US655779A - Control of electric furnaces. - Google Patents

Description

. Patented Aug. l4, I900. w. s. HORRY, 7 CONTROL OF ELECTRIC FURNACES.

(Application filed Feb. 21, 1899. Renewed Jan. 15, 1900.)

(No lloda l.)

THE NORRIS PETERS cu. PHOTO-UTHOI, WASHINGTON, v. c.

I llNiTED ST TES ?A.TENT Orrron.

.WILLIAM SMITH. IIORRY, OF NEW YORK, N. Y., ASSIGNOR TO THE UNION .OARBIDE COMPANY, OF NIAGARA FALLS, NEIV YORK.

CONTROL OF ELECTRIC FURNACES.

srncrrroarrou forming part of Letters Patent No. 655,779, dated August 14, 1900.

-Application filed February 21,1899. Renewed January 151 1900. Serial No. 1,543. (No model.)

To all whom it may concern:

Be it known that I, WILLIAM SMITH HOBBY, a subject of Her'Majesty the Queen of Great Britain, residing at New York city, New York, have invented certain new and useful Improvements in the Control of Electric Furnaces,of which the following is a specification. The invention relates to electric furnaces in general, and it may be applied to any of to them for shifting parts which are so related that their movement accomplishes the regulation of the furnace.

. The object of the invention is to give control ofan electric furnace in its immediate vicinity and also to control it automatically at the will of the attendant and in such manner that with an approximately-constant voltage on the electrodes the current in the furnace shall be maintained approximately constant. Generally the local control is limited to starting and stopping the furnace, which is done by hand, and the continuous control during operation is left to the automatic devices hereinafter described. The control of the furnace or furnaces automatically from a distance is found to be necessary or desirable because all electrical heating processes are in their nature dusty and dirty and give off noxious fumes, so that any delicate contrivan'ce and many heavy mechanical devices unless placed well away from the furnace are found for this reason to work badly. As a consequence of the control of the furnaces in operation from a distance any number of 5 them can be controlled automatically from one small room away from the dirt and dust and in which the performance of each furnace may be carefully noted. The local control at the furnace itself is of great advantage 40 and does away with all signaling apparatus which would otherwise be necessary. The in- Vention' also possesses the advantage or merit of controlling, either automatically or by hand, electric furnaces of great size and power in which control by manual force would be impossible. All thermo elcctric furnaces consist of two members or elements. The elec trodes, two or more, constitute one element and the receptacle for the charge to be smelted 5o constitutes the other member or element. Such furnaces may be regulated in either of three ways: First, the electrodes themselves may bejcaused to approach or recede from each. other. In this case the receptacle for the charge remains fixed and the electrodes would then be the movable member of the furnace. Second, another way to regulate thermoelectric furnaces is to have a movable receptacle. Then the electrodes remain fixed.

In the latter case the movable member is the receptacle and the furnace can be regulated by moving it with respect to the electrodes, and the third way is to move all the electrodes together with respect to the receptacle,

in which case the movable member would be 6 all the electrodes. In the following description I shall refer to drawings illustrating the invention in connection with the second arrangement.

The invention comprises the improvements 7o hereinafter described and claimed.

The nature, characteristic features, and scope of the invention will be more fully understood from the following description,taken in connection with the accompanying drawin gs, forming part hereof, and in which Figure 1 is a diagrammatic View illustrating apparatus embodying features of the invention, and Fig. 2 is a similar view of a por- 7 tion of the apparatus arranged for operation by means of a relay orlocal circuit.

In the apparatus embodying the invention there is a motor constructed and arranged to shift either the electrodes or the receptacle or other parts of which the movement effects control of the furnace-circuit. This motor may be of any known type. For the sake of illustration, the type of furnace illustrated in @Letters Patent of the United States No. 597,880, of January 25, 1898, has been se- 0 lected, although a furnace of the type in which the electrodes are movable in respect to the receptacle might just as well have been selected, and for a like purpose a two-phase electric motor has been selected, although a is run in the other direction the charge is caused to move toward the electrodes. At the left-hand portion of Fig. 1 is shown the apparatus, that is placed near the furnace. On the right are shown the automatic devices, that may, if desired, be placed at a distance. The furnace-receptacle 3 is mounted so as to be capable of revolution in either direction in respect to the electrodes f. The effect of turning the furnace-receptacle in either direction is to effect changes of current in the circuit. It is desirable that the current in the circuit of the electrodes should be kept as constant as possible, and this result is accomplished by the motor turning the receptacle.

