US1427644A - Electric-elevator-control system - Google Patents

Description

S. W. RUSHMOBE.

ELECTRIC ELEVATOR CONTROL SYSTEM. APPLICATION FILED NOV. 7, 1919.

1 427 44 Patented Aug. 29, 1922.

2 SHEETS$HEET I. c9129. 1

nwmron TORI/EV s ars U N l T SAMUEL "W. RUSHMORE, OF PLAINFIELD, NEW JERSEY.

FEJQEQZTRIG"EEIJEVATOR-CdNTROL SYSTEM.

Specification of Letters Patent. Patented Aug, 29, 1922,

Application filed November 7, 1919. Serial No. 336,348.

To all whom it may concern:

Be it known that I, SAMUEL W. BUSH- MORE, a citizen of the United States, and resident of Plainfield, in the county of Unlon and State of New Jersey, have invented certain new and useful Improvements inElectric-Elevator-Control Systems, of which the following is a specification.

' its objects to provide a system of this type This invention relates more particularly to elevator systems for control of a plurality or a bank of elevators, and has as one of in whlch the apparatus shall be relatively simple and inexpensive to manufacture and at the same time, reliable, safe and economical in'operation. v

In its preferred embodiment, the invention particularly concerns that type of elevator control system in which a separately excited elevator motor derives its current from a separately excited generator and in which control is effected without the interposition of series resistances or similar power wasting devices.

A feature of the preferred form of the invention is the use of a single generator of a special known design for supplying at one time any combination of or all of a plurality of elevator motors, the motors being associated with the generator in such manner, that each motor may be operated for delicate control of start and stop as well as speed and direction of movement of the corresponding elevator, independently of all of the other motors and their corresponding elevators. My system, while utilizing buta single generator for operating a plurality of elevators, nevertheless secures the same reliability and flexibility of service as if a separate generator supplied each motor while at the same time effecting a considerable increase in efficiency of operation, decrease in first cost and decrease in space required.

Another feature of the invention is an arrangement whereby the elevators are allowed to effect their downward travel by gravity, and the energy generated in descent'isused to operate the corresponding motor as a generator for returning energy to the source of power. A preferred arrangement for bringing about this result is to provide a manual control for each elevator disposing the same in such manner that when set for downward travel of the elevator the, connections between the corresponding motor and the generator become reversed,

whereby the motor will generate current and supply it to the generator in the proper direction for aiding the prime mover. This reversal of connections between the generator and the motors is preferably effected in such manner as to avoid destructive sparking and preferably this is accomplished by means for effecting an automatic cessation of the'current deliveredto the motor immediately. prior to reversing the circuit connections.

The above and other features of my invention will be more fully understood from the following detailed description in connection with the accompanying drawings in Figure 1 is a diagrammatic view of one embodiment of my invention; and

tion.

In these drawings the numeral 1 designates a generator havinga field frame 2 and preferably equally spaced 90 degrees from each other, The armature is provided with four brushes 7, 8, 9 and 10, said brushes being preferably equidistantly spaced 90 degrees .apart, each brush being disposed half way between adjoining field poles.

The generator 1 is separately excited from a pair of mains 11 and 12. For this purpose two parallel field circuits 34 and 35 branch from a lead 33 connected to the main 12, each said field circuit corresponding to one of the field sections, the field circuits being completed to the main 11 in a manner explained below.

In the type of generator just described, current may be delivered to one external circuit through the brushes 7 and 10 and to another separate and independent circuit, through the brushes8 and 9. It will be seen by reference to my Patent No. 587 ,163, granted July 27th, 1897, in which this type of generator is described, that the same has the property of maintaining the different ex- Figure 2 is a similar view of a modificaternal circuits which it may supply, subtor shown on the drawings has but two magnetic field sections, comprising four poles and four brushes as above described, said gcncrator supplying the current for operating two elevators as will be described more fully below. It is well known, however, that generators of the type described may be built with any number of pairs of poles within the limits of practical use and that consequently any number of elevators may derive their operating current from a single generator of the type referred to, the latter having a pair of poles and a pair of brushes for each elcvator.

The type of generator shown and described will be designated by me a multivoltage generator and each individual segment or portion of the generator that supplies one of the independent external circuits, will be designated a generator section.

Referring again to the drawings, 1 have shown two separate elevator motor circuits A and B, the circuit A being fed from the brushes 7 and 10 and the circuit B from the brushes 8 and 9. As the two circuits A and B have the same elements identically arranged, the detailed description will be confined to circuit A, it being understood that it also applies to circuit B or to any additional elevator motor circuits where a multivoltage generator of a number of poles greater than shown in the drawings is employed.

