US2717056A - Elevator dispatching systems - Google Patents

Description

D. SANTlNl ET AL 2,717,056

ELEVATOR DISPATCHING SYSTEMS Sept. 6, 1955 Filed NOV. 30, 1951 5 sheeaswsheet l f System of Lewis Potent l953ll5, Modified as shown in windows.

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jag/m f ATTORNEY P 6, 1955 D. SANTlNl ET AL ELEVATOR DISPATCHING SYSTEMS 5 Sheets-Sheet 2 Filed NOV. 30 1951 2 I l I I I l I I I l I l I I I l l l I I I I I TASS Fig.|A.

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Apparatus Shown in Block 2|6 of Fig.|.

WITNESSES: {427% Bloc k 2l6 Fig.3.

Apparatus Shown in Block 2l8 of Fig.2.

AUG AMSTZ ASL BUG BMST2 l BSL BS3 -(l CU6 CMSTZ -G CSL CS3 q 7 DUG DMSTZ DSL INVENTORS Donilo Sontini g d John Suozzo.

ATTORNEY United States Patent ELEVATOR DISPATCHING SYSTEMS Danilo Santini, Tenafly, and John Suozzo, Paramus, N. J., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application November 30, 1951, Serial No. 259,066

24 Claims. (Cl. 187-29) This invention relates to multi-car elevator systems, and it has particular relation to dispatchers for dispatching elevator cars at suitable intervals from a dispatching v tional dispatching system. A non-rotational dispatcher dispatches elevator cars from the dispatching floor substantially in the order of arrival of the cars at the dispatching floor. Although aspects of the invention may be employed in a rotational dispatcher, the invention is particularly suitable for the non-rotational dispatcher and will be discussed with respect to a nonrotational dispatcher.

The demand for elevator service is subject to substantial variation throughout the day. If the dispatching interval of an elevator dispatcher is selected for a predetermined service demand, any variation in the service demand may result in a bunching of the elevator cars at the dispatching or other floors and may result in poor service to intending passengers.

In the D. Santini patent application, Serial No. 113,845, filed September 2, 1949, and assigned to the same assignee, now Patent 2,589,292, an elevator dispatcher has a dispatching interval which is selected for a predetermined service demand. For example, the interval may be selected to provide suitable service under conditions of a heavy demand for service from intending passengers. However, the dispatch of elevator cars from the dispatching floor is expedited under certain conditions.

Let it be assumed that the dispatching interval is selected for a heavy service demand and that it represents a compartively long time value. As long as the heavy service demand continues, a car arrives at the dispatching floor as each preceding car at the dispatching floor is dispatched. Substantially only one car is present at r the dispatching floor under these conditions.

If the demand for elevator service decreases, cars will tend to accumulate at the dispatching floor. However, in response to the accumulation of a predetermined number of cars at the dispatching floor, the dispatching interval for the next car to be dispatched is decreased from the aforesaid long value to a medium value of time. Following the dispatch of a car upon the expiration of a medium dispatching interval, succeeding cars again are dispatched in accordance with long dispatching intervals until the predetermined number of cars again accumulates at the dispatching floor.

In the event that a number of cars greater than the predetermined number accumulates at the dispatching floor, the dispatching system automatically decreases the dispatching interval of the next car to be dispatched to a short value of time. The second car to be dispatched A rotational dispatcher for a bank of 2,717,056 Patented Sept. 6, 1955 is dispatched after the expiration of the medium interval of time measured from the departure of the first car. The third and succeeding cars thereafter are dispatched in accordance with the long dispatching intervals.

Preferably the next car to be dispatched from a dispatching floor is selected as promptly as possible after the arrival of the car at the dispatching floor. This enables the car attendant to open his doors and load his car while awaiting the expiration of his dispatching interval. A suitable signal may be given to each attendant in an attendant-operated system for the purpose of notifying him that his car has been selected as the next car to be dispatched from the dispatching floor. At the same time a suitable signal, such as a floor lantern, may be actuated at the dispatching floor for the purpose of notifying intending passengers that the car adjacent the floor lantern will be the next car to leave the dispatching floor. Assuming that a car has been selected as the next car to leave the dispatching floor and that the dispatching interval for the car has expired, the car may be started in any suitable manner.

The foregoing system is quite satisfactory as long as a heavy service demand exists for the elevator cars and as long as the periods of low service demand are of short duration. However, in some applications wherein long periods of low service demand are encountered, the foregoing system may result in excessive car travel during such periods of low service demand.

In accordance with one aspect of the invention, the operation of the foregoing system during long periods of low service demand is modified in order to prevent excessive car travel. In order to initiate such a modification, the service demand is measured. Thus, the service demand may be measured by determining the time rate of registration of car calls registered for passengers within the elevator cars and of floor calls registered by intending passengers desiring elevator car service.

As a further illustration, the service demand may be measured by measuring the time rate of elevator car departures from a dispatching floor. However, such a measurement may necessitate a comparatively long time interval for each count of car departures in order to obtain an accurate measure of the service demand.

In a preferred embodiment of the invention, the time rate of stops made by the elevator cars is utilized as an indication of service demand. Thus, if a large number of elevator car stops during a suitable time interval indicates that a heavy service demand exists, the elevator car system may be permitted to operate in accordance with the teachings of the aforesaid Santini patent application. However, if a small number of elevator car stops are measured during the selected time interval, thus indicating a low service demand, the dispatching interval between successive elevator cars may be increased for the purpose of eliminating excessive travel of the elevator cars.

If an elevator car is loaded rapidly at a dispatching floor, it is desirable that dispatch of the elevator car he expedited. To this end, the invention expedites the dispatch of an elevator car from a dispatching floor when the elevator car has received a predetermined loading such as or of its capacity. At the same time, provision is made to prevent impact loads from affecting the dispatching operations. When an elevator car arrives at a dispatching floor with a full load of passengers, sufficient time is allowed for the discharge of the passengers before the elevator car can be dispatched.

It is, therefore, an object of the invention to provide an improved elevator dispatching system which is responsive to the demand for elevator service.

