US2184762A

US2184762A - Control system

Info

Publication number: US2184762A
Application number: US228308A
Authority: US
Inventors: Harold W Williams; Santini Danilo
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1938-09-03
Filing date: 1938-09-03
Publication date: 1939-12-26
Anticipated expiration: 1956-12-26

Description

Dec. 26, 1939. H. w. WILLIAMS ET AL CONTROL SYSTEM F iled Sept. 3, 1938 MT? EY a 5m mw .mmfl f 2 R m F W 6 MM 5 m Z QT Z fiw Z 2:62, a ,7 2 7 5. w w 1 34 3 WW 3% g; 3; a V k 5, W Q w 4. w

Patented Dec. 26, 1939 I UNITED STATES CONTROL SYSTEM Harold W. Williams, Englewood, and Danilo Santini, Tenafly, N. J., assignors to Westinghouse Electric Elevator Company, a corporation of New Jersey Application September 3, 1938, Serial No. 228,308

22 Claims.

Our invention relates to control systems and more particularly to the automatic forcing of the generators in leveling operations of elevators.

One object of the invention is to improve the automatic leveling operation of elevator cars when they make a stop at a floor.

Another, object is to provide in Ward Leonard systems, for automatically forcing or increasing the strength of the field of the generators, where they are used for operating elevators, at the time the cars are being leveled with the floors when making a stop at a landing.

Another object is to provide a system in which the manual operation of a selective switching means will condition the system to operate with either a maximum amount of forcing, or a timecontrolled forcing, or a current modified forcing of the generator at the start of the leveling operation. v

Other objects of the invention will be apparent from the following description thereof in conjunction with the accompanying drawing, in

" which v Figure l is a straight-line diagrammatic representation of an elevator system embodying our invention, I

Fig. 1A is a representation of the relays embodied in Fig. 1, showing them with their coils and contact members disposed in horizontal alignment with their positions in the straight line circuits of Fig. 1, so that the reader may readily determine the identity of any relay, the number and kind of its contact members and the position of its coil and contact members in the straight line circuit.

Fig. 2 is a diagrammatic representation of the elevator car shown in Fig. 1 and the position of its leveling camsand leveling switches with relation to a floor landing,

Fig. 3 is a view in side elevation of a switching mechanism for the forcing means, and

Fig. 4 is a view in front elevation of the switch mechanism shown in Fig. 3. g

The relays in the drawing are given the following reference letters:

U=up direction switch D=down direction switch B=brake relay I=intermediate speed relay H=high speed relay P=door and gate interlocking relay :forcing relay K=auxiliary forcing relay T=time delay relay for controlling period of forcing S=retiring magnet for fioor leveling switches Referring more particularly to the drawing, we have illustrated an elevator system including a car C supported by a cable I0 passing over a hoisting drum H to a counterweight l2. The drum H is mounted on a shaft is operated by a hoisting motor M which is provided with an armature MA and a field winding MF, the latter being connected across a pair of supply conductors L+ and L to give the motor constant excitation while the system is in operation. An electromagnetic brake l4 controlled by a brake coil 15 is provided for preventing operation of the hoisting drum when the hoisting motor is deenergized.

A variable voltage system of control of the Ward Leonard Type is provided for the hoisting motor wherein its armature MA is connected in a loop circuit 5'! and it with the armature GA of a generator having a separately excited field winding GF. This winding should have sufiicient ampere turns so that the maximum current through it will generate sufiicient voltage on the generator armature to produce the maximum desired speed in the motor at no load.

The armature GA of the generator may be driven at a constant speed by means of a main driving motor it having a squirrel-cage rotor 2| and a 3-phase star-connected stator winding IS. The outer leads of the stator winding may be connected by a plurality of switches 2Q to any suitable source of electrical energy represented by the supply conductors Ll L2 and L3.

The direction and speed of the hoisting motor may be controlled by controlling the direction and value of the excitation current for the generator field winding GF. The direction is controlled by an up direction switch U and a down direction switch D while the value is controlled by a plurality of resistors M and 1'5, operated by an intermediate speed relay I and a high relay H.

The operation of the up and the down direction switches and the selection of the speed relays is controlled by a switch CS which may be mounted in the car for operation by the car attendant in starting and stopping the car and controlling its speed.

The brake coil 5 is controlled by a brake relay B disposed to be energized when either the up or the down direction switch is energized to move the car.

A door and gate interlocking relay T, controlled by the closing and opening of the contact members on the hatchway doors and car gate (not shown), is provided for preventing operation of the car, while the car gate or any door is open. This relay includes a time delay resistor r8.

An automatic leveling system is provided for causing the car to level itself with the floor if it overruns or underruns the fioor level when a stop is being made at a landing, and also for returning the car to the fioor if the load on the car causes the cables to stretch sufliciently to change the position of the car with reference to the floor while the stop is being made. Leveling apparatus of this character is old and well known in the art. It is here shown as represented by a down leveling switch SD and an up leveling switch SU mounted on the car and a down cam DC and an up cam UC mounted on the hatchway wall. When the car makes a stop at a fioor, these switches and cams operate to so control the hoisting motor as to level the car with the floor and keep it level with the floor. While the car is level with the floor, the switch levers are at rest between the cams so that neither of the switches is operated while the car remains level with the floor. If the car starts to move up above the floor level or stops above the floor level, the lever SD is engaged by the cam DC and caused to operate its members SDI and SD2 to level the car down to the floor. If the car moves below the floor level or stops below the floor level, the up lever SU engages the up cam U0 and thereby operates its contact members SUI and SUE to cause the car to move upwardly to a position level with the floor. Normally, the switch levers are held in a retired position out of engagement with the cams by a retiring coil S while the car is passing the various floors (not shown) but which releases the levers to fall into position for leveling the car at a floor whenever the car is to stop at that floor.

