US2040184A - Elevator control system - Google Patents

Description

May 12, 1936 A. PlNTO ET AL ELEVATOR CONTROL SYSTEM Fil ed May 4, 1935 3 Sheds-Sheet 1 May 12, 1936 A. PINTO ET AL 2,040,134

ELEVATOR CONTROL SYSTEM Filed May 4, 1935 s Sheets-Sheet 2 I34 fi 30: W BP 6F I53 52 "WW 1&3 will ikjlfifl LU Z5 r25!)- I l 5 151% G Ll) 25.2 h 4 5| 264 M can; (E a VW INVENTORS BY ATTORNEY May 12, 1936 A. PINTO ET AL ELEVATOR CQNTROL SYSTEM Filed May 4, 1935 3 Sheets-Sheeti ASR 40 ilk (P NV RS I. ENTO ATTORNEY but do not wish for various Patented May 12, 1936- ELEVATOR CONTROL SYSTEM Anthony Pinto, New Rochelle, and Raymond Alonzo Waite, Yonkers, N. Y., assi'gnors to Otis Elevator Company, ration of New Jersey New York, N. Y., a corpo- Application May 4, 1935, Serial No. 19,766 25 Claims. 1'72152)' The invention relates to control systems for elevators.-

Various improvements have been made from time to time in the operation of elevators. Among such improvements is the mechanism for bringing the elevator car toan exact level with the desired landing in stopping, regardless of whether the car underruns or overruns the landing. such mechanism usually being referred to as self levelling mechanism. There have' been many elevators installed since the advent of self levelling which are not provided with this improvement. Many owners of such installations, as well as of installations made prior to levelling, are desirous of hav-= ing elevators equipped with levelling apparatus reasons to install a complete new elevator system. In many of these instances, the elevators are operated on direct current under what is usually termed resistance control, i. e., an installation in which the elevator car is started by connecting the hoisting motor armature to the source in series with resistance and the resistance cut out to bring the car up to full speed, and in which the car is slowed down by including resistance in series with the armature and additional resistance across the armature and cutting this additional resistance out of circuit. It is particularly to such type of control system for elevators that the present invention is applicable although it is useful in connection with certain other arrangements and can be applied to new installations.

The invention involves the provision of self levelling mechanism in resistance control elevator installations.

One feature of the invention is to utilize a direct current generator to supply current at a low voltage to the armature of the hoisting motor of a resistance control installation during the levelling operation.

Another feature is to have the generator in operation prior to the levelling operation but to excite the generator separately excited field winding only for the levelling operation.

Another feature is to utilize a compound wound generator and to render the series field winding of the generator effective during levelling.

Still another feature is to connect the generator armature in the circuit of the hoisting motor armature during full speed operation of the car and for rendering the generator series field winding effective during such full speed operation.

Other features and advantages will become apparent from the specification taken in connec- 'motor field.

tion with the accompanying drawings and the subjoined claims.

The invention may be carried out in various ways. The generator may be driven all the time the elevator car is in service or for less periods as 5 for example only while the car is running. The generator armature may be connected permanently in series with the hoisting motor armature or disconnected at times but connected to the hoisting motor armature for the levelling operation. For the levelling operation, the hoisting motor armature is disconnected from the source and connected across the armature of the generator and the separately excited field winding of the generator is connected to the source to cause the generator to supply current to the hoisting motor armature to bring the car to the fioor level.

In the drawings:-

Figure 1 is a schematic wiring diagram of an elevator control system embodying the invention;

Figure 2 is a fragmental schematic wiring diagram of a portion of the elevator system exemplified by Figure 1, illustrating particularly the connections for the generator; and

Figure 3 is a wiring diagram, similar to Figure 2-, illustrating variations which may be made in the circuits.

Referring first to Figure 1, certain parts of the elevator control system have been omitted from the wiring. diagram in the interest of simplification. This figure is a modified form of straight in which the operating connections between the contacts of the switches and their operating mag- 5 nets are indicated by dot and dash lines. Parts of the system, particularly the coils and contacts of the switches employedtherein, may not be in the preferred points in the circuits, certain changes being made in order to make the type of wiring diagram employed as simpleas possible.

The elevator hoisting motor has its armature designated l l and its field winding l2. The hoisting motor is provided with a starting resistance, '45

arrangedin steps I3, l4, i5, i6, and I1, and a slow down or by-pass resistance arranged in steps I8, 20, and 2|. 22 is a discharge resistance for the hoisting motor field winding While 23 is a resistance for controlling the strength of the hoisting 24 and 25 are the direct current supply mains for applying power to the hoisting motor under car switch control. 26 is a double pole knife switch for controlling the connection of the system to the supply mains. To suit the type of diagram employed, the blades of this switch'are shown separated.

The driving motor for the generator which applies power to the hoisting motor for the levelling operation has its armature designated 21, its series held winding 28, and its separately excited fleld winding ll. The armature of the generator is designated 3!, its series tleld winding 32, and

its separately excited field winding 1:. A resistance 34 is arranged in shunt to the generator series field winding. A resistance 38 is provided for controlling the strength of the generator field. Four additional resistances 3B, 31, I8, and it are provided for controlling the strength of the gen erator ileld. A resistance arranged in steps l4, l8, and 48 is provided for controlling the voltage applied to the armature of the driving motor.

l1 and I. are the up slow speed contacts and the down slow speed contacts respectively of the levelling switch, the levelling switch up and down fast speed contacts being designated 50 and 5! respectively. 52 is the armature and B3 is the fleld winding 0! the motor 54 for moving the rollers of the levelling switch into position to clear the levelling cams.

I! is the release coil for the elevator motor electromagnetic brake. This coil is provided with discharge resistances I6 and 51 for controlling the application of the brake during stopping. The car switch is designated as a whole by the numeral I. II is the safety switch in the car. Other safety devices are indicated by legend. M is the gate contacts while 2 designates door contacts, only one pair of door contacts being illustrated as indicative 0! door contacts for each hatchway door, all these door contacts being arranged in series relation.

The electromagnetic switches have been designated as follows:

AIL-Auxiliary levelling switch B-Brake switch C--Speed switch D--Down direction switch DC-Door contact relay DH-Direction holding switch DB-Down set-up switch E-Speed switch F-Field switch Fit-Series fleld relay G-Speed switch H--Accelerating switch nip-Inching relay J-Acceleratlng switch K-Accelerating switch LD-Levelling down direction switch LI -Levelling fast speed switch Lit-levelling relay LBLoad switch LII-Levelling up direction switch ILA-Driving motor accelerating switch llS- -Driving motor starting switch P--Potential switch Flt-Protective relay Bi -Series field switch ERA-Driving motor starting relay U-Up direction switch Us- Up set-up switch Inductance coils are designated by the character X.

Upon the closing of the knife switch 2', the elevator motor field winding i2 and actuating coil ll of potential switch P are energized,. the circuit for field winding l2 being through resistance 23 and the circuit for coil 65 ext ndi through contacts I. of switch P, the various safety devices indicated by legend and including safety switch ill. Potential switch P, upon operation, engages contacts 81, 88, and I0, preparing the control and power circuits. It also separates contacts 66 to insert cooling resistance in circuit with its coil, separates contacts 12 to remove the short-circuit for step iii of the hoisting motor armature by-pass resistance and engages contacts 59 in the circuit for the brake release coil 55.

Assume that the system is arranged for an installation of several floors and that the car is at rest at the first floor landing. In order to start the car in the up direction, the operator moves the car switch into position where its contact bar 15 bridges contacts l6, ll, 18, I0, 8!), 3i, and 82. Upon contact bar 15 engaging contact '18, a circuit is completed for actuating coil 35 of up direction switch U and actuating coil 88 of brake switch B. This circuit is from supply line 24 through the left hand blade of switch 2|, by wire 81, through contacts 61 and 10 of switch P, wire 88, by wire 89 through coil 88 of switch 3 and contacts 30 of speed switch E, wire Si, by wire 92, through coil 85 of switch U, wire 93, contacts 54 of direction holding switch DH, car switch contacts 11 and 18, by wire 95, through interlock contacts 96 of down direction switch D, wire 81, contacts SI of door contact relay DC, door contacts 62, gate contacts 8!, lower blade of safety switch 60, wire I00, right hand blade of switch 28, to supply line 25. If either the gate or door is not closed so that the gate contacts ii or door contacts 62 are separated, the circuit passes through coil lill of door contact relay DC. This coil is of high resistance, preventing sufllcient current being supplied to the coils oi switches U and B to eifect their operation. This current, however, is sufllcient to operate the door contact relay, which separates its contacts 98. This prevents the starting of the car until the door and gate contacts are all closed and the car switch has been returned to neutral to effect the deenergization of coil "ii. A circuit is also completed upon contact bar I5 engaging contact 18 for coil N2 of levelling relay LR, this circuit extending from the coil to car switch contact ll through car switch contact 18.