It is a second object of the invention to provide an elevator dispatching system wherein the intervals between successive elevator cars are dependent on the number of elevator cars at a dispatching floor and on the service demand.

It is a third object of the invention to provide an elevator dispatching system wherein the interval between the dispatch of certain successive elevator cars is dependent on the time rate of service demand.

It is a fourth object of the invention to provide an elevator dispatching system wherein the dispatching interval between successive elevator cars is decreased as elevators accumulate at a dispatching fioor and wherein the decrease is prevented if the service demand is below a certain value.

It is a fifth object of the invention to provide an elevator system which is controlled in accordance with a function of the time rate of service demand.

It is a sixth object of the invention to provide an improved elevator dispatching system wherein the dispatch of an elevator car is expedited in response to a predetermined loading of the elevator car.

It is a seventh object of the invention to provide an elevator dispatching system as set forth in the preceding paragraph wherein a loaded elevator car is provided with sufiicient time to discharge passengers at a dispatching floor.

It is an eighth object of the invention to provide an ele' vator dispatching system as defined in the preceding two paragraphs wherein false operation of the dispatching system in response to impact loads is prevented.

Other object of the invention will be apparent from the following description taken in conjunction with the accompanying drawings in which:

Figure 1 is a schematic view with circuits shown in straight line form showing a portion of an elevator system embodying the invention.

Fig. 1A is a key representation showing contacts and coils of electromagnetic relays and switches shown in Fig. 1. If Figs. 1 and 1A are placed in horizontal alignment it will be found that corresponding contacts and coils of the two figures are substantially in horizontal alignment.

Fig. 2 is a schematic view with circuits shown in straight line form showing an additional portion of the elevator system of Fig. 1.

Fig. 2A is a key representation showing contacts and coils of electromagnetic relays and switches shown in Fig. 2. If Figs. 2 and 2A are placed in horizontal alignment it will be found that corresponding contacts and coils of the two figures are substantially in horizontal alignment; and

Fig. 3 is a schematic view with circuits shown in straight line form of a modified system embodying the invention.

The invention is applicable to banks of elevator cars containing various numbers of elevator cars. For the purpose of discussion, a system will be described with reference to a bank containing four elevator cars, but it is to be understood that it may be employed with banks having different numbers of elevator cars. The cars will be designated by the letters A, B, C, and D, and components specific to the respective cars will be designated by the letters A, B, C, or D, followed by other suitable designating characters. Thus AU, BU, CU, DU designate lower terminal relays associated respectively with the elevator cars A, B, C, D.

Relays are employed which may have make or break contacts. Make contacts of a relay interrupt a circuit as long as the relay is deenergized. Energization and pick up of the relay close the make contacts. The break contacts of a relay are closed to complete an electrical circuit as long as the relay is deenergized. Energization and pick up of the relay open its break contacts to interrupt a circuit. The various contacts of a relay are each identified by the reference character applied to the relay followed by a reference character specific to each set of contacts.

The following relays are specific to the car A:

AU -Lower terminal relay AN Next relay AS Auxiliary start relay AMSTLoad expediter relay ALT -Time delay relay The following relays are common to all cars:

18, 23, 3S Interval relays 2E and 3E Expediter relays T Time period relay US Start relay HT Heavy traflic relay R Reset relay ST Reset stop relay Q Stop quota relay When a number of elevator cars are associated in a bank, it is desirable that they be dispatched from one or more dispatching floors according to suitable schedules. In most installations of banks of elevator cars, the dispatching fioors usually are the upper terminal floor and the first or street floor of the building served by the bank. It may be assumed that if the building has a basement, a special operation is necessary to move the elevator car below the first floor or dispatching floor to the basement. For the purpose of the present discussion, it will be assumed that the elevator cars operate between the first floor which comprises the lower terminal of dispatching floor and the highest floor which serves as the upper terminal or dispatching fioor.

It will be understood that similar dispatching equipment may be provided for each of the dispatching floors. With reference to Figs. 1 and 2, it will sufiice to describe in detail the dispatching equipment associated with the lower dispatching floor.

As cars reach the dispatching floor, it is desirable that the next car to be dispatched from the floor be selected as promptly as possible. This enables the car attendant to fill his car as he waits for the expiration of his dispatching interval. The selection of the next car to be dispatched is effected by selecting mechanism which is operated in part by a constant-speed motor 3) (Fig. 2). This motor is releasably coupled to a cam 41 by means of an electromagnetic clutch RC. When the winding of the clutch RC is deenergized, the motor 39 is disconnected from the cam 4-1. When the winding is energized, the motor is connected to the cam 41 and rotates the cam for the purpose of selecting the next car to be dispatched from the dispatching fioor.

Energization of the electromagnetic clutch RC is con- 1 trolled in part by lower terminal relays AU. BU. CU and DU. For example, when the elevator car A is at or adjacent to its lower terminal, the brush A35 engages the contact segment Ac to connect the winding of the upper terminal relay AU across the direct-current buses L1 and L2 which represent a source of direct current. The contact segment Ac may be located in the hoistway for the elevator car A adjacent the first floor whereas the brush A35 may be mounted on the elevator A to engage the contact segment Ac when the elevator car is adj cent Generally, however, the contact segment and the brush are incorporated in a floor selector in a conventional manner. When the lower terminal relay AU is energized, it closes its make contacts AU ."U2 and AU3. In closing, the contacts AU2 prepare the winding of a next relay AN for subsequent energization. The purpose of contacts AU3 will be discussed below.

Closure of the make contacts AUl completes an energizing circuit for the electromagnetic clutch RC as follows:

L1, AUI, RC, ANl, BN1, CNl, DNl, L2

If some car of the bank has already been designated as the next car to leave the dispatching floor, one of the sets of the break contacts AN 1, BN1, CN1 or DN1 will be open to prevent energization of the electromagnetic clutch RC. It will be assumed, however, that no car has been so designated and that the electromagnetic clutch RC is energized upon arrival of the car A at the lower dispatching floor.