In the operation of a variable voltage system, and particularly where it is used in connection with an elevator, there are many variations in the conditions under which the generator and the motor operate which cause variations in the desired speed of the motor. For instance, there may be changes in the friction of the driven parts, the resistance value of the windings, changes in load, changes in brush contact, etc., which may cause the speed of the motor to vary from what it should be in response to any selected setting of the car switch. In order to overcome these difficulties, a regulator R is provided for correcting the energization of the field of the generator so that the speed of the motor will be automatically held accurately at the desired value at all times when the car is in operation.

The regulator R comprises an armature RA, a series or current responsive field winding RFI, a shunt or voltage responsive field winding RFZ, and a differential field winding RF3.

The armature of the regulator is operated at constant speed as by directly connecting it to the generator shaft 2!], and it is arranged to be connected in series circuit relation with the generator field winding GF so that the voltage generated in the regulator armature in response to the speed and load of the motor and the current flowing through the generator field winding GF will cause a current to fiow through the main generator field winding which will be a function of the departure of the motor speed from a predetermined value corresponding to the particular setting of the car switch for the main field winding. Under certain load and operating conditions, no voltage will be generated in the armature of the regulator, since under these conditions, the speed of the motor corresponds to the setting of the car switch. For all other conditions. however, a voltage will be generated in the regulator armature in such direction and value as to cause the required current to flow through the main field winding of the generator to operate the motor at the desired speed.

The series field winding RFI is connected in series relation in the loop circuit l1 and I8 so that all or a portion of the current from the generator G will flow through it. A shunt r1 may be provided for adjusting the flow of current through the series winding RFI. The high resistance or shunt field winding RFZ is connected across the loop circuit to be responsive to the voltage applied to the motor. A resistor 26 is disposed in series with the winding RFZ to reduce the heat loss in it and consequently the effect of a change in its resistance, due to temperature rise, to a minimum. Portions of the resistor may also be included or excluded from its circuit, for other purposes as hereinafter described.

The two windings RFI and RF2v are differentially related so that the resultant flux is a tune tion of the speed of the motor as measured by its, counter E. M. F., that is, the flux generatedby the series field winding RF! is proportional to the IR drop of the motor armature and the flux A generated by the shunt field winding RFZ is proportional to the voltage impressed across the terminals of the armature of the motor. Thus, the. resulting flux, due to the differential relation! ship between the two windings, is a function of the counter E. M. F. of the motor. Since this flux results from the combined action of the current flowing through the motor armature and the voltage applied thereto, it is also a function of the load carried by the motor.

As soon as a voltage appears in the regulator armature, indicating that the speed of the motor has departed from the desired speed, a change in the flow of current through the main field winding of the generator takes place in such direction as to tend to restore the speed of the motor to the desired speed.

It is desirable to independently control the flow of current through the main field winding GF of the generator from two sources, one of the sources comprising the energized conductors L+ and L across which the car switch CS is connected and the other source comprising the regulator armature RA. For this purpose, a Wheatstone bridge circuit is employed comprising the customary four branches, three of which may be resistors Tl, 1'2 and r3, the remaining branch comprising the differential field winding RF3 of the regulator and the main field winding GF of the generator. The armature of the regulator is connected across a pair of opposite terminals of the bridge circuit, while the remaining pair of terminals is connected through the car switch to the energized conductors L+ and L-.

For a further detailed description of the regulating means included herein, reference may be had to Patent No. 2,094,377, issued September 28, 1937, upon the application of Danilo Santini and Kenneth M. White, and assigned to the Westinghouse Electric Elevator Company.

In the operation of Ward Leonard systems of the above-mentioned character in connection with elevators provided with leveling means, it is desirable to provide for rapid strengthening or forcing, the main field Winding of the generator when the car is starting a leveling operation. In order to accomplish this. we have provided a novel and improved system for causing the regulator to act as a regulating means while the car is making a run from one floor to another floor and to act as a forcing means when the car starts a leveling operation. We effect this operation bv so controllin the connection of the regulator shunt field winding RFZ in the loop circuit as to cause the regulator to strengthen the supply of current to the mainfield winding of the generator when it is thrown into operation in starting aleveling operation, but to regulate the supply of current to the main field winding when the car is making a floor to floor run.

This controlling means may comprise a forcing relay Q and an auxiliary forcing relay K. The forcing relay Q is provided for controlling the circuits through the shunt field winding RFZ' to cause it to effect operation of the regulator asa regulator while the car is making floor to floor runs and as a forcing means when the car starts a leveling operation.

The auxiliary relay K is operated by the car switch to so operate the forcing relay when the car starts a floor to floor run that it will connect the regulator for operation as a regulator during such floor to floor run.

in the preferred form of our system, a reactance or inductive shunt 22 is provided to be connected in the circuit of the shunt field winding' RFZZ when a forcing action is desired. The inductor: shunt is shown as comprising a magnetic circuit composed of two members 23 and 2t and a coil 25. member 23 and 24 are separated at two-places by air gaps or non-magnetic shims 2t and Ellis. The reactance may be adjusted by increasing or decreasing the air gaps I25 and 26d. A manually-operated switch 28 is provided for connecting tic coil 25 in the circuit of the winch ing RFZ when it is desired to operate the system with the relactance included. When the caris in a floor to floor operation, the forcing relay Q opens its contact members Qi and closes its contact members Q2, thereby increasing the amount of resistor T5 in the circuit while connecting the winding RF2 directly to that resistor and thus short circuiting the inductance 22 so that the series field RFE and the shunt field RF! of the regulator will build up at the same rate and will always be in phase while the regulator is acting in its regulating capacity.

