US2082657A - Elevator system - Google Patents

Description

June 1, 1937. D. SANTINI r 2,082,657

' ELEVATOR SYSTEM I Filed Jul 31, 1936 'wrm asszs v INVENTOR 2i Pan/70 bnf/nf.

ATToy- EY Patented Jest-e 1, 1937 ELEVATOR SYSTEM Danilo Santini, Chicago, Ill., assignor to Westinihouse Electric Elevator Company, Chicago, IlL, a corporation of Illinois Application July 31, 1936, Serial No. 93,619

'7 Claims.

My invention relates to elevator systems or the variable voltage type and particularly to such systems using levelling switches to automatically control movements of the car within a levelling zone adjacent a floor, so as to bring the car platform to an approximately flush position with reference to the floor, or to maintain it level with the floor during loading and unloading operations.

In such systems, it frequently happens that the car is stopped slightly beyond the floor at which it is to be levelled, and the first levelling operation is a return movement carrying the car in reverse direction to or slightly beyond the floor. A further levelling movement in the initial direction may be employed to return the car to the floor in case of over-run.

During such levelling operations, the generator field must be reversed, and the rapidity with which the entire operation can be accomplished depends to a great extent upon the rate at which the generator excitation can be changed. It has heretofore been found that the process of reversing the generator excitation can be accelerated by producing an over-compounded generator voltage characteristic, so that the armature current of the generator tends to materially assist in building up the reversed generator field.

It is an object of my invention to provide novel and simplified apparatus for producing an over-compounded condition of the generator of a variable voltage elevator system during ievelling operation.

A further object of my invention is to provide novel and simplified apparatus for producing an over-compounded generator characteristic in a variable voltage elevator system employing levelling apparatus, by means of the auxiliary generator provided, in some systems for regulatlon purposes.

Other objects of my invention will become evident from the following detailed description taken in conjunction with the accompanying drawing, in which:

Figure 1 is a diagrammatic view of an elevator system embodying my invention; and,

Fig. 2 is a diagrammatic view, ancillary to Fig. 1, showing the mechanical relationship of the relay coils and contacts shown in Fig. l.

Referring to Figs. l and 2 in detail, an elevator car (not shown) is driven by means of a cable I which passes over a suitable hoisting drum or sheave 2 to a counterweight (not shown). The drum 2 is mounted on the same shaft with an elevator brake 3, biased to braking position and released by means of an electros magnetic release coil 4, in well known manner.

The motive equipment for the elevator car comprises a pair of direct-current di nammeleetric machines 5 and 8, of which the machine 5 is mechanically connected to the drum 2 and,

' under average load conditions, serves as a motor.

The machine 6 is driven at substantially constant speed by any suitable means (not shown) and serves as a variable voltage generator for supplying the motor 5. A small auxiliary machine is provided for regulating the excitation of the generator 6, to control the speed of motor 5, as will be hereinafter more fully explained'. I

The motor 5 is provided with the usual armature 8, which is connected in a local circuit with the armature 9 of the generator, and with a motor field winding Mi.

The auxiliary machine 1 is provided with a series-type field winding It included in the local circuit of the motor and generator armatures 8 and 9, in parallel relation to a shunt H. A pair of shunt-type resistors l2 and i3 are connected in circuit with the series-type winding l0 and the shunt l i in any suitable manner to permit the percentage of armature current circulated through the series-type winding Ill to be changed from an initial high value to a final low value, without opening the local circuit of the main machine armatures 8 and 9.

In addition to the series-type winding 10, the auxiliary machine I is provided with a separate excitation winding H, which is connected in series with a separately excited winding l5 of the generator 6. The series circuit, consisting of the separate excitation winding 14 and the separately excited winding I5, is connected with three bridge resistors l6, l1 and I8 to form a balanced Wheatstone bridge circuit it], as. explained in the copending application of D. Santini and K. M. White, Serial No. 38,770, filed August 31, 1935 and assigned to Westinghouse Electric Elevator Company.

The armature of the auxiliary machine 1 is connected across one diagonal of the Wheatstone bridge circuit l9, and the remaining diagonal of the Wheatstone bridge circuit I9 is serially connected to suitable accelerating resistors 20 and 2|. The entire circuit comprising the Wheatstone bridge circuit 49 and the accelerating resistors 20 and 2| is arranged to be connected to a pair of constant-voltage, direct-current supply conductors Ll, L2 by either of a pair of direction switches U and D, corresponding to the up and "down" direction of car travel, respectively.

In addition to the series-type winding II and the separate excitation winding it, the auxiliary machine I is provided with a shunt-type winding 72 connected across the terminals oi! the motor I in series with a current-limiting resistor 23. The resistor 23 serves to minimize the changes of current in the shunt-type winding 22 caused by variations or resistance of the latter with changes oi temperature of the auxiliary machine I.

