US1423497A - Electric-arc mechanism for searchlights - Google Patents

Description

L. C. JUSEPHS, JR. ELECTRIC ARC MECHANISM FOR SEARCHLIGHTS.

APPLICATION FILED JUNE 9. 1939.

1,423,497, Patented July 18, 1922.

L. C. JOSEPHS, JR. ELECTRIC ARC MECHANISM FOR SEARCHLIGHTS.

APPLICATION FILED JUNE 9,1919.

Patented J uly 18, 1922.

3 SHEETS SHEET 2.

L. C. JUSEPHS, JR. ELECTRIC ARC MECHANISM FOR SEARCHLIGHTS.

APPLICA ION FILED JUNE 9.1919.

Z w 2 W B h hm J P0 Iv d3 2 W n 1% a P UNITED STATES PATENT OFFICE.

LYMAN C. JOSEPHS, JTL, OF THE UNITED STATES ARMY, ASSIGNOR TO ,NEWTON D.

I BAKER, SECRETARY OF WAR, TRUSTEE.

ELECTRIC-ARC MECHANISM FOR SEARCHLIG'HTS.

Specification of Letters Patent.

Patented July 18, 1922.

(FILED UNDER THE ACT OF MARCH 3, 1883, 22 STAT. In, 625.)

ment in Electric-Arc Mechanism for Search lights, of which the following is a specification. 7

The invention described herein may be used by the Government, or any of its officers or. employees in prosecution of work for the Government or by any other person in the United States without payment of any royalty thereon.

My invention relates to electric arc mechanisms for light projectors or searchlights and has for its object to provide a simple and reliable arc mechanism and means for operating same.

Further objects of my invention are to provide means for automatically controlling the burning of the arc' and for readily dissipating the heat generated by it.

In my co-pending application, Serial No. 301,569, filed June 7, 1919, there is shown and described a portable field Searchlight of the open type, in which the arc mechanism is carried in an enclosing casing that is sup:

ported and operated from the front of the mirror. The are mechanism shown therein, while extremely simple, is not well adapted for properly controlling the burning of a high intensity arc.

According to the present invention, I provide an improved form of arc mechanism that is particularly well adapted for burn ing a high intensity are and means for controlling the operation of the same, that is advantageously arranged for the convenience of the operator.

I further provide means for electromagnetically controlling the flame of a high intensit arc and for dissipating the heat generated by it.

In the accompanying drawings:

Fig. 1 is a three-quarters view in per-.

ing from opposite ends of the arc casing.

Fig- 5 is a transverse sectional view of thearc casing and mechanism.

Fig. 6 is an enlarged detailed view of the negative carbon holder along the line 5-5 of Fig. 5.

Fig. 7 is a detailed sectional view of the rotating mechanism for the positive carbon.

Fig. 8 is a similar view of the negative carbon holder on the line 88 .of Fig. 6.

Fig. 9 is a fragmentary detail of the positive carbon feeding mechanism.

Fig. 10 is a similar view of the motor construction associated with the feeding mechamsm.

Fig. 11 is a sectionized detail of the motor construction shown in Fig. 10.

Fig. 12 is a detail of the negative electrode feeding mechanism.

- Referring to Figs. 1 and 2, the carriage generally comprises a rectangular frame 1 supported by axles 2 that are provided with wheels 3. A turntable 4 is rotatably carried upon the frame 1 by rollers 5 and is provided with upward extending trunnion. arms 6. It is to be understood that the turntable and carriage may be of any suitable form, as they form no part of the present invention.

A mirror frame 7 is pivotally mounted between the trunnion arms 6 by means of trunnions 8. A mirror 9 is carried within the frame 7. A hollow cylindrical casing 10, which contains the arc mechanism, is centrally supported in front of the mirror 9 by a plurality of arms 11 that are secured to the rim of the mirror frame 7.

Referring now to Fig. 5, the arc mechanism comprises a positive carbonhead 12 centrally supported within the casing 10 by means of radial arms 12* secured to. the easing 10. A cupshaped shield 13 surrounds the head 12 and 'is secured thereto by means of bolts 14. The shield 13 is insulated from the head 12 by insulating washers 15 and 16. The shield 13 is preferably composed of copper, or any other metal that easily conducts heat and is made of ample cross section, so that a considerable mass of metal of high heat conductivity and having a large radiatin surface, surrounds the positive head 12. he shield 13 is provided with a slot 17 the purpose of which will be hereinafter described. A tip or bushing 18, also formed of a metal having a high heat con ductivity, such as copper, extends through a central opening 19 in the shield 13 and is clamped against the insulating washer 15 by means of the shield 13 and the insulating washer 16, which is provided with a flange opening 20. v

A positive carbon 21 extends through the head 12 and the bushing 18 and projects beyond the end thereof. Current is conducted to the carbon 21 by means of brushes 22, which are located in slots 23 provided in the head 12 and flexible leads 24 that are connected to a cable 25 which extends through the casing 10. The carbon 21 is adapted to be moved longitudinally b means of a roller 26 that engages the si e of the carbon 21 and is mounted on a shaft 27. The shaft 27 is rotatably supported by means of a bracket 28 that is secured tothe arms 12*. As best shown in Figs. 1 and 3, the shaft 27 is connected to a second shaft 29, which extends to a point outside the easing 10 by means of an insulating coupling 30. An operating shaft 31 is mounted at one end in a bracket 32 secured to the rim of the mirror frame 7 and is connected at its other end to the shaft 29 by means of a universal joint 33. The shaft 31 is provided with an operating handle 34 by ,means of which movement of the positive carbon 21 may be obtained through the shafts 27, 29 and 31.

