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Publication numberUS1008370 A
Publication typeGrant
Publication dateNov 14, 1911
Filing dateDec 1, 1909
Priority dateDec 1, 1909
Publication numberUS 1008370 A, US 1008370A, US-A-1008370, US1008370 A, US1008370A
InventorsLouis Robillot
Original AssigneeLouis Robillot
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Automatic fire-alarm.
US 1008370 A
Abstract  available in
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)



APPLIGATION FILED 13110.1,1909- 1,008,370. Patented Nov. 14,1911. f l

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Speoication of Letters Patent.

Patented Nov. 14, 1,911.

Application led December 1, 1909. Serial No. 530,809.

To all whom it may concern:

-zen of theRe ublic of France, No. 6 Square t. Amour,

in Automatic Fire-Alarms, of which the following is a specification.

Automatic fire alarms at present employed are usually contrivances dependent upon the expansion of metals or gases under the in- `fluence of heat, or upon the ready fusibility of certain fatty substances or metallic alloys.

These insulated contrivances, which should be installed in large numbers to aii'ord appreciable security, are connected to electric alarm contrivances, -by conductors which may be broken in case of lire, before the alarm devices have performed` their func-` tion. In addition these contrivances are frequently ineffective by reason of their tardy action.

The present ,invention has for its object the provision of an alarl'nwhich shall afford really eilicient protection to premises and buildings against fire, and relatesrspeciically to the construction of the cable ernployed in devices of this character. This alarm utilizes the destructive' action of fire and the expansive actions produced by heat to effect a contact between two insulated electric conductors, situated very near one another, whereof the insulating covering is destroyed almost instantaneously by -lames -the conductors being constructed and connected to an electric battery, and to electric alarm devices in a manner which will be described by reference to the accompanying drawing in whichz-- i y y Figure 1 is a diagrammatic representation of the installation, and r-Figs 2 and 3 are larger scale views of two examples of constructlon of a cable carrying bilar strands which constitute the chief element of this invention. Figs. 4 and 5 are transverse sectional views of complete cables of thert pes illustrated, respectively, in Figs. 2 an 3.

For the purpose of this invention an electric circuit comprises two conductors a, b, insulated from one another, and also insulated at one of their extremities a1, b1. At

i their. other extremities the two conductors i are connected, the'one at b2 to the positive Be it known that I, Louis Rornror, citi residing at. Besanon, France, have invented new and useful Improvements pole of an electric battery c, the other at az to the negative pole of the same battery through the medium of an indicator el, comprising the local circuit e, j of an electric bell system g. The indicator d and :he bell or bells g which are in series, are installed in places chosen so that they are under watch night and day. When any ame reaches the alarm circuit, contact between the two conductors a, b, is brought about by means of the arrangement described above, und the alarm is give l V Two return wires las', connected tothe two wires a, b, of the alarm circuit at their free ends a1, b1, are led to the place of observation, where they are joined to the two terminals of a junction piece j, 1:, which allows the effective condition of the circuit and the proper working capability of the alarm contrivance to be tested at any moment. The

indicator d has-as many indicating surfaces as there are alarm circuits in the establishment to be protected. A separate jtnction is employed for testing each of the 11n es.

consequence of its great flexibility, its strength, its small section and its lightness, the said electric cable alarm lendsitself to a multiplicity of combinations, and to' very varied applications to .installations fcr 4protection against fire. It may be applied in various other ways.

The new cable would advantageously be used as a double wire in rooms for all Intlar electric installations of low voltage, especially for telephone and bell. installations. The use of this cable, the price'o'f which is very small, would simplify installation and lessen the breakdowns and expenses of upkeep which are considerable items in connection with leads now in use. Thr twowire electric cable alarm can be equally7 well applied to electric apparatus for protection against burglary, since, as said above, the two threads whlch compose it make contact with one another, and can consequently cause the actuation of a bell, through the medium of an indicator, when the cable is cut by any instrument. One r-nn obtain complete security in respect cf lhis latter application, and also for protection against arson by adopting thc following form for the electric cable alarmlzv-As shown .in transverse section in Fig. 4, on a very much cnlarged scale, the new cablev is primarily composed of six wires of copper or other metal of a very small diameter, each being covered with a ver thin layer of silk thread or other insu ating material c', the wire being twisted together in pairs so as to form three bifilar strands. rI'hese three strands are located in three equidistant helical grooves m, n, o, formed 1n a wire p of Coppel` or other metal, and constituting the safety core of the cable. The cable thus formed is then covered with a thin layer of cotton thread or other soft material d', and finally with a tube e of metal of fusible allo The grooves` above referred to are of a depth at least as eat as, and preferably greater than, the iameter of these twisted strands, the purpose of this .construction being to hinder tampering with the strands, but should the strands be molested then owin to the fit thereof in the grooves, and the t 'n insulation around the strands it would be practically impossible to interfere with one strand without affectin the other and thus giving the alarm. or certain parts of installations, la flexible conductor could under the same conditions be vemployed, the metallic tubular protector being rep aced by a winding of tape.