When the car stops, the relay Q opens its contact members Q2 and closes its contact members Q1! thereby inserting the inductance 22 t speed. field RFZ and decreasing the t of the resistor To in circuit with that winding. If the car starts at aleveling operation to the floor at which it is making a stop, the relay Q d so not pick up and the high resistance field RFE has to build up through the inductance 22. This means that the low resistance field RF! will luiild up much faster than the high resistance field Rs Up until the time the high resistance field reaches full strength, the regulator acts as series generator building up its voltage .v the current that it sends through the generator s unt field GE and the low resistance field RIM. high resistance field RFZ reaches full stren th. the voltage in the generator will assume its normal value and the regulator will assume its normal regulating functions.

In some installations, it may be desirable to provide amount of field forcing in proportion to the load required. We accomplish this by associating a coil Illa in series with and forming a portion. of the load circuit [8 with the inductance 223 to secure the desired result. The series circuit is associated with the inductance 22 through the use of a transformer Sll, on one leg of which the portion ltd of the conductor 58 is coiled as a primary winding and on the otF-ier leg of which a secondary winding all is disposed. The secondary winding '3! extends to and is coiled around the body 23 of the inductor 22.

The two windings 25 and 3! of the inductor 22 should be so wound as to aid each other. .In this manner, when the car is leveling full load up, the line current will increase the flux through the core of the inductor so as to increase the time delay. But when the car is leveling with a light load, then the amount of current through this winding will be proportionately smaller and the inductance will decrease in the same ratio, thus allowing the high resistance field RFZ to build up at a more rapid rate, thereby decreasing the time delay. A manually operated switch is provided for connecting and disconnecting the trans,

' the relay Q are open and the high resistance field EFF. is completely disconnected from its position across the loop circuit, with the result that the c unter provides a maximum amount of forcing when the car starts leveling.

In further installations, it may be desirable to limit the length of time the maximum forcing will be effective. In order to do this, we provide a time delay relay T for causing the relay Q to cose its contact members Q2 for re-connectthe field winding RFZ across the loop circuit after a predetermined length of time to stop the forcing action of the regulator and to start it in its regulating activity. The time delay relay T connected to be prepared for its timing action by the operation of either the up direction switch or the down direction. switch, and a manually operated switch at is provided for connecting the contact members Tl of the relay T in circuit with the coil of the relay Q whenever it is desired to have the time delay relay control the length. of the forcing period. It is also possible to use this time delay relay for limiting the length of the forcing period-in connection with any other arrangement of our system.

ments for effecting forcing, it may be advantageous to cause the regulator to stop its forcing action and startits regulating action as soon the car starts to move in a leveling operation. When this means for cutting out the forcing action is used, it will be found advisable usually to introduce sufficient inductance in the inductor to obtain the maximum delay required.

The means for stopping the forcing action when the car starts is illustrated as a switching device 33. This device comprises a copper disk at, a permanent magnet 35, a switching arm 36 and a pair of contact members Xi and X2. The copper disk M is mounted upon the outer end of the hoisting motor shaft !3 so that it will rotate therewith. The permanent magnet 35 is fixed to the lower end of an arm 3'1, the upper The link should be hingedly connected to the shaft 35 to swing toward the face of the disk to permit the permanent magnet to be attracted thereto. he contact members X! and X2 are disposed on a pair of standards and Al, and the switching arm 36 has its upper end affixed to the rotatable shaft 33 with its lower end depending between the contact members XI and X2. The contact members Xi and X2 are electrically connected in parallel circuits (see Fig. l) for the forcing relay Q. Hence, when the car starts, the rotation of the disk, past the permanent magnet, generates eddy currents in the disk and thereby causes the magnet to be attracted to and held by the disk so that it will move therewith, thus rotating the shaft 38 and thereby operating the switch arm into engagement with either the contact member XI or in accordance with the direction of operation of the car. The engagement of one of the contact members by one of the switching members energizes the relay Q, thereby effecting connection of the field winding RF2 for causingthe regulator to stop its forcing action and take up its regulating action. A switch 43 is provided (see Fig. l) in the circuit of the relay Q for connecting and disconnecting the switching device 33 from control of the relay Q, as desired. When the switch is closed, the device 33 will energize the relay Q when the car starts and when the switch is open, the device 33 will not affect the relay Q at any time.

An assumed operation with the inductance 22 in use is as follows: It will be assumed that the switches 29 are closed to connect the driving motor Hi to operate the generator G at constant speed, and the switch 45 is closed to connect the control system represented by the conductors L+ and L- to a source of direct current energy.

It will also be assumed that the switch 28 is closed and that the switches 32 and 42 are open to cause the system to work with the inductance 22. The field winding ME for the hoisting motor M is now energized, and the driving motor It, the generator G and the regulator R are rotating at constant speed. It will be assumed that the car gate and hatchway doors (not shown) are closed and that the gate contact members 45 and the door contact member at are, therefore, closed to energize the door and gate interlocking relay P to permit the starting of the car.

Assuming now that the attendant for the car C moves the car switch CS in a counter-clockwise direction to move the car upwardly to another floor, this causes the contact members 4'! and -18 to engage, thereby energizing the retiring magnet relay S and the auxiliary forcing relay K by a circuit extending from supply conductor L+ through P4, ll, 48, K and S to conductor L-. The energized coil S causes the leveling switch levers SD and SU to be withdrawn from their operative position adjacent the cams DC and UC so that the leveling switches will not strike the leveling cams as the car moves from floor to floor. The energized relay K closes its contact members KI, thereby energizing the forcing relay Q by the circuit L+, Kl, Pl, Q, L. The energized forcing relay Q will prevent operation of the regulator as a forcing device and cause it to act as a regulating device while the car is making its floor to floor run because it closes its contact members Q2 to connect the voltage-responsive field winding RFZ across the loop circuit ii and 18 connected to the terminals of the armature oi the hoisting motor and opens its contact members Q! to insert more of the resistor rt in series with said field Winding. With this connection of the field winding RFZ, the regulator will supply a correcting flow of energy to the generator while the car is operating on its floor to floor run.