Brake switch B, upon operation, engages contacts I84, completing circuits for the coils I05, I08 and ll! of the driving motor starting relay SR, up set-up switch US and down set-up switch DB, respectively. The circuit for coil III of the driving motor starting relay is from potential switch contacts 81, wire 81, contacts I", coil l0! 0! relay SR, inductance coil Xllll, wire I", wire llfl. wire III, by wire H2, through potential switch contacts 68, the right hand blade of switch 28, to supply line 25. Coils Hi6 and Ill of the set-up switches are connected in a circuit parallel to that of coil I05, extending through inductance coil Xi. Coils I08 and II! are holding coils and are not strong enough to elect the operation of their switches.

Coil I05 causes the operation of the driving motor starting relay SR, which engages its contacts III, completing a circuit for coil H6 of driving motor starting switch MB. This circuit is from wire 88, by wire ill, through contacts Iii and coil III, wire lit, to wire H2.

The driving motor starting switch MS operates to engage contacts-III, I22, and I23 and to separate contacts I24. The separation of contacts I24 disconnects by-pass resistance I25 from across driving motorannature 21. The engagement-ot contacts I2I and I23 connects the driving motor armature and field winding to the supply lines. Thecircuit for the armature is from wire 81, by wire I26, through contacts I2I, wire I21, through armature 21, series field 28 and resistance steps 46, 45, and M, by wire I28 through contacts I23, to wire I I2. The driving motor separately excited field winding 30 is connected in parallel with the driving motor armature and series field winding and the starting'resistance. The completion of these circuits causes the starting of the driving motor and the driving motor accelerating switch MA, coil I30 of which is connected across the motor armature by engagement of contacts I22 of switch MS, operates to engagecontacts I3I to short-circuit resistance steps 44, 45, 46 in sequence and finally to shortcircuit series field winding 28. This brings the motor-generator set to full speed.

Brake switch B, upon operation, also engages contacts I33, I 30 and I and separates contacts I36. The separation of contacts I36 disconnects discharge resistance 51 from across the brake release coil 55. The engagement of contacts I34 establishes the circuit for brake release coil 55, this circuit being from wire 81 by wire I40 through contacts I34 by wire I M through brake release coil 55, potential switch contacts 69, brake switch contacts M2, wire III, to wire II2. Coil 55, upon being energized, acts to release the brake. Contacts I42 separate upon the release of the brake to insert cooling resistance I39 in series with the brake release coil.

Up direction switch U, operating at the same time as brake switch B, engages contacts I48 and I45 and separates contacts M6 and I41. Contacts I81 are interlock contacts and control the connection from supply line 25 to the feed contact I68 of the car switch for downward car travel. Contacts I85, upon engagement, prepare a holding circuit for coil 85 of the up direction switch. The engagement of contacts i445 and separation of contacts I46 connects the=armature Ii of the elevator hoisting motor to the supply lines in such way as to cause current to be supplied thereto in a direction to eiiect upward movement of the elevator car. The circuit for the elevator hoisting motor armature is from potential switch contacts 61, by wire 81 through resistance steps I3, I4, I5, I6, and 81, hold down coil I50 and contacts I SI of down direction switch D, wire I52, contacts I58 of series field switch SF, generator armature 3i, hoisting motor armature Il, up direction switch contacts I44, to wire H2.

The completion of the circuit for the elevator hoisting motor armature and the release ofthe brake causes the elevator motor to start the car in the up direction. The engagement of contacts I35 of brake switch B short-circuits resistance 23 in circuit with the elevator motor separately excited field winding I2, bringing the elevator motor field to full strength for the starting operation.

The levelling relay LR operates as a result of the completion of the circuit for its coil I02 to engage its contacts I55, This completes a circuit for the levelling switch motor 54, the circuit being from wire 88 by wire I56 through the armature 52 and field winding 53 of the levelling switch motor and contacts I55 of relay LR, wire I51, wire H8, to wire 2. The levelling motor acts to move the levelling switch operating rollers so as to clear the cams during the movement of the car. This operation will be explained later.

The engagement of contacts I33 of brake switch 3 completes the circuit for coil I of speed switch C and for coil I8I of up set-up switch US. This circuit is from wire 88, by wire I62, through contacts I33 of switch B, by wire I63 through coil I60 of switch C, and coil I6I of switch US, to car switch contact 19, this contact being connected by segment 15 to car switch feed contact 18. Upset-up switch US, upon operation, separates contacts I65 and I66 in preparation for the levelling operation. It also engages contacts I61 to complete a circuit for voltage coil I68 of load switch L8. This circuit is from wire 88, wire I10, by-wire I1I through contacts I61 of switch US, through coil I68 of switch LS, wire II8, to wire H2. The purpose of the load switch is served during the levelling operation, and willbe explained later. Y

Speed switch C, upon operation, engages contacts I13, I14, and I15 and separates contacts I16. The separation of contacts I16 removes the short-circuit for step 20 of the elevator hoisting motor by-pass resistance and the engagement of contacts I15 short-circuits step I3 of the elevator motor starting resistance. This increases the voltage applied to the elevator motor armature.

The engagement of contacts I14 completes a circuit for coil I19 of the direction holding switch DH, this circuit being from wire 88 by wire I11 through contacts I18 and I88 of the levelling direction switches, inductance coil X I8I, and coil I19 of direction holding switch DH, contacts I14 of switch C, wire H8, to wire H2. The direction holding switch upon operation, separates contacts 94 and I84. The engagement of contacts I83 establishes a holding circuit for coil of: up direction switch U through contacts I45 of this switch, while the separation of contacts 94 breaks the initial energizing circuit for coil 85. l82 and I84 serve a similar purpose with respect to the coil of down direction switch D for down car travel.

The engagement of circuit for coil I85 of cult is from wire 88, by wire 562 through contacts I33 of switch B, contacts I13 of switch C and coil I85 of switch E to car switch contact 80, this contact being connected by segment 15 to car switch feed contact tion, engages contacts E86, I81, and E88 and separates contacts 90 and I90. The separation of contacts 90 removes the short-circuit for coil I9I of levelling relay LR. Coil I 9! serves as a holding coil for the levelling relay, and its purpose will be explained later. The engagement of contacts I81 completes a circuit for the holding coil I92 of speed switch C, this circuit being from wire 88, wire I93, by wire I 94 through coil I92 and contacts I81, wire I95, wire I96, wire H8, to wire H2. The purpose of the holding coil for switch C also will be explained later. The separation of contacts I 90 removes the shortcircuit for step 2i of the elevator hoisting motor by-pass resistance and the engagement of contacts I88 short-circuits step It of the elevator motor starting resistance. This further increases the voltage applied to the elevator motor armature.

The engagement of contacts I86 completes a circuit for coil I91 of speed switch G. This circuit is from wire 88 by wire I62 through contacts I 33, by wire I98 through contacts I86 and coil I91, to car switch contact 8|, this contact being connected by segment 15 to car switch feed concontacts I18 completes a I82 and engages contacts I83 and Contacts 1 speed switch E. This cir-,

18. Switch E, upon operatact 10. Switch G, upon operation, engages contacts 200, 20I and 202 and separates contacts 203. The engagement of contacts 20l completes the circuit for the holding coil 204 of speed switch E, this circuit being from wire 00, wire I03, wire I94, by wire 205 through coil 204 and contacts 20I, wire I95, wire I96, wire IIO, to wire H2. The purpose of the holding coil for switch E will be explained later. The separation of contacts 203 disconnects the elevator hoisting motor by-pass resistance from across the motor armature. The engagement of contacts 202 prepares a circuit for short-circuiting step I5 the elevator hoisting motor starting resistance by contacts 206 of accelerating switch H. In the event that, due to load conditions, the elevator hoisting motor does not start upon the release of the brake and the completion of the circuit for the hoisting motor armature by the direction switch, the operation of the speed switches to gradually increase the voltage applied to the motor armature causes the starting of the car.

The engagement of contacts 200 completes the circuit for coil 201 of accelerating switch H. This circuit is from wire 00, by wire I93 through contacts 200, by wire I06 through coil 201, wire II8, to wire II2. Switch H, upon operation, engages contacts 206 and 200. The engagement of contacts 206 short-circuits step I oi the elevator motor starting resistance, further increasing the voltage applied to the motor armature.

The engagement of contacts 206 completes a circuit for coil 2I0 of accelerating switch J. This circuit is from wire 80, by wire I93 through contacts 200, by wire 2 through contacts 206 and coil 2I0, wire I06, wire II8, to wire H2. Switch J, upon operation, engages contacts 2I2 and 2I3. The engagement of contacts 2I2 short-circuits step I6 of the elevator motor starting resistance, further increasing the voltage applied to the motor armature. 1

The engagement of contacts 2I0 completes a circuit for coil 2 of accelerating switch K. This circuit is irom wire 88, by wire I93 through contacts 200, contacts 2I3 and coil 2|! wire I96, wire IIB, to wire II2. Switch K, upon operation, engages contacts 2I5, 2I6 and 2". The engagement of contacts 2 I 6 establishes a circuit through current coil 2I9 of load switch LS, contacts 202 and contacts 2I2, shunting step I1 of the elevator motor starting resistance. Coil 2l8 being of very low resistance, the engagement of contacts 2I6 causes the full line voltage to be applied to the motor armature.

