US2036629A - Electric elevator system - Google Patents

Description

April 7, 1936; G. B. GROSVENOR ELECTRIC ELEVATOR SYSTEM Filed Marh 1, 1923 e Sheets-Sheet 1 INVENTOR 1 11W 5 km April 7, 1936.

Y G. B GROSVENOR ELECTRIC ELEVATOR SYSTEM Filed March 1, 1923 6 Sheets-Sheet 2 INVENTOR V EYS P 1936" e. B. GROSVENOR 2,036,629

ELECTRI C ELEVATOR SYSTEM Filed March 1, 1923 I e Sheets-Sheet s VV/T/VESS INVENTOH bJul'ub'ub 3y a My:

April 7, 1936. G. B. GROSVENOR 2,035,629

" ELECTRIC ELEVATOR SYSTEM Filed March 1, 1923 6 Sheets-Sheet 4 07/ 7/1 1556 nv l/E/V TOR 0 Br /Zlw w April 7, 1936. G. B. GROSVENOR 2,036,629

ELECTRIC ELEVATOR SYSTEM Filed March 1, 1923 e Sheets-Shet 5 W/7/VE66 a 1 I v MQWYS IN VE IV T01? April-7; 1936.

Filed March 1, 1923 6 Sheets-sheet 6 Patented Apr. 7, 1936 PATENT oFF cE ELECTRIC ELEVATOR SYSTEM Graham B. Grosvenor, Chicago, 111., assignor to Otis Elevator Company, Jersey City. N. J., a corporation of New Jersey Application March 1, 1923, Serial No. 622,142

41 Claims.

My invention relates to electric elevator systems and more particularly to systems in which the elevator is brought to rest at the landings by automatic means.

An elevator is primarily a device for raising or lowering objects from one level to another and in order to get the maximum service from a given equipment, it is necessary to have the elevators operate at the highest possible average speed consistent with safety and comfort. This is an important consideration in buildings where floor space is valuable and trafilc dense. In my Patent No. 1,632,225 I have described an elevator system in which the elevator is automatically slowed down and stopped at landings as desired by the operator, who initiates the slow-down and stop at some time prior to reaching the landing.

The operation of an elevator from one landing to another comprises acceleration and retardation, and in runs of distances great enough for maximum speed to be attained, full speed running. In an ideal system, the time speed curves of acceleration and retardation must be of a definite form to come from rest to full speed and from full speed to rest in a minimum time. The retardation must be completed at or just prior to reaching'the landing.

The object of my invention is to provide an elevator system that will fulfill these conditions.

tion is to be initiated.

The retarding of the car, for stopping at the fioor for which the operator has set the switch, is automatically commenced at a fixed distance from the fioor, depending upon the speed, and thereafter the retardation is automatically e1- fected, according to the load, so that the kinetic energy of the load is always brought to a predetermined value depending on the load at or just prior to reaching a point at a fixed distance from the power. When the power is disconnected the braking force is increased and the car brought to rest level with the landing without the necessity for correction by supplementary manual or automatic low speed operation.

In the accomplishment of these objects, I utilize many of the features of my Patent No. 1,632,225 and I have found that the elevator system described in my Patent No. 1,566,399 is peculiarly adaptable to bring about the desired re= sults.

To give a clear understanding of the novel points of my invention, it will be described in connection with the accompanying drawings, in which r Figure l is a schematic view of an embodiment of my invention in which the elevator is always moved from one landing to another and reaches maximum speed in runs from one floor to an adjacent iioor, the starting of the elevator being 2 under control of the operator whereas the stopping is performed automatically after being initiated by the operator.

Figure 2 is a wiring diagram illustrating the circuits of the apparatus of Figure 1.

Figure 3 illustrates an arrangement for getting the desired acceleration and retardation of the elevator by controlling the time constant of the field of the generator supplying current to the elevator motor.

Figure 4 illustrates'another arrangement for getting the desiredacceleration and retardation by the use of a motor operated field rheostat for the generator supplying current to the elevator motor. 4

Figure 5 is a schematic View showing the general arragement of an embodiment in which the elevator is always moved from one landing to another, but in which the height between floors is such that maximum speed is not reached in ms from one floor to an adjacent floor. The starting of the elevator is under control of the operator while the stopping is automatically done after being initiated by the operator.

Figure 6 is a wiring diagram of the circuits used in connection with Figure 5.

Figure 7 is a wiring diagram of a modification of the arrangement of Figure 5 in which the elevator may be stopped by the operator independently of the automatic stopping means.

Referring more particularly to the drawings, an alternating current motor i is shown'as driving a direct current generator 2 and an exciter 3. Power is supplied to motor I by mains 4, 5 and It will be understood that the usual switches andF' starting devices may be used with motor I. and directional switches become self-holding Generator 2 has a separately excited field I which is supplied with=current from exciter 3, which is a shunt wound generator. In circuit with field 1 is a resistance 3 which may be shortcircuited by contacts 3 and II. A resistance II is connected across the terminals of field I. A

series field |2 for generator 2 is used between its armature and reversing switch l3. Elevator hoisting motor I4 .is supplied with power by generator 2 through reversing switch 3 and is a separately excited motor. Sheave I3 is driven by motor l4 and a suitable number of cables I pass over it, one end of the cables being attached to the elevator I1 and the other to counterweight II. A brake l3, having a slidably mounted core 24 and a plate 20 held againstdisc 2| by'spring 22, serves to hold the elevator at rest. Disc 2 is secured to the shaft of sheave II and rotates with it. To release the brake, coil 23 is energized by current from exciter 3 so that core 24 is attracted and spring 22 thereby compressed.

A govemor 25, suitably located, is driven by cable 26 from the elevator and is equipped with contacts 21 and 23, the object of which is to stop the elevator in case of overspeed, as will be more.

fully described later. A car switch 23 is mounted in the elevator I! and by it the operator controls the movements 0! the elevator. An emergency switch 30 is also mounted in the elevator Elevator I1 is equipped with a solenoid operated switch 3| which, when rendered operative by the operator, acts through the control circuits to slow down the elevator. Switch 3| has a coil I16 and a magnetic core with an extension 33. Assuming coil I16 energized and the elevator going down, extension 33 will be attracted by the armature 34, which is mounted stationary in the hatchway, as soon as it comes opposite it. Contacts on switch 3| will open and the elevator will slow down.

When elevator |1 approaches the landing, the extension 40 of the core of the solenoid operated switch 35, which is similar to switch 3|, is attracted by the armature 36, thereby causing contacts on switch 35 to open, which provides a partial application 01' the brake preparatory to stopping.

The solenoid operated switch 31, when elevator l'l arrives at a floor landing, has its extension 39 opposite the stationary armature 38. The magnetic attraction causes extension 38 to move, which motion opens contacts on switch 31, thereby disconnecting elevator motor |4 from its power supply and fully applying the brake so that elevator |1 stops level with the floor landing.

To obtain the most efiicient transportation for floor to floor travel, the elevator should have the maximum acceleration and retardation allowable its and should attain the maximum speed midway between two adjacent floor landings. rangement is advantageous in elevator transportation for buildings having high floor heights and especially so where it is desirable that elevators stop at all landings.

Consider elevator I! to be caused to travel irom'landing 4| to landing 42. The operator, by moving handle 43 of car switch 29 in the proper direction, engages a series of contacts in the car switch 29 which complete circuits to directional and fast speed switches on the control panel, as will be described in detail in connection with Figure 2. The elevator immediately accelerates; the operator may now permit the car switch handle 43 to return to center. The fast speed This arupon being energized but are subject to being released automatically by the solenoid operated switches 3| and 31 when these switches attain a definite relation to the armatures 34 and 44.

When'elevator I1 is midway between landings H and 42, the elevator will be at full speed and switch 3| will be in the proximity of armature )34 which causes its contacts to open. This will release the fast speed switch, thus causing the armature 45. This causes. a relayto open contacts 48 and 41, thereby inserting a suitable resistance 43 in serieswith the brake magnet coil 23. The brake is then applied partially by the spring 22, the'pressure o! which will then be greater than the holding power of the brake magnet coil 23 by a predetermined amount. The length of armature 43 is chwen so that when elevator I1 is level with landing 42, extension 40 will be opposite its center.

The elevator will continue to approach the landing at low speed .with the brake partially applied until the extension 33. of solenoid operated switch 31 is magnetically attracted by armature 44 when switch 31 will open its contacts, thereby releasing the directional' switches and interrupting the power to the elevator motor and ,at the same time fully applying the brake to bring the car to a stop level with the landing. Armature 44 is of the proper length to permit of the elevator being stopped by dynamic braking and by the electro-mechanical brake from low speed after disconnecting the elevatormotor from its power supply. I have found that 'an armature extending one inch above and below the position of the arm 39, when the elevator is level with the landing, gives good results.

In order that accurate stops may be made with variations of load in the elevator, it is important that the effect of gravity due to such variations be compensated for by corresponding variations inthe kinetic energy of the moving parts. This maybe done by fixing the speed of the elevator, at the low speed from which stopping is done, in some direct proportion to the unbalanced load being lifted by the elevator motor. Means for accomplishing this are described in my Patent No. 1,632,225.-

It is to be noted that armature 34 serves to determine the point at which slow down will commence when the elevator approaches landing 42 from above. Armature 34 also determines the points of slow-down as the elevator approaches landing 4| from below.

