US1761668A - Searchlight - Google Patents

Description

June 3, 1930. F. R. HOUSE 6 1,761,668

S EARCHLIGH'I Filed March 19, 1924 2 Sheets-Sheet l Ill I I ,.-mn

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June 3, 1930. F. R. HOUSE 1,761,668

SEARCHLIGHT Filed March 19, 1924 2 Sheets-Sheet 2 A I IV ..lullll: i

II [I II llli [Illllll llllllll llllll Patented June. 3, 1930 Um'rnb STATES FRANK R HOUSE, OF BALDWIN HARBOR, LONG- ISLAND, NEW YORK, ASSIGNOR, BY MESNE ASSIGNMENTS, T9 SPERBY GYROSCOPE COMPANY, INC., A GORFORATIQN 01! NEW YORK SEARCHLTGHT Application filed March it, 19%. aerial No. M0385.

This invention relates to high intensity searchlights but more particularly to the feeding mechanism for the electrodes. The invention has for its principal object the provision of a greatly simplified but more efiicient means for feeding both the positive and the negative electrodes in such manner as to insure the maintenance of a constant arc length. y

W This invention has for one of its specific objects the provision of a novel feeding and rotating means for the positive electrode which obviates the necessity of providing means for feeding the electrode and other 15 means for rotating said electrode. This invention provides for a single means for accomplishing both functions.

A. further object of thisinvention is the provision of a novel feed control meansior a the negative'electrode which is simple in construction and eificient in'operation to maintain the arc length constant.

A further object of the invention consists in providing a negative head which obviates at the necessity of transmitting current through the entire negative electrode, which has heretofore necessitated such expedients as copper plating of the electrode in order to overcome the great resistance ofiered by the said negaao tive electrode. By myinvention T transmit the current only through the forward end of the electrode adjacent the tip thereof.

A further object is the provision of means for mounting the negative electrode so as to 35 insure alignmentof the axis thereof at the tip in the vertical plane through the positive electrode axis.

' A further object of my invention is the provision of novel means in the negative head whereby the negative electrode may be retracted rapidly to its extreme ineffective limit" without the necessity of operating mechanism, such as screws, etc., which results only in very slow movement of the electrode.

A further object of this invention is the provision of means for eliminating variations in the arc length due to variations in the mechanism which nontrols the length of the are because of the radiation of the heat from v the are. My invention contemplates the provision of fiat temperature means for the purpose of controlling the arc length which is not afiected, or afiected to only an inapprociable degree, by variations in temperature.

Uther objects and advantages of this invention will be come apparent as the description Tn the accompanying thereof proceeds. drawings Fig. 1 is a front view partly sectioned, and with parts omitted for the purpose of claritying the drawings, of the operating mechanism of a high intensity arc lamp having my invention applied thereto.

Fig. 2 is a detail view showing the gearin for rotating the positive electrode.

Fig. 3 is a wiring diagram.

Fig. l is a bottom view of the device shown in Fig. l.

Fig. 5 is a plan view of the negative carbon holder.

Fig. 6 is a view of the negative carbon holder.

Fig. 7 is a section taken on the line 7-7 of Fig. 6.

Fig. 8 is a section taken on the line 8-8 of Fig. 1.

Fig. 9 is a view similar to Fig. 6 showing a modified form of holder.

Referring to the drawings, l have shown a high intensityarc light comprising a base 10 supporting brackets 11 and12 upon whlch are mounted the positive and negative heads respectively. The driving mechanism for feeding and rotating the electrodes comprises a motor 15 operating through gearing l6, l7, shaft 18, links 19, 20, said shaft and links being connected by universal omts 21, 22 to drive an eccentric 25 (see Fig. 4) carrying acrank pin 26. Said crank pin engages a ll-shaped slot 27 formed in a rec1procat-- ing member 28, comprising a shaft portion 29 operating in fixed guides 30 and 31 to constrain the motion of said member 28 to lateral reciprocatory motion in a straight line.

