US503538A - Electric-arc lamp - Google Patents

Description

(No Model) Witwe/aoco L. E. HOWARD. ELECTRIC ARG LAMP.

-Patent 2 Sheets-Sheet 1.

ed Aug. 15, 1893.

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L. E. HOWARD. ELECTRIC Anc. LAMP.

No. 503,538. 4 Patented Aug. 15, 189s.

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LOUIS E. HOWARD, OF PLAINFIELD, NEW JERSEY.

ELECTRIC-ARC LAMP.

SPECIFICATION forming part of Letters Patent No. 503,538, dated August 15, 1893. Application filed December 20, 1892. Serial No. 455,754. (No model.)

To all whom it may concern,.-

Be it known that I, LOUIS E. HOWARD, a citizen of the United States, residing in Plainfield, in the county of Union and State of New Jersey, have invented certain new and useful Improvements in Electric-Are Lamps, of which the following is a specification.

The object of my invention is to increase the eiiiciency and prolong the duration of the electrodes of an electric arc-lamp, and to this end my invention comprises a chamber with transparent walls inclosing the portions of the positive and negative electrodes between which the arc is formed, which chamber is fitted to the negative carbon, so as to be practically air and gas-tight, but which is provided with an opening above the horizontal plane of the arc and adjacent to the positive electrode. i

My invention also embraces other features Which will be hereinafter more particularly described and pointed out in the claims.

In the accompanying drawings, which illustrate a form of electric arc-lamp embodying my invention, Figure l is an elevation, showing the inclosing outer glass in section. Fig. 2 is a vertical transverse section of the transparent chamber inclosing the light-giving portions of the electrodes. Fig. 3 is a horizontal section of the same in the plane of the dotted line 3 3. Fig. 4 is a similar section illustrating the modified form of chamber shown in vertical section in Fig. 5. Fig. 6 is a plan and Fig. 7 'an elevation of the hood or reflector, and Fig. 8 illustrates an alternative construction of the negative electrode shown in Figs. 2 and 5.

In the drawings, A is a closed oase or box containing the mechanism by which the upper or positive electrode is caused to be fed downward by the automatic action of the electric current, or a portion thereof, traversing the circuit. This mechanism, in itself, forms no part of my invention,-and may therefore be of any suitable and well-known construction adapted to the purpose. The vertical carbon-holder A', which is moved by the mechanism last referred to, terminates in a clamp A2 in which the upper or positive carbon C is grasped, held and moved. Depending from the box 0r case A is a frame B, B, which serves to support the negative electrode D and its dependent parts, as hereinafter described. The negative electrode D is heldin a suitable clamp E ailixed to the lower yoke of the frameB. I prefer to construct the negative electrode with a central core or tip of carbon, which core or tip is surrounded by a body of heat-conducting metal, which tends to reduce its temperature when subjected to the intense heat of the arc, as hereinafter explained. The chamber which incloses the portions of the positive and negative electrodes, between which the arc is formed, consists preferably of a cylinder E of glass, or other transparent and sufficiently heat-resisting material. This cylinder is set into a flanged socket or base F, of non-conducting and non-combustible material, such, for example, as that commercially known as vulcabeston, which socket or base is supported by a collar d upon the negative electrode. The socket or base F is iitted airtight to the negative electrode D which passes through its center. A disk of asbestus felt e may with advantage be placed within the base or socket F to protect it from injury by the heat developed in the arc and also to serve as an air-tight packing for the joint between the cylinder and socket. The upper end of the cylinder E rises a short distance above the upper end of the negative electrode D, which is the point at which the arc is formed.V The top of the cylinder E is closed by a head G,

the liange gof which forms a socket which receives the upper end of the cylinder. This head is of the same material as the base F, and is in like manner protected from the effects of excessive heat by a disk of asbestus felt e. A hollow cone H preferably of metal, is fitted into the head G, and this cone is provided at its upper and smaller end with a metallic thirnble H', which has an axial opening through which the positive electrode C may freely pass in its descent. The interior of the cone H may with advantage be provided with a metallic reector h of aluminium or silver, which may be ilanged out at the bottom to form an annular disk covering the lower surface of the asbestus disk e. The base F and the head G may be clamped together so as to hold the cylinder E firmly in place between them, by bolts I I as shown in Figs. 2 and 3, but in case the obscuration of light caused by such bolts is for any reason objec- ICO tionable, the alternative construction curved projections a o; are formed upon the exterior of the cylinder E, and by horizontally rotating said cylinder, these are caused to engage with curved recesses formed at y y within the flanges ofthe base F and the head G, and as these recesses are in the form of a portion of a spiral or screw-thread, the parts thus become firmly secured to each other, whereby the use of the bolts I I is rendered unnecessary.

The cylindrical chamber E, which contains the light producing' portion of the apparatus, is preferably inclosed within a transparent or translucent globe K, which is supported upon a fianged collar 7a affixed to the lower part or yoke of the frame B. The globe K has a circular opening' at the top, which is covered with a closely fitting conical reflecting hood L, made in two separable parts Z Z2 so as to admit of convenient removal and replacement. These two parts are hinged to each other at Z3 and are also secured together at an opposite point by a spring-latch m which takes hold of a shoulder m', but may easily be lifted and disengaged therefrom. The hood L is fitted with non-conducting thimbles at o and 0 through which pass the descending portions B of the frame, and also with a similar thimble at o forming a fixed guide through which passes the positive electrode C and is thereby held rigidly in position during its descent.