Push- buttons 49 and 30 are provided on the car switch 29 for the purpose of operating the elevator in emergencies and emergency switch 3|! is supplied to bring the car to rest immediately if desired.

With electrical equipment where circuits may be energized intermittently, the resistance of these circuits will be subject to definite variation determined by the temperature change of the conductors through which the current flows. It is, therefore, desirable that certain elements,

particularly the field windings of the motor generator set, exciter and elevator motor, should be wound with conductors which will have a negligible temperature coefficient in order that the resistances of these circuits will remain constant. In this way, speed characteristics of the equipment will be kept within definite bounds, which is an important consideration in the automatic slowing down and stopping of elevators.

Figure 2 is the wiring diagram for the system of Figure 1, the operation of which is referred to in detail.

An A. C. motor I of a motor generator set driving an exciter 3, all of which are mechanically coupled, is connected to an A. C. source of supply through main line switch 5I and feeders 4,

5 and 6. Motor I should have as nearly constant speed as possible under different loads.

The exciter 3 is shunt wound and self-excited, and supplies a substantially constant voltage through main switch 56, fuses 54 and 55 to feeders 52 and 53.

The generator 2 is of constant polarity and the strength of the shunt field 1, when the elevator is at rest, is governed by the resistance of its circuit which is from feeder 52 through line 51, resistance 58, line 59 to shunt winding 1 of generator 2, line 60 to feeder 53.

Upon closing of the emergency switch 30 on the elevator, a circuit is obtained from feeder 52 through fuse 6|, line 62, potential switch coil 63, line 64, terminals GG of traveling cable 66, line 68, emergency switch 33, line 59, terminals AA of traveling cable 66. line 10 to lower hatchway, limit switch contacts 1i and 12, line 13 through hatchway, limit switch contacts 14 and 15, line 16, governor switch contacts 28 and 21, lines 11 and "I8, fuse 19 to feeder 53.

The potential switch, which is of the normally magnetically operated gravity returning type, is then energized and closes contacts and SI, 82 and 83, 84 and 85, 86 and 81, at the same time opening contacts 88 and 89,

Assume, the elevator to be run in the up direction. In this case, car switch handle 43 is moved to the left until car switch contactor 90 touches car switch contact points 9I, 92 and 93. The operation of this elevator being full automatic, the wiring is so arranged that no action is obtained until car switch handle 43 is moved to the ex-- treme running position at which time current may be distributed from the last contact finger engaged, which finger is termed the car switch feed.

A circuit is then obtained from feeder 53 through fuse 19, line 18. contacts 86 and 81, lines 94 and 95, bottom contacts 96 and 91 of the down direction switch, line 98', terminals FF of traveling cable 66, line 99, car switch finger 93, car switch contactor 90, car switch finger 9i, lines 99 and I00, terminal automatic switch contacts II and I02, line I03, terminals D-D of traveling cable 66, line I04, the up direction switch magnet coils I05 and I06, lines I01 and I09, contacts 82 and 83,.line 62,-fuse 6| to feeder 52. The up direction switches then close their respective contacts. These switches are of similar design to the potential switch. For the direction switches, two switches are utilized for each direction of travel. the magnet coils of each pair being connected in series, which results in both coils being energized at the same-time.

The contacts controlled by the up direction switches are then closed or opened as follows:- Contacts I09 and H0, III and H2, H3 and H4,

H5 and H6 are closed in the respective pairs as shown. Contacts Ill and H8 and II9 and I2 are opened in respective pairs.

With the up direction switches closed, the circuits that function to start the elevator in motion are as follows:Feeder 52, through fuse 6i, line 62, contacts 83 and 62, line I08, contacts II6 and IE5, lines I2I, I22, I23, magnet coil I24 of the auxiliary brake switch, line I25, terminals H-H of traveling cable 66, line I26,

contacts I21 and I28, line I29, emergency switch 30, line 69, terminals AA of traveling cable 66, line 70, contacts 1| and 12, line 13, contacts 14 and 15, line 16, contacts 26 and 21, lines 11 and 18, fuse 19 to feeder 53.

Magnet coil I24 when energized, causes the auxiliary brake switch to close contacts 46 and 4.1, which contacts short-circuit resistance 48, which is in series with brake magnet coil 23. The brake magnet coil 23 is then sufficiently energized to release the brake to permit the elevator motor to start. The circuit for the brake magnet is as follows:-From feeder 59, through line I30, contacts 8i and 80, line I3I, brake magnet coil 23, line I32, contacts 41 and 46, line I33, contacts I09 and H0, line I34 to feeder 52.

The generator 2, having a definite field at all times the elevator is in service, is enabled to deliver current to the elevator armature at a predetermined low voltage immediately upon the closing of the directional switches.

The field of the elevator motor I4 has a constant value and is connected to the feeder as fo1lows:-Feeder 52, through line I36, adjusting resistance Isl, line I39, shunt field coil I39, line I40 to feeder 53.

The elevator motor I4, having a constant field, will be enabled to start upon the armature of elevator motor I4 receiving current from the armature of generator 2.

The armature of elevator motor I4 receives power from generator armature as follows:- From armature terminal I42 of generator 2 through line I43. series field I2, which is subject to variable strength as determined by adjustment of resistance I 44 connected in parallel with series field I2, line I45, contacts H2 and III, line I46, line I41, contacts 85 and 84, line I48, elevator motor armature terminal I49, through armature winding out through armature terminal I50, lines I5I and I52, contacts H4 and H3, lines I53 and I54. armature terminal I55 and through armature winding of generator 2.

The elevator motor has now started but as the car switch 29 must be moved to the extreme position in order to start the elevator motor in motion, the necessary circuits to obtain fast speed have a so been made. resulting in the elevator accelerating to high speed as soon as the elevator has been started by means of the car switch.

The circuit for the fast speed switch is as follows:From feeder 52, through fuse 6|, line 62. contacts 83 and 02, line I00, contacts H6 and H5, lines I25, I22 and I56, through fast speed switch magnet coil I51, line I58, terminals I-I of traveling cable 66, line I59, terminal slow down contacts I60 and I6I, line I62, contact 92 in the car switch. contactor 90, contact 93, line 98, terminals F-F of traveling cable 66, line 98',

contacts 91 and 96, lines and 94, contacts 81 and 89, line 18, fuse 19 to feeder 53.

The fast speed switch magnet coil I51 causes contacts I63 and I64 to close, short-circuiting resistance 58, which is in series with the shunt field winding of generator 2. This increases the voltage across the shunt field winding of the generator 2, resulting in the building up of the magnetic field at a definite time rate determined by the character 01' the field circuit.

The building up of the magnetic field produces an increasing voltage in the armature wind ing of generator 2, which voltage is now imposed upon the armature of the elevator motor I4,

' causing the elevator to accelerate until the voltthe coils to keep these switches closed, but insufiicient current to enable the switches to pull in were they open.

To accomplish this, contact finger points 9|, 92 and 93 in car switch 28 are tied together through suitable resistances, which resistances prevent the magnet switches on the control panel from pulling in if theyare open. When the car switch has been moved to starting position, these resistances are short-circuited an the current in the magnet coils of the up direction and fast speed switches is increased to a value that is sufficient to close the switches controlled.

Car switch finger point 93 is tied to contact finger point 9| through lines 98 and I68, contacts I66 and I81, line I68, resistance I89 and line 99.

Car switch finger point 93 is tied to contact finger point 92 through lines 98, I85 and I18, contacts HI and I12, line I13, resistance I14 and line I15.

The coil I16 of the magnetically operated slowdown switch on the car is energized from feeder 53, fuse 19, lines 18 and 11, contacts 21 and 28 on the overspeed governor, line 16, contacts 15 and 14 on the up overtravel limit, line 13, mm tacts 12 and H on the down overtravel limit, line 18, terminals A-A of traveling cable 68, line 89, emergency switch 38, line I29, automatic slow-down coil I16, line I11, terminals B-B of traveling cable 66 line I2I, contacts H5 and H8, line I88, contacts 82 and 83, line 82, fuse 6I to feeder 52.

When the elevator is approximately midway between two adjacent floors, aprojection of the core of magnet coil I16 will be opposite the stationary armature 34 (see Figure 1 for arrangement). The motion of the core will open contacts HI and I12 which are included in the self holding circuit for the magnet I81 of the fast speed switch on the control panel. Contacts I83 and I84 on the fast speed switch will open inserting resistance 58 in series with the field winding 1 of the generator. The field of generator 2 will discharge through resistance II which is across winding 1. The time rate of field discharge will be determined by the resistance II connected across the terminals of field 1 and may be increased or decreased,.as desired, by changing the value of resistance II. As the generator field discharges its energy, the voltage of the generator will decrease until the minimum volt- 'age determined by the value of the series resistance 88 has been reached and the elevator will then run at low speed.