As the cam 41 rotates, it closes successively the camoperated switches AY, BY, CY and DY. This continues until the cam closes the switch of a car located at or adjacent the dispatching floor. Thus, when the cam closes the switch AY, a circuit is completed for the next relay AN:

L1, AU2, AN, AS4, AY, L2

Had any of the other switches BY, CY, or DY been closed, the associated next relays EN, CN, DN would have remained deenergized for the reason that the cars B, C and D are assumed to be away from the lower dispatching fioor, and the contacts BUZ, CUZ and DUZ of their terminal relays are open.

When the next relay AN is energized, it opens its break contacts ANT and closes its make contacts AN2 and AN3. The opening or" the break contacts ANl deenergizes the winding of the electromagnetic clutch RC, and the cam 41 consequently stops rotating. The selecting mechanism cannot be operated again until the break contacts AN1 have been reclosed.

In closing, the contacts ANZ prepare the relay AS for subsequent energization.

Closure of the make contacts AN3 completes the selection of the car A as the next car to be dispatched. The closure may be employed in various Ways for completing the selection. In the specific embodiment herein illustrated, closure of the contacts AN3 illuminates a next signal lamp ANL through the circuit:

L1, AN3, Asz, AHL, ANL, L2

The next signal lamp ANL is located on the car A and informs the attendant or intending passenger that the car has been selected as the next car to leave the dispatching floor. Consequently the car can be loaded. It should be noted that this selection is effected rapidly.

Closure of the next relay can be employed for other functions. For example, such closure may be employed for illuminating hall lanterns at the dispatching floor to indicate to intending passengers which car had been selected as the next car to leave the dispatching floor. Such a hall lantern AHL may be connected in parallel with the r lamp ANL, but is shown in Fig. 2 connected in series with the signal lamp ANL. Similar hall lanterns may be connected in series respectively with the next signal lamps of the remaining cars.

The dispatching system also starts each of the cars from the dispatching floor after the expiration of a suitable dispatching interval. To this end the motor 39 is releasably coupled to a timer cam 43 through an electromagnetic clutch SC. The winding of this clutch is energized through the circuit:

L1, 131, SC, AS1, BS1, CS1, DSl, L2

When the winding is energized, the cam 43 is actuated away from a starting position to operate a cam-operated switch S. When the electromagnetic clutch is deenergized, a spring 45 returns the cam 43 to its starting position. The construction of the motor 39 and the electromagnetic clutches may be similar to that illustrated in the Eames Patent 2,121,587.

Each of the contacts ASL BS1, CS1 and D51 opens when its associated car is ordered to start from the dispatching floor. Until contacts ASli, BS, CS1 and D51 are all closed, the electromagnetic clutch cannot be en ergized and a succeeding timing interval cannot be initiated.

When the timing cam 43 reaches the switch S, the

S switch contacts close to energize the interval relay 1S through the circuit:

L1, AMSTI, BMSTl, CMST1, DMSTIl, 18, S, ASl, BS1, CS1, BS1, L2

The contacts AMST1 BMST1, CMSTI and DMSTl must be closed to indicate that none of the cars at the dispatching floor is loaded in excess of a predetermined value.

The interval relay 18 opens its break contacts 181 and 1S4, and closes it make contacts 152 and 133. The contacts 1S2 establish a holding circuit around the switch S. The contacts 181 in opening deenergize the winding of the electromagnetic clutch SC, and the spring 455 promptly restores the timing cam to its starting position. The contacts 1S3 control in part the energization of the expediter relays 2E and 3E. The contacts 184 in opening deenergize the interval relay 25. This relay has a time delay in dropout which is determined in any suitable manner as by a resistor 47 which is connected across the winding of the relay 28. The resistance value of the resistor 47 may be adjustable to permit adjustment of the dropout time of the interval relay 28.

It will be understood that the interval relay 2S normally is energized. When the contacts open and the interval relay 23 times out, it opens its make contacts 281 and closes its break contacts 252. Closure of the break contacts 282 has no effect on the operation of a system as long as the expediter relay 2E remains deenergized and contacts 2E1 remain open.

Opening of the contacts deenergizes the normallyenergized interval relay 33. The relay 38 also has a time delay in dropout. The time delay may be obtained in any suitable manner as by means of a resistor 49 which is connected across the winding of the time interval relay 38.

Upon the expiration of the time delay of the relay 38, it drops out to close its break contacts 351. This completes the following circuit for the start relay US:

L1, 381, US, L2

Thus, the dispatch interval required for energizing the start relay US is the sum of the delays introduced by the switch S and the relays 2S and 38.

When energized, the start relay US closes its make contacts U81. If a car is adjacent a dispatching floor (contacts AU2, BUZ, CUZ, or DUZ are closed) and if one of the cars at the dispatching floor has been selected as the next car to be dispatched (contacts ANZ, BN2, CN2, or DNZ are closed), a start circuit is established for one of the cars as follows for the car A:

L1, AUZ, AS, AN2, US1, L2

to energize the auxiliary start relay AS.

When the start relay AS is energized, it opens its break contacts AS1, A82 and A34, and closes its make contacts ASS and AS5. The opening of the contacts A81 interrupts the energizing circuit for the relay 1S and prevents further energization of the relay 18 or of the electromagnetic clutch SC until the car A has departed from the dispatching floor.

Opening of the contacts A82 extinguishes the next lamp ANL in the car A (and the hall lantern AHL). Closure of the contacts A83 starts the car A in any suitable manner.

Opening of the contacts AS4- deenergizes the next relay AN. Contacts ANll reclose to permit selection of another next car. Contacts AN2 open, but a holding circuit around these contacts is maintained by the contacts ASS. Contacts AN3 open to prevent reenergization of the hall lantern and next signal.

When the relay 13 was deenergized by opening of the contacts ASl, it closed its contacts 181 and opened its contacts 182 and 183 without immediately affecting thereby the system operation. However, at the same time the break contacts 154 closed to pick up the relay 28. The relay 28 in turn closed its make contacts 281 to energize the relay 3S and opened its break contacts 252. As a result of its energization the relay 3S1 opened to deenergize the relay US. The opening of the make contacts US1 has no immediate effect on the operation of the system.