It has been hereinbefore stated that it, the negative electrode is constructed with a central core or tip of carbon, surrounded by a body of heat-conducting metal. One method ot' effecting this is illustrated in Fig. 2, in which the positive electrode C is in contact at its lower end with a block of carbon D forming the tip of the negative electrode, which is inserted into the end of a solid rod of metal D having' considerable mass and being a good conductor of heat. In Fig. S I have shown a different, and in some respects a preferable construction, in which the carbon tip D is in the form of a cylindrical rod or pencil, inclosed within a hollowheat-conducting cylinder or tube D2 which is contracted at its upper end, and hence prevents the carbon pencil D from being forced out by the pressure of the feeding-spriugD3 which spring serves to maintain the incandescent tip of the carbon in close contact with the contracted end of the tube, and thus to continually absorb and conduct away the heat therefrom.

The mode of operation of my improved lamp is as follows:-XVhen the lamp is suspended in an electric circuit by means of the conducting hooks a a the positive current passes into the metallic frame of the lamp, and thence through the carbon-holderA to th e positive electrode C, forming the arc between its tip and the tip D of the negative electrode D. From the clamp E2 of the negative electrode, which is insulated from the frame B, the current goes out through the insulated wire b.

The regulating coil which controls.the feeding of the positive carbon may be arranged in the usual manner in a shunt spanning the arc. When the arc is formed between the tips of the positive and negative electrodes the oxygen of the atmospheric air within the chamber E is rapidly consumed, and as oxygen from without can only enter through the narrow opening at the top of the supplementary chamber formed by the cone Il, which it does very slowly, the arc continues to burn in an atmosphere constituted principally of nitrogen, and for this reason the carbon of the positive electrode is consumed much more slowly than it is in the open air. The ingress of air to the chamber surrounding the arc is further prevented by the construction hereinbefore described, involving a metallic wall around the feed opening through which the positive carbon passes. This wall localizcs the heat, as it were, and in some way, probably by reason of increase in tension of the gases by such localized heat, more effectually prevents the ingress of air, whereas more or less of the heated gases as their volume increases by decomposition of the carbons can find egress through the narrow air space between the metallic thimble II and the positive carbon. Furthermore, by maintaining the negative electrode at a comparatively low temperature, which I effect, as hereinbefore explained by surrounding its point of incandescence with a heat-conducting envelope, I cause the vaporized carbon from the positive electrode to be redeposited upon the negative electrode, in sufficient quantity to build it up as fast, or nearly as fast, as it is consumed, and thus the life of both carbons is greatly prolonged.

In lamps of this type it is important that the arc-inclosing envelope should be as small as possible in order to maintain a high telnperature of the inclosed gases. Such a construction, however, brings the wall,when made of glass, to a very high temperature, and renders them exceedingly liable to fracture, if made of glass of ordinary composition, when the outside of the glass is exposed to ordinary atmospheric temperatures. By the use of the auxiliary inclosing chamber K danger of breakage may be to a large extent avoided, although the envelope E is composed of glass of ordinary composition, but by providing the outer globe K with a hood or cap, as described, thus forming a chamber practically closed at all points, the air within this outer globe becomes raised to a comparatively high temperature after the lamp has been in operation for a short time, and the inner envelope E is perfectly protected from sudden changes of temperature and can therefore the better perform its function of inclosing the highly heated gases around the arc. In addition to this fact, the outer globe serves as a guard against direct contact of rain or drafts with the inner envelope.

I have found that the best results are attained in practice by so constructing the ap- IOO IIO

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paratus that the arc is formed near the top of the inclosing chamber, as illustrated in Figs. 1, 2 and 5. But I do not herein claim this feature, but reserve it to another pending application filed by me,Serial No. 477,036, filed June 9, 1893.

Other patentable features also described herein are not claimed but are reserved to the companion application just referred to.

I claim as my invention- 1. An arc lamp having its are inclosed within a transparent or translucent envelope, an auxiliary transparent or translucent envelope and feed openings in the envelopes closed on all sides surrounding said arc-inclosing envelope, whereby the tWo sides of the arc-inclosing envelope are maintained at a comparatively uniform temperature and fracture is avoided.

2. In an electric arc-lamp, the combination with the positive and negative electrodes, of an inclosing cylindrical chamber or envelope of transparent material, surrounding the are,

` an auxiliary inclosing transparent chamber closed on all sides, and a conical reflector Within the upper end of said chamber encircling the positive carbon.

3. An arc lamp havingits arc inclosed Within a transparent or translucent envelope pro vided With a redecting cap at the top, said envelope being inclosed in an auxiliary outer protective envelope also provided with a refleeting cap, whereby all the rays of light thrown upwardly from the arc are utilized externally of the lamp.

' 4. In an electric arc-lamp, the combination With the movable positive electrode, of an inclosing globe, and a hood closely tting the open top of said globe, and provided with a metallic guide in open communication with the atmosphere through which said movable electrode is made to pass for the purpose described.

5. An arc lamp having its arc inclosed Within a transparent or translucent envelope provided With a separable top, an outer transparent or translucent envelope for the purpose described, said outer envelope being closed on allsides, and being provided with detachable cover.

In testimony whereof I have hereunto subscribed my name this 17th day of December, A. D. 1892.

LOUIS E. HOWARD.

Vitnesses s FRANKLIN L. POPE, CAROLINE E. DAVIDSON,

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