The series field I2 asssists in decreasing the total magnetic field, due to'the regenerative action of the elevator motor when slowing down. The current in the series field is reversed during slow-down period and the magnetic flux due to. it will be in opposition to that of the sepa-' I88, contacts H8 and H8, lines I2I, I22 and I86,

contacts I18 and I19, line I88, terminals JJ of traveling cable 88, line I8I, automatic brake and stopping switch coils I82 and 131 in paral-- lel, line I29, emergency switch 38, line 89, terminals A--A of traveling cable 66, line 18, contacts 1I and 12, line 13, contacts 14 and 18, line 18, contacts 28 and 21, lines 11 and 18, fuse 19, line 83.

Upon approaching the fioor the core of magnet I82 is caused to move when it comes opposite armature 38 This opens contacts I28 and I21 and deenergizes magnet I24, causing contacts 46 and 41 to open thereby inserting resistance 48 in series with brake magnet 23. This weakens brake magnet 23 which can no longer counteract the action of the brake springs entirely, resulting in partial application of the brake shoes.

The elevator continuesto approach the floor landing until the magnet core of magnet 131 comes opposite stationary armature 38 at which time contacts I88 and I61 will open and the up direction switch magnets I85 and I88 will be deenergized. The up direction switch in dropping out opens contacts I89 and H8, III and H2, H3 and H4 and H5 and H6. The opening of these contacts permits full application of the brake, interrupts power supply to the elevator armature as well as current to the automatic switches on the car, and to the fast speed switch on'the control panel.

The elevator will now come to rest from low speed approximately level with the landing. through the action of the electro-mechanical brake and the dynamic braking action of resistance I85, the circuit of which is as follows: From elevator armature terminal I49 through line I48, contacts and 85, lines I41 and I83, contacts H8 and H1, line I84, dynamic resistance I88, line I86, contacts I81 and I88, lines I89 and I5I, armature terminal I53 and elevator motor armature winding.

The potential switch which is controlled by the magnet 83 may be opened by various safety means such as the emergency switch 38 in the car, overtravel limit switch contacts 1I and 12 or 14 and 15 in the hatch, overspecd governor contacts 21 and 28 and other usual safety devices. Upon deenergizing the potential switch 'magnet coil 83, contacts 88 and BI, 82 and 83, 84 and 85 and 86 and 81 are opened while contacts 88 and 89 are closed. The contacts that'.open interrupt power supply to the elevator motor-armature and all operating circuits and the electro-mechanical brake is applied. The contacts 88 and 89 connect dynamic stopping resistance I90 across the elevator motor armature leads I49 and it through leads HI and I92. Thus, in the event of an emergency stop, dynamic braking assists in bringing the car to rest.

From the above description of Figures 1 and 2, it is seen that in this embodiment of my invention, under normal operation, the starting of the elevator is under control of the operator whereas its acceleration and stopping are automatically controlled; the operator merely selecting, at some time previous to the elevator reaching it, the floor at which he desires to stop and then manipulating the car switch to throw the automatic stopping means into operative condition. Since the elevator reaches full speed in making one fioor runs, the stopping is accomplished by the same means whether the elevator is caused to travel one fioor or two or more fioors before stopping.

The rate of acceleration of an elevator, when controlled by the system outlined in Figure 2,

is dependent upon the inductance and resistance of the field circuit of the generator 2, since these determine the time constant of the field circuit, which governs the rate at which the voltage will increase across the generator terminals. The rate of voltage rise, in turn, determines the rate at which the elevator motor will accelerate. In Figures 1 and 2 the generator is so designed that its inherent time constant gives the proper acceleration. The retardation is dependent upon the rate at which the voltage of the generator decreases and this may be governed by the value of the discharge resistanceacross the elevator field, after the high speed switch is opened. The higher the resistance the greater the retardation. In Figures 1 and 2 the resistance II is properly chosen to give the same rate of retardation as acceleration.

Under certain conditions, it is desirable to use special apparatus and circuits to afford adjustment of the rate of acceleration and retardation by other means than the inductance and resistance of the generator field winding.

It is well known that the ratio of inductance to resistance of a circuit is a measure of the time,

. required to increase or decrease current in an electrical circuit between minimum and maximum values. Therefore, by increasing the inductance of the circuit in which is included winding I, the time required for current in the circuit to change in value may be increased.

In Figure 3 such an inductance I93 is shown inserted in series with field winding I of generator 2. This inductance may be varied by removing the core-I98 or by securing core I08 at any particular position between the limits or complete removal or entirely within the inductance coil I93.

The inductance coil I93 affords a means for obtaining any desired rate of acceleration less than that determined by the time constant of the generator field, as the growth of current in the field winding I can be delayed. This, in turn, delays the building up of the magnetic field developed and therefore the voltage of generator 2. A magnetic circuit contains energy which is a function of the magnetic field developed and when discharging or attempting to reduce the current through the magnet coil producing this field, the collapsing field induces a voltage in the magnet coil which sets up a voltage opposing any change in current. By utilizing a resistance across the magnet coil the time of discharge can be governed by permitting the induced voltage in the coil to circulate current through the field coil and resistance.

The resistance across the coil is useful in retardation during the dissipation of the greater proportion of the contained energy of the magnetic field. However, when the greatest portion of the energy has been dissipated, the time rate of discharge of the field energy is materially decreased as is well known from curves showing decaying current in a circuit including inductance.

In order to obtain an approximately uniform rate of discharge, resistance I94, Figure 3, is connected in series with contacts E95 and I90 across field winding 7 and inductance coil I93. Solenoid winding new controls contacts B95 and i96 and is connected so that it is subjected to the voltage of generator Coil i9? is so wound that it will cause contacts 505 and we to be opened by gravity when the a voltage has decreased to some low value, whereby resistance 394 will become inoperative, which will be equivalent to increasing the resistance of the discharge path of field I and inductance coil I93 at the time that the rate of discharge is desired to be increased.

Figure 4 illustrates another means for governing the rate of change of current in the field winding I of generator 2. I98 is a special form of field rheostat where contact points I99 are so connected to resistance 200 that the increase and decrease of current in'the field coil I may be determined by the amount of resistance inserted or removed by each step of the rheostat. Resistance II is paralleled across the field coil for protective purposes and is of a sufiiciently high value not to materially afiect the rate of change of current in the field winding I.

The rheostat consists of a contact arm 20I mounted upon a sprocket 202 driven, for example, by chain 203 which engages a sprocket wheel 204 mounted upon armature shaft 205 of a shunt motor 206, the field 201 of which is connected across the line.

The contact arm 20! moves at a definite rate of speed determined by the speed or motor 206. Contact am 2M engages a series of contacts I09 short-circuiting resistance in the circuit of field winding l.

When accelerating the fast speed coil 208 is energized which exerts a pull on core 209 against the spring 2I0. This opens contacts 2 and M2 and contacts 283 and m, then closes contacts H2 and. M5 and contacts 2 and 2I6. A circuit is then obtained from and through line 2", contacts 2I8 and 289, line 220, contacts H6 and 2, line 22I, armature terminal 222, armature winding, armature terminal 223, line 224, contacts 2I2 and 2I5, line 225 to negative.

Motor 200, having a constant field, turns in a direction that will carry contact arm 20! up until all of contact points I99 have been in contact with the arm in turn. When all of resistance 200 is short-circuited, the arm 20I will be at its limit of traveland will strike arm 226, moving it against spring tension 22] about its pivot and opening contacts 2 I8 and 2 I 9 thereby disconnecting armature of motor 206 from the power supply and stopping the motor.

As contact arm 20E leaves its lower limit of travel, spring 228 pulls back on arm 229 closing contacts 230 and 23I.

When retarding, magnet coil 208 is deenergized and spring '2I0 pulls on core 209, opening contacts 2I6 and 2I4 and contacts 2I5 and 2I2, then closing contacts 2 and M2 and contacts 2" and 2. This reverses current in the armature winding of motor 206, causing it to return contact arm to lower limit of travel where contact arm will strike arm 229, opening contacts 230 and 23L The circuit for armature or motor 206, when the elevator is being retarded, is as follows: Through line 233, contacts 230 and 23!, line 232, contacts 2 and 2 l2, line 224, armature terminal 223, armature winding, armature terminal 222, 1ine,22l, contacts 2 and H3, lines 234 and 225 to negative.

It will be understood that in the embodiments of Figures 3 and 4 are shown only the elements governing the rates of acceleration and retardation of the elevator motor, and also that solenoid coils I51, Figure 3, and 208, Figure 4, may be used in connection with the systems described in Figure 2 similarly to coil I51 of the fast speed switch. When using generators having laminated magnetic circuits, the time constant of the field may be less than one second and, as the time required to accelerate a high speed elevator to six hundred feet per minute should be about two seconds, means must be provided to regulate the time required to build up the generator voltage. The means shown in Figure 4 is particularly advantageous in'accomplishing this end since, not only may the time required to build up the generator field be accurately determined, but the rate of acceleration during diiferent parts of the period of acceleration may be as desired. This latter is done by the selection of suitable values of the steps of the resistance 200. For example, a constant rate of acceleration or an acceleration giving equal increments'of energy in the moving parts may be obtained. The rate of retardation may also be governed accurately and may be made different from the rate of acceleration by causing the speed. of motor 206 to be different in its two directionsof rotation in any well known way, as for instance by inserting resistance in its armature circuit in one direction.

