a bottom terminal control relay which relay is energized to close the contacts as long as there are no cars waiting at the lower floor or lower terminal in condition to receive passengers.

The circuits for driving the timing motors for the top and bottom dispatching machines and for controlling the speed of these motors according to demand are illustrated in Figure VIII. As shown in Figure VIII, power from alternating current supply leads L1 and L2 is fed through normally closed contacts H6 of a night program relay in line 25 (to de-energize the system during the night) or contacts THA of a two car special service relay THA. From these contacts, closed during regular operation; the current may flow through lead 45' to an autotransformer AT shown in line 27. Also permanently connected to the lead 45 is a primary 46 of a motor current supply transformer 47. The return side of the primary 46 is connected through down detent relay contacts DD in line 3 1, and a lead 43, to a switch arm 49 adapted to contact any of a plurality of switch points or taps 50 of the auto-transformer. Current may also flow from the lead 45 to a full wave rectifier 51 shown at lines 38 and 39 and back through the return lead L2. The rectifier 51 has output leads L3 and L4 which supply current to the circuits shown in Figures VI, VII and IX as well as to the shunt fields TMTF of the top terminal timer motor TMT and to the shunt field TMBF of the bottom terminal timing motor TMB. These fields are shown at line dill of Figure VIII.

The armature circuit of the top timing motor TMT at line 33 is energized from. a secondary 52 of the trans former 47 by way of a full wave rectifier 53 one terminal which is connected through a lead 54 to one side of the armature TMT of the timing motor. From the rectifier 5'3 current also flows through a second rectifier 55, and a third rectifier 56 the output lea-d 57 of which is connected to the other side of the armature of the timing motor. The second rectifier is energized from a secondary 58 of a second transformer 59 having a primary 60 connected through contacts NCB3 in line 31) (of the bottom terminal number relay NCB3) to the lead 45. These particular contacts are closed as long as fewer than three cars are located at the bottom terminal. Should three or more cars be simultaneously standing at the bottom terminal the contacts NCB3 in line 34) are opened to deenergize the transformer 59 and thus decrease the speed of the timing motor TMT. A third transformer 61 having a primary 62 connected to the supply lead 45 through normally open contacts NCT3 in line 28 has its secondary 63 arranged to energize the third rectifier 56 and thus supply additional voltage to the timing motor TMT whenever the contacts NCT3 are closed, i. e. whenever three or more cars are simultaneously standing at the upper terminal. Thus the timing motor for the top dispatching machine, the timing motor TMT, runs at normal speed as long as there are less than three cars at either terminal. Should three cars be standing simultaneously at the top terminal the contacts NTC3 are closed which adds the voltage of the transformer 61 to the supply circuit for the timer motor armature thus increasing its speed. Likewise, if three or more cars accumulate at the bottom terminal the contacts NCB3 in line 35) are opened thus decreasing the voltage supplied to the timer motor armature thereby decreasing its speed. Similar circuits including rectifiers 64, 65, 66 energized from transformers 67, 68 and 69 respectively supply current to the armature circuit of the bottom terminal timing motor TMB. The transformer 67 has its primary 70 continuously energized from the lead 45 as long as the up detent contacts DU in line 37 remain closed. Thus the secondary 71 of the transformer 67 continuously supplies alternating current voltage to the rectifier 64 to supply voltage to the timing motor armature circuit. Likewise as long as there are less than three cars at the upper terminal contacts NCT3 in line 36 are closed to energize a primary 72 of the second transformer 63 so that its secondary 73 may supply voltage to the rectifier 65 and thus increase the voltages applied to the armature of the timing motor. Likewise if more than three cars accumulate at the lower terminal the contacts NCB3 in line 35 are closed to energize primary 74 of the transformer 69 so that its secondary 75 supplies voltage to the rectifier 66 and thus further increases the voltage supply to the timing motor TMB.

In this arrangement the accumulation of three or more cars at the upper terminal causes the upper dispatch timer motor to run faster and causes the bottom dispatch motor to run slower thus tending to resynchronize the timers and secure balance in the dispatching of the cars. If, in a larger bank of a elevators having six or more cars, three cars should simultaneously arrive at the upper terminal while three cars are at the bottom terminal then both of the car counting relays NCT3 and NCB3 would be energized thus energizing transformers 61and 69 and de-energizing transformers 59 and 68 thus leaving the timing motors to run at normal speed. Thus the difference in timing motor speeds occurs as long as there is an unbalance in the number of cars at the terminals and there are more than two cars, i. e. three or more cars, at one of the terminals.