As the car A leaves the dispatching floor, the contact A35 is moved out of engagement with the contact segment Ac. Consequently, the lower terminal relay AU is deenergized. Contacts AUl open to maintain the winding of the electromagnetic clutch RC deenergized until another car is at or adjacent the dispatching floor. Contacts AU2 open the circuit for the auxiliary start relay AS. Contacts AU3 open to decrease the possible energization of the expediter relays 2E and 3E.

The auxiliary start relay AS on being deenergized closes its contacts A51 to permit subsequent energization of the electromagnetic clutch SC. Contacts AS2 close to prepare the next signal lamp ANL for subsequent energization, and contacts ASS open to interrupt the starting circuit. Also, contacts AS close to prepare the relay AN for subsequent energization and contacts ASS open.

If a dispatching interval expires before a car reaches the dispatching floor, the start relay US remains energized. As soon as a car reaches the dispatching floor, the car is promptly selected for dispatching, and one of the next relay contacts AN2, BN2, CN2, or DN2 closes to energize the appropriate auxiliary start relay. Consequently, the first car to reach the dispatching floor is promptly dispatched.

In the preferred embodiment of the invention, the dispatching interval which is the sum of the intervals determined by the switch 5, and the interval relays 2S and SS is set for a heavy service demand. As long as the service demand continues, a car reaches the dispatching fioor as another car leaves the dispatching floor to provide efiicient system operation.

Should the service demand momentarily decrease, cars may tend to accumulate at the dispatching floor. Efficient operation under these conditions is assured by the expediter relays 2E and 3E.

The current supplied to the expediter relays 2E and SE is dependent on the number of cars at or adjacent the dispatching floor. For example, if the car A is adjacent the dispatching floor, its brush 35 engages the contact segment Ac to energize the lower terminal relay AU. If the relay 15 is energized at the same time, a circuit is established for the expediter relays as follows:

L1, AU3, AR, 51, 183, 2E in parallel with ER-j-SE, L2

A manually operable switch 51 may be included in this circuit to render the circuit ineffective or efiective as desired.

The expediter relays 2E and 3E are designed to require a certain minimum current before they can pick up. The expediter relays may be of similar construction, but the relay 3E has in series therewith a resistor ER which restricts the current through the relay 3E to a value lower than that traversing the relay 2E. The resistor AR further restricts the current supplied to both of the expediter relays.

The parameters of the circuit are so selected that the relays 2E and 3E pick up when different numbers of elevator cars are adjacent the dispatching floor. As a specific example, the relay 3E may pick up when at least three elevator cars are adjacent the dispatching floor, whereas the relay 2E picks up when only two elevator cars are adjacent the dispatching floor. It will be understood, however, that the number of elevator cars to which the relays 2E and 3E respond may be selected in accordance with the requirements of each elevator installation.

The expediter relays 2E and 3E control the effectiveness of the relays 2S and 38 in delaying energization of the start relay US. For example, if the expediter relay 2E is energized by the presence of two cars adjacent the dispatching floor, the contacts 2E1 close. Consequently, if a heavy service demand exists (contacts HTl are closed), as soon as the interval relay 2S drops out, the following energizing circuit is established for the start relay:

L1, HT1, 2S2, 2E1, US, L2

Under these conditions a car may be dispatched from the dispatching floor before the interval relay 35 has dropped out.

Next assume that the expditer relay SE is energized by the presence of three elevator cars adjacent the dispatching floor. Under these circumstances the start relay US is energized through the circuit L1, 3E1, US, L2

Therefore, a car may be dispatched from the dispatching floor before the interval relays 2S and 38 drop out.

If desired, a dispatching system may be provided for the upper terminal or upper dispatching floor Which is similar to that described for the lower dispatching floor.

If the start relay US must await the timing out of the switch S and the interval relays 2S and 38, a long dispatching interval results. If the start relay US is energized after the switch S and the interval relay 28 have timed out, a medium dispatching interval results. Finally, if the start relay US is energized after the switch S alone times out, a short dispatching interval results.

The effect of the expediter relays then is to decrease the accumulation or bunching of cars at the dispatching floor. Inasmuch as the expediter relays never dispatch two cars simultaneously, there is no tendency for the cars to bunch after leaving the dispatching floor. In this way optimum service is rendered intending passengers of the elevator system under all conditions of service demand.

The operation set forth in the preceding two paragraphs is satisfactory as long as the service demand remains heavy or if the periods of low service demand are of short duration. However, it long periods of low service demand are anticipated, it may be desirable to modify the dispatching system to prevent excessive car travel. For this purpose, provision is made to measure the time rate at which stops are made by the elevator cars. The measuring apparatus includes a notching or stepping switch SS (Fig. l) which includes a pair of diametrically opposite contact arms 201 and 203, which are mounted for rotation about an axis 205. Rotation of the contact arms is efiFected by means of a ratchet wheel 207, which is secured to the arms for rotation about the axis. A pawl 209 is positioned for reciprocation to advance the ratchet wheel 207. When the coil of the stepping switch is energized, the pawl 209 is moved downwardly without rotating the ratchet wheel as a result of the attraction of the coil for a magnetic armature secured to the pawl. At the same time, contacts SS1 associated with the stepping switch are opened. If the coil thereafter is deenergized, a spring 211 pulls the pawl 209 upwardly as viewed in Fig. l to advance the ratchet wheel and the contact arms one step. This operation is repated for each energization and deenergization of the coil of the stepping switch, and such operation of stepping switches is well known in the art.

The coil of the stepping switch SS is energized and deenergized once for each stop of each of the elevator cars. The energizing circuit for the coil is completed through any one of a plurality of parallel circuits A213,

u B213, or C213, one of which is provided for each of the elevator cars. The parallel circuits are connected between the conductor L1 and a conductor 210. Suitable contacts for controllinug these parallel circuits will be discussed below.

The contact arms 201 and 203, as they are advanced, successively engage commutator segments CS1 to CS9. Thus, the position of the contact arms indicates the number of stops made by the elevator cars. If it is desired to control apparatus in accordance with a predetermined number of stops, a stop quota relay Q may be associated with the appropriate commutator segment. In this case, it will be assumed that the stop quota relay is to be energized when either of the contact arms engages the commutator segment CS7 which represents six car stops. In order to facilitate resetting of the stepping switch, a reset stop relay ST is associated with the commutator seg ment CS9.