The engagement of contacts 2I1completes a circuit for coil 2l8 of field switch F. This circuit is from wire 80, by wire I62 through contacts I33 of switch B by wire 220 through coil 2l8 and contacts 2I1 to car switch contact 82, this contact being connected by segment to car switch feed contact 10. Switch F, upon operation, separates contacts 22I, removing the" short-circuit for resistance '23 for the elevator separately excited field winding, increasing the field strength and bringing the elevator hoisting motor up to full speed.

The engagement of contacts 2I5 oi switch K completes a circuit for coil 222 of series field relay FR. This circuit is from wire 01, by wire I26 through contacts I2I,contacts2|l,induetarme coil X223 and coil 222, by wire I through contacts I23, to wire II2. Relay FR, upon operation, engages contacts 224 which canpletes the circuit for coil 226 of series field switch SF. This circuit is from wire 81, by wire I26 through con- "motor armature.

tacts I2I, by wire 226 through contacts I22, by wire 221 through contacts 220 and coil 22!, wire I20, to wire I I2. The series field switch operates to separate its contacts I52, removing the shortcircuit for series field winding 22 of the generator. This renders the generator efiective as a series generator in series with the elevator hoisting motor.

This arrangement provides an eiiective load compensation whereby substantially constant speed is obtained for full speed operation. The generator acts to provide a voltage of proper polarity and of a value which counteracts any tendency or the elevator motor to vary its speed due to load conditions. For example, assume that the elevator motor is lifting a heavy load. This causes positive current of high value to flow in the hoisting motor armature circuit. This current, passing through the series field winding, causes a high excitation of the generator.,

The generator thus generates a voltage which is added to the voltage applied from the source 2|, 25 to the motor. Thus, any tendency of the elevator motor to decrease in speed due to increase in load is efiectively counteracted by the generator's applying an additional voltage to the elevator motor to maintain the speed thereof sub stantially constant. Similarly, should the elevator motor be lowering a heavy load so that the tendency is to overspeecl, the generator series field is excited in the opposite direction by the current oi. negative value which flows in the hoisting motor armature circuit thereby causing the generator to apply a voltage which opposes the line voltage and thereby counteracts the tendency of the hoisting motor to increase in speed.

The amount of compensation provided by the generator is controlled by means of an adjustable resistance 34 connected across the series field winding. The operation of the series field switch to render the generator efiective for full speed operation is delayed by means of the inductance coil X223 in series with coil 222 of the series field relay, this inductance delaying the operation of the relay after the applicati n of source voltage to the motor armature and the weakening oi. the motor field, substantially until the motor comes up to full speed. The generator, with this arrangement. is rendered ineil'ective during the accelerating period, thereby oviating any undesirable effect due to heavy accelerating currents. This permits a small generator to be used.

To stop the car, the car switch is centered as the car arrives at a predetermined distance from the landing at which it is desired that a stop be made. The centering of the car switch moves segment 15 oil contacts 82, II, 80, 18, 10, and 11. Thisbreaics the circuit for coils 2l8, I91, I85, IBI, I60, and I02 of switches F, G, E, US, C, and LR respectively.

The deenergization oi coil 2I0 of field switch 1' results in the reengagement of contacts 22I to short-circuit resistance 23 for the elevator motor field winding I2. This causes the car to slow down. The deenergization of coil I91 0! speed switch G results in the separation of contacts 202 to reinsert resistance steps I6, I6, and I1 in circuit with the elevator motor armature and in the reengagement oi contacts 203 to connect steps I8, 20, and 2I of the by-pass resistance across the This causes further slow down of the elevator car.

Switch G also separates contacts 200 to deenerglze coils 201, 2I0 and 2I4 of accelerating switches H, J, and K respectively. The accelerating switches thereupon drop out to separate contacts 206, 2I2, and 2H5, the steps of resistances I5, I6, and I1 respectively controlled by these contacts having already been reinserted in the armature circuit by the separation of contacts 202 of speed switch G. Accelerating .switch K also separates contacts 2I1 in the circuit for coil 2I8 of field switch F, this circuit having already been broken by. the centering of the car switch, and separates contacts 2I5 to break the circuit for coil 222 of series field relay FR. The series field relay drops out to separate contacts 224,.breaking the circuit for coil 225 of series field switch SF. This switch reengages its contacts I53 to shortcircuit the series field winding 32 of the generator during the slow down period.

Speed switch E does not drop out immediately the circuit for its coil I85 is broken by the disengagement of car switch segment 15 from contact 80, this switch being maintained operated by its holding coil 204. The circuit for this holding coil is broken by the separation of contacts 20I of switch G. The breaking of this circuit, however, is delayed until after switch G has otherwise performed its functions upon dropping out, this delayed action being indicated by the elongation of the stationary contacting elements of contacts 2IlI. Upon the deenergization of holding coil 204, switch E drops out toseparate its contacts I 86 in the circuit for coil I91 of switch G,

this circuit having already been broken by the centering of the car switch. It also separates contacts I88 to reinsert step I4 of the starting resistance in circuit with the motor armature and reengages contacts I90 to short-circuit step 2I of the by-pass resistance. This causes further slow down of the car.

Switch E also reengages contacts 90 to shortcircuit coil ISI of levelling relay LR. Coil I02 of the levelling relay having been deenergized by the centering of the car switch, the relay is maintained operated up to this time by coil I9I. The deenergization of coil I91 causes the levelling relay to drop out, separating its contacts I55 and thereby breaking the circuit for levelling switch motor 54. In this manner, the operating rollers of the levelling switch are extended for engagement by the levelling cams. Referring to Figure 2, the levelling switch motor is operatively connected to the levelling switch by means of. an arm 230 on the motor shaft, a connecting link 23I and a lever 232. In the starting operation, the motor 54 being energized, arm 230 rotates, acting through link 23I and lever 232 to move the levelling switch as a whole about a pivot. In this manner the levelling switch operating rollers 233 and 234 are moved into position where they do not engage the levelling cams 235 and 236 during motion of the car, a stop being provided to determine the extent of the movement. It is to be understood that levelling cams are provided for each floor. The levelling switch is pivoted on a bracket 231 secured to. the car frame. In the stopping operation, upon the deenergization of the levelling switch motor, a spring (not shown) moves the lever 232 and therefore the levelling switch back into the first described position with the rollers 233 and 234 extended for engagement by'the levelling cams. Each pair of levelling contacts 41, 48, 50, and 5| comprises a stationary contact and a movable contact operated by the engagement of its corresponding roller and levelling cam. The fast speed contacts 50 and 5I are arranged to separate before their corresponding slow speed contacts 4! and 48 in the levelling peration. Springs (not shown) are provided for causing the separation of the contacts of the pairs as the levelling operation is effected and stops are provided for determining the extent of movement of the rollers as they ride oil the levelling cams.

It will be assumed that the car has not reached the landing and that the up levelling switch operating roller 233 has notmoved onto the vertical surface of up levelling cam 235 at the time levelling switch motor 54 is deenergized. Switch E, by the delayed opening of its contacts I81, postpones thedropping out of switch C until after switch E has performed its functions in dropping out. The separation of contacts I81 breaks the circuit for holding coil I 92 of switch C, which drops out to separate its contacts I13, I14, and I and to reengage its contacts I18. Contacts I13 are in the circuit for coil I85 of switch E previously broken by the centering of the car switch. The separation of contacts I15 removes the short-circuit for the remainder of the starting resistance for the motor, while the reengagement of contacts I16 short-circuits step 20 of the by-pass resistance. This causes further slow down of the elevator car.

The separation of contacts I14 is delayed, as 3 indicated by the elongation of the stationary contacting elements thereof. Upon separation of these contacts, the circuit for coil I19 of direction holding switch DH is broken. Means are provided to delay the dropping out of the holding switch so as to obtain the desired retardation. Inching relay IR has its coil 240 connected across the motor armature and its contacts 2 connected in a circuit by-passing coil I19 of switch DH. These contacts are'in engagement so that this by-pass circuit is complete at this time. Switch DH is maintained operated by the action of inductance coil XI8I in series with coil "9 and the resistance connected in this closed circuit. The values of resistance and inductance in this circuit are preferably such that the direction holding switch is maintained operated until the levelling mechanism assumes control.

