US1645966A - Arc lamp - Google Patents

Description

Oct. 18, 1927. 1,645,966

M'. L. PATTERSON ARC LAMP Filed March 16. 192.2 2 Sheets-Sheet 1 6.2 avwem toz 2 Sheets-Sheet 2 M. L. PATTERSON ARC LAMP Filed March 16. 1922 Oct. 18, 1927.

Patented Oct. 18, 1927.

UNITED STATES 1,645,966 PATENT OFFICE.

MARTIN L. PATTERSON, OF IBOGOTA, NEW JERSEY, ASSIGNOR TO THE SPERRY GYRO- SCOPE COMPANY, OF BROOKLYN, NEW YORK, A CORPORATION OF NEW JERSEY.

ARC LAMP.

Application filed March 16, 1922. Serial No. 544,191.

This invention relates to are lamps, and more particularly to means for extingulshing the arc and stopping its operatlng mechanism when one or both of the electrodes has stopped feeding.

In modern arc lamps, and especially those used in searchlights or in motion picture projecting apparatus, the arc electrodes are fed through their respective holders rather than advancing the holders with the electrodes. Also, preferably, a separate feed is provided for each electrode, the negatlve feed being automatically controlled in accordance with the are potential, i. e., are

length, as determined by the positions of the arcing tips of the electrodes and the positive electrode feed being governed by the position of its arcing end. Such a feedv has a serious efi'ect, however, i. e., when the outer end of an electrode has passed beyond the means for feeding it through the holder,

no further feeding takes place, the inner end or tip may continue to burn away until, if not watched, it will burn back into the metallic holder and arcing will take place between the holder and the opposite electrode, thus causing damage to, or destruction of the holder.

.It is one object of the present invention to provide means forautomatically extinguishing he are when one or both of the electrodes stop feeding, because of having passed beyond their feeding means.

Other objects and advantages will hereinafter appear.

In the accompanying drawings wherein I have shown what I now consider to be the preferred embodiment of my invention,

Fig. 1 is a side elevation, partly in section, of a searchlight mechanism, including a wiring diagram. Y

Fig. 2 is a side sectional view of the positive electrode supporting head and the means for controlling the position of said electrode.

Fig. 3 is an end section of the positive feed mechanism.

In the drawing there is shown a control box 10 slidably mountedby projections 11 operating in guide-slots. 12 in theside-walls which extend downwardly from the drum of the light. Upon box 10 are mounted the sup orts 15 and 16 for the ne ative carbonhol er 17 and the positive car on-holder 18, I respectively. Within the control box 10 is mounted the mechanism for controlling the feeding of the carbons 19 and 20, and for a full disclosure of said mechanism, reference is made to the patent to Elmer A. Sperry, No. 1,362,575, granted December 14, 1920. It may be briefly stated however, that the negative carbon is held between rollers 21- on opposite sides thereof and that Said rollers are operated to feed the carbon in one direction or the other by means of gearin a. 22, 23, 24 operated by a rod 25 connecte by a link 26 and gearing 27, 28 to ratchetwheels 29 and 30, having oppositely disposed teeth. Said ratchet-wheels are mounted on a fixed shaft 31, but pawls 32 and 33 000perating with ratchet-wheel 29 and pawls 34 and 35 cooperating with ratchet-wheel 3O 'are mounted upon a slide 40 which is reciprocated by a bar 41 operated by a motor 100 and other mechanism (not shown), the shaft 31 operating in a slot 39- in the wall of slide 40. The pawls are normally held out of contact with the ratchet-wheels by links42 and 43 fixed to opposite arms of a lever 44 to the end of one of which arms is pivoted the core 45 of a solenoid 46. The solenoid is of such strength that its magnetism is sufficient to draw u on core 45 to counterbalance a spring 4 when the arc is of proper length and voltage, but as the arc lengthens due to burning away of the carbons, the voltage increases, the core 45 is more strongly attracted by the solenoid and lever 44 is tilted to bring one set of pawls int engagement with their corresponding .1 ratghet-wheel. With each reciprocation of slide 40, said ratchet-wheel will be operated to feed the negative carbon toward the positive carbon. When the proper voltage is established, core 45, lever 44, and hence the r set of operatin pawls will move back to counter-balance position. Should the voltage fall below'the predetermined point, the magnetic pull by the solenoid upon core 45 would 7 be insuflicient to counter-balance. spring 47, and lever 44 would be tilted in the opposite direction to render the other set of pawls eflective to move the negativecar bon away from the positive carbon until the voltage reaches'the predetermined point.