The stepping switch S operates to count the number of car stops made, but it is desired to control apparatus in accordance with the time rate at which the stops are made. To this end, a time period relay T is provided which is energized through make contacts of a reset relay R. The time period relay has a substantial time delay in dropout which may be determined, at least in part, by a resistor 215 which is connected across the relay. The stepping switch must operate to energize the stop quota relay Q within a time interval required for the time period relay T to drop out if the stop quota relay Q is to be effective for a control operation.

A heavy traffic relay HT is energized only if the elevator cars have made a predetermined number of stops (make contacts Q1 are closed) and if this number of stops has been made within the time interval measured by the time required for the time period relay T to drop out (break contacts R2 are closed). When the heavy traffic relay HT picks up, it completes a holding circuit through its make contacts HT2 and through the make contacts T1 of the time period relay. Consequently, this holding circuit is interrupted if the time period relay T is allowed to drop out.

A resetting operation of the stepping switch SS is initiated by energization of the reset relay R through break contacts T2 of the time period relay T or through make contacts Q2 of the stop quota relay Q. Such energiza-..

tion can take place only if the break contacts ST1 of the reset stop relay are closed. When energized, the reset relay R establishes a holding circuit through its make contacts R3 which is interrupted when the break contacts ST1 of the reset stop relay open.

The operation of the stepping switch and its associated circuits now may be considered. It will be assumed that the contact arms 201 and 203 are in their reset position, as shown in Fig. 1, and that the make contacts R1 have opened to deenergize the time period relay T. The time period relay consequently starts to time out.

During the time required for the relay T to drop out, the contact arms 201 and 203 are advanced one step for each car stop made by the elevator cars in service in the elevator system. It will be assumed first that three stops are made by the elevator cars before the time period relay T drops out. Consequently, the contact arm 201 is in engagement with the commutator segment CS4 at the time the time period relay T drops out.

When the time period relay T drops out, it opens its make contact T1 and closes its break contacts T2. If the heavy traflic relay HT was previously energized and was held energized through its holding circuit, the opening of the contacts T1 deenergizes the heavy traflic relay.

The closing of the break contacts T2 completes an energizing circuit for the reset relay R through the break contacts ST1 of the reset stop relay. The reset relay R thereupon closes its make contacts R1 to reenergize the time period relay T. The opening of the break contacts R2 prevents energization of the heavy traffic relay through the make contacts Q1 of the stop quota relay. Closure of the make contacts R3 completes a holding circuit for the reset relay R through the break contacts ST1 of the reset stop relay. Closure of the make contacts R4 com-.

pletes an energizing circuit for the stepping switch SS through the break contacts SS1. Consequently, the stepping switch repeatedly steps the arms 201 and 203 in a clockwise direction as viewed in Fig. 1.

When the contact arm 201 reaches the commutator segment CS7, an energizing circuit is established for the stop quota relay Q. The resultant closure of the make 10 contacts Q1 has no effect on the system for the reason that the break contacts R2 are open. Closure of the contacts Q2 also is without effect for the reason that the contacts R3 are closed.

In response to continued stepping of the contact arms, the contact arm finally engages the commutator segment CS9 to complete an energizing circuit for the reset stop relay ST. This relay opens its break contacts ST1 to deenergize the reset relay R.

As a result of its deenergization, the reset relay opens its make contacts R1 to initiate a time-measuring operation of the time period relay T. Consequently, this relay starts to time out. The break contacts R2 reclose but have no eti'ect for the reason that the make contacts Q1 are now open. The make contacts R3 open, but such opening has no immediate eifect on the operation of the system. The make contacts R4 open. The spring 211 now advances the contact arms to their reset positions, and the stepping switch now is conditioned to measure again the number of elevator car stops during the period being measured by the time period relay T.

The stepping switch SS may have a slight time delay in each stepping operation to permit pick up of the reset stop relay ST and dropout of the reset relay R after one of the contact arms reaches the commutator segments CS9 before the stepping switch can operate one of the contact arms beyond the commutator segment CS1. Thus the: stepping switch may be given a short delay in dropout in a conventional manner.

It now will be assumed that the elevator cars make a total of six stops before the time period relay T times out. When the contact arm 203 reaches the commutator segment CS7, an energizing circuit is established for the stop quota relay Q. This relay closes its make contacts Q1 to complete an energizing circuit for the heavy traffic relay HT through the break contacts R2. In addition, the make contacts Q2 close to complete an energizing circuit for the reset relay R through the break contacts ST1.

The heavy traffic relay HT may be employed in any suitable manner for controlling the operation of the dispatcher. For example, if the contacts represented by the switch 51 (Fig. 2) are closed only when the heavy traffic relay HT is energized, the expediter relays 2E and 3E will be effective for expediting dispatch of elevator cars only while the heavy traffic relay is energized. However, for present purposes, it will be assumed that the heavy trafiic relay HT has make contacts HTl which control the elfectiveness of one of the circuits for energizing the start relay US. When the heavy traffic relay is energized, the make contacts HTl are closed to permit energization of the start relay through the contacts 282 and 2E1. Consequently, if only two elevator cars are at the dispatching floor, one of the elevator cars will have its dispatch expedited only if the heavy trafiic relay is energized.

The heavy trafiic relay also closes its make contacts HT2 (Fig. 1) to establish a holding circuit which is corn-- pleted through the make contacts T1 of the time period relay. Consequently, if the heavy traflic relay once picks up, it remains picked up until the time period relay T is dropped out.

It will be recalled that the energization of the stop quota relay Q also resulted in energization and pickup of the reset relay R. This relay closes its make contacts R1 under the assumed conditions before the time period relay T has dropped out. The opening of the break contacts R2 has no immediate effect on the operation of the system. The closing of the contacts R3 establishes a holding circuit for the reset relay R, which is completed through the break contacts ST1 of the reset stop relay ST. The make contacts R4 close to reset the stepping switch SS in a manner which will be clear from the foregoing discussion. It will be recalled that when the stepping switch SS is reset, the reset relay R is dropped out and opens its make contacts R1 to initiate a new timing-out period for the time period relay T.