In Figure 5 a direct current source of supply is shown and a direct current motor for driving the motor generator set, also an arrangement of switches on the elevator to control the slow-down and stop under the conditions of variable speed in approaching landings.

The direct current motor 235 may be connected through any well known iorm'of rheostat or starting switch to the direct current source of supply. I

Shunt field winding 236 together with its protective parallel resistance 231 is connected across the line. the exciter is not necessary as in Figures 1 and 2 since direct current is already available.

The compounding of motor 235 is arranged so that the series field 238 is connected to oppose the shunt winding 235 in order to provide for higher speeds of the motor generator set with increased loads on the equipment. The higher 'speed of the motor generator set with load on With direct current source of supply,

low changes of current values in the feeders due to load on the equipment and resistance 240 is chosen to give the right degree of compounding. For buildings where the height of the floors and the speed of the elevators will not permit 5 of full speed being reached in one floor runs, means must be provided so that the slow-down may be initiated at fixed distances from the fioor landings determined by the speed at which the elevator is traveling. For this purpose, in Figure 5, four automatic slow-down switches are employed upon the car, each switch having a separate row of stationary armatures in the hatchway. Two of these switches are used for each direction of travel, one switch of each pair for 1 tially the same as the similar switch in Figure l. 20

Consider the elevator descending from landing 249 to 250. Immediately upon starting up, the coils of switches 242 and 243 are energized. The coils of switches 2H and 244 are controlled by means which will react in direct proportion to the speed of the elevator as, for example, by a relay connected across the elevator motor terminals. As the voltage at the armature terminals is a function of the motor and elevator speed, the coils of switches 2 and 244 may be energized only when approximately full speed of the elevator has been reached, by,adjusting the controlling relay to suit. Such being the case, the coils of switches 2 and 244 will not be energized when running between adjacent floors and elevator can accelerate in the down direction until the core of switch 242 is opposite stationary armature 246. At this time, a contact will be opened by the core of switch 242 and the fast speed switch will open and the elevator will slow down. Armature 246 is so located that the proper distances for acceleration and retardation will be provided for one fioor'runs. The partial application of the brake and stopping of the elevator will be accomplished in the same manner as with Figure 1.

When running from landing 249 to 25l, the car switch handle 23 is kept at the running position until elevator platform is near landing 250; at this time the elevator will be fully accelerated which is feasible with ordinary floor heights as found in building construction. The coil of switch 2 will therefore be energized, and upon returning car switch handle to neutral, the elevator will continue to run at high speed until 55 the core of switch 2 is opposite stationary armature 245 at which time the core of switch 241 will open its contact and retard the elevator through a greater distance than that for a one floor run (equal to the vertical distance between 00 stationary armatures 245 and 252) which additional distance will be required forslow-down from, the greater speed.

For the up direction of travel, switch 243 is utilized. For one floor runs, for example, operating betweenlanding 25] and 250, switch 243 and stationary armature 248 coact to cause slowdown. For two or more floor runs in the up direction with the destination being landing 243, switch 244 is used in connection with stationary 70 armature 241.

Figure 6 is a wiring diagram for an installation as out-lined in Figure 5. The source of power supply for the elevator motor armature is provided for by a motor generator set, the motor 7 potential switch magnet 26! 235 of which may be started by any method suitable, such as the rheostat 254. Power for operating motor 235 is supplied through main line switch 253. The shunt field winding 236 and its protective resistance 23! are connected across the power feeders when main line switch 253 is closed.

The series field 238 of motor 235 is connected so as to provide differential compounding to compensate for load and drop in voltage through various windings, contacts and leads. Resistance 246 is connected in series with the series field winding 236 to increase the ratio of inductance to resistance to obtain a lower time constant of this circuit. Resistance 236 is connected so as to shunt current around the series field winding 236 to obtain the proper degree of compounding. Permanent field is provided for the generator 2 to obtain constant polarity voltage from the armature of the generator. This circuit is obtained through main line switch 253, feeder 5255, line 256, resistance 251, line 256, inductance coil I93, field winding 1, line 259 to feeder 255. This provides a weak field for generator 2, the armature of which will provide a low potential of constant polarity with the elevator at rest. The series field winding I2 is connected to provide for over-compounding with the resistance I44 shunted across the series winding I2 to obtain the required amount of accumulative effect. By having the winding 1 saturate the field structure when full potential is applied to the winding, the over-compounding of generator 2 may be made effective only at low voltage of the generator 2 while the differential compounding and.

shunt field of the driving motor 235 may be so adjusted to be effective at high speed of the elevator, which will be obtained when generator 2 provides full voltage for the armature of elevator motor !4. With the motor generator started, the elevator may be put into service by the closing of the emergency switch 36 on the elevator. The closing of the switch 36 completes a circuit from feeder 254 through fuse 266, potential switch magnet coil 26!, line 262, terminals A'A' of traveling cable 66, line 263, emergency switch 36, line 264, terminals B'B' of traveling cable 66, line 265, contacts 266, 251 of the bottom overtravel limit switch, line 268, contacts 269 and 216 of the top overtravel limit switch, line 21!, contacts 212 and 213 of the overspeed governor switch, line 214, fuse 215 and to feeder 255. The when energized, causes the switch controlled to close contacts 216 and 211, 218 and 219, 286 and 26f, and 282 and 283, and opens contacts 284 and 285.

The elevator is now prepared to be operated by car switch 29 mounted on the elevator. The method of connecting the various circuits entailed is such as to permit the elevator to continue to run to a definite point after the elevator has been started, by movement of the car switch handle 43 of the car switch 29, even though the switch handle 43. be returned to center or neutral position. The operation of the elevator does not differ materially for either direction of travel, with the exception that selective means must be provided for the direction of elevator motor armature current and the automatic slow down and stopping of the elevator at a landing. The function of each successive circuit closed or opened is identical for either direction.

Consider elevator to be operated in the up di rection. In this case the car switch-handle 43 will be moved to the left to the extreme position at which time contactor 286 in the car switch will engage the series of contact fingers 281, 286 and 289. The elevator cannot be started until contact finger 289 is engaged, since contact finger 289 provides direct connection to the power supply and is termed the up car switch feed. Consider that car switch handle 43 is placed in the extreme up position. The initial circuit which functions is obtained from feeder 255 through fuse 215, line 214, contacts 262 and 283, line 296, contacts 26l and 292, line 293, terminals C'C' of traveling cable 66, line 264, contact finger 269, contactor 266 and contact finger 281 of the car switch 26, line 265, terminal automatic contacts 296 and 291, line 266, terminals D'-D of traveling cable 66, line 296, up direction switch magnet coils 666 and line 362, contacts 216 and 219, line 363, fuse 266 to feeder 256. The up direction switches are closed by the energizing of coils 366 and SM and contacts 665 and 365, 366 and 36 i, 366 and S69, and 3 I6 and 6! I are closed in their respective pairs. Contacts 3I2 and 3I3 and 354 and 3I5 are opened. The auxiliary brake magnet switch which short-circuits resistance 3I6 in series with the brake magnet 23 and its discharge resistance I35 is closed by the energizing of magnet coil 3I1, circuit for which is completed as follows:From feeder 254'through fuse 266, contacts 218 and 219, line 362, contacts 3!! and 3|6, lines 3I8 and 3 I9, auxiliary brake magnet coil 3II, line 326, terminals E-E of traveling cable 66, line 32!, contacts 322 and 323 of automatic brake switch on the elevator, line 263, emergency switch 36, line 264, terminals B'B' of traveling cable 66, line 265, contacts 266 and 261, line 268. contacts 269 and 216, line 21!, contacts 212 and 213, line 214, fuse 215 to feeder 255.

The brake magnet coil circuit is completed from feeder 254 through line 324, contacts 365 and 364, line 325, contacts 326 and 321, line 328, brake magnet coil 23 and its discharge resistance I35, line 329, contacts 216 and 211 to feeder 255. The brake magnet coil is then fully energized and releases the brake shoes from the brake wheel. The brake being released, the elevator motor I4 will start, its field winding I39 and protective resistance I4i are of constant strength and connected permanently across the line when main line switch 253 is closed. The closing of the up direction switch completes the armature circuit as followsz-From the armature of generator 2' through line 336, series field I2 and parallel resistance I44, line 33!, contacts 361 and 366, line 332, contacts 28! and 286, line 333, armature winding of the elevator motor, line 334, contacts 368 and 369, line'335, and back through armature winding of generator 2. The elevator motor will now run at low speed but will automatically accelerate to high speed because of the car switch handle having been brought over to the extreme position to start the elevator. The circuit for the fast speed magnet coil 34! is obtained from feeder 254 through fuse 266, line 363, contacts 219 and 216, line 362, contacts 3!! and 3|6, line 3I8, fast speed switch magnet coil 34!, line 336, terminals FF' of traveling cable 66, line 331, contacts 338 and 339 of the terminal automatic switch, line 346, car switch contact finger 283, contactor 286 and contact finger 289, line 294, terminals C'-C of traveling cable 66, line 263, contacts 292 and 29!, line 296, contacts 263 and 282, line 214, fuse 215 to feeder 255. The fast speed switch magnet coil 34! when energized closes contacts 342 and 343 which short-circuit resistance 251 in series with the field winding 1 of the generator 2 connecting the field winding 1 across the-line from feeder 254 through line 286, contacts 343 and 342, line 258, inductance coil I83, field winding 1, line 258 to feeder 256.