Said reciprocating member 28 has plvoted thereto at 32 a pawl 33 adapted to engage a ratchet 34 each time the reciprocatingmem-. ber 28 moves toward the right (in said Fig. 4) The rotation of ratchet 34 willcause rosaid shaft 35 having a gear 36 at its upper end meshing with a gear 37 at one end of the sleeve which is supported in fixed hub 38. Said sleeve has fixed thereto at its other end beyond hub 38 a bracket 40,-upon which is fixed or supported the entire positive electrode rotating and feeding mechanism so that as the ratchet 34 is rotated, bracket 40 will be rotated to cause rotation and feeding of the positive electrode by the mechanism now to be described.

Said bracket 40 has fixed thereto. a hub 41 through which extends a shaft carrying a gear 42 at its end, said gear 42 being adapted to roll around a gear 43 fixed to the end of hub 38 between bracket 40 and said hub. As bracket, 40 is rotated by the actuation of ratchet 34, planetary gear 42 is carried around the gear 43 and in so doing is rotated about its own axis. The shaft which carries gear 42, carries at its other end a worm 45 meshing with a gear 46 (see Fig. 8), said gear 46 being mounted upon a shaft 47 carrying at its other end a pinion 48 meshing With a gear 49, which is geared to a similar gear 50. Each of said gears 49 and 50 is mounted on-the same shaft with rollers 51 and 52, respectively, in engagement with the positive electrode P. It is thus apparent that actuation of ratchet 34 in rotating bracket 40 rotates also the positive electrode and at the same time feeds said electrode, because the rollers 51 and 52 are not only driven in a direction to feed the electrode but are at the same time rotated bodily together with the bracket 40, which supports them. This construction results in a continuous and constant rotary and feeding movement of the positive electrode.

Pawl 33 is normally supported upon a guide or shelf of such dimensions and so positioned that pawl 33 rides over the end of said guide'60 only near the end of the stroke of reciprocating member 28, so that said pawl engages, say, 1, 2, or 3 teeth. This number of teeth can be adjusted so that the amount by which the positive carbon is constantly fed forward is less than the normal rate of consumption of the positive electrode. With such a construction, it is apparent that the positive electrode will continue to lose ground until it burns back sufficiently to cause the flame to engage the 'so-called third electrode 61 and establish a circuit through electromagnet 62, as will be apparent from the wiring diagram of Fig. 3. When said magnet 62 is energized, it attracts its armature 63 to which is fixed the guide of shelf 60 so that the latter is drawn downwardly out of the path of pawl 33 and said pawl is now free to engage the ratchet 34 throughout the entire stroke of reciprocating member 28 toward the right. The de ree of movement of ratchet 34 for each stro e of member 28 is now much greater than the rate of constant feed when pawl 33 is riding upon guide 60 and hence the positive electrode will be fed forward much more rapidly until the flame from the arc disengages electrode 61 thus breaking the circuit through magnet 62 and permitting the shelf or guide 60 to be raised to its normal position under the action of spring 65. Thereafter, the positive electrode is again fed forward at a constant rate less than the normal rate of consumption of said electrode. From the above description it will be apparent that I em loy a single mechanism for accomplishing t e two functions of rotating and feeding the positive electrode. It will be understood that the invention applies equally well to those lamps in which the positive electrode feed is controlled by the usual thermostat in place of the third electrode, said thermostat closing the same circuit which is here closed by the engagement third, electrode.

The negativeelectrode N is adapted to be clamped in a clamp or holder 70, mounted upon a carriage 71 through which extends loosely, without threaded engagement theref with, a screw shaft 72. Engagement between the screw shaft 72 and the electrode is effected by means of a finger 75 extending from the clamp-70 (see Fig. 7) and en aging between adjacent threads of the s aft 72 but not extending to the base thereof. R0- tation of the entire carriage and electrode is prevented by means of a tongue 76 extending of the flame with the" downwardly from the carriage 71 and en gaging in a slot within bracket 12.

The clamp 70 is pivotally mounted in carriage 71 about pivotal axis 77 \so that by grasping a portion of said clamp, as for instance finger or extension 78 formed integral therewith, said clamp and electrode N may be swung upwardly to disengage finger 75 from threaded shaft 72 and permit the entire carriage, clamp and electrode to be moved rapidly downwardly to its extreme lneffective limit, since as shown in Fig. 7, the threaded shaft 72 extends freely through the carriage 71. In this manner, by inserting a suitable tool, such as pliers, and swinging the clamp upwardly, the negative electrode may be very rapidly retracted to its GXCIGIIIGIII- effective position.