It will be assumed that the up levelling switch operating roller 233 moves onto the vertical surface of up levelling cam 235 before direction holding switch DH drops out. The engagement of levelling switch up slow speed contacts 41 completes a circuit for coil 242 of the levelling up direction switch LU, coil 243 of auxiliary levelling switch AL and coil 244 of brake switch B. This circuit is from wire, 88, by wire 245 through coil 244 and coil 243, by wire 246 through coil 242 and interlock contacts 241 of levelling down direction switch LD and levelling-switch contacts 41, wire 248, wire I51, wire II8, to wire II2. Contacts 250 of protective relay PR in shunt to coil 244 are separated at this time, permitting the energization of this coil by the levelling switch.

'Coil 25I of the protective relay is connected wire III, through contacts II, wire III, contacts 41, wire III, wire I", wire III, to wire III.

'Ihe auxiliary levelling switch AL, upon operation, engages contacts III. The purpose oi this switch will be explained later.

The levelling fast speed switch'LF, upon operation, engages contacts III to short-circuit the portion 0! resistance II employed to cause the levelling operation to take place at slow speed.

The levelling up direction switch LU, upon operation, separates contacts "I and I11 and engages contacts III, III and III. Contacts III are electrical interlocks in the circuit ior coil 2" oi levelling down direction switch ID. The separatbli oi contacts III iorces the dropping out engagement oi contacts III and III oi the levelling up direction switch. The circuit ior field winding II is irom wire I1,'wire III, by wire III through contacts III oi the levelling up direction switch and contacts III oi down set-up switch DB, by wire III, through iield winding II by wire I", through resistance II (contacts III being maintained separated by holding coil III oi up set-up switch US aiter the deenergization oi coil' III by the centering oi the car switch), contacts III oi the levelling up direction switch, by wire III through contacts III oi levelling iast speed switch, wire III, to wire III. .Thus, upon the operation oi the levelling mechanism to bring the car to the floor landing, the hoisting motor armature is disconnected irom the main source oi supply and is supplied with current by the generator oi the motor-generator set, the armature oi the generator and the armature oi the hoisting motor being connected in a closed circuit due to the reengagement oi contacts III oi the up direction switch, which by-passes steps II, III, and II oi the by-pass resistance through the hold down coils oi the direction switches and contacts III oi the down direction switch.

With the generator separately excited iield winding II connected to the. source and with contacts III oi the levelling iast speed switch in engagement, a voltage is generated by the generator which causes the elevator motor to run at a suitable iast levelling speed in the up direction, the brake being maintained released owing to the iact that brake switch B is maintained operated by its coil III.

OontactsIII oi levelling up direction switch .LU are arranged in parallel with contacts III 0! accelerating switch K. The engagement oi contacts III completes the circuit ior coil III oi series ileld relay FR. This relay engages contacts III to complete the circuit ior coil III oi series field switch SF. which separates its contacts III to render the generator seriesfleld winding eflective ior the levelling operation. The operation oi the series iield relay FR is delayed by inductance coil III in order that the current in the generator armature-elevator motor armature circuit may adjust itseli to such value that the proper series field strength ior the revelling operation is obtained.

As the car nears the landing, roller III rides oi! the vertical suriace onto the oblique surface oi cam III. This results in the separation oi up fast speed'levelling contacts II, deenergizing actuating coil III oi the levelling fast speed relay LF. Relay LF', upon dropping out, separates its contacts III to remove the short-circuit for resistance 3!. This decreases the voltage applied to separately excited ileld winding II oi the generator, decreasing the generator voltage to a value to cause the elevator motor to run at slow levellin speed. Shortly beiore the car reaches an exact level with the landing, roller I33 rides oii the oblique suriace oi cam I35, thereby separating slow speed levelling contacts 41. This breaks the circuit for coil III oi auxiliary levelling switch AL, coil III oi levelling up direction switch LU and coil I of brake switch B. Thelevelling up direction switch operates its contacts III and III to disconnect the generator separately excited field winding II irom the source oi supply, while brake switch B separates its contacts III to deenergize brake release coil II, applying the brake and bringing the car to a stop. At the same time switch B reengages its contacts III to connect discharge resistance II in parallel with discharge resistance II ior the brake release coil ior obtaining the desired application oi the brake shoes. Switch B also separ ates contacts III to reinsert resistance II in the circuit with elevator motor field winding II, reducing the voltage applied to this winding while the car is at rest.

The levelling up direction switch also separates its contacts III to deenergize coil III of series iield relay FR, which in turn separates its contacts III to deenergize coil III oi series field switch SF. The series iield switch reengages its contacts III to short-circuit generator series field winding II.

Switch 13, upon dropping out, also separates contacts III to disconnect coil III of the driving motor starting relay. and holding coil III oi setup switch US irom the source oi supply. These switches do not drop out immediately, however, relay SR being delayed by the eii'ect oi inductance coil XIII and dischargeresistance III and switch US being delayed by the effect of inductance coil XIII and discharge resistance III. The purpose oi the delay in the dropping out oi these switches will be seen irom later description. Switch US, upon dropping out, separates contacts III and engages contacts III and III. The separation oi contacts I" deenergizes coil III oi loadswitch LS. The reengagement of contacts III and III shortcircuits levelling control resistances II and II, respectively. Relay SR, upon dropping out, separates contacts III to deenergize coil III oi the driving motor starting switch MB. This switch drops out to separate its contacts III and III, disconnecting the driving motor oi the motorgenerator set from the source oi supply. At the same time, switch MS reengages contacts III to disconnect by-pass resistance III across the armature II of the driving motor, bringing the motorgenerator set to a stop. Switch MS also separates contacts III, disconnecting coil III oi the driving motor accelerating switch MA across the driving motor armature II. This switch drops out, separating its contacts III and III in preparation ior the next operation.

In the event oi overrun, assuming in the above example that the car overruns the floor to the extent of causing the engagement oi down slow speed levelling contacts 48, a circuit is completed for coil 21 5 of the levelling down direction switch. This circuit may be traced from wire 88, by wire 245 through coil 244 of switch B and coil 243 of switch AL, by wire 216, through interlock contacts 21? of levelling up direction switch LU, coil 215, contacts 48, wire 248, wire I51, wire H8, to wire I i2.

The brake switch B engages its contacts I04, reestablishing the circuit for the coils I05 and I06 of driving motor starting relay SR and up set-up switch US, respectively. As previously explained, these switches are maintained operated after contacts N34 disconnect their coils from their source of supply by the action of their respective inductance coils and discharge resistance. This portion of the system is adjusted so as to maintain these switches in operated conditionduring an overrun until the circuit for their coils is again established as a result of the engagement of the slow speed levelling switch contacts for returning the car to the floor, these contacts being levelling down direction switch contacts 48 in the example:

assumed. Thus, upon an overrun, relay SR is maintained operated, maintaining the driving motor'for the motor-generator set in operation. Also, up set-up switch US is maintained operated with its contacts I and IE5 separated.

The levelling down direction switch LD, upon operation, engages its contacts 280 and 28I, completing a circuit for the generator sepaFately excited field winding 33. This circuit may be traced from wire 81, wire 253, by wire 282, through contacts 280, by 1 wire 283 through resistance 36 ,(cqntacts I65 being maintained separated by the up set-up switch as above explained), by wire 289,

through field winding 33, contacts 284 of down set-up switch DS and contacts 28I by wire 288 through resistance 35, wire I28, to wire H2. Due to the reversal of the flow of current through field winding 33 from that during levelling with the car approaching the floor in the up direction, the car is caused to start in the down direction, the brake being lifted as a result of the engagement of contacts I34 of brake switch B. Since levelling fast speed switch LP is not operated, resistance 35 is included in the circuit, causing the voltage generated by the generator to be such as to cause the hoisting motor to operate the car at slow levelling speed. l

The levelling down direction switch LD also engages contacts 285 to complete a circuit for the coil 222 of the series field relay FR, contacts 285 being arranged in parallel with contacts 262 of levelling up direction switch LU. The series field relay causes the operation of the series field switch SF as before to remove the short-circuit for the generator series field winding 32. This operation is delayed by the action of inductance coil X223, to insure that the current in the generator armature-motor armature circuit has fallen to a low value before the series field winding is rendered effective.

As the car returns to the floor, it is stopped by the separation of levelling switch slow speed contacts 48 in a manner similar to that for approaching a floor in the up direction. If the overrun is great enough to cause the engagement of levelling switch down fast speed contacts 5I as well as contacts 48, coil 252 of the levelling fast speed switch LF is energized. As before, switch LF engages contacts 258, causing the voltage generated to be of a value to cause the elevator motor to run at its fast levelling speed. Shortly after the car is returned to the floor, the driving motor starting relay SR drops out, causing the discontinuance of the operation of the motor generator set.