The field winding 1 of generator 2, connected across the line, builds the field up to full strength which increases the voltage of the generator 2 at a definite rate, depending upon the value of inductance I83 and the character of the field circuit. The elevator motor l4 accelerates to full speed, following approximately the voltage induced in the armature winding of generator 2. As described in connection with Figure 3, coil I91 causes the engagement of contacts I85 and I96 to connect resistance I84 across the field winding 1 and inductance coil I83 when the generator voltage reaches a certain value.

The car switch handle 43 may be returned to neutral which will remove the bridging of contact fingers 281, 288 and 289 by the contactor 286. However, the contact fingers 288 and 281 are bridged by resistance which permits sumcient current to flow to hold in the up direction switches but not sufficient current to close these switches through an appreciable air gap, as when they are open. This circuit is obtained from contact finger 288 through line 344, contacts 345 and 348 of the automatic stopping switch, line 341, resistance 348, line 285 to car switch finger 281. This makes the up direction switches selfholding subject to the opening of the contacts 345 and 346 of the automatic stopping switch.

Car switch fingers 288 and 288 are bridged from finger 268 through line 344, contacts 388 and 38I, line 382, contacts 883 and 384, line 385, resistance 386, line 381 to contact finger 288. The resistance 386 is so selected as to permit the fast speed switch to be self-holding subject to the opening of contacts 388 and 38I or 383 and 384 of the automatic slow-down switches for the up direction.

The automatic slow-down, brake and stopping switches are so constructed and when the coils are energized, the cores may be attracted by iron plates or armatures mounted stationary in the hatch. The movement of the cores results in the opening of the contacts provided on the switches, resulting in slowing down, partial brake application and stopping of the elevator motor. When the elevator is running at high speed, contacts 398 and 388 are opened when fast speed switch magnet coil 3 is energized. The opening of contacts 388 and- 388 deenergizes the automatic brake and stopping magnets on the car, sothat slow-down must first be initiated preparatoryto stopping. before the brake can be partly applied or the direction switches opened.

The slow-down contacts in each direction are controlled by two individual slow-down magnets, the purpose of which will appear from the follo-wing:

The distance between adjacent floors is frequently of such a value that it is impossible to obtain full speed in one floor runs with equipment that is furnished to obtain the maximum passenger transportation for regular service. In such cases, to obtain the minimum running time between adjacent floors, the run must consist of acceleration and retardation only; that is, slow-down must be initiated before full speed is attained, but notso early that an extremely long period of slow-down is obtained. When a .two or more floor run is made, full speed is attained, and, therefore, a greater distance for reaoaaeao tardation is necessary. To take care of these two conditions, the automatic slow-down switches are provided in two groups, one for single fioor runs, the other for two or more floor runs.

The group for one floor runs consists of one switch for each direction of travel, and these are energized immediately upon starting' The cores of these switches are attracted by stationary armatures atthe minimum distance from the landing required to slow down the elevator for one floor runs.

The automatic switches for slowing down in two or more floor. runs are arranged to be inop erative until the elevator is approximately at full speed, which will be attained when the elevator motor armature has maximum potential at its terminals. When this voltage is reached a properly wound magnet coil is sufiiciently energized to cause it to close contacts which complete the circuit to the magnet coil of the slowdown switches for two or more fioor runs. When the elevator arrives at the distance from a landing required to retard the elevator from its full speed preparatory to stopping, contacts which release the fast speed switch are openedby the motion of the core of the automatic slow-down switch when it is attracted by a stationary armature in the hatch.

Consider the elevator at full speed, the potential across the armature of elevator motor I4, Figure 6, is a maximum and the magnet coil 488 being connected across elevator armature lines 333 and 334 is energized sufiiciently to cause the switch to close contacts 48I and 482. A circuit is then completed from line 254 through fuse 268, line 383, contacts 218 and 218, line 382, contacts 3 and SM, line 3I8, contacts 48I and 482, line 483, terminals G'-G of traveling cable 66', line 484, magnet coil 485 for the automatic up slowdown switch, line 263, emergency switch 38, line 264, terminals B'-B' of traveling cable 66, line 265, contacts 266 and 261, line 268, contacts 288 and 218, line 21I, contacts 212 and 213, line 214, fuse 215 to feeder 255.

The car switch handle 43 may be now returned to center at or near a landing previous to the one it is desired to stop at. Magnet coil 486 being energized, the core is attracted by a stationary armature 188 in the hatch set at a distance required to retard the elevator preparatory to stopping. Contacts 388 and 38I are opened, which open the circuit of the fast speed switch nragnet coil 3. The opening of this circuit causes the fast speed switch to release, thus opening contacts 342 and 343, inserting resistance 251 in the circuit of field winding 1 of gen-v erator 2. The energy in field 1 is discharged through resistance I84, the voltage of generator 2 decreases, and the speed of elevator I4 decreases with it. The time of retardation is gov-. crned by resistance I84 and inductance I33 as previously explained.

Bottom contacts 388 and 388 on the fast speed switch close with the decnergizing of coil 3. A circuit is completed through contacts 398 and 398 as follows:--Feeder 254 through fuse 268,

line 383, contacts 218 and 218, line 382, contacts 3 and 8I8, line 3I8, contacts 398 and 388, line 486, terminals H'-H' of traveling cable 66, line 481, automatic brake switch coil 488 and automatic stopping switch coil 489, in parallel, line 263, emergency switch 38, line 264, terminals B'B' of traveling cable 66, line 265, contacts 266 and 261, line 268, contacts 268 and 218, line 2'", contacts 212 and 213, line 214, fuse 215 to feeder 255.

The automatic brake and stopping switch coils are now energized. Upon approaching the floor, and at a short distance from it, a stationary armature is placed to cause attraction for the core of the automatic brake switch magnet coil 468, at which time contacts 322 and 323 will be opened, which will deenergize auxiliary brake magnet coil 3l1, and this will open contacts 326 and 321, inserting resistance 316 in series with brake magnet coil 23, thus causing partial brake application.

Upon nearly reaching the floor landing, the elevator will bring the core of magnet coil 469 opposite a stationary armature 10! in the hatchway, the attraction of which will cause contacts 345 and 346 to open, thereby deenergizing the up direction switch magnet coils 360 and l This causes the opening of the armature and operating circuits andapplies full brake application by deenerging brake magnet 23 completely. As explained in connection with Figure 3, coil I91 is wound to permit the separation of contacts 495 and I96 under the influence of gravity when the generator voltage reaches a predetermined value. The separation of these contacts disconnects resistance I94, thus increasing the resistance of the discharge path of field 1 and inductance coil I93 at the time that the rate of discharge is desired to be increased.

In one floor runs, magnet coil 406 will not be energized suificiently to close contacts 4M and 462 which complete the circuit for magnet 405, so that the switch controlled by magnet 405 will be inoperative and it will pass by its cooperating stationary armature 166 in the hatchway without functioning. A circuit is completed for magnet coil 4l6, however, which will cause magnet coil 446 to be energized, and its core to be attracted by a stationary armature 162 in the hatch. Armature 1.02 is located nearer the landing being approached than armature 166, by an amount determined by the-difference in speed between two floor and one fioor runs. This circuit extends from feeder 254 through fuse 266, line 363, contacts 219 and 218, line 302, contacts 3 and 346, lines 346 and 4H, terminals I'I' of traveling cable 66, line 412, magnet coil 4|6, line 263, emergency switch 30, line 264, terminals B'-B' of traveling cable 66, line 265, contacts 266 and 264, line 268, contacts 269 and 210, line 21!, contacts 212 and 213, line 214, fuse 215 to feeder 255.

The switch controlled by magnet coil 4 l 0 opens contacts 393 and 394 which are in series with contacts 390 and 39| of the switch controlled by magnet coil 405. The fast speed switch magnet coil 34! is deenergized, contacts 342 and 343 open and the elevator slows down, as described above in connection with two fioor runs. The partial application of the brake and the stop at the landing are also as described above.

The push buttons 49 and 50 are provided for emergency operation at slow speed, these buttons bridging the extreme contact finger points only (as for example, 231 and 289) of the car switch. High speed operation is prevented by eliminating the connection corresponding to the intermediate contact finger points in the car switch 21.

In Figure 7 a motor generator set is utilized as in Figure 6.

The elevator motor l4 has its shunt field winding I39 connected in series with resistance 4 i 3 and across the line. Contacts 4 and 455 are governed by the action of a speed governor driven The car switch M6 .is constructed so as to have three positions for either direction of travel; one is common to each and is the neutral position; the second position is where contactor 4H will engage the full series of contact finger points on either side; and the third is where contactor 4l1 will engage the first or lower three contact fingers only. This latter position is the position provided when it is desired to obtain automatic slowdown and stopping. The neutral position will permit stopping at will. The extreme position will render the automatic slow-down and stopping inoperative.