Assuming now that the attendant moves the switch CS another step into engagement with the contact member 50, the brake relay B and the top direction switch U are thereby energized through the circuit L+, P4, 41, 50, D4, U, S, L. The energized brake relay B closes its contact members BI, thereby energizing the brake coil IE to release the brake M, thus permitting operation of the hoisting drum H. The closing of the contact members B2 creates a self-holding circuit for the forcing relay Q so that relay will remain energized to prevent operation of the regulator as a forcing means until the brake is again applied.

The energization of the up direction switch U closes its contact membersUl and U2 in the circuit for the generator field winding GP to cause the generator to operate the hoisting motor at low speed. The circuit for the field winding GF extends from the supply conductor L+ through Ul, 'rl GI", U2, r4, r5, L-. The energized generator operates the hoisting motor to rotate the hoisting drum and start the car to move away from the floor at which it is located.

Assuming now that the car attendant moves the car switch another notch so that its contact members All and iii are closed, this energizes the intermediate speed relay I by a circuit extending from L+, Pt, ti, SI, P3, I, L-. The intermediate speeo'. relay I closes its contact members Il, thereby shorting out the resistor T4 in the circuit for the field winding GF to increase the speed of the moving car from low speed to intermediate speed,

Assuming now the the car attendant closes the switch another notch, thereby closing the contact members 5? and 52 thus energizing the high speed relay H by the circuit 13+, P 3, 57, 52, P2, H, L, the energized high speed relay H closes its contact members HI, thereby short circuiting the resistor in the circuit for the generator field winding GF, This causes the car to run at its normal high speed.

It will be assumed now that the car attendant desires to stop at the next floor and, therefore, reverses the car switch OS to open its contact members 4'! and 52'. This deenergizes the high speed relay H which opens its contact members Hi and thereby inserts the resistor T4 in the circuit for the generator field winding GF, thus reducing the speed of the hoisting motor and causing the car to decrease its speed. Assuming that the car attendant reverses the car switch CS still further and opens the contact members 4'! and 5|, this deenergizes the intermediate speed relay I which opens its contact members II and inserts the resistor M in the circuit of the generator field winding GP to reduce the car to its intermediate speed.

Assuming that the car is now ready to stop at the floor at which the attendant desires to land, and that the car attendant centers the switch CS to stop the car level with the floor, the centering of the car switch opens its contact members 41, 5G and 68 and thereby brings the car to a stop at the floor. The opening of the contact mem bers i'i and 5D deenergizes the up direction switch U and the brake relay B.

The deenergization of the up direction switch s eaves U opens its contact members '0'! and U2, thus deenergizing the generator field winding GP to stop the car. The deenergization of the brake relay B opens its contact members Bl, thereby deenergizing the brake coil l5 which applies the brake Mto stop the car and hold it. The car is now stopped. level with the floor and the door and gate (not shown) are opened, thereby opening the gate and door contact members 46 and 4'! to prevent operation of the car in a floor to floor run while the gate or any door is open, but not to prevent a leveling operation of the car.

The deenergization of the brake relay also opened its contact members B2 which opened the self-holding circuit of the forcing relay Q, thereby deenergizing that relay thus causing it to open its contact members Q! and close its contact members Q2. The opening of the contact members Q2 inserts the inductance 22 in series with the voltage responsive field winding RFZ, and the opening of the contact members Q! inserts an additional amount of the resistor 15 in series with the inductance 22 and the field winding RF2. Hence, the forcing relay has now operated to so connect the voltage-responsive field winding RFZ of the regulator that the regulator will act as a forcing means instead of a regulating means if the car starts a leveling operation while making its stop at the floor.

The opening of the contact members 51 and 13 by the centering of the car switch deenergized the retiring magnet S and the auxiliary forcing relay K. The deenergized magnet S permitted the leveling switches SU and SD to move outwardly from their inactive position to engage the leveling cams and cause the car to level with the floor, if it moves out of its level position. The deenergization of the relay K did not affect the relay Q because of the self-holding circuit of that relay.

As an example of a leveling operation and the forcing action which will take place at the start of the leveling operation, it wi l be assumed now that the cables lll supporting the car stretch by reason of the load on the car so that the car loses its level position with the floor and moves down to a point where the up leveling lever SU engages the up cam UC. The engagement of the lever SU with the cam causes the lever to move, thus opening its contact members SUI and closing its contact members SU2. The closing of the contact members SUZ energizes the up direction switch U and the brake relay B to start the hoisting motor to move the car upwardly, as described in the prior operation.

Inasmuch as the forcing relay Q is not now energized, its contact members Q! are closed and its contact members Q2 are opened. Thus the circuit for the voltage responsive field RFB of the regulator extends through the inductance 22 and the central portion of the resistor r6 as follows: Loop circuit conductor is, RF2, switch 28, coil 25, central portion resistor r6, contact members Ql, loop conductor ll. Thus the high resistance field RFZ has to build up through the inductance 22 which means that the low resistance field RF! will build up much faster than the high resistance field Up to the time the high resistance field reaches full strength,

1 the regulator will act as a series generator,building up its voltage by the current it sends through the generator shunt field G and the low resistance field RFL As soon as the highresistance field RF2 reaches its full strength, the voltage in the regulator will decrease to its normal value and the regulator will then become a regulating means instead of a forcing means.

As the car moves upwardly in its leveling operation, the leveling lever SU runs off the up cam U0 and thereby opens its contact members SUZ, thus deenergizing the up direction switch and the brake relay B and thereby stopping the car as it comes level with the floor.

We have described the leveling operation which takes place when the car levels with fioor after making an up stop, but it will be apparent that' a similar leveling operation will take place at any time the car stops short of a floor or overruns a floor.