Considering the excitation of the auxiliary machine I, the separate-excitation winding ll, the series-type winding II, and the shunt-type winding 12 all influence the current supplied to the separately excited winding ll oi the main generator 6, as does the amount of resistance provided externally to the Wheatstone bridge by the accelerating resistors 20 and 2|. However, the Wheatstone bridge circuit I9 separates the eflects of the auxiliary machine I and the accelerating resistors 20 and ii, so that the auxiliary machine I provides the same current component in the separately-excited field winding it for all values of accelerating resistance; and the accelerating resistors 20 and II provide the same current component for all values of armature current in the auxiliary machine 1.

The separate excitation winding It acts to produce a voltage component of the main generator 8 tending to raise the elevator car when the "up" direction switch U is closed, and to lower the car when the down direction switch D is closed. The series type winding it tends to assist the separate excitation winding I when the direction of power fiow in the local circuit is from the generator 6 to the motor I. The shunt-type winding 22 acts in a direction to oppose the separate excitation winding II. The Wheatstone bridge circuit may be balanced by making the bridge resistors l6, l1 and I! each equal in resistance to the sum of resistance of the field windings I4 and IE, but is preferably designed so that the ratio oi. the resistance of resistor ii to that oi resistor I1, is the same as the ratio of the total resistance of field windings i4 and I! to the resistance or resistor it. The advantages of the latter more general relationship are explained in the copending application of D. Santini and K. M. White, Serial No. 93,618, filed July 31, 1936, a continuationin-part of the copending application Serial No. 38,770, mentioned above.

An intermediate speed relay V and ahigh speed relay Ware provided for short-clrcuiting the accelerating resistors 20 and II, respectively, during acceleration of the car.

A pair of levelling switches It are preferably mounted on the car and controlled by means of a retiring coil 25 in such manner that, upon energization of the retiring coil 25, the levelling switches 24 are withdrawn from a vertical column of the hatchway space in which are located levelling cams for each floor, one such cam being illustrated at 26. Upon deenergization of the retiring coil 25, the levelling switches 24 are moved by suitable biasing elements such as springs (not shown) into position to engage the cam 26 of the next fioor in the direction of car travel, when the car reaches a predetermined levelling zone adjacent the fioor. As the mechanical construction of such levelling switches and retiring mechanism is well known in the art, it has been illustrated diagrammatically rather than in detail.

A field forcing relay FF is provided for controlling the efiect of the series-type winding iii in compounding the main generator 6. The field forcing relay FF, in deenergized position, provides connections 01 the series-type winding Ill, shunt ii and shunt-type resistors l2 and II, such that the main generator 6 is cumulatively compounded to a degree considerably greater than necessary for fiat speed regulation of the motor 5. In its energimd or operated position, however, the field forcing relay FF reduces the compounding of the main generator 6 to a degree suitable for maintaining approximately fiat speed-regulation oi the motor 5. In order to prevent interruption of the main armature circuit, the front and back contacts of the field forcing relay F'F are of the overlapping type.

The field forcing relay FF is provided with any suitable means, shown as a dashpot,'for introducing a time delay of the order of to 1 second after energization of its coil, before operation oi! its contact members. This relay,

, however, is preferably designed to drop out without substantial time delay.

A car switch 11 is provided for successively energizing the retiring coil 25, direction switches U or D, and the speed relays V and VV to effect acceleration, and to successively deenergize these elements to efiect deceleration and stopping of the car.

The operation of the above-described apparatus may be set forth as follows: It is assumed that the elevator car is standing at the first fioor in condition to be operated in the upward direction, and the various relays and switches of Figs. 1 and 2 are in the position shown. To operate the car in the upward direction, the car switch 21 is rotated gradually in the counterclockwise direction. the car switch 21 to its first operative position, a circuit is completed for the retiring coil 25, and the latter operates to withdraw the levelling switches 24 from the position in which theycould engage the hatchway cams such as 26.

Upon further rotation of the car switch 21 in counter-clockwise direction to its second operative position, an energizing circuit for the up direction switch U is completed, and the latter closes. The up direction switch U, in closing, establishes a connection of the Wheatstonc bridge circuit I! in series with the accelerating resistors Ill and II, to the supply conductors Li and L2, and also establishes an energizing circuit for the release coil 4 of the brake 3 and the coil of the field forcing relay FF.

In response to connection of the Wheetstone bridge circuit IS in series with the accelerating resistors 2!) and 2! to the supply conductors Ll and L2, a component of field current is clrculated through the separate excitation winding ll of the auxiliary generator I and the separately excited winding I! of the main generator ii. The auxiliary generator I and the main generator 6, accordingly, build up voltage in such direction as to cause the elevator car to move upward.