The elevator motor is conventionally shown with an armature 13 and field poles 14 separately excited from the mains 11-12 through leads 15-16. The generator brush 7 is connected by a lead 17 to the central contact 18 of a motor reversing switch 19, andfrom the generator brush 10, a lead 20 is connected to the right hand contact 21 of the reversing switch and a spur 22 from said lead being connected to the left hand reversing switch contact 23. The movable reversin switch as shown has two preferably parallel blades 25 and 26 mounted upon an insulating support 27 pivoted as at 24-. Leads 28 and 29 respectively connect the main brushes of the motor 13 to the blades 25 and 26. As shown in the drawings blade 25 engages contact 23 and blade 26, contact 18. Current will therefore be supplied froin the generator to the elevator motor, and when the reversing switch is moved to the right into contact with limiting stop 32, it will reverse the connections between the generator and the motor.

For effecting the control of the elevator, I provide preferably a manually operated controller C in the elevator car (not shown). This controller comprises a pivoted arm 36 cooperating with two sets of symmetrically disposed contacts 37 and 37'. By way of example the set comprises three contacts 39,

1 name y;

41) and 11, a rcsistancc -12 connecting contacts 39 and h) and a resistance 13 connect:- ing contacts 10 and +1. The corresponding contacts on the right hand side of the concontroller arm and a lead 4:6 to lead 16 and hence to the main 11, thus completing the generator field circuit.

The reversing switch 13) is magnetically operated from the mains 11-12, the controller C governing such operation. To this purpose there are preferably a pair of electro-Inagnetic coils 17 and 18 on opposite sides of the reversing switch 19, said coils having a common core 19 connected to the end of the insulating switch support 27. Both electro-magnetic coils 17 and 48 are connected at one end as shown at 50 and .51 respectively to the lead 15. The other end of the coil 417 is connected by a lead 52 to the control contact 11 and the second terminal of coil s18 is connected by a lead 53 to the control contact 11. The electro-Inagnctic coils -17 for operating the reversing switch thus derives its current from the mains 11 and 12, the circuit being from the main 12 through lead 15 tolead 50 to coil 17 and from the coil through lead 52 to contact 41 and when control arm 36 is in any position to the left of neutral the current passes through said arm to lead 46, thence to lead 16 and back to the main 11. The circuit for coil e8 is similar to that for coil 17, it being necessary to move the arm 36 to the rightof neutral for energizing the coil.

When the controlarm '36 is in the central or neutral position, it is electrically separated from all of the controller'contacts. Accordingly the field circuit corresponding to the section A of the generator is broken, and the coils 47 and 18 of the reversing switch are not energized. The field 14 of the motor, however, is fully excited from the mains 11 and 12, through the leads 15 and 16.

The elevator is preferably provided with automatic electric brakes (not shown) on the hoist drum (not shown). Should this brake fail, and the car starts moving by gravity either downward by excess loader upward by excess of counterweight, it will drive the motor 13, and by reason of the fact that at this time the armature is short circuited through the low resistance generator armature and the field poles are excited, a large and effective dynamic braking current will be generated. The short circuit current in the armature will become so heavy I even. at slow rotation that the car could move by. gravity at only a creeping pace should the brake fail. My system thus acts as an uxiliary safety device for preventing unrestrained falling of the car,

In normal operation when the car is to ascend, the operator moves the controller arm 36 in the appropriate direction. Assumingthis direction to be't'oward the left in the specific embodiment shown, the first contact-reached by the arm will be contact 41. At this time the full voltage of the supply mains 11 and 12 will be applied across the terminals of the electro-magnetic coil 47, the

circuit being from main 12through lead 15, lead 50, electro-magnetic coil 47, lead 52, contact 41, arm 36, lead 46 and lead 16, back to the main 11. The electro-magnetic coil 48 remains unexcited. Accordingly the core 49 will be sucked toward the left, moving the pivoted reversing switch, so that its arms 25 and 26 will respectively connect stationary contacts 18 and 21. At the same time the generator field circuit corresponding to the sectionA' will. have become partially energized, the circuit bein from the main 12 through lead 33, to the i ield coils 34, through the lead 45 to contact 39, then through the resistances 42 and 43 in series to contact 41 through control arm 36, lead 46 and lead 16, back to the main 11.

The generator field being now excited and the reversing switch being connected as described, current will be supplied from the generatonbrush 7 through lead 17 to the stationary contact 18, through the blade 25 and lead 29 through motor armature 13 and from the armature through the lead 29 to the blade 26, contact 21 and lead 20 to the generator brush 10. The motor 13 being separately excited from mains 11-12, now operates to cause the elevator car to ascend at slow speed.

Upon further movement of the control arm 36 toward the left the resistances 43 and 42 will be successively cut out of the generator field circuit and when the contact 39 is reached by arm 36 the full voltage of the mains l1 and 12 will be'applied tothe field of the section A of the generator, and the elevator car will ascend at full speed.