vWhen the tip of the positive electrode movesaway from the focal oint of the reflee-tor, the rays of light will e concentrated by a 'lens 111to pass through an aperture 112'in the thermostat and strike upon the 110 so that rod 50 is moved upwardly into openings 120 in a collar 121. Said collar when rod 50 is in lowered position, normally is in frictional engagement with a gear 53 which is constantly rotated through gear 52, shaft 51 and gearing within the control box, b motor 100. The collar 121 is provided wit an internal thread 125 with which meshes a gear 126 mounted upon the hub 127 of gear 53, said gear 126 being fixed to a shaft 128 to the opposite end of which is fixed a pinion 129 meshing with a gear 130 fixed upon a shaft 131 to which is also fixed on feed roller 132. Said feed roller 132 and a cooperating feed-roller 133 are carried by arms 134 and 135 'pivotally mounted on the hub 127 of gear 53 and pressed into engagement with the positive electrode by a spring 136. Gear 130 meshes with a gear 137 fixed to the shaft 138 to which feed-roller 133 is attached.

It will be apparent from the above de- 'scription that if gear 126 is rotated, gear 129 will also be rotated to rotate in opposite directions gears 130 and 137, and hence,

rollers 132 and 133. While collar 121 moves with gear 53 all of the hereinbefore mentioned gears and rollers will be carried thereby and there will be no movement of gears 126 and hence of the rollers relative to thecollar. But if ,the collar 121 is held while gear 53 rotates, the gear 126 Will travel around the thread 125 and will be rotated about the axis of shaft 128 to rotate the feedopenings 120 in the collar 121, car 126 will 7 rotate and the feed-rollers will eed the posit1ve carbon forwardly. When the positive carbon reaches the focal point, the rays of light from said carbon will not be concentrated by lens 111 to pass through opening 112, and hence strip 113 will not be energized to cause closing of the circuit by contacts 115 and 116. The circuit will thus be broken, the magnet 117 will be de-energized to release armature 118 and cause rod 50 to drop out of engagement with the openings in dollar 121. No further feeding of the positive carbon will take place until the tip thereof burns away from the focal point.

From the above description it will be apparent that the negative electrode is fed toward or away from the positive,.in according rollers, the thermostat controlled mech-.-

anism would still function to rotate the rollers in a direction for feeding the positive carbon inwardly to maintain the inner end of the positive carbon at the predetermined point, but the carbon having left the rollers,

the latter will rotate wthout feeding the positive carbon. At the same time the negative feed would continue to maintain the arc. This results in the inner end of the positive carbon burning into the head and injuring the mechanism'therein. To prevent such an occurrence the head 18 is provided with a contact 60 positioned outwardly of the rollers in said head and adapted to bring intoaction means for extinguishing the arc when the carbon becomes too short. Said contact preferably forms part of the shunt circuit which includes the solenoid 46. It will be apparent that as soon as the outer end of the positive carbon passes inwardly beyond contact 60, and before it has left the rollers, the circuit through solenoid 46 will be broken, spring 47 will no longer be counterbalanced and a set of pawls will be brought into contact with the corresponding ratchet-wheel to feed the negative carbon outwardly, thus lengthening the arc, increasing the arc potential and finally extinguishing the arc. Also shunted across the main lines 61 and 62 is a circuit-breaker indicated diagrammatical- 1y at 64 and operated by a high voltage coil 65. The latter is designed not to function when the are potential is of a certain, normal predetermined value, but upon a predetermined increase in are potential it will operate the circuit-breaker to break the circuit of the motor and the other feed operating mechanism and also the arc circuit. Hence, when the outward end of the positive carbon passes beyond the contact 60 and the negative carbon is operated outwardly to increase the are potential, the high-voltage coil will, when the predetermined increase in potential has been effected, operate the circuit-breaker. While the circuit through the arc may be broken at the arc before the circuit breaker opens, the circuit-breaker is desirable for at least tworeasons, first, it will break the are before the negative has fed back too far so as to endanger the reflector 101 and second it breaks the circuit of the motor 100 to stop the feed whichthe breaking of the circuit at the arc does not do. The circuit-breaker device is rendered effective or ineffective at will by a switch 67. While a two-pole circult-breaker has been illustrated, it will be understood that a single-pole circuit-breaker may be used if desired.

If the negative carbon is consumed until its outer end leaves the rollers in head 17, the arc will lengthen, since the inner end of the positive carbon is held in constant position, and the are potential will increase until it is extinguished at the are or until the high-voltage coil operates the circuit-breaker. The device will, of course, function also in the exceptional case where both carbons leave the respective feed rollers substantially simultaneously.