As the motor 5 accelerates, it develops a terminal voltage which acts upon the shunt type field 22 to oppose the excitation component sup plied by the separate excitation winding I. When the speed of the motor approaches a value corresponding to the excitation current clrculated through the separately excited winding l5, with both accelerating resistors 20 and 2i in circuit, the shunt type field winding 22 pro- Upon initial rotation of duces sufficient effect to approximately buck out the excitation component furnished by the separate excitation winding It.

During the initial accelerating operation of the motor ii, the field forcing relay FF is in the position shown, and the maximum compounding effect of the series type winding it is effective in the auxiliary generator l to produce rapid. building up of the magnetic field of thoracic generator 5.

At the expiration of its time interval of Upon further counter-clochwise movement of the car switch 2? to its third operative position, the intermediate speed relay V closes to short circuit the accelerating resistor as. In response to closure of the intermediate speed relay V, an increased component of field current is circulated through the separately excited field winding l5, and the speed of the elevator motor ti increases to intermediate value. As the compounding effect of the series type winding ill has been reduced to that necessary to maintain flat speed regulation of the motor 5, the auxiliary generator 1 operates to maintain the speed of the motor 5 constant at its intermediate value.

Upon further counter-clockwise movement of the car switch 27 to its final operated position, the high-speed relay W closes to short circuit the remaining step of accelerating resistance 2|, thereby causing the elevator motor 5 to accelerate to high speed and remain at such high speed, irrespective of the value or direction of elevator load.

Assuming that the car is to be brought to a stop at some upper floor, such as the fourth floor, the operator commences to center the car switch at a sumcient slow-down distance in advance of the fourth floor to effect a comfortable landing. As the car switch is gradually centered, the speed of the motor 5 is brought through its intermediate speed to its low speed, at which it is maintained until the car approximately reaches the levelling zone for the fourth floor.

When the car reaches the levelling zone for the fourth fiocor, the operator centers the car switch, thereby dropping out the lip-direction switch U and the retiring coil 25. The up-direction switch U, in dropping out disconnects the Wheatstone bridge circuit is, thereby deenergizing the main generator 6, and also deenergizes the release coil 4 of the brake 3, thereby permitting application of the brake to bring the car to rest.

Upon deenergization of the retiring coil 25, the levelling switches 24 move under operation of their biasing means, into a position to engage the cam 26 for the fourth floor. If the car platform is now flush with the fourth floor, both levelling switches 26 will be open, and no operation of the levelling mechanism will occur. If, however, the car has slightly overrun the fourth floor, as is commonly the case, the lower levelling switch 24 will be closed, and the upper levelling switch M will open.

In response to closure of the lower levelling switch 24, a circuit is completed for the down direction switch D, and the latter closes to establish energization of the main generator 6 in the direction to cause downward movement of the elevator car. The down direction switch D, in closing, also establishes a circuit for the release &

coil l of the brake 3 and the energizing coil of the field forcing relay FF. The field forcing relay FF, however, does not immediately openate because of its time element, and the full compounding effect of the series type winding it is available to accelerate the reversal of geuer ator excitation. As the car moves downward, the

lower levelling switch it opens when the car platform is approximately flush with the fourth floor, and the down direction switch D drops out to bring the car to rest.

The time element of the field forcing relay FF is made such that the major part of the hold forcing operation is accomplished before the car starts to move during levelling movements. with such a relay adjustment, field forcing occurs mo mentarily during every starting operation but is removed in suflicient time to prevent material interference with the speed regulating operation of the auxiliary machine.

Although I have illustrated my invention in connection with accelerating anddecclerating ap paratus of the simplest type, it will be understood that the invention is equally applicable to automatic landing systems and other more compli cated automatic systems known in the" art.

- I do not intend thatthe present invention shall be restricted to the specific structural details, arrangement of parts, or circuit connections herein set forth, as various modifications thereof may be effected without departing from the spirit and scope of my invention, I desire, thereforathat only such limitations shall be imposeda's are indicated in the appended claims.

- I claim as my invention:

1. In an elevator system of the variable voltage type, an elevator car operable in a hatchway past a. floor, variable voltage motive equipment for said car comprising a plurality of dynamo-elec ,to-floor runs, levelling mechanism controlled by the position of said car for relevelling said car to said floor, and means effective during an op eration ofsaid levelling mechanism for modifying the operation of said auxiliary machine.