It should be noted that the average dispatch interval is not changed by the operation of the car counting relays since one of the dispatching timing motors is speeded up while the other is slowed up thus maintaining a nearly constant average.

The average timing interval may be adjusted by selection of a proper tap 50 of the autotransformer AT in line 27 as may be required to supply the proper voltage between the leads 45 and 48. If a clock operated program selector is employed and it is desirable to use different timing intervals for different parts of the program, the switch arm 49 may be brought around to a terminal 76 so that the voltage may be selected according to which one of the program selector contacts PS1 to PS5 in lines 29 to 33 may be closed, these contacts being connected through multiconductor cable 77 and branch leads 78 to the tenninals 50 of the autotransformer.

In this arrangement the timing motors tend to runat the same speed thereby giving approximately the same number of dispatching signals at the upper terminal as are given at the bottom terminal. These signals are not necessarily given simultaneously as they are in some dispatching systems nor are they given exactly half cycle apart as they are in machines designed for dispatching.

an odd number of cars. Rather the signals are given at more or less uniform time intervals and if the system, for any reason, gets out of balance such that more than a certain number of cars accumulate at one terminal one of the timers is speeded up and the other slowed down until the excess number of cars are dispatched and the system rebalanced. Since this rebalancing takes place regardless of the cause of the unbalance this system is immediately effective in maintaining correct balance as cars are taken in or out of service or if they are unduly delayed for any reason.

The remaining control circuits for the dispatching system are illustrated in Figure IX. In this figure the circuits shown in lines 41 to 46 inclusive relate to dispatching from the upper terminal while the remainder of the circuits shown in this figure relate to dispatching from the bottom terminal.

As was mentioned previously the down dispatch relay KD and the up dispatch relay KU are latch relays which are arranged to be reset by the respective dispatch timing motor contacts TMT-A or TMB-A. When the upper terminal down dispatch KD is reset by the current flow from the line L3 through the timing motor cam operated contacts TMT-A shown in line 45 the dispatch relay KD is reset and gives a dispatch signal to the elevators at the upper floors until one of the elevators leaves that terminal. The departing car trips the upper terminal dispatch relay KD by current fiow through the lead L3, lead 34 (line 4, Fig. VI) to the return lead L4. The upper dispatch timing motor is stopped or detented should the timer close its timing contacts B in line 43 at such time as (a) there are no signals registered, as indicated by starting signal relay contacts SSC in line 44 being closed; (b) there is no car at the upper terminal available for dispatching, as indicated by closure of contacts CDT; or (c) timed dispatching is not required as indicated by closure of the RD contacts in line 41. This last condition may occur during periods of heavy up traffic when it is desired to send the cars down as soon as they are available. A fourth set of contacts TH-l in line 42 relate to a two car operation of the bank and are arranged to detent the timer under certain conditions of operation.

A manually operated cutout switch is provided in line 46 in combination with a down push button dispatching control that may be used to give down dispatching signals manually in advance of or in addition to the timer initiated down dispatch signals. Thus if a starter should press the down dispatch button in line 46 he would immediately reset the down dispatch relay KD thus giving a dispatch signal. Since this may occur prior to the closing of the timer contacts A in line 45 the cars may be manually dispatched ahead of the regular timing interval. A cut out switch CO is provided to prevent unauthorized manual dispatching.

The up dispatching circuits include more relays since they provide additional functions. For example, a starter at the lobby floor may be provided with a release control which holds the cars at the lobby floor without a through up dispatch relay contacts KU in the same line. Thus this circuit for the starter release dispatching relay SR cannot be completed until the up dispatch latch relay KU in line 54 has been reset by current flow through the bottom dispatch timing motor contacts TMB-A in line 54. Therefore, the ordinary up dispatch time signal interval is first given by closing the contacts TMB-A in line 54 to reset the up dispatch latch relay KU. This in turn prepares a circuit for the starter release relay SR. Since it is undesirable to require the starter to hold the starter release push button SRP closed until the car leaves, a sealing contact SR in line 58 is provided to bypass the push button as soon as the starter release relay SR is energized. Should it be desirable to eliminate or bypass the starter release push button SRP a cutout switch in line 57 is closed to maintain the circuit for the starter release relay continuously prepared so that this relay is energized as soon as the latch relay KU is reset.