When the controller arm 36 cooperates with contact 39, the resistances 42 and 43 are in series with the electro-ma et 47 so that the full voltage across the mains Hand 12 is no longer applied to the said electro-magnet, a lesser voltage being sufiicient to hold the switch closed than that needed for efiecting closure. The elevator will ascend as long as the controller arm 36 remains in cooperation with contact 39, the usual limit switch (not shown) being employed to automatically cut off the current when the car reaches its greatest height.

The speed of the elevator may be regulated for a slower speed by moving thecontroller arm intoengagement with contact 42 and it may be still further'retarded by placing the arm 36 in cooperation with contact 41. When it is desired to stop the elevator, the controller arm 36 is returned to neutral position. As. .the arm 36. successively cuts resistances 42 and 43 intothe gen-- I I erator field, a gradual deceleration of the car thus takes place prior to stopping.

When controller arm 36 has reached the contact 41 the full voltage of the supply mains 11 and 12 is again applied across the coil 47 the current supplied to the motor from the generator having been reduced by the insertion of the resistances 42 and 43 in series with the field-section.

As soon as control arm 36 is moved out" of engagement with contact 41 into neutral position the generator field circuit is broken and the voltage, and magnitude of current supplied to the motor 13 is quickly cut down.

When it is desired to cause the elevator to descend, the control arm is moved to the right. The action upon the reversing switch in this event is to 'move said switch so that its blades 25 and'26 respectively are in engagement with the stationary contacts 23 9 and 18. When the switch is in this position, current is at first supplied from the generator section to the motor 13 in a direction the reverse of that for lifting'the car, and the motor their acts'to. overcome any resistance 10 opposing descent of the car. If, on the other hand, the elevator and its load have a greater mass than the counterweight, the elevator thereupon descends by gravity, operating the motor 13 as a generator and when the motor is driven at a sufliciently high speed to generate a voltage in excess of the generator section A, it will deliver current back to said section, thus assisting the prime mover by reducing the output required from the generator. As is obvious from the above description, the return of the reversing switch from the last-described position will take place without objectionable sparking.

As above noted, the description of the operation of elevator motor system A will also appl to the system B or to as many additional elevator motors as may be supplied from a multi-voltage generator with the appropriate number of poles. In this system each elevator motor is operated independently of all of the others so that com plete flexibility of service may be secured. In idle hours less than the full number of elevators, or if desired only a single elevator may be set into operation, and this, regardless of the number of sections that the multivoltage generator may have.

In my preferred arrangement I employ the reversing switch described to reverse the 0 direction of current in the field coils of the hoist motor but, particularly with large motors, an appreciable amount of time is required to discharge and remagnetize the field, Whereas the action of the switch in the n main circuit is practically instantaneous.

In the above described apparatus of Figure 1, any desired source of power may be used for driving the armature l at the desired operatin speed. Such source of power may operate through the shaft on which the armature is mounted or if desired, may con sist of suitable connections whereby one pair of poles and one pair of brushes of the generator are connected to the line so as to act as a motor for driving said generator armature.

One way of thus connecting one pair of poles and brushes for driving purposes is indicated in Figure 2. In this figure the coils of the right hand pair of field poles are energized as in Figure 1 through wire 33 connected to one side of the power circuit 12, the return to the other side of the power circuit 11 being throughwire 16. The brushes 8, 9 are connected to 11 and 12 respectively by wires 17, 20. Thus arranged the right hand pair of field poles and the armature windings between brushes 8 and 9 operate as the driving motor while the other pair of poles and rushes 7, 10 are operating in the manner described above in connection with Figure 1.

As before stated, there may be any desired number of pairs of poles and brushes. Any one or more of said pairs may be used for motive power purposes and any other one or more of said pairs can be used for generator purposes.

Although I have disclosed and described my system specifically for elevator operation, it is to be understood that it is susceptible 01"". a variety of analogous uses, as for instance to the control of electric mine hoist systems. I

As my invention is capable of numerous embodiments without departing from the scope thereof, all matter contained in the above description or shown in the accompanying drawings is to be interpreted as illustrative, and not in a limiting sense.

I claim:

1. In an electrical system in'combination, a multi-voltage generator having a plurality of pairs of poles, a plurality of pairs of brushes associated, one pair with each pole pair, separate load circuits subject to reversal of power interchange with the gen erator connected each across a separate and distinct pair of said brushes, means for controlling each said load circuit independently of the others for frequent and rapid interchange of energy between the circuits.

2. In an electrical elevator system in combination, a multivoltage generator, having a plurality of pairs of poles, a plurality of pairs of brushes, associated, one pair with each pole pair, a plurality of elevator motors, connected each across a separate and distinct pair of said brushes, and means whereby the starting, acceleration, stopping and reversal of each of said motors may be independently controlled whereby energy regenerated by one of the elevator motors will fiow through the windings of the generator to supply current to another of said motors.

Signed at New York city in the county of New York and State of hew'York this 6th day of November, A. D. 1919.

SAMUEL W. RUSHMORE.

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