The starting of the car in the down direction is accomplished in a manner similar to that for starting the car in the up direction, and will be described only briefly. ,The operator moves the car switch into position where segment 15 bridges contacts 286, 281, I48, 289, 290, HI, and 292. The bridging of contacts I48 and 281 completes a circuit for coil 86 of brake switch B and coil 293 of down direction switch D. This circuit maybe traced from wire 81, by wire 89, through coil 86 of brake switch B and contacts 98. of switch E,

wire 9|, by wire 294 through coil 293 of switch D,

contacts I82 of switch DH, contacts 281 and I 48 of the car switch, by wire 295 through interlock contacts I41 of switch U, to supply line 25 as traced for coil 85 of switch U. The circuit for coil I02 of levelling relay LR. is by way of contacts 286 of the car switch. The circuit for coil'I 60 of speed switch C is by wire 296 through coil 291 of down set-up switch DS. The circuit for coil I85 of speed switch E is by way of car switch contact 290 and wire 219. The circuit for coil I91 of speed switch G is by way of car switch contact 29I and wire 298. The circuit for coil 2I8 of field switch F is by way of car switch contact 292 and wire 300. The down direction switch D, upon operation, engages contacts 30I and 302 and separates contacts I5I and 96. The engagement of contacts 302 prepares the holding circuit for coil 293 of switch D, which is later completed by the engagement of contacts I84 of switch DH. The engagement of contacts 30I and the separation of contacts I5I completes the circuit for the armature of the elevator hoisting motor for operating the car in the down direction. The down set-up switch DS separates contacts 265 and 284. Further than this, the operation of starting the car in the down direction is the same as for starting the car in the up direction. The slowing down and stopping of the car during its downward travel is similar to that described for the slow down and stopping of the car during its upward travel. Such operation will not be described as it is believed that it will be understood from previous description.

Load conditions have not been considered in the description of operation up to this point. Means are provided which are effective during levelling to compensate for the load on the hoisting motor. This compensation is effected by means of load switch LS acting on resistance in circuit with generator field winding 33. The load switch is provided with a current coil 2I9 and a voltage coil I68. The voltage coil is ineffective to cause operation of the load switch but acts to maintain the switch, once operated, in operated condition. The current coil is rendered effective during acceleration upon the operation of the last accelerating switch K. With this arrangement, the load switch operates when the current which flows in the current coil at the time that coil is rendered effective is at or above a predetermined value.

It will be assumed that the switch is adjusted to operate at balanced load, it being understood that the exact point at which the switch operates is determined by the characteristics of the particular installation. Upon operation of the switch, it separates contacts 305 and 305 and engages contacts 301 and 308, these contacts controlling resistances 38, 31, 38, and 41. The set-up switches switch contacts 305 and 306 are separated while load switch contacts 301 and 300 are engaged. Also, contacts I65 and I06 of the up set-up switch US are separated due to the fact that the car is travelling in the up direction. Under such conditions, the generator field winding circuit for the up levelling operation does not include resistance 31 and includes only a portion of resistance 40 as resistance 31 is short-circuited by contacts 266 of the down set-up switch DS and all but a portion of resistance 40 is short-circuited by load switch contacts 000. This gives the desired higher value oi generated E. M. F. for lifting the car and its load up to the floor.

11, under the conditions above assumed, the car overruns the floor, resistance 36 is included in the circuit with field winding 33 for the return operation because load switch contacts 305 and up set-up switch contacts I66 are separated, thereby" giving a lower value of generated E. M. F. to compensate for the load on the elevator motor now being an overhauling one, i. e., the car and its load overbalancing the counterweight.

If the car had been running in an up direction lightly loaded so that the load switch is not operated, the load is an overhauling one (the car being overbalanced by the counterweight) so that, with load switch contacts 308 separated, resistance 40 is included in the generator field winding circuit to provide a lower value of generated E. M. F. In case of an overrun under such conditions, it becomes necessary to lift a load (the counterweight) to return the car to the floor so that, load switch contacts 305 being in engagement, only a small portion of resistance 36 is included in the generator field winding circuit, thereby giving a higher value of generated E. M. F. to compensate for the load.

The action is similar for downward car travel. Assume that the car is travelling downwardly lightly loaded, which means that the elevator motor is lifting a load. Contacts 266 and 284 of down set-up switch D5 are separated because the car is travelling downwardly, while contacts 305 and 306 of the load switch are separated and contacts 301 and 308 of the load switch are engaged, owing to the fact that the motor is lifting a load. Thus, during underrun conditions, only a'small portion of resistance 38 is included in the generator field winding circuit to give a higher value of generated E. M. F. and during underrun conditions all of resistance 31 is included in the field winding circuit to give a lower value of generated E. M. F. becausethe load for returning the car to the floor is an overhauling one. In case the car is heavily loaded during its downward travel, the elevator motor is lowering a load, so that the load switch is not operated. Therefore all of resistance 3B is included in the field winding circuit during underrun conditions while only a portion of resistance 31 is included in this circuit during overrun conditions.

Should the car, while standing at a floor, be moved downwardly from the floor into the level ling zone, as by the taking on of a heavy load, the protective relay PR, acts to prevent the liftmg of the braketo move the car until the motorgenerator sethas been started and has come up to a predetermined speed. The coil 261 of the protective relay is connected across the driv n8 motor armature 2l so as to be subject to the counter E. M. F. of the driving motor and therefore the speed of the motor-generator set. Contacts 250 of the protective relay are connected in shunt to coil 244 of the brake switch B. Thus, coil 244 cannot be energized by the levelling mechanism to operate the brake switch and thus to effect the release of the brake until the driving motor has come up to a certain speed. Additional contacts 254 on driving motor accelerating switch MA serve a similar purpose. These contacts prevent the operation of the levelling fast speed switch LE to place a load on the generator by short-circuiting resistance 36 under such conditions, in the event the car sags into the fast speed levelling zone, until the motor-generator set comes up to a predetermined speed, the coil I30 of this switch being subject to the armature 21 of the driving motor of the set. The auxiliary levelling switch AL acts under such conditions to effect the starting of the motor-generator set.

The coil 243 of this switch is connected in a circuit common to the coils of the levelling direction switches so as to operate the switch when either one of the levelling direction switches operates. Contacts 259 of the auxiliary levelling switch are connected in parallel with contacts I04 of the brake switch to cause the operation of the driving motor starting relay SR and thus the starting of the motor-generator set when the operation of thebrake switch is prevented due to coil 244 being short-circuited by contacts 250. Thus, should the car, while standing at a floor, sag into the levelling zone, the" motor-armature set is started by the action of switch AL but the operation of bringing the car back to the floor and the placing of any considerable load on the generator are delayed until the motor-generator set attains a predetermined speed.

Should any of the safety devices operate or should the safety switch 60 in the car be operated. the potential switch A is deenergized. This switch, in dropping out, breaks the control circuits, causing the car to be brought to a quick stop. Involved in this emergency stopping operation is the separation of contacts 69 of switch A to prevent the connecting of resistance 51 across the brake coil, giving a hard braking action, and the engagement of contacts 12 of switch A to connect a small portion of by-pass resistance across the hoisting motor armature, resistance steps I8, 20, and 2! being excluded from the by-pass circuit.

The inching relay IR, having its operating coil 240 connected across the elevator motor armature H and its contacts MI in the by-pass circuit for coil I19 of the direction holding switch DH, acts to prevent the direction holding switch being held in by the efiect of inductance coil XIBI unless the elevator motor is up to a certain speed. This permits the attendant in the car to inch the car without having to wait on any time elements in the event that he throws his car switch too far over in performing the inching operation.

Many of the control operations previously described are in the nature of refinements, and may be varied or omitted entirely. Also, the manner of effecting other control operations may be modified. The motor-generator set has been described as starting up with the starting of the release coil is' completed by the engagement of illustrating the principles of operation of appli-' cants invention as exemplified by Figure 1. The manner of starting and stopping the car is not shown as this may be accomplished in several ways. The contacts of direction switches, however, are shown, these being designated M4, I46, ll, and 30! to correspond with the designations of such contacts in Figure 1. These contacts are "operated in accordance with the direction of car travel desired, as, for example, by the manipulation of a car switch or the pressing of a push button, to complete a circuit for the armature H of the elevator hoisting motor. The armature 3| of the generator of the motor-generatorset is included in this circuit and may be driven only While the elevator motor is in operation or all i the time the elevator is in service or for other periods, as, for example, by maintaining the set in operation for a predetermined time interval,

after the car is stopped. The switch B for controlling the electromagnetic brake ER is illustrated as having a coil controlled by the levelling mechanism. The other coil of the-switch may be energized in any suitable manner in starting, depending upon the installation. No control is illustrated for field winding ii of the hoisting motor, as this may be arranged to suit the requirements of the particular installation. If desired, a full field may be maintained on the hoisting motor so long as'the elevator car is in service.