The head 18 comprises, in addition to the parts 140 and 141 in which are contained the feed-rollers and the actuating mechanism; associated therewith, a nose-picce 145. The part 141 ,is provided' with a hub portion 146 which extends forwardly into the nosepiece from which it is insulated by insulating material 147. The hub portion 146 extends over the hollow support 16 through which air is blown from a blower or fan 150 and distributed around said hub portion by fins or baflies 151 fixed thereto to cool the electrode and holder. The air issues through an aperture 152 in the nose piece. The portion of the nose piece in front of insulating material 147 is provided with a bore through which the positive electrode extends and with an annular chamber 155 surrounding said bore. The bore is insulated from the electrode by a dead air space 153.

In order to prevent diffusion of the light issuing from the negative electrode, the nose piece 145 maybe provided with a lightgathering peripheral extension or screen 160 ormed preferably integraltherewith. The screen diverges in a direction opposite to that of the rays of light issuing from the negative electrode and since it is positioned near the negative electrode, it will effectively intercept the rays of light issuing from the negative electrode.

In accordance with the provisions of the patent statutes, I have herein described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and tthat the invention can be carried out by other means. Also, while it is designed to use the various features and elements in'the combination and relations described, some of these may be altered and others omitted Wltl'lOllt interfering with the more general results outlined, and .the invention extends to such use.

Having herein described my invention what I claim and desire to secure by Letters Patent is:

1. The combination with an arc lamp having a pair of electrode holders and means for feeding an electrode through each holder, of means controlled by the position of the outer end of one of the electrodes with a circuit-breaker in the lamp circuit, and a coil connected across said circuit for actuating said circuit-breaker when the potential drop across the arc reaches a predetermined value.

4. The combination with an arc lamp having a pair of electrode holders and means for feeding each electrode throughits holder, of means for withdrawing one of said electrodes to lengthen the arc and increase the are potential when the other electrode stops feeding, and means for automatically breaking the feed circuits when the potential drop across the arc reaches a predetermined value.

5. The combination with an arc lamp hav ing a pair of electrode holders and means for feeding an electrode through each holder, said means comprising feed-rollers engaging said electrodes, of means controlled by the length of one of said electrodes for automatically breaking the arc circuit before said outer end reaches its feed-rollers.

6. The combination with an arc lamp having a pair of electrode-holders and means for feeding an electrode through each holder, said means comprising feed rollers engaging said electrodes, of means controlled by the position of the outer end of one of said electrodes withurespect to its holder,

before said outer end reaches its feed-rollers,

7 The combination with an arc lamp having a pair of electrode holders and means for feeding a positive electrode through one of said holders and a negative electrode through the other of said holders, said means comprising feed-rollers engaging said electrodes, of means controlled by the position of the outerend of the positive electrode with respect to its holder, before said outer end reaches its feed-rollers, for feeding the negative electrode backwardly to lengthen the arc to extinguish the same, and other means for automatically breaking the lampclrcuit at such'time. v

8. The combination with an arc lamp having-a pair of electrode holders and means for feeding an electrode through each holder, said means comprising feeding means engaging said electrodes, of means controlled by the length of one of said electrodes, before said outer end reaches its feed-rollers, for feeding the other electrode backwardly to lengthen the are, a circuit-breaker in the lamp circuit, and a voltage coil connected across the circuit for actuating said circuitbreaker when said are is extinguished or the potential drop thereaoross reaches a predetermined value.

9. The combination with an arc lamp having a pair of electrode holders and means by the breaking of the circuit through said' magnet by said outer end feeds the other electrode backwardly to lengthen the are to extinguish the same and increase the arc potential.

10. The combination with an arc lamp having a pair of electrode holders and means for feeding a positive electrode through one of said holders and a negative electrode through the other of said holders, said means comprising an electromagnet, and feeding rollers engaging said electrodes, of a contact in the circuit of said magnet and positioned outwardly of the positive feed-rollers, so that the outer end of the positive electrode engages and passes beyond said contact before engaging the positive feed-rollers, the circuit'through said magnet being broken when the outer end of the positive electrode passes beyond said contact, means whereby the breaking of the circuit through said magnet operates the negative electrode outwardly to lengthen the arc and additional means responsive to the lengthening of the are for automatically breakmg the lamp circuit.

11. The combination with an arc lamp having a pair of electrode holders and means for feeding an electrode through each holder, of means controlled by the position of the outer end of one of theelectrodes for extinguishing the arc and rendering inoperative the feeding means.

12. In an arc lamp adapted to employ a pair of electrodes, means for feeding the electrodes and means controlled by the arc po tential for extinguishing the arc and stopping the feeding means.

13. In an arc lamp adapted to employ a pair of electrodes, of means for feeding one electrode to position, means for advancing or retracting the other electrodein accordance with the arc length, and means for causing said last named means to retract said electrode to extinguish the are when said first named means is about to cease to function.

In testimony whereof I have aflixed my signature.

MARTIN L. PATTERSON.

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