Manual dispatching is also provided by means of the cutout switch in line 47 and an up manual dispatch button in the same line. When this button is pushed, provided that the cutout switch is in the position shown, current flows from the =line L3 through the cutout switch in line 47, the push button in the same line, then through the coil of the manual dispatch relay MDT in line 48 and through the up dispatch latch relay contacts KU in the same line. These dispatcher relay contacts KU are closed as soon as the relay is tripped following the departure of a car from the lower floor. The manual dispatch relay MDT thereupon closes its contacts in line 48 to seal itself in and closes its contacts in line 50 to permit current to flow through the normally closed bottom dispatch timer relay contacts TMB-C, the now closed manual dispatch contacts MTD in line 50 then through an interval reset relay RF in line 49. This relay immediately closes its contacts in line 51 to establish a holding circuit. The manual dispatch relay MDT is of the quick pickup slow release type so that it maintains its normally open contacts closed for a brief time interval after its coil is de-energized.

As soon as the interval reset relay RF in line 49 is energized it closes its contacts RF in lines 58 and 60 to energize the timer relay reset motor 18. It will be recalled from Figure II that the timer reset motor 18 is arranged to drive the cam shaft of the dispatch timer at a high rate of speed. Therefore the cam is rapidly driven around to first close its timing contacts TMB-A at line 54 thereby energizing the reset coil of the up dispatch relay by means of current flowing from the line L3, through the timer contacts A in line 54, the manual dispatch relay contacts MDT in line 55 and the reset coil KU of the up dispatch relay. As the up dispatch relay KU is reset it opens its contacts in line 46 thereby de-energizing the manual dispatch relay MDT. This relay being of the slow release type, does not immediately release but maintains its contacts closed for a brief time interval thereafter. The interval reset relay RF, however, is still energized through its own contacts RF in line 51. Therefore the reset motor 18 continues to run at full speed until the dispatching mechanism comes around to open the contacts TMB-C in line 50 thereby de-energizing the interval reset relay RF and stopping the motor 18. Thus within a very short time from the pressing of the up manual dispatch button in line 47 the bottom terminal dispatching machine timer is advanced, first to give an up dispatch signal by way of the starter relay release relay SR energized when the up dispatch relay KU is reset, and then to continue the timer rapid motion until the contacts TMB-C are open thereby setting the timer to give a full time interval before the next regular dispatching signal.

It is, of course, assumed under this condition of manual dispatching that the starter release push button SRP in line 56 is bypassed by the cut-out switch so that the dis- 16 patch signal is given immediately upon the reset of the up dispatch relay KU.

The bottom terminal dispatching timing motor TMB may be detented, that is stopped, under certain conditions. Thus if the contacts DU shown in line 37 are open by energization of the up detent relay DU in line 52 the timing motor is stopped. The up detent relay DU is energized when the dispatch timer closes its TMB-B contacts shortly before it would give a regular signal in the event that: (a) there are no calls registered requiring movement of any car, i. e. the contacts SSC in line 53 are closed; (b) the program is set for immediate up dispatching to serve heavy down trafiic in which case RU contacts in line 51 are closed, or (0) there may be no cars at the lower terminal available for dispatching which condition is indicated by closure of the BDT contacts in line 52. Under any of these conditions the up detent relay DU is energized as soon as the timer reaches a position approximately one-tenth of a normal time interval before the next regular dispatch signal. The timer stops at this position and waits until dispatching signals are again required.

An additional feature is the resetting of the up dispatching timer should a car leave the bottom terminal before the receipt of a dispatching signal. Should this occur Within a certain minimum time interval from the time that car was available for loading at the lower terminal then current may flow from the line L3 at line 49 through bottom terminal minimum time relay con tacts BDTZ, then through the car counting reset relay contacts NCBR that close momentarily as a car leaves the terminal, then through contacts KUT of an auxiliary dispatching timing relay to the coil of the interval reset relay RF. In this circuit the contacts KUT are closed as long as the coil of the relay KUT in line 12 is deenergized. This occurs as long as there is no dispatching signal registered. Likewise this condition holds for a few moments after a dispatching signal is registered. The energization of reset relay RF advances the timer cam rapidly until the TMB-C contacts open, which occurs just after the normal dispatch signal position. The dispatch relay KU is not reset as the cam turns past the normal dispatch position because contacts RF in line 54 are open during this reset operation. This has the effect of resetting the bottom terminal dispatching timer to give a full time interval for the next car to leave. Without this feature if the car leaves ahead of the receipt of the regular dispatch interval the next car will receive a dispatch signal as soon as it arrives and thus the timing is too short. If the next car ignores the first dispatch signal to Wait for a second the timer detents and there is no second signal. The resetting of the timer as the car leaves, however, avoids these difiiculties and provides a regular full timing interval for the next car in the event that the car leaves without the receipt of a signal. It should be noted that this reset occurs only in the event there are no other cars available for loading at the main terminal. If other cars are there then the dispatch selector contacts BDT2 are open and this resetting circuit cannot be completed.