In starting the car, the circuit for the brake contacts 534! of brake switch B, releasing the brake. The circuit for the hoisting motor armature H is completed by the operation of the directionswitch'the circuit including generator armaturetl and starting resistance SR in series with the motor armature with by-pass'resistance BF connected across these armatures. The by pass resistance is increased during acceleration and finally disconnected and the starting re-- sistance is short-circuited in steps and finally the .armatures of the hoisting motor and generator are connected directly to the source, bringing the hoisting motor up to full speed.

When the car is to stop at a landing, starting resistance SR is reinserted in circuit with the elevator motor armature l l and generator armature 3i and by-pass resistance BP is reconnected across these armatures and short-circuited. When the levelling mechanism takes control, the elevator motor armature H is disconnected from the source of supply and connected in a local circuit with armature 3! of the generator through contacts M5 and i5l of the direction switches. As this takes place, the levelling mechanism completes the circuit forthe generator field winding 33 to render the generator effective to apply voltage to the elevator motor to bring the car to the landing level. The generator series field winding 32 is rendered effective for the levelling operation by the operation of switch SF so as to compensate for load. 'When the car comes to an exact landing level, generator field winding 33 is disconnected from the source and the brake is applied to bring the car to a stop.

The series field winding 32 of the generator may be controlled so as to be rendered effective during full speed operation of the elevator motor as well as during levelling. With the series field rendered effective for full speed operation, the generator acts to compensate for load so as to pro- I vide substantially the same speed of the elevator I car, regardless of load. By using a generator of the proper size and characteristics, the series field winding may be left in during the acceleration and retardation periods. In such case, the generator wouldact as an accentuator in that during acceleration it would act to increase the voltage applied to the elevator motor armature as the speed in acceleration steps takes place, due to the increased current flow each time the voltage applied to the elevator motor armature is increased.

Any suitable arrangement for controlling the circuit for the separately excited field winding 33 of the generator for levelling may be employed. This includes not only the circuits but also the levelling mechanism itself. Other forms of levelling mechanism than that diagrammatically illustrated in this figure may be employed, a diagrammatic illustration of one form of levelling control mechanism being made in'this figure for convenience.

The levelling mechanism is illustrated as acting through levelling direction switches LU and L!) for controlling, the circuits for generator field winding 33 and as acting through brake switch B to control the action of the elevator hoisting motor brake. vIn the arrangement shown, the levelling mechanism acts through levelling fast are simplified for illustrating the principles of operation. The manner of starting and stopping the car is not shown. The contacts of the direc-= tion switches are designated l-ld, l lti, it'll, and till as before. The direction switches may be provided with a walking beam to serve as a mechani= cal interlock, in which event the back contacts of both direction switches cannot be closed at the same time. Such arrangement is assumed and only contacts l5! are shown closed, on the assumption that the car has been travelling in the up direction. The armature ill of the generator of the motor generator set is not arranged in the hoisting motor armature circuit. Instead it is lo cated in the circuit for the icy-pass resistance BP. The starting resistance is arranged in two parts. The starting resistance SSR controlled by the speed switches is arranged in the armatiu'e circuit inside the direction switch contacts, while the resistance ASR controlled by the accelerating switches is arranged in the armature circuit outside the direction switch contacts. This arrangement, as well as the arrangement of Figures 1 and '2, is found in many existing elevator instal lations.

The brake BR is released in starting the car by the completion of the circuit for the brake release slstance B? and generator armature ii are connectedaerossthearmature ll otthe hoisting motor and starting resistances SSH. and ASR' are connected in series therewith. The by-pass resistance is increased during acceleration of the hoisting motor. Disconnection oi the by-pass re sistance also disconnects generator armature II from across the hoistingmotor armature. The series resistances SSH. and ASR are decreased during acceleration and finally armature II or the hoisting motor is connected directly to the source of power. This brings the elevator car up to lull speed.

In slowing down and stopping the car at a landing, starting resistance ASR is reinserted in circuit with the elevator motor armature II and then starting resistance SSR is reinserted in the motor armature circuit. The by-pass resistance BP and the generator armature 3| are connected across the motor armature at the time starting resistance SSR is reinserted in circuit, and the value of the by-pass resistance is decreased as the short-circuit for the steps of starting resistance SSR is removed. When the levelling mechanism takes control, the elevator motor armature is disconnected from the source of supply and connected in the local circuit with armature ii of the generator through con-- tacts 6, closed in response to the operating of the levelling mechanism. The levelling mechanism also causes the closure of contacts 3H, which by-pass contacts 315 to maintain the brake release coil energized and the brake rcleased. As this takes place, the levelling mechanism completes the circuit lot the generator field winding 33 to render the generator effective to apply voltage to the elevator motor to bring the car to the landing level. The generator series field winding 32 is rendered effective to compensate for load during levelling by the operation of switch SF. when the car comes to on exact landing level, generator field winding 33 is disconnected from the source and the brake is applied to bring the car to a stop.

The contacts ll, 48, 50, and 5| of the levelling switching mechanism are illustrated as acting through electromagnetic switches LB, LU, LD, and LP to control the levelling of the car, con tacts iii and 3 being provided on switch LB.

The arrangement of the generator armature in the by-pass circuit has the advantage that the armature is not subjected to the peaks oi starting current and therefore a smaller generator may be employed. However, this arrangement lacks the advantage of the generator providing load compensation for full speed operation, as with the generator armature arranged in series with the motor armature as in the case of Figures 1 and 2. In case of change-over installations, the character of the installation may determine the point where the generator armature is placed in the circuits.

Circuits are also shownin Figure 3 for con trolling the starting and stopping of the driving motor for the motor-generator set. In the arrangement shown, the motor-generator set is arranged so that it may be maintained in operation all the time the car is in service, a manual switch SS being arranged in the control circuits for the driving motor to start and stop the driving motor at will.

The switch SS comprises a bridge member 320 which, when turned counterclockwise, bridges contacts "I to complete a circuit for coil 322 01' driving motor startinfl switch MS. This switch engages contacts 323 and 314. The engagement ot contacts 323 completes the circuit for the armature 21 and separately excited field winding 3. 01 the driving motor. The engagement of contacts at connects coil 325 0! driving motor accelerating switch MA across armature 21 ot the driving motor. Whenthe voltage of the driving motor rises to a predetermined point, switch MA operates to engage contacts 326 and 321. Contacts 321 short-circuit resistance in series with the driving motor armature, applying full line voltage to the driving motor to bring it to full speed. Contacts 325 establish a circuit for coil 322 of driving motor starting switch MS, by-passing contacts "I and bridge member 320. The starting switch may thereupon be released and is returned to the position shown as by a spring. In contact with contacts 330. To stop the driving motor, switch S5 is turned counterclockwise, moving bridge 328 into position where it disengages contacts 330. This breaks the circuit for coil 322 oi switch MS and switch MS drops out, disconnecting the driving motor from the source oi supply. The driving motor starting switch MS is illustrated as provided with an additional pair of contactsfli arranged to short-circuit the generator armature and series field winding when the motor-generator set is not in operation. This may be provided on installations where it may be desired to operate the elevator car at times without the levelling control.

The invention is particularly applicable for changing over existing resistance control installations, i; e., elevator installations in which the elevator motor is controlled by resistance in series with the motor armature and resistance connected in the by-pass circuit for the motor ammture. Such installations may be changed over to embody the invention in a very simple manner by the addition of the small motor-gen orator set and suitable mechanism ior controlling the operation of this set.

its many changes could be made in the above construction'and many apparently Widely dili'crcut embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What claimed is:

1. In a control system Ior an elevator car in which the car is started by connecting the hoisting motor for the car to a source of direct current with resistance in series with the motor armature and accelerated by cutting this resistance out of circuit, and in which the car is retarded by including resistance in series with said armature and connecting resistance in parallel with said armature, a direct current generator, means for driving the generator, means for causing said driving means to drive said generator at least while the car is in operation, means for connecting the field winding of said generator to said source, levelling mechanism, means for disconnecting said hoisting motor armature from said source and connecting it across the armature of said generator to cause said generator armature to supply current to the hoisting m0- tor armature for the operation of bringing the car to an exact landing level under-the control of said levelling mechanism, and 'meansresponthis position, bridge 328 remains in sive to the operation of said levelling mechanism goo ies source when the landing.

2. In a control system for an elevator car in which the car is started by connecting the hoisting motor for the car to a source of direct. cur rent with resistance in series with the motor ormature and accelerated by cutting this resistance out of circuit, and in which the car is retarded by including resistance in series with said arinature and connecting resistance in parallel with said car becomes level with the armature, a direct current generator, driving means for the generator, means for causing said which the car is startedcy connecting the hoist= ing motor for the car to a source or direct cur-- rent with resistance in series with the motor armature and accelerated Soy cutting this resistance out of circuit, and in which the is retarded by reincluding said resistance in series with said armature and connecting resistance in parallel with said armature, a direct current generator, driving means for the generator, means for causing operation of said driving means to drive said generator all the time the car is in service, icyelling niechanismand means responsive to the operation of said levelling mechanism :"or disconnecting said hoisting motor armature from said source, for connecting the armature oi said hoisting motor across the armature or said generator and for connecting the field winding of said generator to said source to cause said generator armature to supply current to the hoisting motor armature for the operation of bringing the car to an exact landing level under the control of said levelling mechanism.