The feeding of the negative electrode 15, of course, accomplished by rotatlng threaded shaft 72 in one direction or the other which causes corresponding feeding or retractive movement of the electrode. Rotation of shaft 72 in one direction or the other is accomplished by means such as gear 80 fixed at one end to the shaft 72 meshing with gear 81 on the upper end of shaft 82 extending through base 10 and having a pair of ratchet wheels 8384 at its lower end. Said ratchet wheels have their teeth oppositely disposed and said ratchet wheels are adapted to be engaged by pawls 8586, respectively, each 35 spring 94. In other 5 ber 28 moves toward the left (in Fig. 1) said pawls would ordinarily engage their ratchets to operate the'negative electrode one in one direction andthe other in the other directlon. Obviously it is desired to have only that pawl in engagement with its respective ratchet as is necessary to advance or retract'the negative electrode depending upon the length of arc. For this purpose there is provlded a guide member 90 interposed between pawls .85 and 86 and fixed to one end of a bell crank.

91 whose other arm 92 forms the armature of a voltage coil 93-. Normally said armature is retracted by a spring 94 so that guide 90 normally maintains pawl 85 out of engagement with its respective ratchet but permits pawl 86 to engage its ratchet and actuate it in a direction to constantly feed the negative electrode forwardly. When, however, the

are becomes too short the voltage is increased and sufficient current is induced in coil 93 to attract armature 92 against the action of spring 94: and oscillate guide 90 to the other end of its movement to render pawl 86 inefiective and permit pawl 85 to engage its re spective ratchet and thus retract the negative electrode. The length of are at which the retraction of the negative electrode begins may be varied by varying the tension of words the tension of spring 94 will determine the arc length.

While it has been stated above that the ten-' sion of spring 94: determines the length of arc, it has been found that variations in tem- 40 perature of the surrounding medium during the operation of the-light tend to vary the operation of coil 93 so that when a great amount of heat is radiated from the arc, coil 93 will attract armature 92 sooner than it otherwise would and thus maintain a different length of arc than the one determined upon. This would result in improper current conditions in the arc and would impair its efficient operation. To obviate this difficulty I have made coil 93 of a material having a very low resistance so that said coil'is but slightly affected by temperature variations, and providing the necessary resistance b coupling in series with said coil 93, a resistance unit 95 having a-flat temperature coefiicient.

Said units are well known in the art and may consist of a nickle-chrome alloy.q

By this means it will be apparent from Fig. 3 that the necessary resistance is supplied but that the total resistance 9395 will be affected by temperature changes only inthe ratio which resistance 93 bears to resistance 95. This ratio can be made as small as desired and will be limited by the fact that vari- ,ations of 1 to 3 volts in the are are permissible.

oftemperature changes.

It has hitherto been usual to pass the current through the negative bracket 12 and the entire length of electrode N before reaching the tip. By my invention I press the forward endflof negative electrode N into firm gripping engagement with said bracket 10 at its forward supporting seat 100. This firm contact renders it easy for the current to travel through bracket 12to seat 100 and immediately to the forward end of the electrode rather than through the l entire electrode, which offers a very high resistance. The firm engagement of the electrode N with its seat 100 is efiected by the following mechanism.

- The rear end of the electrode is adapted to be gripped in seats 101, 102 provided in two relatively movable members 103, 104. respectively, of the clamp or holder 70,said members being clamped firmly together by means such as a thumb screw 110. As hereinbefore stated the entire clamp is pivotally mounted within carriage 71 for movement about pivotal axis 7 7. The clamp is provided with extensions 112, each adapted to be engaged by one endof a spring 113 the other end of which is fixed to the pivotal shaft 77 in the carriage 71. This arrangement tends to swing the entire holder 70 clockwise'so as to press the forward end of said electrode downwardly into firfn engagement with seat 100. The projection is made of such length that when the forward end of the negative electrode engages seat 100 it does not reach the bottom of the threaded channel, thus'allowin full downward pressure to be applied to t e electrode. I

The firm engagement of the negative electrode with its seat insures alignment of the to a diameter slightly in excess of the electrode diameter to permit the electrode to slide freely therethrough when the holder 70 is raised about its pivot 77. Normally, however, the pressure between the front end of the electrode and seat 100 will cause the rear end of the electrode to be pressed against one side of the bore and held firmly in position, as shown in said Fig. 9.