By reason of the foregoing operation, it is een that the use of the inductance device 22 and the forcing relay Q will provide a system for securing a desirable forcing operation by the regulator when a leveling operation is started.

An assumed operation of the system in which the voltage responsive field RFZ is disconnected from the loop circuit l1 and IE to provide for maximum forcing is as follows. The system is conditioned for this operation by opening the switch 28, thereby rendering the inductor 22 inoperative. The switches #32 and 43 are also open to render the timing device T and the car control device 33 ineffective. Assuming now that car attendant operates the car switch CS to start the car and then to stop it on an up trip as previously described, then as the car comes into a stop at the floor and the up direction switch U is deenergized, the forcing relay Q is deenergized as previously described upon the stopping of the car. tion of the forcing relay opens its contact members Q2, thereby disconnecting the voltage re sponsive field RFZ from the loop circuit l'i and E8. The disconnection of the field RF2 conditions the regulator R for operation as a forcing device in case the motor is started in a leveling operation by the leveling switches instead. of by the car switch.

Assuming again that the cable l8 supporting the car stretch by reason of the load on the car so that the car drops downwardly from. its level position with the floor, then the up leveling lever SU engages the up cam UC and is thereby operated to open its contact SIM and close its contact members SUEK. the contact members SUE energizes the up direc tion switch U and the brake relay B to start the car upwardly in leveling action. Inasmuch as the relay Q is not energized and its contact members Q2 are opened, the voltage responsive field winding RF? is disconnected from the loop circuit, thereby causing the regulator to supply a forcing flow of energy to the generator field winding as the motor starts its leveling operation. As the car moves upwardly into a posi tion level with the floor 53, the leveling lever SU slips off the leveling cam U0 and is thereby operated to open its contact members SUE, thus deenergizing the up direction switch and the brake relay B. This stops the car level with the floor.

It is usually desirable to employ the time delay relay T for stopping the maximum forcing after the expiration of a predetermined period of time instead of permitting it to continue until 1e motor stops its leveling operation.

An assumed operation of the timing relay is as follows: The switch-35 is closed to render the relay T effective for limiting the maximum forcing action of the regulator. In the present case The deenergiza- The closing of a iii.)

this relay is disposed to be energized at all times except when one of the direction switches is operated. When a direction switch is operated, it opens the circuit for the relay T and thereby causes its contact members TI to open after the expiration of the predetermined time for which the relay is designed.

Assuming now that the cables stretch again and that the car again drops below its level position, the downward movement of the car causes the up leveling lever SU to engage the cam U0 and thereby close its contact members SU2 thus energizing the up direction switch U and the brake relay B to move the car upwardly as previously described. The energization of the up direction switch U opens its contact members U3 in the circuit of the delay relay T and that relay starts its timing period. Inasmuch as the contact members T! of the relay T are open in the circuit for the forcing relay Q, that relay remains deenergized and, therefore, as the motor starts to move the car upwardly, the voltage responsive field winding RFZ is still disconnected from the loop circuit I1 and i8 and the regulator R acts as a forcing device for the generator field winding. However, as soon as the time delay relay T reaches the expiration of its delay, it closes its contact members TI and thereby energizes the forcing relay Q to close its contact members Q2 in the circuit of the winding RFZ, thus connecting the field winding RFZ across the loop circuit I! and I8. Inasmuch as the field winding RF2 is again connected across the loop circuit, it causes the regulator to stop acting as a forcing device and start acting as a regulating device. Hence it is seen that when the switch 42 is closed, the time delay relay T limits the time the regulator acts as a forcing device to the predetermined period for which the relay T is designed and it is, of course, obvious that the trained engineer can design for whatever suitable period of maximum forcing that he desires.

It will also be apparent that the time delay relay may be used to limit the forcing activity of the regulator in connection with any one of the variations of the system so far described and its use is determined solely by opening or closing the switch 42.

An assumed operation of the car device 33 for stopping the forcing action as soon as the car starts is as follows: In connection with this device it will be assumed that the voltage responsive field windings RFZ is to be entirely disconnected for maximum forcing, that the switch 132 is opened to render the time delay relay T ineffective, and that the switch 43 is closed to render the car operated device 33 effective. Assuming again the previously described levelling operation where the car, while standing at a floor, drops below the level of the floor, then the downward movement of the car operates the levelling lever SU to close its contact members SUE and, thereby energizes the up direction switch U and the brake relay B to cause the car to move upwardly. The energized up direction switch U closes its contact members UI and U2 to energize the generator field winding GP to start the hoisting motor. As previously described, when the car was stopped at the floor, the forcing relay Q was deenergized by the setting of the car switch and thus opened its contact members Q2, thereby disconnecting the voltage responsive field winding RFZ from the loop circuit I! and It to prepare the regulator for providing a forcing flow of energy for the generator field winding if the car should start a. levelling operation. Now, as the car starts the up levelling operation with the field RFZ disconnected from the loop circuit, the regulator applies a maximum forcing effect as the motor starts the car. However, as soon as the motor starts the car, the rotation of the motor shaft I3 causes the copper disc 34 to rotate past the permanent magnet 35. This action creates eddy currents in the copper disc thus attracting the magnet 35 to the disc and causing it to rotate therewith. The rotation of the magnet 35 moves the switch arm 36 into engagement with the contact member X2, thereby energizing the forcing relay Q by a circuit extending L+, X2, 43, Q, Ll

The energized relay Q closes its contact members Q2 thus reconnecting the field winding RFZ across the loop circuit I! and I8. The reconnection of the winding RFZ causes the regulator to stop its forcing action and start its regulating action. When the car moves up level with the floor, the levelling lever SU moves off the up cam U0 and thereby opens its contact members SUZ to deenergize the up direction switch U and brake relay B. The deenergization of these two relays deenergizes the generator G and applies the brake M to stop the hoisting motor and the car. The stopping of the hoisting motor stops the rotation of the copper disc 34, and thereby releases the permanent magnet 35 so that it drops back, under the influence of gravity, to its normally inoperative position and thus opens the contact members X2. The opening of the contact members X2 deenergizes the forcing relay Q and leaves it prepared for the next operation when, if the car starts a floor to floor run, it will be energized by the energization of the relay K, but if the car does not start a floor to floor run but starts another levelling operation, it will remain deenergized at the start and thus again control the field winding RF'Z to cause the regulator to supply a forcing flow of energy to the generator at the start of the levelling operation.