The field winding 1 of generator 2 is'connected permanently across the line in series with resistance 4l8 so that when the motor generator set is running the armature of generator 2 has a low potential of constant polarity.

The closing of the emergency switch M9 in the elevator completes a circuit for the potential switch magnet coil 423 after which the elevator may be operated. This circuit extends from feeder 426 through fuse 422-, potential switch coil 423, lines 424 and 425, terminals F"F of traveling cable 439, line 426, through each side of emergency switch 45 9, line 421, terminals M"--M of traveling cable 439, line 428, contacts 429 and 430 of bottom overtravel limit switch, line 43!, contacts 432 and 433 of the top overtravel limit switch, line 434, contacts 435 and 436 of the overspeed governor, line 431, fuse 438 to feeder 425.

The potential switch will be closed by the energizing of the coil 423, closing contacts 440 and 44d and contacts 442 and 443. Contacts 444 and 445 will be opened.

Moving car switch handle 446 so that contactor 4il will engage contact finger 45! will not complete a circuit. Continuing until contactor covers contact fingers 45! and 452, a circuit will be completed from feeder 426 through fuse 422, line 441, contacts 443 and 442, line 451, up direction switch coils 456 and 459, line 466, contacts 46!, 462 and 463, line 464, terminals B"-B" of traveling cable 439, line 465, terminal stopping switch contacts 466 and 461, line 466, resistance 469, contacts 410 and 414 to car switch contact finger 452, contactor 4I1, car switch contact finger 45I, line 412, emergency switch 449, line 421, terminals M-M" of traveling cable 439, line 428, contacts 429 and 430, line 43!, contacts 432 and 433, line 434, contacts 435 and 436, line 431, fuse 438 to feeder 42L The resistance 469 is of such value that the up direction switches cannot be closed by the magnet coils a circuit is obtained from feeder42fl through fuse 422, line 441, auxiliary brake relay magnet 448, line 449, terminals G"-G" of the traveling cable 499, line 459, car switch finger 454, contactor 411, contact finger 451, back to feeder 421 as before.

The energizing of magnet coil 449 closes contacts 413 and 414 and contacts 415 and 419. Contacts 419 and 414 provide a self-holding circuit for coil 448 when the car switch handle is returned to center or automatic stopping position and will be considered later as it has no given function'at this time. Contacts 415 and 419 short-circuit resistance 411 in series with the brake magnet coil 23 preparatory to the direction switch going in to provide full excitation of the brake magnet when lifting.

tacts 418 and 419, contacts 489 and 481 and contacts 492, 489 and 494. Contacts 495 and 499,

contacts 481 and 498 and contacts 499, 491 and 492 are closed. The brake magnet 29 is energized upon closing of the up direction switch through a circuit from feeder 429 through line 499, contacts 499 and 491, lines 494 and 495, contacts 499 and 492, lines 499 and 491, contacts 415 and 419, line 498, brake magnet coil 29 and protective resistance 195 in parallel, line 499 to feeder 421. The armature circuit of elevator motor 14 is completed from armature of generator 2 through line 599, series filed 12 and parallel resistance 144, line 499, contacts 488 and 491, line 591, contacts 449 and 441, line 592, through elevator motor 14 armature winding, line 593, contacts 495 and 499, line 594 to armature of generator 2.

' A circuit is established for the fast speed switch at this time also, the resistance of this circuit being such that the fast speed switch cannot be closed by its magnet coil 599 but can be held closed once the switch has pulled in and reduced the air gap of the magnetic circuit. This circuit extends from feeder 429, through line 499, contacts 489 and 481, lines 494 and 495, contacts 489 and 499, line 595, fast speed magnet coil 599, line 591, resistance 599, line. 599, terminals D"D" of-the traveling cable 499, line 519, contacts 511 and 512 of the terminal stopping switch, line 519, resistance 514,'line 515, contacts 519 and 511 of the automatic slow-down switch, line 519, contact finger 459, contactor 411, contact finger 451 and back to feeder 421 as before.

Moving car switch contactor 411 to cover contact finger .455 short-circuits resistance 514 and contacts519 and 511 by bridginglines 519 and 519. This increases the current in the fast speed magnet coil 599, enabling it to pull in, closing contacts 519 and 529 and opening contacts 521 and 522.

The closing of contacts 519 and 529 short-circuits resistance 419 in series with field winding 1 of the generator 2 which increases the voltage of l the generator at a rate consistent with the building up of the generator. The armatures of the elevator motor 14 and generator being now tied together electrically, the elevator motor increases its speed.

The circuit of field winding 1 of the generator 2 then extends from feeder 429 through line 529, contacts 529 and 519, line 524, field winding 1, line 525 to feeder 421.

A generator 529, the separately excited field 529 of which is connected to feeders 429 and 421 through lines 529 and 599 for permanent excitation is driven at a speed proportioned to the speed of the elevator. As shown, it is belt driven from a pulley mounted on the speed governor, which in turn is driven by an iron rope traveling over the governor sheave and secured to the elevator car. The speed of the generator being a function of the speed of the elevator, it follows that the voltage will correspond to the speed of the elevator also. Three magnet coils are supplied with energy by the generator 526 and so adjusted as to function at definite car speeds.

In order to provide for one fioor runs as well as two or more floor runs without having anextremely long period of slow speed running for the one floor runs, the automatic slow-down magnet is made to be inoperative at that point in the hatch at which it-shou1d be efl'ective for two or more fioor runs.

This is done as follows for each floor landings- Two stationary armatures are provided for slowing down automatically, the farthest one from the fioor being utilized for two or more fioor runs, the closest one for one floor runs. Then when running to any particular landing, two slow-down points are passed, the first stationary armature to be met with will attract the core of the automatic slow-down switch as well as the second. For two or more fioor runs, the first stationary armature initiates the slow-down. For one floor runs, the automatic slow-down switch will be rendered inoperative when passing the stationary armature by virtue of contacts 591 and 592 and contacts 599 and 594, which will bridge contacts on the automatic slow-down switches. Contacts'591 and 592 will be for the up direction and bridge contacts 519 and 511, through lines 589 and 581, terminals I"--I" and J "J" of the traveling cable 499, and lines 599 and 591. Contacts 599 and 594 are used for the down direction of travel.

When the elevator has reached a point in the hatch that the automatic slow-down switch core has passed the first stationary armature, the

speed of the elevator is sufficient to provide a voltage from generator 529 sumcient in value to energize magnet coil 595 through lines 549.and

541 so that contacts 591 and 592 and contacts 599 and 594 will open, permitting the automatic slow-down switch to become eflective.

Auxiliary brake relay magnet coil 542, through lines 543 and 544 is energized sumciently to operate its contacts at a voltage corresponding to the speed attained in one fioor runs.

The magnet coil 542 then causes contacts 541 and 549 to close and contacts 545 and 549 to open. The closing of contacts 541 and 549 has the same function as the contacts 415 and 419 controlled by the magnet 448 as both pairs of contacts are connected in parallel and through lines 491 and 499 short-circuit resistance 411 in series with the brake magnet coil 29. Upon the opening of contacts 545 and 549, the self-holding circuit for magnet coil 449 is opened and it is prevented from holding in after car switch handle 449 has been returned to intermediate or neutral position.

The purpose of this particular circuit arrangement is to provide partial application of the brake when approaching a landing. Immediately upon moving car switch handle to running position and starting the elevator, then returning the handle to the action of the switches controlled by magnet coils 448 and 542, is as followsz-The circuit of magnet coil 448 is completed and short-circuits resistance 411 through contacts 415 and 416 to permit quick release of the brake. Contacts 413 and 414 permit magnet coil 446 to be self-holding by a circuit completed as follows after car switch cont-actor 4l1 uncovers contact finger point 454: --From feeder 420, through fuse 422, line 441, magnet coil 448, contacts 414 and 413, line 549, contacts 546 and 545, lines 550 and 431, fuse 438 to feeder 42L When the elevator has reached a predeter-' mined speed, generator 526 will have a voltage sufllcient to cause magnet coil 542 to close its switch, contacts 548 and 541 will then shortcircuit brake resistance 411 and contacts 545 and 546 will open the circuit of magnet coil 448. Magnet coil 448 will then be deenergized and open contacts 413 and 414 and contacts $15 and 416.

After the slow-down has been initiated, the voltage of generator 526 will decrease with the decreasing speed of the elevator to a point that will permit the switch controlled by magnet coil 542 to return to normal position by gravity opening contacts 411 and 418 and inserting resistance in in series with the brake coil 23, thus providing partial application of the brake. Contacts 16 and 416 are used to short-circuit resistance Q11 and then opened.

The arcing across contacts 541 and 554i! upon these contacts breaking is eliminated by the use oi'condenser 551 connected across the contacts 5&1 and 54B,through lines 491 and tilt. To further insure the elimination of the arc, resistance @11 is inserted in a short-circuited inductance coil 552 ii resistance 411 is inductive, as for ex ample if wound in a helix. Across the contacts 7 565 and 545 a condenser 553 is used to eliminate the arcing across these contacts when releasing magnet coil 448.