If the number of car stops is sufficient to again energize the stop quota relay Q before the time period relay T drops out, the heavy trafiic relay HT remains energized, the stepping switch SS is reset, and the time-period relay is energized and started on another timing-out period. This sequence continues until the number of car stops registered is insufficient to energize the relay Q before the time period relay T drops out. It will be recalled that the time period relay on dropping out opens its make contacts T1 to deenergize the heavy trafiic relay HT. The heavy trafiic relay then opens its make contacts HTl (Fig. 2) to prevent the start relay US from being energized through the contacts 252 and 2E1.

From the foregoing discussion, it is clear that as long as a heavy service demand continues in the elevator system the make contacts HTl are closed to permit an elevator car (if two elevator cars are simultaneously at a dispatching floor) to be dispatched with a medium interval. However, if a low service demand exists for a sufiicient period, the heavy traflic relay HTl operates to its dropped-out condition to open its make contacts HTl. Under these circumstances, if two elevator cars are at the dispatching floor, one cannot be dispatched with a medium interval but must wait for the expiration of the full dispatch interval. This eliminates unnecessary car travel during prolonged periods of low service demand.

If an elevator car is at a dispatching floor and is loaded before the expiration of its dispatch interval, it is desirable that the dispatch of the elevator car be expedited. To this end, suitable apparatus is provided for measuring the load carried by the elevator car. As shown in Fig 1, the elevator car A is provided with a load switch LS. This load switch is pivoted by means of a pivot LSP to the elevator car A and is biased towards the elevator car by means of a spring LSS. The rope or cable Ca which supports the elevator car is secured to the lever of the load switch. The load switch lever carries a movable contact 219 which is biased by the spring LSS into engagement with a fixed contact 221. When the elevator car A is loaded to a predetermined extent, such as to 80% or 90% of its rated capacity, the contacts 219 and 221 open.

The contacts 221 and 219 control through conductors 221a and 219a the energization of a load expediter relay AMST. This relay has a delay in dropout which may be introduced at least in part by a resistor 223 connected thereacross sufficient to make the relay insensitive to load changes due to impact. Such load changes may be caused by a passenger stepping heavily or jumping into an elevator car.

When the load expediter relay AMST is deenergized and drops out, it closes its break contacts AMST2 (Fig. 2). These contacts are connected in series with make contacts AU6 of the lower terminal relay AU to complete a starting circuit for the elevator car A when the elevator car is at the dispatching floor. It will be noted that the contacts AMST2 and AUG are connected in series across the contacts AS3 of the auxiliary start relay.

When the elevator car A reaches the dispatching fioor with a full load of passengers, sufficient time should be provided to permit discharge of the passengers. To this end, make contacts ALT1 (Fig. 1) of a time delay relay are connected in series with make contacts AUS of the lower terminal relay across the contacts 219 and 221 of the load switch. Consequently, as long as the contacts AUS and ALT1 are closed, the relay AMST cannot be deenergized to expedite the dispatch of the elevator car A. Break contacts AU4 of the lower terminal relay permit deenergization of the relay AMST only at the lower dispatching floor.

The time delay relay ALT has a time delay, which may be provided in part by a resistor 225 connected thereacross, suflicient to permit the discharge of sufficient passengers from a loaded elevator car to assure reclosure of the contacts 219 and 221. For many elevator cars, a time delay in dropout of the relay ALT of the order of seven seconds suffices. The relay ALT conveniently may be energized through conductors 212 and 214 and through contacts of a relay (described below) which are closed while the elevator car is running and which are open when the elevator car stops at a floor. Consequently, when the elevator car reaches the dispatching fioor, the time delay relay ALT is deenergized and starts to time out. Until it times out, the load expediter relay AMST is inefiective to initiate a dispatch of the elevator car.

In order to show a dispatching system embodying the invention in a complete elevator system, Fig. 1 shows the elevator system illustrated and described in the F. E. Lewis Patent No. 1,953,115. Since most of the components of the Lewis system are employed in the form therein illustrated, only those parts of the Lewis system which have been modified are shown in detail in windows in Fig. 1.

In the Lewis system the elevator cars are dispatched in an upward direction by means of a dispatcher which connects a conductor 181 or a conductor 157 to a bus L2. In the present Fig. 1, the dispatcher of the Lewis patent is replaced by an elevator dispatching system which operates at suitable times to connect the same conductors 181 and 157 to the bus L2. It will be assumed that the cars C and C of the Lewis patent correspond to the elevator cars A and B which are referred to in the preceding discussion of the invention.

By inspection of Fig. 1, it will be noted that when the make contacts A83 are closed or when the contacts AU6 and AMST2 are closed, the conductor 181 is connected to the bus L2. Under either of these circumstances, the elevator car C of the Lewis patent is dispatched in the manner set forth in the patent.

In a somewhat similar manner, if the contacts BS3 or if the contacts BU6 and BMST2 are closed, the conductor 157 is connected to the bus L2. Under either of these circumstances, the car C of the Lewis patent is dispatched from the lower dispatching floor in the manner set forth in the Lewis patent.

If third and fourth cars are employed by Lewis, they would be dispatched from the lower dispatching floor in a similar manner by operation of the contacts CS3, CU6 and CMST2 for the third car and by contacts DS3, DU6 and DMST2 for the fourth car. It will be recalled that in the Lewis patent, for multiple car operation of this type, the switches 27, 27, 26 and 26 are open, and the switches 25 and 25 (see the Lewis patent) are closed.

In order to operate some of the circuits of the elevator dispatching system, certain relays of the Lewis patent have been modified. Thus make contacts and are added to the relays 9 and 10 of the Lewis system (similar contacts would be added for the relays 9' and 10' of the car C and for similar relays employed for other elevator cars incorporated in the Lewis system). These added contacts are employed in the parallel circuits A213, B213 and C213, which are employed for controlling the energization of the coil of the stepping switch SS.

