US657450A - Electric-arc lamp. - Google Patents

Description

No. 657,450. Patented Sept. 4, I900.

I L B PRENTISS.

ELECTRIC ABC LAMP.

(Application filed July 15, 1899.)

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UNITED STATES PATENT EETCE.

IRVING R. PRENTISS, OF LYNN, MASSACHUSETTS, ASSIGNOR TO THE GENERAL ELECTRIC COMPANY, OF NEW YORK.

ELECTRIC-ARC LAM P.

SPECIFICATION forming part of Letters Patent No. 657,450, dated September 4, 1900.

' Application filed J ly 15, 1899. Serial No. 723,893. (No model.)

Ton, whom it may concern:

Be it known that I, IRVING R. PRENTISS, a citizen of the United States, residing at Lynn, in the county of Essex, State of Massachusetts, have invented certain new and useful Improvements in Arc-Lamps, (Case No. 944,) of which the following is a specification? This invention relates to arc-lamps. It-s object is to provide a focusing lamp in which the arc is maintained on a substantially-uniform level and to dispense with gearing or wheel-work in its control.

In carrying out the invention I provide a gravity-fed positive electrode and a negative electrode relatively movable thereto intermittently controlled by a derived-circuit coil which raises it at short intervals, so as to maintain the are at a substantially-uniform level, suitable gripping or detaining devices being provided for supporting the negative against downward displacement when fed toward the arc. By such an organization each electrode is practically under independent control, the negative being fed from time to time, in accordance with the carbon consumption, toward a practically-constant arc-level and the positive being permitted to gravitate downwardly at a different rate of feed.

Other novel features will be definitely indicated in the claims appended to this specification.

In the accompanying drawing, which diagrammatically illustrates the invention, 1 2 represent, respectively, positive and negative electrodes of a focusing arc-lamp, each preferably mounted on an independent carbonholder 3 4:, to which the electrode is clamped in any suitable way. The are is sprung and its length graduated by means of a magnet-coil 5 in series with the are, said coil controlling an armature, to which is linked one element of the clutch for the carbon-holder. The particular type of clutch shown in the drawing is a Brush clutch in which two jaws are pivotally connected to a tilting lever 6, linked to the armature. One of these jaws spans the carbon-holderand the other has a comparativelysharp edge, which lies parallel with and engages one side of the carbon-holder. A stop 7, fixed to a stationary part of the lamp or lamp-frame, controls the feed intermissions,

.around the arc to regulate the feed.

the clutch being released and permitting the carbons to come into contact under the influence of gravity when the projection 8 on one of the clutch members drops against the stop. The controlling-magnet for the positive electrode is provided also with a differentially-acting coil 9 in a derived circuit The negative-carbon holder is fed upwardly by the derived-circuit coil 9, acting on an armature which controls a lifting-clutch 10. A suitable detent fixed to the lamp-frame, which may with convenience be a clutch similar in construction to that already described and which is shown at 11, is provided to hold the .negative carbon when fed upwardly by the shunt-coil which controls it. This controlling-coil is preferably an independent coil from that used on the controlling-magnet for the positive carbon, but might be the same, though with a less degree of advantage. The active range of the armatures should be proportioned according to the relative consumption of the electrodes, so that the amount of upward feed of the negative shall be just enough to maintain a practically-constant arc-level.

12 is a resistance in circuit with the cutout 13 in a shunt around the lamp, which maintains the integrity of the supply-circuit when the lamp is not in operation.

With this construction the operation of the lamp may be-described as follows: When the current is turned on, the series coil 5 lifts the positive electrode and strikes the arc, the clutch 6 binding on the carbon-holder upon an upward movement of the armature. The cut-out 13 is simultaneously opened. As the arc lengthens under the consumption of carbon the differential coil 9 weakens the lifting-magnet and shortens the arc. This action will continue until the controllingarmature moves over a sufficient range to bring the projection 8 into contact with the fixed stop 7, when the clutch releases the carbonholder and the positive electrode is fed downwardly under the influence of gravity. When the current through the shunt-circuit reaches a maximum value, the negative carbon is lifted by the action of the coil 9 and clutch 10, being held in its raised position by clutch 11., which permits upward movement, but checks any downward movement. The throw of the armature controlled by the coil 9 should be adjusted so as to compensate for the consumption of the negative carbon and will vary, other things being equal, according to the size of the carbon and the amperage of the circuit. Current maybe led into the positive and negative electrodes by brushes engaging the carbon-holders, as shown at 12 and 13, or in any other convenient way.

It will thus be seen that I provide a focusing arc-lamp in which the arc is maintained on a substantially-uniform level by simple and inexpensive feeding devices and with out the employment of gearing or wheelwork.

The type of cut-out employed may of course be different from that shown and may provide for closing the circuit around the lamp in case of accident to the carbons, as onthe wellknown Brush lamp. As the cut-out forms no part of my invention, I have not deemed it necessary to illustrate in full the various details of practical arc-lamps.

\Vhat I claim as new, and desire to secure by Letters Patent of the United States, is-

l. A focusing arc-lamp, comprising relatively-movable positive and negative electrodes, a series regulating-coil for the positive, a shunt-coil for intermittently lifting the negative, and a clutch fixed to the lamp for supporting the negative when fed up ward.

2. A focusing arc-lamp, comprising relati vely-movable positive and negative carbons, means for striking the arc, and a shunt-circuit controlling an intermittent upward and downward feed of the negative and positive electrodes, respectively.

3. A focusing arc-lamp, comprising movable positive and negative electrodes,the positive being fed by gravity, a clutch controlling said feed, a differential coil having windings in series and shunt relation to the arc respectively for controlling the clutch, an independent clutch and a coil in the shunt-circuit for intermittently operating it to raise the negative electrode, and a detent for locking said negative electrode in position when raised.

4. A focusing arc-lamp, comprising a gravity clutch-fed electrode, and a negative electrode intermittently raised by a lifting-coil in shunt to the arc, a detent for holding it in position when raised, the range of movement of the shunt-controlled armature being graduated according to the average rate of consumption of the negative electrode.

In Witness whereof I have hereunto set my hand this 12th day of July, 1899.

IRVING R. PRENTISS.

lVitnesses:

BENJAMIN l3. HULL, MABEL E. JACOBSON.

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