Automatic magnetically operated switches are mounted upon the elevator and controlled by magnet coils 554, 555 and 556 and operate by magnetic attraction of a movable core for a sta-- tionary armature mounted in the hatchway. This motion causes contacts mounted upon the switches to open and function as outlined. The magnet coils 555 and 556 are in circuit immediately upon starting while magnet coil 5541 is energized only at low speed.

The circuit for magnet coils 555 and is ohta-ined from feeder are through line 6%, contacts ittl'and Q81, lines 494 and 495, contacts 389 and Q96, line 551, terminals C"-C" of traveling cahle 43d, line 5558, magnet coils and 556, line tilt), snap switch 56d, line 412, through emergency swimh M9, line $21, terminals M"-lvi" of traveling cable 439, line 428, contacts 129 and @351, line 53!, contacts 432 and 5533, line @3 5, con= tacts 435 and @365, line 431, fuse 338 to feeder 12i.

Consider the elevator as having been brought up to full speed and car switch handle W5 returned to intermediate or automatic stopping position. At this time contactor 311 will cover car switch finger points 45L 152 and This permits the up direction and fast speed switches to remain closed but the circuit is obtained through resistance 439 for the up direction switch and resistance 5% for the fast speed switch. These circuits are subject to the action of the automatic switches mounted upon the elevator. When the core of magnet 558, which is the automatic slow-down for the up direction, passes the stationary armature in the hatch provided for up slow-down for any given fioor, contacts 5l6 and 5i1 are opened, which open circults of the magnet coil 506. Magnet coil 506, when deenergized, releases its switch, which opens contacts Bill and 520 and inserts resistance 8 in series with field winding 1 of generator 2, reducing the voltage of generator 2 and consequently that across the armature of elevator motor i4 and the elevator. slows down. Its rate of slowing down is determined by the value of resistance 538 which is the discharge resistance for the energy in the field of generator 2 and is connected across the field terminals through wire 524, contacts 531 and 536, wire 539, main 42! and wire 525. Contacts 531 and 536 are closed by coil 535 as the elevator accelerates by current from generator 526.

As the elevator speed decreases, the speed of generator 526 decreases and the voltage of generator 528 decreases in direct proportion to the decrease in speed of elevator motor l4. When this voltage has decreased to a predetermined value, magnet coil 535 is deenergized sufficiently to permit the switch controlled -by it to release and open contacts 536 and 531, which open the circuit through resistance 538. By opening this circuit this discharge path is eliminated from the circuit of field winding 1 of generator 2, increasing the rate at which the voltage of generator 2 will decrease. This increases the rate of retardation and since a field winding of high inductance is inherently slow in deenergizing, particularly toward the end of discharge, it provides a means for reaching slow speed in less time without too rapid retardation at any time during the slow-down period.

With further decrease in speed; a greater de crease in voltage of generator 526 is obtained until a point is reached where magnet coil 5 12 is deenergized sufiiciently to permit contacts 5 31 and 568 to open, inserting resistance Q11 in series with brake coil 23, causing partial brake application.

TWhen the elevator platform is near the landing, the core oi. magnet coil 5% is attracted by -a stationary armature causing it to open contacts Gi li and 311.

The circuit for mwnet coil s is obtained from feeder 452d through line 493, contacts and 4 81, lines 1% and 495, contacts 489 and tilt, lines 551 and 561, bottom contacts 522 and of the speed switch, line 562, terminals H"-L-l" of the traveling cable 439, line 583, automatic stopping switch coil 554, line 559, snap switch sec, are, emergency switch did, line 421 and hack to -feeder 12i as before.

Gc-ntacts 31d and :116, when opened, interrupt circuit through resistance 69 in the circuit of the up direction switch magnet coils, releasing the up direction switches. The main bottom contacts close when the up direction switches release and apply a dynamic stopping action in two steps. The first step is completed across the armature leads 5M and 553 from 5&3 through line 5%, contacts 518 and 419, inductance resistance line 561, contacts 568 and 589, line 51d to tilt. This step provides for gradual dynamic braking action by the use of the in ductance which prevents a sudden rush of current immediaixaly upon closing contacts 418 and are. The contacts are so arranged as to permit this circuit to close first upon stopping.

Contacts liiil and 48i complete a circuit from 5696 through line tilt, contacts 483 and 48!, line 51d, resistance 512, contacts 513 and 514, line 51 1- to line 533 completing a low resistance circuit across the armature feeders of elevator motor l4 and applying a low resistance dynamic stop for the elevator motor l4.

For manual control, that is stopping by centering car switch handle 446, a magnet coil 516 in series with suitable resistance 5", is connected across leads 540 and SM from generator 526. The strength of magnet coil 5'16 is proportioned to the speed 01' the elevator 'and is so adjusted to close contacts 518 and 519 at a suitable speed after starting and to open them at a speed suitable for stopping. For example, they may close at 20% full speed and release at full speed. The contacts 518 and 519 provide a circuit which will permit the direction switches to remain energized until the speed of the elevator has dropped to say 10% of full speed. Neither the car switch nor automatic stopping switch can function until after this low speed has been reached. This prevents stopping suddenly from high speed and allows the elevator to retard at a comfortable rate to a speed suitable for stopping when the car switch is centered when running at full speed. The circuit obtained, for instance, in the up direction is from feeder 420 through fuse 422, line 441, contacts 443 and 442, line 451, up direction switch magnet coils 458 and 459, line 460, contacts 46! and 462, line 582, resistance 58!, line 580, contacts 519 and 518, lines 424 and 425, terminals F"F" of the traveling cable 439, line 426, emergency switch 9, line 421, terminals M --M" of the traveling cable 439, line 428, contacts 429 and 430, line 431, contacts 532 and 433, line 434, contacts 435 and 436, line 437, fuse 438 to feeder 42!. The centering of the car switch handle 445, while not stopping the elevator instantly, opens the test speed magnet circuit, when the elevator will be immediately retarded and stopped by the action of the magnet 515.

The various emergency devices provided such as emergency switch" 9, overtravel limits and overspeed governor operate to open the circuit of magnet 423, controlling the potential switch and it caused to act, result in the opening the contacts 440 and 44!, which disconnects the armature of the elevator motor from lines leading to the reversing switch. Contacts 444 and 445 close and connect a dynamic stopping resistance 583 across armature leads 502 and 503 to provide the proper degree of stopping when this means must be resorted to.

Snap switch 560 may be used to open the circuits of the contacts on the automatic slow-down and stop switches to disable them and the car will then be under manual control only.

In order to obtain uniform and accurate stops under different conditions of loading and speed,

' it is important that all switches be quick-acting and have a definite time for opening and closing. Also that the contacts, especially in the armature circuits, be of a low and constant resistance.

I have found that there is a great advantage in using switches mounted on the car and cooperating with means in the hatch for controlling the slow-down and stop of elevators instead of floor-controllers located in the motor-room and driven from the elevator mechanism. This is due to the difilculty of coordinating the movements of the car and floor-controller and also to the small distances available for the operation of switches on a floor-controller.

I desire to point out that in my present invention, I provide means for controlling the rates of acceleration and retardation ofthe elevator as desired so that they may be substantially the same under all conditions of loading. Also that I provide means for slowing down the elevator at fixed distances from the landings proportional to certain selected speeds corresponding to the conditions of elevator service. I have described conditions wherein the elevator does not reach its full speed in one floor runs, but does so in two floor runs. It is apparent that my invention may be readily adapted for elevators of very high speed, say eight hundred feet per minute, where three slow-down distances may be required, one distance for one door runs, one for two floor runs and a third for three or more floor runs, it being assumed that the elevator will reach full speed in three floor runs.

I also wish to point out that I provide means for causing the preliminary application of a braking force before the power supply to the elevator motor is interrupted, this braking force being of a predetermined strength and preventing the momentary acceleration of the car by gravity between cutting oiI the power and applying the final braking force. Furthermore, as a part of the braking operation has already occurred, the application of the final braking force is able to accomplish its purpose that much more quickly. I believe this principle to be broadly new for the purpose here employed, whether these forces are developed in one brake or a plurality of brakes, and the illustration of the principle as applied to the use of a single brake is intended to illustrate the broad principle as stated.

I claim:-

1. An elevator system comprising, an elevator car, a plurality of switches for causing the slowing down of the elevator car to be initiated at different distances from a desired landing, an electromagnet for each switch for causing the operation thereof, each electromagnet having a portion of its magnetic circuit on the elevator car and the remainder of its magnetic circuit in the elevator hatchway.

2. An elevator system comprising, an elevator car, a plurality of switches carried by the car for causing the slowing down of the car to be initiated at different distances from any one of a plurality of landings including at least one intermediate landing, an electromagnet for each switch also carried by the car, each electromagnet having a plurality of armatures in the elevator hatchway, one for each of said landings, for cooperating therewith to cause the operation of the switch for which it is provided.

3. An elevator system comprising, a plurality of landings including at least one intermediate landing, an elevator car, a plurality of electromagnets carried by the car, each electromagnet having a plurality of armatures arranged in the elevator hatchway, one for each of said landings, a switch carried by the car and actuatable by the coaction of one of said electromagnets and any one of the armatures therefor to initiate the slowing downof the elevator car at a predetermined distance from the landing for whiclrthat armature is provided, and another switch also carried by the car and actuatable by the coaction of another of said electromagnets and its armature ifor such landing to initiate the slowing down of the elevator car at a less distance from such landing in the event of the slowing down of the car at such landing not having been initiated by the first named switch.