Inasmuch as the car actuating device 33 caused the field winding RFZ to be reconnected to change the regulator from a forcing device to a regulating device when the car started, it will be seen that we have provided means whereby the maximum forcing operation of the regulator Will be stopped by the starting of the car, thereby limiting the forcing action to just the period when it is most desired in the starting of the hoisting motor. Also, it will be obvious that the switching means 33 operated by the starting of the car may be used to stop the forcing action upon the starting of the car, when the inductive device 22 is used or when the inductive device 22 controlled by the transformer 30 is used as well as when they are not used.

In View of the system illustrated and described, it will be apparent that we have provided a forcing system in which a regulator may be connected for supplying a correcting force of energy to a generator when the motor energized by the generator is in normal operation but in which the regulator will be connected for supplying a. forcing flow of energy to the generator when the motor is used for special purposes like in starting an elevator car in a leveling operation.

It will also be apparent that, although our improved system is particularly useful in elevator systems, it may be used with advantage in many 76 1. In a direct-current control system, a motor connected to a load device, a generator for energizing the motor, said generator having a field winding, a regulator for the generator, said reg- Y ulator having a plurality of field windings including a voltage-responsive field winding, and means for controlling the connections of the voltageresponsive winding to cause the regulator to supply either a forcing flow of energy or a correcting fiow of energy to the generator field winding.

' 2. In an elevator system having a car serving a plurality of floors, a motor for operating the car, a generator provided with a field winding and having its armature connected in a loop circuit with the armature of the motor for energizing the motor, control means for causing the motor to start, run and stop, a leveling means for causing the motor to level the car with any floor at which it makes a stop, a regulator for the generator, said regulator having a plurality of field windings including a voltage-responsive field winding connected across the loop circuit, and means for controlling the connection of the voltage responsive field winding to cause the regulator to supply a correcting flow of energy to the generator field winding when the car makes a run from one floor to another floor and to supply a forcing flow of energyto the generator field winding when the leveling means starts to level the car with a floor.

3.In an elevator system having a car serving a plurality of floors, a motor for operating the car, a generator provided with a field winding and having its armature connected in a loop circuit with the armature of the motor for energizing the motor, control means for causing the motor to start, run and stop, a leveling means for causing the motor to level the car with any floor at which it makes a stop, a regulator for the generator, said regulator having a plurality of field windings including a voltage-responsive field Winding connected across the loop circuit, and means responsive to operation of the control means to control the motor for controlling the connection of the voltage-responsive field winding to cause the regulator to supply a cor recting flow of energy to the generator field winding when the car makes a fioor-to-floor run and to supply a forcing fiow of energy to the generator field winding when the leveling means starts to level the car with a floor.

4. In an elevator system having a car serving a plurality of floors, a motor for operating the car, a generator provided with a field winding and having its armature connected in a loop circuit with the armature of the motor for energizing the motor, a pair of direction switches for causing the motor to start, run and stop, control means for operating the direction switches to make a run from one fioor to another floor, leveling means for operating the direction switches to level the car with the floors, a regulator for the generator, said regulator having a pluralityof field windings including a voltage responsive field winding connected across the terminals of the armature of the motor, a forcing relay responsive to operation of the control in starting a run from a floor to a floor for controlling the connections of the voltage responsive field winding to cause the regulator to supply a correcting force of energy to the generator field winding While the car is making its fioor-to-floor run and responsive to operation of the control means and operation of the leveling means for controlling the connections of the voltage-responsive field winding to cause the regulator to supply a forcing flow of energy to the generator field winding when a leveling operation is started.

5. In an elevator system having a car serving a plurality of floors, a motor for operating the car, a generator provided with a field winding and having its armature connected in a loop circuit with the armature of the motor for energizing the motor, control means for causing the motor to start, run and stop, a leveling means for causing the motor to level the car with any floor at which it makes a stop, a regulator for the generator, said regulator having a plurality of field windings including a voltage-responsive field winding connected across the loop circuit,

means responsive to operation of the control means to control the motor for controlling the connection or" the voltage responsive field winding to cause the regulator to supply a correcting flow of energy to the generator field winding when the car makes a fioor-to-fioor run and to supply a forcing flow of energy to the generator field winding when the leveling means starts to level the car with a floor, and a time delay device for limiting to a predetermined length of time the time the regulator supplies a forcing how of energy to the generator field Winding.

6. In an elevator system having a car serving a plurality of floors, a motor for operating the car, a generator provided with a field winding and having its armature connected in a loop circuit with the armature of the motor for energizing the motor, control means for causing the motor to start, run and stop, a leveling means for causing the motor to level the car with any floor at which it makes a stop, a regulater for the generator, said re ulator having a plurality of field windings including a voltageresponsive field winding connected across the loop circuit, means responsive to operation of the control means for controlling the connection of the voltage responsive field winding to cause the regulator to supply a correcting flow of energy to the generator field Winding when the car makes a floor-to-fioor run and to supply a forcing fiow of energy to the generator field winding when the leveling means starts to level the car with a floor, and means responsive to a starting action of the car in a leveling operation forstopping further forcing action of the regulator.