4. In a control system for an elevator car in which the car is started by connecting the hoisting motor for the car to a source of direct current with resistance in series with the motor armature and accelerated by cutting this resistance out of circuit, and in which the car is retarded by including resistance in series with said armature and connecting resistance in parallel with said armature, a direct current generator, a driving motor'ior the generator, a manually operable switch, means responsive to the operation of said switch for connecting said driving motor to said source to drive said generator, levelling mechanism, means for completing a local circuit in? cluding the armature'of said generator and the armature of said hoisting motor in series rela tion, and means for disconnecting said hoisting motor armature from said source and for connecting the field winding of said generator to said source to cause said generator to supply current to the hoisting motor for the operation of hiringing the car to an exact landing level under the control of said levelling mechanism.

5. In a control system for an elevator car in which the car is started by connecting the hoisting motor for the car to a source of direct current with resistance in series with the motor armature and accelerated by short-circuiting this resistance in steps, and in which the car is retarded by reincluding said resistance in series with said armature and connecting additional resistance in parallel with said armature and decreasing the amount of said additional resistance in steps; a direct current generator, the armature of said generator being connected in series relation with the hoisting motor armature; a motor for driving said generator; and means for causing said hoisting motor to level the car with the landing at which. a stop is losing made, said means comprising levelling mechanism, means for connecting the armature of said generator and the armature of said hoisting motor in a local circuit, means for disconnecting said hoisting motor armature from said source and means responsive to the operation of said levelling mechanism for connecting the field winding of said generator to said source to cause said generator armature to supply current to the hoisting motor armature for the operation of bringing the car to an exact landing level under the control of said levelling rnecl'lanisni.

ii. In a control system for an elevator car in which the car is started by connecting the hoistlug motor for the car to a source of direct current with resistance in series with the motor armature and accelerated by short-circuiting this resistance in steps, and in which the car is retarded by reincluding said resistance in series with said armature and connecting additional resistance in parallel with said armature and decreasing the amount of said additional resistance in steps, a direct current compound wound generator, the armature of said generator being connected in series relation with the hoisting motor armature; a motor iordr'iving said generator; means for causing said hoisting motor to level the car with the landing at which a stop is being made, said means comprising levelling mechanism, means for connecting the armature of said generator and the armature-of said hoisting motor in series relation in a local circuit, means for disconnecting sald hoisting motor armature from said source, and means responsive to the operation of said levelling mechanism for connecting the field winding of said generator adapted for separate excitation to said source to cause said generator armature to supply current to the hoisting motor armature for the operation of bringing the car to anexact landing level under the control of said levelling mechanism; means for controlling the efiectiveness of the series field winding of said generator; and means for causing operation of said controlling means to render said series field winding effective during levelling.

7. In a control system for an elevator car in which the car is started loy connecting the hoisting motor for the car to a source of direct current with resistance in series with the motor armature and accelerated by short-circuiting thisresistance in steps, and in which the car is retarded by reincluding said resistance in series with said armature and connecting additional resistance in parallel with said armature and decreasing the amount of said additional resistance in steps; a direct current compound wound generator, the armature of said generator being connected in series relation with the hoisting motor armature; a motor for driving said generator; means for causing said hoisting motor to level the car with the landing at which a stop is being made, said means comprising levelling mocha-- nism, means for connecting the armature of said generator and the armature of said hoisting motor in series relation in a local circuit, means for disconnecting said hoisting motor armature from said source and means responsive to the operation of said levelling mechanism (or connecting the field winding of said generator adapted for separate excitation to said source to cause said generator armature to supply current to the hoisting motor armature for the operation of bringing the car to an exact landing level under the control of said levelling mechanism; and means for rendering the series field winding of said generator ineflective except during levelling and full speed operation of said hoisting motor.

8. In a control system for an elevator car in which the car is started by connecting the hoisting motor for the car to a source of direct ourrent with resistance in series with the motor armature and accelerated by short-circuiting this resistance in steps, and in which the car is retarded by reincluding said resistance in series with said armature and connecting additional re sistance in parallel with said armature and decreaslng the amount of said additional resistance in steps; a direct current compound wound generator, the armature of said generator being connected in series relation with said additional resistance so as to be connected across the hoisting motor armature along with said additional resistance; a motor for driving said generator; means for causing said hoisting motor to level the car with the landing at which a stop is being made, said means comprising levelling mechanism, means for excluding said additional re sistance from the parallel circuit for the hoisting motor armature thereby connecting'the armature of said generator and the armature of said hoisting motor directly in series in a local circuit; means for disconnecting said hoisting motor armature from said source and means responsive to the operation of said levelling mechanism for connecting the field winding of said generator adapted for separate excitation to said source to cause said generator armature to supply current to the hoisting motor armature for the operation of bringing the car to an exact landing level under the control of said levelling mechanism; and means for rendering the series field winding of said generator ineifective except during levelling.

9. In a control system for an elevator car; a

source of direct current; a direct current hoisting motor for the car; 'a direct current generator; driving means for the generator; means for causing operation of said driving means to drive said generator so long as the elevator car is in service; means for causing current to be supplied to said hoisting motor from said source for full speed operation of the car; means for causing said hoisting motor to level the car with a desired landing in stopping; and means for causing current to be supplied to said hoisting motor by said generator at a low voltage for the levelling operaiion.

10. In a control system for an elevator car; a source of direct current; a direct current hoisting motor for the car; a direct current generator having a separately excited field winding; driving means for the generator; means for causing operation of said driving means to drive said generator at least when the elevator car is running; means for connecting the armature of said hoisting motor to said source in series with re sistance to start the car; means for cutting out said resistance to bring the car up to full speed means for including resistance in series with said armature and foriconnecting additional resistance in parallel with said armature to slow down the car; and means for causing said hoisting motor to level the car with a desired landing in stopping, said levelling means comprising means for connecting said field winding of said generator to said source and means for disconnecting the hoisting motor armature from said source and connecting it across the armature oi said generator to cause said generator armature to supply current to the hoisting motor armature for the levelling operation.

11. In a control system for an elevator car;

- a source of direct current; a direct current hoisting motor for the car; a starting resistance for said motor; a by-pass resistance for said motor; a direct current generator; driving means for the generator; means for causing operation of said driving means to drive said generator so long as the elevator car is in service; means for connecting the armature of said hoisting motor to said source in series with said starting resistance to start the car; means for cutting out said starting resistance to bring the car up to full speed;

means for reincluding said starting resistance in series wih said armature and for connecting said by-pass resistance in parallel with said armature to slow down the car; and means for causing said hoisting motor to level the car with a desired landing in stopping, said levelling means comprising levelling switching mechanism, and means responsive to the operation of said levelling switching mechanism for connecting the field winding of said generator to said source, for disconnecting the hoisting motor armature from said source and for connecting the armature of said generator directly across the armature of said hoisting motor to cause said generator armature to supply current to the hoisting motor armature for the operation of bringing the car to an exact landing level under the control of said levelling switching mechanism.

12. In a control system for an elevator car; a source of direct current; a direct current hoisting motor for the car; a starting resistance for said motor; a by-pass resistance for said motor; a direct current generator, the armature of which is connected permanently in series relation with the armature of said hoisting motor; driving means for the generator; means for connecting the armature of said hoisting motor to said source in series with said starting resistance to start the car; means for cutting out said starting resistance to bring the car up to full speed; means for reincluding said starting resistance in series with said armatures and for connecting said bypass resistance in parallel with both arinatures to slow down the car; and means for causing said hoisting motor to level the car with a desired landing in stopping, said levelling means comprising, levelling switching mechanism, and means responsive to the operation of said levelling switching mechanism ior connecting the field winding of said generator to said source, for disconnecting the hoisting motor armature from said source and for connecting the armature of said generator directly across the armature of said hoisting motor to cause said generator armature to supply current to the hoisting motor armature for the operation of bringing the car to an exact landing level under the control of said levelling switching mechanism.

13. In a control system for an elevator car; a source, of direct current; a direct current hoisting motor for the car; a starting resistance for said motor; a by-pass resistance for said motor; a direct current generator, the armature of which is connected permanently in series relation with the armature of said hoisting motor; driving means for the generator; means for connecting the armature of said hoisting motor, with said bypass resistance in parallel with both armatures, to said source in series with said starting resistance to start the car; switching means for disconnecting said by-pass resistance from across said armatures and for cutting out said starting resistance to bring the car up to full speed. and for reincluding said starting resistance in series with saidarmatures and reconnecting said bypass resistance in parallel with said armatures to slow down the car; and means for causing said hoisting motor to level the car with a desired landing in stopping, said levelling means comprising means for connecting the armature of said generator directly across the armature of said hoisting motor and for disconnecting the hoisting motor armature from said source, levelling switching mechanism and means responsive to the operation of said levelling switching mechanism for connecting the field winding of said generator to said source to cause said generator armature to supply current to the hoisting motor armature for the operation of bringing the car to an exact landing level under the control of said levelling switching mechanism.