The six conductors of the cable or of the flexible conductor alarm, distinguished by insulating coverings of different colors could be em loyed at need, to form one, two or three dou le wire circuits, of which each wire of the circuit will be composed of one or more elements by connecting in each bilar strand one element to one of the threads a of a circuit, and the other element to the second thread b of the circuit (Fig. According to the exampleabove, cable and flexible conductor alarms with two or four strands could also be constructed, by means of one or two strands formed of two insulated conductors twisted together, and located in one or two helical grooves in the metallic safety core.v Cables and ilexible conductors of the same type y could also be formed of eight or even more conductors by varying the number and size of the grooves in the core, and by insertin when needed several bitilar strands in eac of these grooves or by emplo ing as a safety core a metallic wire of su cient cross section to permit of any increase in the number of grooves if and when required.

The alarms described above have the great advantage of being unbreakable by tension, and being incapable of division by any In addition these cables or conductors give means without the alarm being given."

the warning signal very promptly under the action of a llame'.

. The metallic safety core, instead of being 'formed by a single grooved wire p (Fig. 2)

may be constructed, as shown in cross section in Fig. 3, of a plurality of spaced metallic wires 9, helically wound on a central metallic wire g, and between which are interposed the biiilar conductorsa/-b and h-i, forming the various electric circuits of the alarm. The auxiliary central and exterior metallic wires g 1', thus employed to form thevcarrier may be bare or insulated; they may be made of steel, iron, bronze, copper or of any other metal or alloy, but it is advantageous to employ, for this purpose, a metal or alloy of considerable hardness and tensile strength.

By simultaneousl windin around the central wire the bi lar stran s a-b, h-i, and the auxiliary exterior wires r arranged as described above, a cable is obtained of which the strands comprise the auxiliary metallic wires and the bilar conductor strands interposed. For exam le in the case of Fig. 3 which is that o an alarm cable of six conductors, there being three bifil'ar strands, the construction is that of a seven element cable composed of a central -auxiliary wire forrrling a core on which are helically wound three auxiliary wires and three betilar conducting strands,` the latter alternating with the former, that is to say, each of the bilar strands is interposed between two auxiliary wires. The cable is then covered with a layer of cotton thread or other soft material, d', and finally .with a flexible and fusible metallic tube e According to the latter type, cables and flexible conductors could be constructed with two, four, six, eight or even more conductors, the number of the auxiliary exterior wires bein varied, and if necessary, a plurality .of ilar strands being located in .each of the spaces formed between these wires, or an insulating central wire of a diameter greater than that of the bilar conducting strands and the auxiliary exterior wires can be emplo ed so as to admit of an increase at need 1n the number of biflar conducting strands and auxiliary wires within' the periphery of the cable.

lt goes without saying that the means of insulation between the wires a, b, which arealways close together in the alarm cirl cuit can be varied, and so also can the sys- ,tem of indicators and alarm signals which are interposed in the circuit.

I claim:

A cable of the character described comrising a carrier or support provided with fililicoidal grooves therein, a twisted twostrand conductor arranged in each of said grooves, each. strand of each conductor bename to this specication the presence of ing covered with a thin layer of insulating two subscribing witnesses. material and each of said helicoidal grooves being of a depth at least as great as the LOUIS BOBILLOT' i diameter of the twisted conductor disposed Witnesses:


In testimony whereof I have signed my E. JURAND.

Referenced by
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U.S. Classification174/113.00R, 200/52.00R, 57/212, 174/115
Cooperative ClassificationH01B11/04