One of the sets of contacts 9c and 10c is closed and shortly reopened whenever the elevator car C of the Lewis patent is to stop at a floor. Consequently, it is clear that for each stop of the elevator car C the coil of the stepping switch SS is energized and deenergized. In a similar manner, contacts 9c and 10'c energize and deenergize the coil of the stepping switch SS once for each stopping operation of the elevator car C of the Lewis patent. Each additional car employed in the Lewis system would have similar contacts controlling one of the parallel arms associated With the coil of the stepping switch SS. It will be recalled that the cars C and C of the Lewis system are assumed to correspond to the cars A and B which were mentioned during the initial discussion of the invention.

There is a possibility that two or more cars may stop substantially simultaneously at floors, thus producing only one operation of the stepping switch. However, this will not occur often enough to affect materially the desired system operation.

The relay 2 of the Lewis system has an additional set of make contacts 2 for controlling the energization of the time delay relay ALT through conductors 212 and 214. When the elevator car C of the Lewis patent stops at the lower dispatching fioor on a down trip, the con tacts 2 open to deenergize the time delay relay ALT. A similar set of contacts would be provided for each of the elevator cars employed in the Lewis system and would similarly afiect the operation of the associated elevator car.

The load switch disclosed in the Lewis patent is modified as shown in Fig. 1. It will be noted that the contacts 219 and 221 are employed in place of the contact 135 of the Lewis patent. It will be understood that a similar load switch is provided for each of the elevator cars for the purpose of expediting the dispatch of the associated elevator car when loaded.

The system illustrated in Fig. 1 is of the automatic type wherein the elevator cars are dispatched and operate without car attendants. In order to show how the invention may be incorporated in a system wherein elevator cars are operated by car attendants, a modified system is illustrated in Fig. 3. For the system of Fig. 3, it is assumed that all parts of the elevator system illustrated in the Santini Patent 2,492,010 are employed except for the circuits and parts illustrated in Fig. of the patent. The circuits of Fig. 5 may be assumed to be disconnected or removed. Under these circumstances, the contacts PA1 and PBl in Fig. 4 of the Santini patent remain permanently closed, and the contacts J1 and J2 of Fig. 3 of the Santini patent have no effect on the operation of the system.

Certain contacts are added to the relays of the Santini system. Thus, the relay M of the Santini patent has break contacts AM4 and make contacts AMS added thereto. In addition, the relay G of the Santini patent has make contacts AG3 added thereto. The contacts AG3 and AM4 are connected in series in a circuit A213 for the purpose of energizing and deenergizing the coil of the stepping switch SS (included in the block 216) once for each stopping operation of the elevator car A. Similar comments apply to the corresponding contacts associated with the other elevator cars employed in the system. The parallel circuits A213, B213, C213 of Fig. 3 correspond to the circuits A213, B213, C213, of Fig. 1.

The apparatus in blocks 216 and 218 of Figs. 1 and 2 respectively is also included in the system of Fig. 3. The make contacts AMS are employed for the purpose of controlling the energization of the time delay relay ALT (included in block 216, Fig. 1) through the conductors 212 and 214. Thus, when the elevator car A stops at the lower dispatching floor the make contacts AMS open to deenergize the relay ALT.

For the purpose of measuring the load in the elevator cars of the Santini patent, it is assumed that each of the elevator cars has a load-weighing platform. This is represented in Fig. 3 by a platform 227 which is mounted on the sling 229 which supports the elevator car A by means of yieldable supports 231. The yieldable supports may consist of springs or elastomer pads. When the platform is loaded to an extent which may be of the order of 80% or 90% of capacity, the resilient supports yield sufficiently for an operating pin P to open the normally closed contacts 219 and 221. These operate in the manner previously discussed to expedite the dispatching of the elevator car.

In the embodiment of Fig. 3 the elevator cars are started by means of start lamps ASL, BSL, CSL and DSL for the cars A, B, C and D respectively. Thus when the contacts A83 are closed or when the contacts AU6 and AMSTZ are closed the start lamp ASL is illuminated to indicate to the car attendant that the elevator car A should be started from the lower dispatching floor. The operation of these contacts was set forth in the discussion of Fig. 1 wherein the same contacts are employed. The start lamps for the remaining cars operate in a similar manner to inform the car attendants when the elevator cars B, C and D should start from the lower dispatching floor.

Although the invention has been described with reference to certain specific embodiments thereof, numerous modifications falling within the spirit and scope of the invention are possible. Consequently, the specific embodiments herein disclosed are to be interpreted in an illustrative rather than in a limiting sense.

We claim as our invention:

1. An elevator dispatching system for a plurality of elevator cars serving a plurality of floors, comprising a dispatcher for dispatching the elevator cars from one of the floors, said dispatcher including selecting means for dispatching successively each car to be dispatched from the dispatching floor in accordance with a predetermined schedule, first means responsive to a function of the number of elevator cars adjacent the dispatching floor for modifying said schedule, and second means responsive to a predetermined service demand for service from the elevator cars for modifying said schedule.

2. A system as claimed in claim 1 wherein said second means is responsive to the time rate of accumulation of said service demand.

3. A system as claimed in claim 1 wherein said second means in operating increases the dispatch interval between certain successive ones of said elevator cars.

4. A system as claimed in claim 1 wherein the first means in operating decreases the dispatch interval between certain successive ones of the elevator cars, and wherein the second means under a predetermined condition prevents said decrease in the dispatch interval.

5. An elevator dispatching system for a plurality of elevator cars serving a plurality of floors, comprising a dispatcher for dispatching the elevator cars from one of the floors, said dispatcher including selecting means for dispatching successively each car to be dispatched from the dispatching floor in accordance with a predetermined schedule, first means responsive to a function of the number of elevator cars adjacent the dispatching floor for decreasing the dispatch interval between successive elevator cars accumulated at the dispatching floor, and second means responsive to a predetermined service demand for service from the elevator cars for preventing said decrease of the dispatch interval.

6. A system as claimed in claim 5 wherein the second means includes means for preventing said decrease of the dispatch interval if the service demand decreases.