7. In a Ward Leonard control system, a motor for supplying power to a device, a generator for energizing the motor, said generator having a field winding, a regulator'having a plurality of field windings including a voltage-responsive field winding connected across the terminals of the armature of the motor, an inductance device and meansfor connecting the inductance device in series with the voltage-responsive field winding to cause the regulator to supply a forcing flow of energy to the generator field winding when the motor is being started.

8. In a Ward Leonard control system, a motor connected to a load device, a generator for energizing the motor, said generator having a field winding, a regulator for supplying a correcting flow of energy for the generator field winding, said regulator having a current-responsive field winding, a voltage responsive field winding and a differential field winding, an inductance device, means for connecting the inductance device in series with the voltage-responsive field winding to cause the regulator to supply a forcing fiow of energy to the generator field winding when the motor is being started, and means for limiting the operation of the regulator as a forcing means to the periods in which the motor is started.

9. In an elevator system having a car serving a plurality of fioors, a motor for operating the car, a generator provided with a field winding and having its armature connected in a loop circuit with the armature of the motor for energizing the motor, control means for causing the motor to start, run and stop, a leveling means for causing the motor to level the car with any floor at which it makes a stop, a regulator for the generator, said regulator having a plurality of field windings including a voltage-responsive field winding connected across the terminals of the armature of the motor for causing the regulator to supply a correcting flow of energy to the generator field winding, an inductance device, and means responsive to operation of the leveling means for connecting the inductance device in series with the voltage-responsive field winding to cause the regulator to supply a forcing flow of energy to the generator field winding as the motor is started in its leveling operation.

10. In an elevator system having a car serving a plurality of floors, a motor for operating the car, a generator for operating the motor, said generator having a field winding, a plurality of direction switches for causing the motor to start, run and stop, control means for operating the direction switches to make the car run from one floor to another floor, leveling switches for operating the direction switches to level the car with any floor, a regulator for the generator, said regulator having a plurality of field windings including a voltage-responsive field winding connected across the armature of the motor, an inductance device connected in series with the voltage-responsive field winding to cause the regulator to supply a forcing flow of energy to the generator field winding when the leveling switches cause the start of a leveling action, and a forcing relay responsive to operation of the control means in operating the car for a floorto-fioor run for eliminating the inductance device from the circuit of the voltage-responsive field Winding to cause the regulator to supply a correcting fiow of energy to the generator field winding during said fioorto-fioor run of the car.

11. In an elevator system having a car serving a plurality of fioors, a motor for operating the car, a generator provided with a field winding and having its armature connected in a loop circuit with the armature of the motor for energizing the motor, control means for causing the motor to start, run and stop, a leveling means for causing the motor to level the car with any floor at which it makes a stop, a regulator for the generator, said regulator having a plurality of field windings including a voltage-responsive field winding connected across the terminals of the armature of the motor for causing the regulator to supply a correcting fiow of energy to the generator field winding, a resistor in series with the voltage-responsive field winding, an inductance device, and means for changing the amount of resistance in series with the voltage-responsive field winding and for connecting the inductance device in series with the voltage-responsive field Winding to cause the regulator to supply a forcing flow of energy to the generator field winding at the start of the leveling operation.

12. In an elevator system having a car serving a plurality of fioors, a motor for operating the car, a generator provided with a field winding and having its armature connected in a loop circuit with the armature of the motor for energizing the motor, a control switch for causing the motor to start, run and stop, a leveling means for causing the motor to level the car with any floor at which it makes a stop, a regulator for the generator, said regulator having a plurality of field windings including a voltage-responsive field Winding, means responsive to operation of the control switch to start the car for connecting the voltage-responsive field winding across the terminals of the armature of the motor to cause the regulator to supply a correcting flow of energy to the generator field winding, an inductance device, and means responsive to operation of the leveling means to level the car for connecting the inductance device in series with the voltageresponsive field winding across the armature of the motor to cause the regulator to supply a forcing flow of energy to the generator field winding as the motor is started in its leveling operation.

13. In an elevator system having a car serving a plurality of fioors, a motor for operating the car, a generator provided with a field winding and having its armature connected in a loop circuit with the armature of the motor for energizing the motor, control means for causing the motor to start, run and stop, a leveling means for causing the motor to level the car with any floor at which it makes a stop, a regulator for the generator, said regulator having a plurality of. field windings including a voltage-responsive field winding connected across the terminals of the armature of the motor for causing the regulator to supply a correcting flow of energy to the generator field winding, an inductance device, means responsive to operation of the leveling means for connecting the inductance device in series with the voltage-responsive field winding to cause the regulator to supply a forcing flow of energy to the generator field winding as the motor is started in its leveling operation, and a time delay device for limiting the action of the regulator as a forcing means to a predetermined length of time after the leveling means is operated to level the car.

14. In an elevator system having a car serving a plurality of floors, a motor for operating the car, a generator provided with. a field winding and having its armature connected in a loop circuit with the armature of the motor for energizing the motor, control means for causing the motor to start, run and stop, a leveling means for causing the motor to level the car with any fioor at which its makes a stop, a regulator for the generator, said regulator having a plurality of field windings including a voltage-responsive field Winding connected across the terminals of the armature of the motor for causing the regulator to supply a correcting fiow of energy to the generator field winding. an inductance device, means responsive to operation of the leveling means for connecting the inductance device in series with the voltage-responsive field winding to cause the regulator to supply a forcing flow of energy to the generator field winding as the motor is started in its, levelingoperation, and means responsive to rotation of the motor for causing the regulator to stop its forcing action and start its regulating action.