5 is a small transformerof which the primary is the furnace-circuit itself, (amperes,) and the secondary (amperes) in the wire that surrounds it will be, as is well known, a small portionsay one one-hundredth part-of the furnace-amperes. The current from this transformer operates the solenoid 6, so that when the amperage in the furnace-circuit is high the solenoid lifts its iron core 7, which likewise falls when the furnace-amperage is low. Attached to the iron core 7 is an insulated centrally pivoted beam 8, carrying on its arms contact-bridges in pairs, substantially as shown. When the iron core 7 is drawn into the solenoid, it will cause these pins or bridge-pieces to enter certain mercury- cups 9, 1O, 11, and 12, by which electric circuits are closed that cause the motor 2 to operate and rotate the furnace, so as to cause the amperes in it to be reduced. Should the current in the furnace be too low, the core 7 will fall, as shown in the drawings, closing circuits by way of the cups 13, 14, 15, and 16, which cause the motor and furnace to turn in the opposite direction, thus causing the current in the furnace to increase. If the described arrangement is not sufficiently sensitive and if there is objection to the violent and continuous arcs that are produced at the mercury-cups when the circuits are broken, use may be made of a relay such, for example, as is shown in Fig. 2. Referring to that figure, it will be observed that the iron core 7 operates upon a centrally-pivoted lever 17, provided with contacts 18 and 19,which operate to close the circuit of a local battery 20 either through the solenoid 2]. or the solenoid 22. "hese solenoids operate to draw down against the force of suitable retractile springs arms 23 and 2 1, which carry contact bridges or pins and correspond with the arms of the lever 8 in Fig. 1 in their cooperation with the mercury- cups 9, 10, 11, 12, 13, 14, 15, and 16. The movement of the arms 23 and 2 1 is rapid and positive, so that no continuous arcs can follow. The arrangement is also very sensitive. Just as soon as the furnace-amperes exceed a certain amount the arms quickly carry the pins or contacts into the cups and the motor is started, and at the instant the normal current is restored the pins are carried out of the cups and the motor stops.

In close proximity to the furnace the manual switch 25 is placed. It gives control of the motor from that point. The type of switch illustrated in the drawings is known in the art as a three-pole double-throw switch. In the position shown the automatic mechanism will operate the motor; but if it is desired to stop the furnace the switch is thrown in the opposite position. This causes the motor to turn the other way, and it also short-circuits the solenoid 6, so that it has no power to lift the beam and pins out of the mercury- cups 13, 14, 15, and 16. I11 order to effect this, the poles on the three-pole switch are reversed, as shown and as hereinafter described. The motor will continue to turn the furnace until the attendant pulls the three-pole switch out of its contactsthat is to say, into a plane at right angles with the plane of the paper of the drawings. To start the furnace again, the attendant has only to insert the switchinto its poles in the position shown in the drawings.