7. A system as claimed in claim 5 wherein the second means is responsive to a decrease in the time rate of the service demand for increasing the dispatch interval be tween successive elevator cars accumulated at the dispatching floor to a value longer than that otherwise determined by the first means.

8. An elevator dispatching system for a plurality of elevator cars serving a plurality of floors, comprising a dispatcher for dispatching the elevator cars from one of the floors, said dispatcher including selecting means for dispatching successively each car to be dispatched from the dispatching floor, demand means responsive to the time rate of the service demand for service from the elevator cars, and control means responsive to operation of the demand means for controlling the dispatch interval between certain of the elevator cars.

9. A system as claimed in claim 8 wherein the control means is responsive to a decrease in the time rate of service demand for increasing the dispatch interval between elevator cars at the dispatching floor.

10. A system as claimed in claim 8 wherein the demand means is responsive to the time rate at which stops are made by the elevator cars, and the control means is responsive to a decrease in the time rate at which said stops are made for increasing the dispatch interval between elevator cars accumulated at the dispatching floor.

11. In an elevator system, a structure having a plurality of floors, an elevator car, means mounting the elevator car for movement relative to the structure, control means operable for moving the elevator car and stopping the elevator car at the floors for which elevator service is required, means for measuring the time rate of service demand for the elevator car, and demand means responsive to the measuring means in accordance with the time rate of service demand for the elevator car.

12. An elevator system as claimed in claim 11 wherein the measuring means is responsive to the time rate at which stops are made by the elevator car.

13. An elevator system as claimed in claim 11 wherein the measuring means comprises timing means for repeatedly measuring a time interval, and means for measuring the service demand for each of the intervals.

14. An elevator system as claimed in claim 11 wherein the measuring means comprises timing means for repeatedly measuring a time interval, and means for measuring the number of stops made by the elevator car during each of the time intervals.

15. An elevator system as claimed in claim 14 wherein the last-named means comprises a stepping relay responsive to the stops made by the elevator car.

16. In an elevator system, a structure having a plurality of floors, a plurality of elevator cars, means mounting the elevator cars for movement relative to the structure, control means operable for moving each of the elevator cars and stopping each of the elevator cars at the floors for which elevator service is required, measuring means responsive to the time rate of the service demand for all of the elevator cars in service, and demand means responsive to the quantity measured by said measuring means.

17. An elevator system as claimed in claim 16 wherein the measuring means is responsive to the time rate at which stops are made by all of the elevator cars in service.

18. In an elevator system, a structure having a plurality of floors, a plurality of elevator cars, means mounting the elevator cars for movement relative to the structure, control means operable for moving each of the elevator cars and stopping each of the elevator cars at the floors for which elevator service is required, means for dispatching each of the elevator cars successively from one of the floors, and load-responsive time-delayed means responsive to the loading of each of the elevator cars for expediting the dispatch of the associated elevator cars.

19. In an elevator system, a structure having a plurality of floors, a plurality of elevator cars, means mounting the elevator cars for movement relative to the structure, control means operable for moving each of the elevator cars and stopping each of the elevator cars at the floors for which elevator service is required, means for dispatching each of the elevator cars successively from one of the floors, load-responsive means responsive to the loading of each of the elevator cars for expediting the dispatch of the associated elevator cars, and means effective upon arrival of each of the elevator cars at the dispatching fioor with a load to be discharged for rendering ineffective the load-responsive means for a time sufficient to permit unloading of each loaded elevator car.

20. In an elevator system, a stepping switch, means for energizing the stepping switch to produce stepping operations of the switch in accordance with a service demand of the elevator system, and means responsive to the advance of the stepping switch for modifying the operation of the elevator service offered by the elevator system in accordance with the degree of advance of the stepping switch.

21. In an elevator system, a structure having a plurality of floors, a plurality of elevator cars, means mounting the elevator cars for movement relative to the structure, control means operable for moving each of the elevator cars and stopping each of the elevator cars at the floors for which elevator service is required, and demand means responsive to the time rate of the service demand for all of the elevator cars in service, said demand means comprising timing means for repeatedly measuring a time interval and means for measuring the number of stops made by all of the elevator cars in service during each of the intervals.

22. In an elevator system, a structure having a plurality of floors, a plurality of elevator cars, means mounting the elevator cars for movement relative to the structure, control means operable for moving each of the elevator cars and stopping each of the elevator cars at the floors for which elevator service is required, and demand means responsive to the time rate of the service demand for all of the elevator cars in service, in combination with means for successively dispatching the elevators from one of the floors, means controlled by said demand means for modifying the dispatch interval between successive ones of the elevator cars dispatched from the dispatching floor, and means responsive to the load of each of the elevator cars at the dispatching floor for expediting the dispatch of the elevator car from the dispatching floor, said last-named means being ineffective following a stopping operation of each of the elevator cars at the dispatching fioor for a time sutficient to permit unloading of each of the elevator cars.

23. In an elevator system, a structure having a plurality of floors, a plurality of elevator cars, means mounting the elevator cars for movement relative to the structure, control means operable for moving each of the elevator cars and stopping each of the elevator cars at the floors for which elevator service is required, dispatching means for dispatching each of the elevator cars successively at spaced intervals from a terminal one of the floors, loadresponsive means responsive to the loading of each of the elevator cars at the terminal one of the floors for expediting the dispatch of each elevator car loaded at the terminal one of the floors prior to expiration of the dispatching interval for such loaded elevator car, and means effective upon arrival of each of the elevator cars at the dispatching floor with a load to be discharged for rendering ineffective the load-responsive means for at least two seconds to permit unloading of each loaded elevator car.

24. In an elevator system, a stepping switch, means for energizing the stepping switch to produce stepping operations of the switch in accordance with a service demand of the elevator system, means for resetting the stepping switch to a starting condition at spaced intervals, and means responsive to the advance of the stepping switch during one of the intervals between the resetting operations of the stepping switch for modifying the operation of the elevator service offered by the elevator system in accordance with the degree of advance of the stepping switch.

References Cited in the file of this patent UNITED STATES PATENTS 2,589,292 Santini Mar. 18, 1952

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