14. In a control system for an elevator car; a source of direct current; a direct current hoisting motor for the car; a starting resistance for said motor; a by-pass resistance for said motor; a direct current compound wound generator, the armature of which is permanently connected in series relation with the armature of said hoisting motor; driving means for the generator; means.

for connecting the armature of said hoisting motor, with the armature of said generator in series therewith and with said by-pass resistance in parallel with both armatures, to said source in series with said starting resistance to" start the car; switching means for disconnecting said bypass resistance from across said armatures and for short-circuiting said starting resistance to connect said hoisting motor armature in series with said generator armature directly to said source to bring the car up to full speed and for reincluding said starting resistance in series with said armatures and reconnecting said by-pass resistance in parallel with said armatures to slow down the car; means for causing said hoisting motor to level the car with a desired landing in stopping, said levelling means comprising means for short-circuitlng all of said by-pass resistance to form a local circuit fcrthe armature of said generator and the armature of said hoisting motor, means for disconnecting the armature of the hoisting motor from said source, levelling switching mechanism and means responsive to the operation of said levelling switching mechanism for connecting the generator separately excited field winding to said source, such field winding not being energized except during levelling, to cause said generator armature to supply current to the hoisting motor armature for the operation of bringing the car to an exact landing level under the control of said levelling switching mechanism; and means for rendering the series field winding of said generator inefiective except during levelling and full speed operation of said hoisting motor. I I

15. In a control system for an elevator car; a source of direct current; a direct current hoisting motor for the car; a direct current compound wound generator; driving means for the generator; means for connecting the armature of said hoisting motor to said source in series with resistance to start the car; means for cutting said resistance out of circuit to bring the car up to full speed; means for connecting resistance in parallel with said armature to slow down the car; means for disconnecting the hoisting motor armature from said source; means for connecting the armature of said hoisting motor across the armature of said generator; means for energizing the generator separately excited field winding; means for causing said-hoisting motor to level the car with a desired landing in stopping with current supplied to the hoisting motor by the generator, said levelling means causing the supply of cur rent from the generator to the motor to be discontinued when the car becomes level with the landing; and means for rendering the series. field winding of said generator effective "during-the levelling operation.

' 16. In a control system for an elevator car; a

source of direct current; a direct current hoisting motor for the car; a direct current compound wound generator; driving means for the generator; means for connecting the armature of said hoisting motor with the armature of said generator in series therewith to said source in series with resistance to start the car; switching means for cutting said resistance out of circuit to bring the car up to full speed and for including resistance in series with said armatures and additional resistance in parallel with said armatures to slow down the ear; means for causing said hoisting motor to level the car uith a desired landing in stopping, said levelling means comprising means for disconnecting the hoisting motor from said source and for connecting it to the armature of said generator and means for connecting the generator separately excited field windingto said source to cause said generator armature to supply current to the hoisting motor armature for the levelling operation: and means for rendering the series field winding of said generator effective only during levelling and full speed operation of said hoisting motor.

17. In a control system for an elevator car; a source of direct current; a direct current hoisting motor for the car; a starting resistance for said motor; a by-pass resistance for said motor; a direct current compound wound generator; driving means for the generator; means for connecting the armature of said hoisting motor with the armature of said generator in series therewith and said by-pass resistance in parallel with both armatures to said source in series with said starting resistance to start the car; switching means for disconnecting said by-pass resistance from across said armatures and for short-circuiting said starting resistance to connect said hoisting motor armature in series with said generator armature directly to said source to bring the car up to full speed and for reincluding said starting resistance in series with said armatures and reconnecting said by-pass resistance in parallel with said armatures to slow down the car; means for causing said hoisting motor to level the car with a desired landing in stopping, said levelling means comprising means for disconnecting the hoisting motor from said source and for short-clrcuiting all of said by-pass resistance to form a local circuit for the armature of said generator and the armature of said hoisting motor, and means for connecting the generator separately excited field winding to said source to cause said generator armature to supply current to the hoisting motor armature for the levelling operation; and means for rendering the series field winding of said generator ineflective except during levelling and full speed operation of said hoisting motor.

- 18. In a control system for an elevator car; a source of direct current; a direct current hoisting motor for the car; a direct current generator having a separately excited field winding; driving means for the generator; means for connecting the armature of said hoisting motor to said source in series with resistance to start the car and for cutting out said resistance to bring the car up to iull speed; means for including resistance in series with said hoisting motor armature and resistance across said hoisting motor armature to slow down the car, the armature of said generator being connected in series with the last mentioned resistance across the hoisting motor armature; and

. means for causing said hoisting motor to level the car with a desired landing in stopping, said levelling means comprising means ior connecting the generator separately excited field winding to said source and for disconnecting the hoisting motor from said source and cutting said last mentioned resistance out of circuit.

19. In a control system for an elevator car; a source of direct current; a direct current hoisting motor (or the car; a direct current generator having a separately excited field winding; driving means for the generator; resistance; means for connecting the armature oi said hoisting motor to said source in series with said resistance to start the car; switching means for cutting said resistance out of circuit to bring the car up to full speed; additional resistance; means for reincluding the first mentioned resistance in series with said hoisting motor armature and for connecting said additional resistance across said hoisting motor armature to slow down the car, the armature-oi said generator being included in the circuit for said additional resistance across the hoisting motor armature in series relation with said additional resistance; and means for causing said hoisting motor to level the car with a desired landing in stopping, said levelling means comprising means for disconnecting the hoisting motor from said source and for connecting the armature of said generator directly across the armature of said hoisting motor, and means for connecting the generator separately excited field winding to said source to cause said generator armature to supply current to the hoisting motor armature for the operation of bringing the car to an exact landing level.

20. In a control system for an elevator car; a source or direct current; a direct current hoisting motor for the car; a starting resistance for said motor; a by-pass resistance for said motor; a direct current compound wound generator, the armature of which is connected in series relation with said by-pass resistance; driving means for the generator; means for connecting the armature of said hoisting motor, with the arniature of said generator and said by-pass resistance in series connected in parallel thereto, to said source in series with said starting resistance to start the car; switching means for disconnecting said bypass resistance and generator. armature from acrol said hoisting motor armature and for short-circuiting said starting resistance to connect said hoisting motor armature directly to said source to bring the car up to full speed and for reincluding said starting resistance in series with said hoisting motor armature and reconnecting said by-pass resistance across said hoisting motor armature to slow down the car, said generator armature being reconnected in series with said by-pass resistance across the hoisting motor armature; means for causing said hoisting motor to level the car with a desired landing in stopping, said levelling means comprising means for short-circuiting all of said by-pass resistance to form a local circuit for the armature of said generator and the armature of said hoisting motor, means for disconnecting the hoisting motor from said source, levelling switching mechanism and means responsive to the operation of said levelling switching mechanism for connecting the generator separately excited field winding to said source, such field winding not being energized except during levelling, to cause said generator armature to supply currentto the hoisting motor armature for the operation of bringing the car to an exact landing level under the control of said levelling switching mechanism; and means for rendering the series field winding of said generator effective only during the levelling 0! said car.

21. In combination, a motor of the direct current, rheostatic control type having resistances in series and in parallel with the armature for speed control, connections driving the motor from line current at normal speed, a relatively small low voltage generator in series with the motor, and connections operating the motor solely by current from said generator at low speeds.

22. In combination, a main motor, means for connecting the motor to power lines, a generator having .its armature permanently in series with the motor, a circuit ior connecting the field oi the generator with power lines, and automatic means opening said circuit when the motor, is connected to the power lines.

23. In elevator operating apparatus, a motor. means to connect the motor to power lines for normal operation, an auxiliary generator permanently in series with the motor and having a field, leveling switches, and means controlled by the leveling switches for energizing the field in the direction necessary to supply current in proper direction to the motor for leveling action and with said motor disconnected irom the power lines.

24. In combination, an electric motor, means to connect the motor with power lines for normal operation,'a relatively small generator permanently connected with the motor circuit, said generator having a shunt field, and means to energize said field, only while said motor is disconnected from said power lines, for low speed operation of the motor.

25. In an elevator operating apparatus, a moe tor, power lines, connections from the power lines to the motor for normal operation of the motor at high speed and low speed, a relatively small generator having its armature permanently included in said connections, and means for driving the motor solely by current from the generator tor leveling operations.

ANTHONY PINTO. RAYMOND ALONZO WAI'I'E.

Images