The improved dispatching mechanism including independent timing motors at the upper and lower terminals provides for automatically balancing the system regardless of the number of cars in operation and regardless of their distribution. Thus the unexpected changes in load which may cause unbalance or unexpected delay of a car in responding to a dispatching signal is corrected almost as soon as it occurs by the accumulation of too many cars at one terminal. Such an event immediately changes the dispatching intervals in opposite directions at the two terminals so as to correct the unbalance immediately. This is automatically accomplished without changing the average dispatch interval and thus with a minimum of disturbance of the system.

Various modifications in circuits and details of component parts may be made without losing the advantages to the self-adjusting dispatching system just described.

Having described the invention, I claim:

1. In a dispatching system for a group of elevators, in combination, a motor driven dispatch signal timer for each terminal, relays for signaling the presence of a car at a terminal floor, contacts operated by said relays, a number of cars signal relay for each terminal floor, circuit means including said contacts for operating thev corresponding signal relay when a predetermined number of said contacts associated with the corresponding terminal are closed, and speed control means for each of the motor driven signal timers, said signal relays being operatively connected each to both speed control means and adapted to simultaneously vary the motor speeds to reduce the dispatch interval for the terminal corresponding to the actuated signal relay and to increase the interval for the opposite terminal.

2 In a dispatching system for a group of elevators, in

combination, a motor driven dispatch signal timer for each terminal, relays for signaling the presence of a car at a terminal floor, contacts operated by said relays, a number of cars signal relay for each terminal floor, means including said contacts for energizing the signal relays with currents proportional to the number of elevator cars standing at the corresponding terminals, and speed control means for each of said timers controlled by said signal relays and adapted to decrease the dispatch interval at the terminal having more than a predetermined number of cars standing thereat and simultaneously increase the interval at the opposite terminal.

3. In a dispatching system for a group of elevators, in combination, a motor driven dispatch signal timer for each terminal, means for signaling the presence of a car at a terminal floor, a dispatcher control relay for each terminal, means operatively connected to the signaling means for operating the dispatcher control relay when a predetermined number of cars accumulate at the terminal, interconnected speed control means for said motor driven signal timers, said speed control means being operatively connected with the control relays such that operation of a control relay decreases the timing interval of the associated timer and increases the time of the opposite terminal timer.

4. In a dispatching system for a group of elevators, in combination, means for generating dispatching signals one for each terminal, speed control means for simultaneously increasing the dispatch interval at one terminal while decreasing the interval at the opposite terminal, signaling means for each elevator for signaling the presence of the elevator car at a terminal landing, said speed control means being jointly controlled by said signaling means to respond to the simultaneous reception of a predetermined number of signals.

5. In a dispatching system for a group of elevators,

a motor for driving each machine, speed control means for each motor adapted to drive the motor at any of three speeds, signal means for each elevator for signaling its presence at a terminal floor, and a relay for each terminal floor, each relay being controlled jointly by the signal means to respond to a predetermined number of signals, each relay being connected to the speed control means to reduce the speed of one motor to its slow speed while simultaneously increasing the speed of the other motor to its high speed.

6. In a dispatching system for a group of elevators, in combination, a dispatching machine for each terminal, a direct current motor for driving each dispatching machine, an alternating current power source, a plurality of transformers and rectifiers adapted to be connected to the power source for supplying direct current to each of the direct current motors, said rectifiers having their output circuits connected in series with the motor whereby the motor speed varies with the number of transformers connected, means for each elevator car for signaling its presence at a terminal floor, and a relay for each terminal floor having contacts connected in circuit with said transformers and arranged when energized to disconnect one of the transformers feeding the motor at the opposite terminal and connect one of the transformers for the motor at the adjacent terminal, said relays being jointly energized by said signaling means and arranged to respond when a predetermined number of signals are simultaneously received.

7. In a dispatching system for a group of elevators, in combination, a dispatching machine for each terminal, a direct current drive motor for each dispatching machine, an alternating current power source, a transformer for each motor having its primary connected to the power source, a rectifier connected between the secondary of the transformer and the armature of the motor, at least one other transformer and rectifier for each motor with the rectifier connected in series with the first rectifier, signal means for each elevator for indicating its presence at a terminal floor, a relay for each terminal floor controlled jointly by the several signaling means and responsive to a predetermined number of signals, and contacts on said relays arranged to switch said other transformers into and out of circuit to vary the speeds of the motors.

8. A dispatching system according to claim 7 in which the voltage of the alternating current power source is adjustable.

Eames Jan. 6, 1953 Borden et al. Sept. 22, 1953

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