US679878A - Electric-arc lamp. - Google Patents

Description

Patented Aug. 6; |90I.

. H. BBEMEB.

ELECTRIB ARG LAMP.

- (Appumnm mea my 1e, moo.)

(llo Model.)

me conm Primus 9d.. vnommua., msnmom. n. c.

ro pencils.

UNITED STATES PATENT OFFICE.

HUGO BREMER, OF NEHEIM, GERMANY.

ELECTRIC-ARC LAMP.

SPEGIIA'IION forming part of Letters Patent No. 679,878', dated August 6, 1.901.

vallppl-ication filed July 16, 1900.

: many, have invented a new and useful Improvement in Electric-Arc Lamps, of which the following is a full and clear specification.

lOn the accompanying drawings, Figures l 'to 3 show anew arrangement of the carbon Fig. 4L shows the application of a magnet to said carbons. Fig. 5 shows a holder constructed for said carbons.

The arc-lamps hitherto in general use are provided with carbon electrodes of which the l positive is arranged above and the negative underneath in the same center line. It is a notorious fact that this arrangement greatly interferes with the emission of light, which is still further obstructed by the requisite so mechanisms for regulating the feed.

these evils by providing two pairs of carbons, one positive and one negative pai-r, and arranging the negative pair of carbons not as l hitherto, underneath, but by the side of the Iz 5 positive pair, likewise with the points slant- 1 ing downward. lioth4 pairs of carbons are,

arranged -obliquely toward leach other, as

tive and B the negative pair of carbon penverge from each other both horizontally and vertically. The luminous arc is formed byl .3 5 the four carbon points and cannot vary any more through the consumption, but remains steadily fixed., as it is always formed only at thepoint where two cai-bons meet andI which will remain invariable under any circuml4o stances. Consequently the emission of light is inlno way obstructed, the light 'bein g thrown downward fully and entirely.

Many attempts have already been made ere this to supersede the arrangement hither- 45 to in use of superposed arc-lamp electrodes by another and more eective onegbut no satisfactory result could hitherto be Obtained, because no matter whether the carbon pencils were placed horizontally, obliquely, or

5to vertically alongside of each other no change was introduced into the carbon pencils themselves-and consequently on account of the` I avoid Serial No. 23,783. (No model.)

short distance between the carbon points the arcs are apt to creep in between the sides of the carbon points, which will cause the emission of light to be obstructed all the more in proportion as the arc gets between the thicker parts of the pencils. When two carbon pencils are placed facing each other, the are will a1- ways burn between the most prominent points of the electrodes, and as soon as the distance between these becomes too great for the arc the feeding mechanism is brought into action.

l This will not cause carbons placed parallel to be brought nearer to each other and may not always have this eifect in the case of carbons placed at an acute angle; but if one were to try to obtain this result in the case of carbon pencils placed parallel it would always be the inner surfaces of the carbons which would come into contact first, and consequently the arc would descend to a distance of a very few millimeters. However, the diameter of the carbon pencils would necessarily have to be made too large in proportion to the length of they arc for an arc to be form ed from center to center of the electrodes. In order to remedy these evils and to be able f to use with advantage carbons placed either '-Figs. l to 3 will show, where A is the posiparallel or obliquely toward each other or in 1 a horizontal line, I propose to impregnate the The two electrodes@ a'andb b in each f pair are again placed obliquely toward each 1 other, so that rall the carbon electrodes di-ly carbon electrodes with metallic salts according a special process. In the manufacture of such carbons to the carbon powder is added a quant-ity of about twenty per cent. or more of calcium or magnesium salts, whereupon the mixture is treated in the manner usually employed in the manufacture of carbon pencils. The character of the salts named is that they are vaporized only in a high temperature, and then the vapors are condensed and form a coating on the carbon points and the adjacent metallic parts, which is non-conductive and of a white reflecting color. I thereby obtain with the same voltage a length of arc one to one and one-half times as great, the arc assuming a crescentshaped form, while liuctuations or cessation of the arc are altogether precluded. The eect of vthis arrangement is still further enhanced by confining the admission of air to the carbon points by means of economizers or the like, as proposed by me on a former occasion. Such economizers consist of a IOO chamber and of tubular form, Fig. 1, which is placed around the carbon points and prevents the admission of air. The hot gases of combustion and metallic vapors resulting from the composition of the carbons may collect within said chamber and form a coating, described afterward. The carbon pencils will then no longer burn away to a sharp point; but even ordinary carbon pencils may be employed in the above-mentioned positions provided that the economizer is made of a width not exceeding four times the length of the arc and with its lower margin brought down to a level with or just below the two extremities of the carbon pencils. It is of great importance in the case of such lamps that the carbon pencils should be made with a certain admixture of such metallic salts as will deposit a snowy coating on the reflector during their combustion, whereby the metallic parts will he better protected against the immediate iniuence ot' the heat as well as against the passing` of the arc onto the metallic parts. Admixtures of this nature are, for instance, (among others,) borax, magnesium, and calcium. The deposits produced by them could scarcely be obtained in any other way, as any cement or agglutinant used for affixing the material would be consumed by the great heat existing in the neighborhood of the are, and the coating would therefore come olf in the form of dust. Moreover, deposits consisting of such particles as have already stood the heat in the arc are not liable to be influenced by the heat in the neighborhood of the are, while, c. g., glaze, enamel, and even china or clay would be more or less pulverized or fritted by the heat. If now we select the metallic salt, at the same time, so as to cause the deposit to assume as far as possible a white color, we at the same time insure that the metallic parts in the neighborhood of the arc are always covered with a highly-refiectin g dull-white coating, whereby the emission of light in the downward direction is considerably intensified. I may remark that the coatings obtained in this way will adhere to the metallic parts in a thickness of several millimeters, and it is only after they have exceeded a certain measure of thickness that the excess will fall down when fresh carbon is inserted.