The positive carbon 21 is adapted, to be given a turning movement by means-of a wrench device, best shown in Figs. 5 and 7. A lever 35 is provided with a bifurcated portion between the arms of which a second lever 36 is loosely pivoted'at the point 36. The lever 35 is adapted to be given a reciprocating motion by means of a rod 37 that is connected by an insulating coupling 39 to a rod 38 that extends through the casing 10. The rod 38 is connected at its end to a crank disc 39, as'best shown in Figs. 10 and 11. The disc 39 is driven by a worm wheel 40 that is in mesh with a worm 41 mounted on the shaft 42 of an electric motor 43. The motor 43 is supported from the rim of the mirror frame 7 by means of a bracket 44. The reciprocating motion of the rod 37 causes the levers 35 and 36 to alternately engage and disengage the carbon 21, in a manner similar to the action of a Stillson wrench, thus imparting a step by step turning movement to the carbon 21.

Referring again to Fig. 5, a ne ative carbon 50 is supported by a head 51 that is carried at the end of a conductor-arm 52. The conductor arm 52 asses through the shield 13, being insulate secured to one of the arms 12 by means of bolts 54 and insulating plates 55. Current is conducted to the arm 52 by means of a therefrom at 53,- and is flexible conductor 56=from whence it passes along the arm 52 and then upwardly to the head 51. The head 51 is disposed at an an agle to the axis of the positive carbon 21, so that the flame from the negative carbon 50 impinges upon the positive carbon 21 in such a manner as to tend to keep the positive flame within the crater formed at the end of the positive carbon.

It is well known that in order to maintain a good crater when burning high intensity carbons, the negative flame should impinge against the end of the positive carbon at such an angle that the resultant flame of the two carbons sweeps away from the crater. However, the tendency always exists for the flame to waver, due to irre lar burning or currents of air, which resu ts in the formation of a poor crater with consequent loss of light.

The burning of a high intensity are with a mechanism arranged as shown in Fig. 5, is stabilized by the magnetic field surrounding the conductor arm 52, which tends to direct the flame away from the field. This tendency of the arc flame is further increased by the fact that the slot 17 in the shield 13 is located opposite the conductor arm 52, so that the heated products of combustion from the arc naturally pass through the slot 17, rather than around the edges of the shield .13. The combined influence of magnetic field and a ventilating passage oppositely disposed with respect to the arc, results in a Very steady burning of the are, so all that is necessary to maintain a proper crater is to rotate the positive carbon 21.

The negative carbon is adapted to be moved longitudinally by means of rollers 57, which are located in openings 58 rovided in the negative head 51. The roilers 57 arepivotally mounted in brackets 59 and are adapted to be held in engagement with the sides of the carbon 50 by means of levers 61. The levers 61 are ivotally mounted on the head 51 at 62 and are held in engagement with the brackets 59 by means of springs 63, which are secured to rin 6t that surrounds the carbon 50. One 0 the rollers 57 is mounted on a shaft 65 that is connected through an insulating coupling 66 to a second shaft 67 that extends outside the casing 10. An operating'rdd 68 is carried at one end by a bracket 69 supported from the rim of the mirror frame 7 and is secured at the other end to the rod 67 through a universal joint 70. The rod 68 is provided with a handle 71 by means of which'the rollers 57 may be turned through the shafts 68, 67 and 65.

From the foregoing, it is apparent that an arc mechanism constructed in accordance with my invention is exceedingly simple and that its operation may readily be controlled from the rear of the mirror frame. F urnetic field and natural draft and the heat from the arc is readily' dissipated by the presence of a mass of metal of high heat conductivity and large radiating surface surrounding the positive carbon.

While I have shown my invention in its simplest form, it is obvious that further imrovements and changes may be made therein within ,the scope of the appendedclaims.

I claim as my invention:

1. In a high-intensity arc mechanism, the combination with positive and negative carbons, a shield surrounding the positive carbon and provided with an openin and a housing for the shield, of means or electroinagnetically directing the arc flame into said opening.

2. An electricarc mechanism, comprising a shield, providing a radiating surface and having a ventilatin opening, a casing surrounding the shie d, a positive electrode slidable through said shield, a negative electrode cooperating with the positive electrode to produce an arc flame, and means for establishing an electromagnetic field in the vicinityof the arc flame to direct the latter toward the ventilating opening.

3. An electric arc mechanism, comprising a shield providing an extensive radiating surface of high heat conductivity and having a ventilating opening, a casing surrounding the shield, a positive electrode slidable through said shield, a negative electrode co-operating with the positive electrode to produce an arc flame and means for establishing an electromognetic field in the vicinit of the arc flame to direct the latter towar said ventilating opening.

4. An electric arc mechanism comprising a radially slotted shield providing a radiating surface of high heat conductivity, a casing surrounding the shield, at positive electrode slidable through the central portion of said shield, a negative electrode 00- operating with the positive to produce an arc flame, and means for establishing an electromagnetic field in the vicinity of the arc flame to direct the latter toward the slot in said shield.

5. An electric arc mechanism com rising a shield radially slotted above the p ane of its horizontal axis and providin a radiating surface of high heat conduct1vi ty, a casing surrounding theshield, a positive electrode slidable through said shield,.a negative electrode co-operating with the posi tive electrode to produce-an arc flame and means for electromagnetioally controlling the arc flame and directing the latter toward the slot in said shield.

6. In a high intensity are mechanism the combination with positive and negative electrodes, a slotted shield surrounding the positive electrode and a housing inclosing the shield; of means for directing the are flame I through the slot of said shield.

LYMAN o. JOSEPHS, JR.

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