4. An elevator system comprising, an elevator car, means for bringing the elevator car from rest to full speed, control mechanism in the hatchway, means rendered operative by the operator for cooperation with said mechanism to initiate a reduction of the speed of the elevator car at difierent distances from a selected landing, and means dependent upon the distance travelled by the car for determining the distance from said landing at which said cooperation becomes effective.

5. An elevator system comprising, an elevator car, means for bringing the elevator car from rest to full speed, control mechanism in the hatchway, means rendered operative by the operator in selecting a landing for cooperation with said mechanism to initiate the slowing down of the elevator car at different fixed distances from the landing selected, and means responsive to the speed of the car for determining the fixed distance at which said cooperation becomes efiective.

6. An elevator system comprising, an elevator car, a plurality of landings including at least one intermediate landing, means for starting the car and bringing it up to full speed, a plurality of controls in the hatchway for each landing, mechanism carried by the car for cooperation with one of said controls for any one of said landings as the car arrives at a certain distance from such landing to initiate slowing down of the car from full speed and for cooperation with another of said controls for such landing as the car arrives at a less distance from such landing to interrupt acceleration of the car and cause slow down to take place under conditions where slow down has not been initiated by cooperation of said mechanism with said one control.

7. An elevator system comprising, an elevator car, a plurality-of landings including at least one intermediate landing, a plurality of controls in the hatchway for each of said landings, said controls for any one of said landings being adapted to cause the initiation of the slowing down of the elevator car at different distances from said one landing, and means responsive to the speed of the car for determining which of said controls for said one landing is efiective.

8. A high speed electric elevator system comprising in combination, means for bringing the elevator with definite acceleration up to a predetermined maximum speed, means for slowing down the elevator with definite retardation, slowdown controls in the hatchway at different distances from a landing, manually controlled means for effecting slow-down actuation by the slowdown control nearer the landing when passing it at less than maximum speed, and manually controlled means for efifecting slow-down actuation by the slow-down control farther from the landing only when passing it at the said maximum speed.

9. An electric elevator system comprising, a hoisting motor, a generator to supply current to said motor at a variable voltage, said generator having a field winding, .9; current supply circuit for said generator field winding, and means external to said generator and said field winding current supply circuit for causing substantially a uniform rate of field discharge upon reduction current supply circuit for causing substantially a uniform rate of field discharge upo'n reduction of the field current supplied by said supply circuit, said means comprising resistance shunted across said winding.

11. An electric elevator system comprising, a hoisting motor, a generator to supply current to said motor at a variable voltage, said generator having a field winding, a current supply circuit for said generator field winding, and means external to said generator and said field winding current supply circuit for causing substantially a uniform rate of field discharge upon reduction of the field current supplied by said supply circuit, said means comprising resistance shunted across said winding, and means controlled by the voltage of the generator for increasing the resistance.

12. An electric elevator system comprising in combination, a hoisting motor, a generator to supply current to said hoisting motor at a variable voltage, a field winding for said generator, a current supply circuit for said generator field winding, and means external to said generator and said field winding supply circuit for fixing the rate of field discharge upon reduction of field current supplied by said supply circuit, to cause the retardation of said hoisting motor to be as desired, said means comprising an inductive reactance in said field winding circuit and a resistance of proper value connected in shunt to said generator field winding and said inductive reactance.

13. An electric elevator system comprising in combination, a hoisting motor, a generator to supply current to said hoisting motor at a variable voltage, a field winding for said generator, a source of current for said winding, means external to said generator for automatically fixing the rate of field current increase to give the desired rate of acceleration to said hoisting motor, said means comprising an inductive reactance in said field winding circuit, and means comprising a resistance of proper value connected in shunt to said generator field winding and said inductive reactance for fixing the rate of field current decrease.

14. An electric elevator system comprising in combination, a hoisting motor, a generator for supplying power to said hoisting motor at a variable voltage, a field winding for said generator, means for varying the current in said field winding, a circuit having a certain resistance connected across said field winding, and means for increasing the resistance of said circuit at a predetermined generator voltage as said voltage decreases.

15. The combination with an elevator car and a motor therefor, of manually operable means for initiating movements of the car, electromagnetic means carried partly on the car and partly in the hatchway for varying the motor speed at predetermined points in the hatchway, and electroresponsive means effective after said speed variation for insuring accurate stopping of said car at desired landings without overtravel or undertravel.

16. The combination with an elevator car and. a motor therefor, of manually operable means for initiating movements of the car, electromagnetic means carried partly on the car and partly in the hatchway for decelerating the motor at predetermined points in the hatchway when said manual means is inoperative, and electroresponsive means effective after deceleration of said motor for insuring accurate stopping of said car at desired landings without overtravel or undertravel.

17. The combination with an elevator car and a motor therefor, of manually operable means for initiating movements of the car, electromagnetic means carried partly on the car and partly in the hatchway for varying the motor speed at predetermined points in the hatchway, means for controlling the voltage impressed on the motor, and electroresponsive means effective after said speed variation for insuring accurate stopping of said car at desired landings without overtravel or undertravel.

18.- Thecombination with an elevator car and a motor therefor, of a generator for controlling the motor, means for varying the generator voltage, manually operable means for controlling the voltage-varying means and electroresponsive means operable in accordance with the move- 'ment of said car for controlling the generator when said manual means is inoperative.

19. The combination with an elevator car and a motor therefor, of a generator for controlling thev motor, means comprising a field-magnet winding on the generator for varying the generator excitation automatically in accordance with the motor-load, manually operable means for varying the generator voltage, and electroelectro-responsive means operable in accordance with the movement of said car for controlling the generator when said manual means is inopera- 21. The combination with an elevator car and amotor therefor,'of manually operable means for initiating movements of the car, electromagnetic means carried partly on the car and partly in the hatchway for varying the motor speed at predetermined points in the hatchway, and electroresponsive means eifective after said speed variation for insuring accurate stopping of said car at desired landings without overtravel or undertravel and without interruption of the motor circuit prior to stopping.

22. An electric elevator system comprising, an elevator car, a plurality of landings including at least one intermediate landing, a manually operable control switch having a running position and an automatic slow-down position, means responsive to the operation of said switch to its running position ior causing the starting of the car, control means in the hatchway for each of said landings, and control means carried by the car for cooperating with the control means in the hatchway for any one of said landings to initiate the slowing down of the car at varying distances from such landing, said control means being .rendered eiiective to initiate slow-down by their cooperation upon movement of said control switch said position to said automatic slow-down 23'..An electric elevator system comprising, an elevator" :car, a plurality of landings including .atleast one intermediate landing, a manually op,- 'erable control switch having a running position an automatieslow-down position,

means responsive to the operation of said switch to its running position for causing the starting of the car, control means in the hatchway for each landing, and control means on the car rendered operable upon movement of said control switch from running position to said automatic slowdown position to cooperate with the control means in the hatchway for any one of said landings for initiating the slowing down of the car at diflerent distances from such landing.

24. An electric elevator system comprising, an elevator car, a plurality of landings including at least one intermediate landing, a manually operable control switch, said switch having an operative position and an oil position, means responsive to the operation of said control switch from said oil position to said operative position for causing the starting of the car and adapted to thereafter cause the acceleration thereof to full speed, means for maintaining said first named means operative after its operation in response to movement of said controlswitch to its operative position, a plurality of slow-down controls in the hatchway for each of said landings, and control means carried by the car for cooperating with one or another of the slow-down controls for any one 01. said landings to initiate the slowing down of the elevator car at varying distances from such landing.

25. An electric elevator system comprising, an elevator car, a plurality of landings including at least one intermediate landing, a manually operable control switch in the car, said switch having a running position and an automatic slow-down position, means responsive to the operation oi said switch to its running position for causing the starting of the car and acceleration thereof, means for maintaining said first named means operative upon movement of said control switch from running position to automatic slow-down position, a plurality of slow-down controls in the hatchway for each of said landings, and switching mechanism carried by the car and rendered operable upon movement of said control switch from said running, position to said automatic slow-down position for actuation by one or another of said slow-down controls for any one of said landings to initiate the slowing down of the car at diil'erent distances from such landing.

26. An electric elevator system comprising, an elevator car, a plurality of landings including at least one intermediate landing, a manually operable contrcl switch in the car, said switch having a running position and an automatic slow-down position, means responsive to the operation of said switch to its running position for causing the starting of the car and adapted to thereafter cause the acceleration thereof to full speed, said control switch acting to maintain said means operative so long as it is held in its running position, means for maintaining said first named means operative upon movement of said control switch from running positionto automatic slow-down position, control means in the hatchway for each of said landings, and control means carried by the car for cooperating with the control means in the hatchway for-any one of said landings to initiate the slowing down of the car at different distances from such landin said control means in the car and hatchway being rendered coniointly eifective to initiate slow-down upon movement or said control switch from said running position to said automaticslow-down position. v

1 than electric elevator system an

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