In the case of carbon pencils placed vertically or pointed upward at an acute angle it is advantageous to bring the influence of a magnet or solenoid to bear on the arc so as to project it downward. In order that this action may be uniform, it is necessary that the position of the luminous point is rendered to some extent invariable or that an automatic feed is provided for.

In the case of arc-lamps with carbon pencils pointed upward the best means for projecting the are downward is a magnet energized by the same current which feeds the lamp. As natural magnets are too likely to lose their magnetism and while electromagnets if placed. near the arc suffer too much in their coil-coverings, I have arranged electromagnets c at some distance from the arc and joined to their pole an extension-piece cl of more than twice the length of the magnetcore, Fig. 4. For such extensions ropes spun of thin wire have been found particularly suitable, as they are capable of following most quickly the numerous variations of the current or of the magnetism in the magnet-core itself and can most easily be bent for the purpose of adjustment. As the magnetism required for deflecting the arc must be very faint only, the weakening caused by carrying it to a certain distance is altogether desirable. Moreover, the greater distance of the coils of the electrom agnet from the arc affords the advantage that the coil cannot act direct on the latter. It isa matter of indifference whether the extension-pieces run parallel to the carbons at their ends or are bent below toward the carbon point, as shown in Fig. 4. The arrangement described may also be made so that several extension rods cl d2 issue from each pole of the electromagnet, which are made to act either on one and the same or on several luminous arcs arranged in the same lamp.

In order to reduce the structural length and the size of superstructure of such arclamps as have carbon electrodes placed obliquely and to avoid the difficulties experienced in the manufacture of carbon pencils beyond a comparatively short length on account of the` brittleness of the material, I employ angular carbon-guides, as shown in Fig. 5, whereby it is rendered possible to cause small pieces of carbon pencil to be propelled forward, one behind the other, in a feed-tube e, the whole being arranged so that the two lowermost ends are placed at the proper angle toward each other required for obtaining the desired arc and to check the descent by gravitation of the carbon pencils; but it is necessary in this arrangement in order to facilitate the transition from the vertical to the oblique position that springs fffz, the., should be provided, which will always force the pieces of carbon pencil against the outer side of the tube c, as will be seen from Fig. 5. In this way it is impossible for two pieces of carbon to overlap each other, and the more of such springs independent of each other are provided the more reliable will be the feed. Of course a double bend of the carbon-guide channel may also be arranged in this way.

In order to insure a correct feed in a still greater measure, even in the event of any failure of the action of the springs, each carbon pencil is provided at one end with aconical cavity, so that the point of the next following piece of carbon will lodge in this cavity, thus affordingafurther safeguard against any overlapping of two pieces of carbon. The feeding forward of the carbon may ensue by gravitation only or by means of rollers or by charging with weights.

IIO

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

1. In an electric-arc lamp the combination of two pairs of downwardly-pointed parallel or converging carbon pencils, arcs between them, a' metal chamber surrounding the carbon points, said carbons containing an addition of metallic salts for the purpose described and set forth.

2. In an arc-lamp, an economizer or reiector of metal placed immediately above the luminous point or arc of a pair of downwardly-pointed parallel or converging icarbon pencils,containiug a sufficiently high percentage of metallic salts to yield deposits in such quantities as to cover the adjacent metallic parts with a reecting and protective coating which may be of a white or light-yellow color as described and set forth.

8. In an electricarc lamp the combination of a pair of downwardly-pointed parallel or converging carbon pencils, an arc between them,` a metal chamber surrounding the carbon points, said carbons containing an addition of metallic salts and an electromagnet having extended pole-pieces, said pieces being bent in a suitable angle with regard to the arc for the purpose described and set forth.

4. In an electric-arc lamp the combination of a pair of downwardly-pointed parallel or converging carbon pencils, an arc between them, a metal chamber surrounding the carbon points, said carbons containing an addition of metallic salts and an electromaguet having extended pole-pieces, said pieces being constructed of wire rope and placed vertically with regard to the carbons for the purpose described and set forth.

5. Inv an electric-arc lamp having downwardly-pointed parallel or converging carbons,a guide having a curvedor bent form and provided with springs that enter the tube for the purpose described and set forth. K

HUGO BREMER. Witnesses: A

F. RNKE, H. MLLEB'.

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