1 5. In a Ward Leonard control system, a motor for operating a load device, a generator for energizing the motor, said generator having a field winding, a loop circuit connecting the armature of the generator and'the armature of the motor, a regulator for the generator, said regulator having a plurality of field windings, including a voltage-responsive field winding connected across the loop circuit, an inductance device, means for connecting the inductance device in series with the voltage-responsive field winding to cause the regulator to supply'a forcing flow of energy to the generator field winding when the motor is started, and said loop circuit being provided with a coiled portion associated with the inductance device to change the amount of field forcing in proportion to the load requirement.

16. In an elevator system having-a car serving a plurality of floors, a motor foroperating the car, a generator provided with a field winding and having its armature connectedin a loop circuit with the armature of the motor for energizing the motor, a control switch for causing the motor to start, run and stop, a leveling means for causing the motor to level the car with any floor at which it makes a stop, a regulator for the generator, said regulator having a pluralityof field windings including a voltage-responsive field winding, means responsive to operation of the control switch to start the car for connecting the voltage-responsive field winding across the terminals of the armature of the. motor to cause the regulator to supply a correcting flow of energy to the generator field winding, an inductance device, and means responsive to operation of the leveling means to start the car for connecting the inductance device in series with the voltage-responsive field winding across the armature of the motor to cause the regulator to supply a forcing fiow of energy to the generator field winding asthe motor is started in its leveling operation, said loop circuit having a coiled section associatedlwith the inductance device for causing the inductance device to change the amount of field forcing in proportion to the load require- 'ment when it is connected in series with the volt age-responsive field winding for forcing purposes,

1'7. In an elevator system having a car serving a plurality of floors, a motor for operating the car, a generator provided with a field winding and having armature connected in a loop circuit with the armature of the motor for energizing the motor, a control switch for causing the motor to start, run and stop,'.a leveling means for causing the motor to level the car with any fioor which it makes a stop,'a regulator for the generator, said regulator having a plurality of field windings including a voltage-responsive field winding, means responsive to operation of the control. switch to start the car for connecting the voltage-responsive field winding across the terminals of the armature of the motor to cause the regulator to supply a correcting flow of energy to the, generator field winding, an inductance dev ce, means responsive to operation of the leveling means to level the car for connecting the inductance device in series with the voltage-responsive field'wincling across the armature of the motor to cause the regulator to supply a forcing fiow of energy to the generator field winding as the motor is started in its leveling operation, and a transformer having a primary coil formed by a portion of the loop circuit and having a sec.- ondary coil connected in a secondary circuit disposed on the inductance'device and wound inv field winding, a loop circuit connecting the armature of the generator and the armature of the motor whereby the generator may energize the motor, a regulator having a plurality of field windings including a voltage-responsive field winding electrically connected across the loop circuit for causing the regulator to supply a correcting flow of energy to the generator field winding while the motor is making anormal run, and means for opening the connection of the voltageresponsive field winding with the loop circuit during a starting operation to cause the regulator to supply a forcing flow of energy to the generator field winding as the motor is started.

19. In an elevator system having a car serving a plurality of floors, a motor for operating the car, a generator provided with a field winding and having its armature connected in a loop circuit with the armature of the motor for energizing the motor, control means'ior causing the motor to start, run and stop and to level the car with. any fioor at which it makes a stop, a regulator for the generator, said regulator having a plurality of field windings including a voltageresponsive field winding, and means responsive to operation of the control means to start the car on a fioor-to-fioor run for connecting the voltage-responsive field winding across the terminals of the armature of the motor to cause the regulator to supply a correcting flow of energy to the generator field winding while thecar is in normal operation and responsive to operation of the control. means to level the car for causing the voltage-responsive field winding to remain disconnected from the terminals of the armature of the motor when the motor starts the leveling operation for causing the regulator to supply a forcing flow of energy to the generator field winding at the start of the leveling operation.

20. In an elevator system having a car serving a plurality of floors, a motor for operating the car, a generator provided with a field winding,

and having its armature connected in a loop circuit with the armature of the motor for energizing the motor, control means for causing the motor to start, run and stop and to level the car with any floor at which it makes a stop, a regulator for the generator, said regulator having a plurality of field windings including a voltageresponsive field winding, means responsive to operation of the control means to start the car on a fioor-tc-fioor run for connecting the voltageresponsive field winding across the terminals of the armature of the motor to cause the regulator to supply a correcting flow of energy to the gem erator field winding While the car is in normal operation and responsive to operation of the connected from the terminals of the armature of the motor when the motor starts the leveling operation for causing the regulator to supply a forcing flow of energy to the generator field winding at the start of the leveling operation, and a timing device for limiting the forcing action of the regulator to a predetermined length of time after it starts.

21. In an elevator system having a car serving a plurality of floors, a motor for operating the car, a generator provided with a field winding and having its armature connected in a loop circuit with the armature of the motor for energizing the motor, control means for causing the motor to start, run and stop and to level the car with any floor at which it makes a stop, a regulator for the generator, said regulator having a plurality of field windings including a voltage-responsive field winding, means responsive to operation. of the control means to start the car on a floor-to floor run for connecting the voltageeresp-cnsive field winding across the terminals of the armature of the motor to cause the regulator to supply a correcting flow of energy to the generator field winding while the car is in normal operation and responsive to operation of the control means to level the car for causing the voltage-responsive field winding to remain disconnected from the terminals of the armature of the motor when the 22. In a control system for an elevator motor,

a generator having a separately excited field Winding for controllim the speed of said motor, a regulator comprising a generator whose armature is connected to alter the excitation of the separately excited field of said first-mentioned generator, means responsive to voltage and current conditions in said motor to alter the voltage of said regulator generator to correct the output voltage of said first-mentioned generator such that at any given separate excitation the speed of said motor corresponding thereto is held substantially constant, and inductive means respom sive to a sudden chan e of voltage across said motor terminals for causing said regulator to excite said first-mentioned generator field winding to an abnormal degree.

HAROLD W. WILLIAMS. DANILO SANTINI.