2. In an elevator system of the variable voltage type, an elevator car operable in a hatchway past a floor, variable-voltage motive equipment for said car comprising a plurality of dynamoelectric machines in energy transference relationship excitation means for said motive equipment including an auxiliary machine having a winding of series type energizedin accordance with the armature current of one of said dynamo electric machines, said excitation means being effective to introduce a compounding excitation effect acting in a direction to correct the speed regulation of said motive equipment, starting and stopping means for controlling said motive equipment to eifect starting, acceleration and stopping of said car for runs between floors, and means initially effective during a starting operation of said starting and stopping means for mod- 3. In an elevator system of the variable voltage type, an elevator car operable a hatchway past a floor, variable-voltage motive equipment for Gil said car comprising a plurality of dynamo-electric machines in energy transference relationship, excitation means for said motive equipment including an auxiliary machine having a winding of series type energized in accordance with the armature current of one of said dynamo-electric machines, said excitation means being eflective to introduce a compounding excitation effect acting in a direction to correct the speed regulation of said motive equipment, starting and stopping means for controlling said motive equipment to effect starting, acceleration and stopping of said car for runs between floors, levelling mechanism effective in a zone adjacent said floor for relevelling said car to said floor, and means effective during an operation of said levelling mechanism for modifying the operation of said auxiliary machine to provide an increased compounding excitation effect.

4. In an elevator system of the variable voltage type, an elevator car operable in a hatchway past a floor, variable voltage motive equipment for said car comprising a plurality of dynamo-electric machines in energy transference relationship, ex-

citation means f'or said motive equipment effective to introduce a compounding excitation effect of high value acting in a direction to over-correct the speed regulation of said motive equipment, starting means for controlling said motive equipment to effect starting and acceleration of said car for floor-to-floor runs, levelling mechanism effective in a zone adjacent said floor for relevelling said car to said floor, and time element relay means connected to operate in response to both said starting means and said levelling mechanism for reducing said compounding excitation effect, after a predetermined time delay, to values suitable for fioor-to-floor runs, said predetermined time delay being sufficient to prevent operation of said relay means during the short time interval normally required for a levelling operation.

5. In an elevator system of the variable voltage type, an elevator car operable in a hatchway past a floor, variable -voltage motive equipment for said car comprising a plurality of dynamo-electric machines in energy transference relationship, excitation means for said motive equipment including an auxiliary machine having a winding of series type energized in accordance with the armature current of one of said dynamo-electric machines, said excitation means being effective to introduce a compounding excitation effect of high value acting in a direction to over-current the speed regulation of said motive equipment, starting means for controlling said motive equipment to effect starting and acceleration of said car for fioor-to-fioor runs, levelling mechanism effective in a zone adjacent said floor for relevelling said car to said floor, and time element relay means connected to operate in response to both said starting means and said levelling mechanism for reducing said compounding excitation effect, after a predetermined time delay, to values suitable for floor-to-floor runs, said predetermined time delay being sufllcient to prevent operation of said relay means during the short time interval normally required for a levelling operation.

6. In an elevator system of the variable voltage type, an elevator car operable in a hatchway past a floor, variable-voltage motive equipment for said car comprising hoisting motor and a variable voltage generator having a generator armature connected to said motor and having a separately excited field winding, an auxiliary machine for regulating the speed of said motor, said auxiliary machine having an armature connected to said separately-excited field winding and having a series-type field winding connected in series with said generator armature and said motor, a shunt in parallel relation to said series-type field winding, starting and stopping means for controlling said motive equipment to effect starting, acceleration and stopping of said car for runs between floors, levelling mechanism eflective in a zone adjacent said floor relevelling said car to said floor, and means effective during operation of said levelling mechanism for providing reduced effectiveness of said shunt.

7. In an elevator system of the variable voltage type, an elevator car operable in a hatchway past a floor, variable-voltage motive equipment for said car comprising a hoisting motor and a variable voltage generator having a generator armature connected to said motor and having a separatelyexcited field winding, an auxiliary machine for regulating the speed of said motor, said auxiliary machine comprising a series-type winding connected in series with said generator armature and said motor, a separate excitation winding, and an auxiliary machine armature, three bridge resistors, a Wheatstone bridge circuit having said bridge resistors in three legs and said separately excited field winding and said separate excitation winding in the remaining leg, said bridge circuit having said auxiliary machine armature connected to a diagonal thereof, a separate excitation source connected to the remaining diagonal of said bridge circuit, a shunt in parallel relation to said series-type field winding, starting and stopping means for controlling said motive equipment to effect starting, acceleration and stopping of said car for runs between floors, levelling mechanism effective" in a zone adjacent said floor for relevelling said car to said floor, and means effective during operation of said levelling mechanism for providing reduced effectiveness of said shunt.

DANILO SANTINL

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