For the sake of a further description cir cuits will now be traced, and in this connection it may be stated that the circuit 26 and 27 of the electrodes is assumed to be derived from some appropriate source and that 28 and 29 represent transformers by means of which a two-phase alternating current is supplied and controlled mainly for the purpose of changing the direction of rotation of the motor, although where the latter is of the type of a two-phase electric motor, as shown in the drawings, it may be used to furnish the necessary power for turning the furnace. YVhen the furnace is operating under automatic control, the switch 25 occupies the position shown. Under these circumstances there is a circuit from the transformer 5 by conductors 30 and 31 to solenoid 6, by conductor 32 to common return-conductor 33, and by conductor 31 back to the transformer 5. From the transformer 28 29 there is a circuit which operates the motor 2 in one direction or the other, according to the position of the beam 8. WVhen the latter is in the position shown in Fig. 1, this circuit is by way of conductors 35 and 36 to cup 13, by bridge-piece to cup 14:, by conductor 37 to the center arm of the switch 25, through the same by conductor 38 to the motor. Also from the transformer 29 there is a circuit by way of conductors 39 and 40, bycup15, bridge-piece, cup 16, and conductor 41 to the left-hand arm of the switch 25, and from it by conductor 12 to the other pole of the motor. When the switch-lever 8 has been shifted into its other position, there is a circuit from the transformer 28 by way of conductors 35 43, cup 11, bridge-piece, cup 12, conductor 4C1, left-hand arm of the switch, and conductor 12 to the motor, so that in this instance the circuit was from 28 to 12, instead of from 28 to 38, which change is a part of the change stats 3 that is necessary for reversing the direction of motion of the motor. From 29 there is a circuit by conductors 39 44, cup 9, bridgepiece, cup 10, conductors 45 and 37 to center arm of the switch, and thence by conductor 38 to the motor, so that 29 is connected to 38, which completes the change necessary for reversing the direction of motion of the motor. By tracing the paths of the circuit as above it will be obvious that changes of position of the lever 8 cause the terminals of the motor to be transposed in respect to the sources 28 and 29. From the motor there is a conductor 46, that leads to the common return 33. This conductor 46 carries both phases. When the hand-switch 25 is turned down through one hundred and eighty degrees, the first step toward stopping the furnace has been taken, and the circuits under these circumstances will be traced. The circuit of the transformer 5 is short-circuited through the conductor 30,the right-hand arm of the switch, the conductor 47, and the upper portion of the conductor 34. The result of this is that the weight of the core 7 shifts the lever 8 or, in the case of Fig. 2, the arm 23 into the position shown in the drawings. At the same time the conductor 41 is connected by way of the left-hand arm of the switch and the conductor 48 to the terminal 38 of the motor, and the conductor 37is connected by way of the center arm of the switch and the conductor 49 to the terminal 42 of the motor. The result of this is that the motor turns the receptacle 3 in a counter-clockwise direction, thus uncovering the electrodes by drawing the product away from them. As soon as this has been accomplished the switch may be thrown into its third position, which is at substantially ninety degrees to the plane of the paper. The result of this is the reestablishment of the circuit 30, 31, 32, 33, and 34, so that the core 7 is drawn into the solenoid 6, thus depressing the righthand portion of the lever 8 or, in the case of Fig. 2, the arm 24. In this position of the switch 25 the motor-circuit is broken at the switch, so that the motor remains at rest. Since the right-hand armof the switch is depressed, it follows that as soon as the motorcircuit is completed at the switch 25 the furnace will commence to run in a counter-clockwise direction, which is desirable in starting, and will continue to run in that direction until the core 7 is shifted in the manner described and by reason of changes in the furnace-circuit. To start the furnace again, the switch 25 is again thrown into the position shown in the drawings, and the circuits above described are again completed, so as to reestablish the automatic control of the furnace.

Having thus described the invention in connection with what are believed to be excellent means for practicing it, it may be remarked that the use of a two-phase motoris not essential. A direct-current motor will answer as well and it would preferably be series wound, and it is well known in the art how to start and reverse such a motor by means of the mercury-cups shown. The motor might be a small steam or air engine or a hydraulic engine. In such cases electromagnets or solenoids controlled by the switch 25 can be employed to open and close the con trolling-valves, the relay and mercurycups, above described, being used to start or stop the current in definite directions, or the furnace itself may be of any type and controlled in any way, the controlling mechanism of such furnace being actuated by ap paratus the principles of which have been described.

It will be obvious to those skilled in the art to which the invention appertains that modifications may be made in details without departing from the spirit of the invention. Hence I do not limit myself to the precise construction and arrangement of parts hereinabove set forth and illustrated in the accompanying drawings; but

Having thus described the nature and objects of my invention, what I claim as new, and desire to secure by Letters Patent, is-

1. A system of electric-furnace regulation comprising an electrically-controlled motor geared or attached to the movable member or element of the furnace, electromechanical motor-controlling devices in operative position to the furnace-circuit and adapted to antomatically start and reverse the motor to keep the amperes constant in the furnace, means for switching current into the motor by hand to run it in either direction, and means for permitting and preventing thecontrol of the motor by the electromechanical devices, substantially as described.

2. A system of electric-furnace regulation comprising an electrically-controlled motor geared or attached to the movable member or element of the furnace, electromechanical devices in operative position to the furnacecircuit and adapted to automatically start and reverse the motor to keep the amperes constant in the furnace, and an electric switch for controlling the motor by hand to run itin either direction and for permitting and preventing the control of the motor by the electromechanical devices, substantially as described.

In testimony whereof I have hereunto signed my name.

WILLIAM SMITH HOBBY.

In presence of- H. S. DUDLEY, J. E. MCLAUGHLIN.

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