In accordance with the provisions of the patent statutes I have herein described the principle and operation of my invention, together yvith the apparatus which I now consider to represent the best embodiment thereof,but desire to have it understood that the apparatus shown is only illustrative and that I 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 without interfering with the more general results outlined, and the invention extends to such use.

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

1. In a searchlight having apair of electrodes, means for rotating one of said electrodes, means operated from said first-named means for feeding said electrode, and means for driving said rotating means at a less rate than that necessary to feedthe electrode to compensate for the normal rate of consumption thereof, and for feeding said electrode at faster rate when the tip thereof has burned back a predetermined degree.

2. In a Searchlight having a pair of electrodes, an electrical conductor adjacent one of said electrodes, means for feeding said electrode, at a less rate than the normal rate of consumption thereof, and means for feeding said electrode at'a faster rate when the flame of the arc engages said conductor.

3. In a searchlight having a pair of electrodes, an electrical conductor adjacent one of said electrodes, means for constantly feed ing said electrode comprising a pawl and ratchet mechanism, means for continuously actuating said pawl, means for normally limiting the engagement of said pawl with said ratchet to limit the rate of feed of said electrode to less than the normal rate of consumption thereof, and means actuated by the engagement of the arc flame with said conductor for rendering said last-named means ineffective and permit feeding of said electrode at a faster rate.

4:. In a searchlight having a pair of electrodes, means for constantly feeding one of said electrodes, at a less rate than the normal rate of consumption thereof, said electrode feeding means comprisinga pawl and ratchet mechanism, means for continuously actuating said pawl, means for normally limiting the engagement of said pawl with said ratchet, and means rendered efiective in response to burning back of the tip of said'electrode a predetermined degree for rendering said and means for varying the rate of feed by varying the rate of rotation.

8. In an arc lamp, means for feeding and rotating an electrode at a rate different from the normal rate of consumption, and automatic means responsive to the position of the are for altering the rate of rotation and feed to compensate for the difference between the rate of consumption and the normal feed to maintain the proper position of the electrode.

9. In an arc lamp, means for feeding and rotating an electrodeat a slower rate than the normal rate of consumption and automatic means responsive to the osition of the are for increasing the rate of eed above the normal rate of feed to maintain the proper position of the electrode.

10. In a searchlight having a positive and a negative electrode, a source of power, variable speed mechanism driven thereby, a common means for feeding and rotating the posltive electrode driven from said-mechanism, and separate means driven from said source of power for feeding the negative electrode.

11. In a Searchlight having a positive and a negative electrode, a source of power, variable speed mechanism driven thereby, and a common means for feeding and rotating the positive elect-rode driven from said--mechanism.

'12. In a searchlight having a positive electrode, a common means for continuously rotating and feeding said electrode, means for varying the rate of feed and rotation of said electrode and means responsive to the position of the are for governing said rate of feed.

13. In a searchli ht having a pair of electrodes, means for. eeding the positive electrode at a rate which is different from the normal rate of consumption thereof, and means responsive to the position of the arcing ti thereof for temporarily altering the rate 0 feed to maintain the tip in the focus of the searchlight.

In testimony whereof I have afiixed my signature.

FRANK R. HOUSE.

last-named-means ineffective and permitting feeding of said elect-rode at a faster rate.

5. In an electric arc lamp, an electrode,

means for normally imparting a periodic step-by-step feed to said electrode, and means for varying the amount of feed imparted to said electrode per period.

6. In an electric arc lamp, an electrode, a common means for normally imparting a periodic step-by-step feed and rotationto said electrode, and means responsive to the position of the are for varying the amount of feed and rotation imparted to said electrode per period.

7. In an arc lamp, means for feeding and rotating an electrode at a predetermined rate,

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