US1636939A - Angle plug - Google Patents

Description

Patented July 26, 1927.

UNITED STATES PATENT OFFICE.`

THOMAS J. xnnwIN, or CHICAGO, ILLINCIS, AssIGNoR, BY MESNE ASSIGNMENTS, To

CHICAGO ELECTRIC MANUFACTURING COMPANY, or CHICAGO, ILLI'NoIs, A CCR- roIiATIoN or ILLINOIS.

ANGLE PLUG.

Application inea January 3, 1921. serial No. 434,733.

My invention relates to the class of electric fittings commonly known as attachment plugs and used for affording a detachable circuit connection to a socket for an electric lampv or the like. Generally speaking, my invention aims to provide a cheaply constructed, strong and good looking fitting of this kind which will be easy to wire, which can readily be used to good advantage with wires coming from a direction angular to the axis of the socket, which will afford strong mechanical protection as well as weather-proof protection for the point of afttaclnnent of the wire, and which wil-l readily relieve such connection of any strain on the wire.

In one of its more particular aspects, my invention aims to provide an attachment plug` of this kind having a metallic casing so designed as not only to house the insulating body which carries the wire terminal or terminals, but also completely to hou-se the joint between the wire and such terminal or terminals, and having a portion of this casing disposed for relieving these terminals of any strains on the wire. Furthermore7 I aim to provide exceedingly simple and effective means for attaching the wire; to provide simple means for holding the insulating body which supports the wire terminal or terminals, and for permitting a ready connecting of the wires to the same; to provide a casing so arranged as to facilitate' this wiring even when the wire comes from a genn eral direction at right angles to the axis of the socket with whichthe plug is-tobe used, andv to provide simple means for mechantcally protecting the resulting. joint or con-` nection. provide an attachment plug with ai casing having its main portion formed from a` single'piece ofdie cast metal and havingy aseparable cap so arranged: as to take thrust 0E the connection to the wire, and alsoarranged so that it can be used with equal facility with metal-sheathedl wire. Still further and more detailed objects will appear from the following specification and fromthe accompanying drawings, in which Fig. l is a side4 elevation of a single pole anglespl'ug embodying my invention, to gether with a section of the rear end of a lamp socket interlocked with this plug.-

Moreover, my invention aims to- Fig. 2 is a section through the same angle plug, taken along the medial plane of the angle and showing the cap of the plug as engaging a wrapping of tape on the wire.

Fig. 3 is a similar section through a donbl'e-pole angle plu-g, showingv the cap as engaging a knot in the two wires. v

Y F ig. 4 is a transverse section through Fig. 2 along the correspondingly numbered line of that figure.

Fig. 5 is a reduced section through the main metal portion of Fig. 2 showing the disposi-` tion of the wire before the same is attached to the wire terminal, and also showing this metal elbow as equipped with cross-pins at right angles to the medial plane of the angle plug.

Fig. 6 is a fragmentary horizontal section taken along the line 6 6. of Fig. 2.

Fig. 7 is a perspective view of the wire terminal. i

lVhere the wire or wires which are to connect to an attachment plug come from a direction substantially at right angles to the axis of the socket with which the plug is tio be used, it has heretofore been customary to construct angle plugs (sometimes also known as elbow plugs) with the wire terminal andA contact terminal portions carriedby a tubular elbow molded of insulating ina-1 terial and to conceal the attachment of the wire or wires by a cap threaded upon this insulating body. Owing to the nature of the insulating compounds generally used for such purposes, the resulting plugs have proven tool brittle to stand knocks, and too easily softened to retain a firm grip in hot weather on the imbedded pins which interlock such plugs with the lamp sockets. Nor has-the angular shape of the insulation lent itself to the employment of a' metal shell such as would be highly desirable where fittings of this kind are likely to be subjected to rough treatment, as in the case of connector' plugs for use with the electric head'glamps on Ford automobiles. Moreover, the attaching of-a wire wit-hin a tubular elbow is difficult to performy with the proper firmness for preventing a strain on the wire from severing the connection vor possibly rupturing the wire at its point of attachment.

Tov overcomeV all of these difliculties7 my invention aims to provide connector plugs employing tubular metal elbows which will alord the desired mechanical protection, and to provid-e an elbow-shaped metal casing which can readily be made of a die casting; to provide the insulating portion in a relatively small .torni which can readily be machined out ot hard rubber, thereby permitting of a less fragile torni ot insulation than that ordinarily obtainable in a molded composition; to provide a simple and ineX- pensive torni ot wire terminal which can readily be attached to suoli a cheaply manufactured insulating part and which will et- 'fectively anchor the wire without appreciably weakening` the latter; to arrange the parts so that the wire can readily be attached to the terminal while the latter is disposed outside oit the tubular elbow; to providesirnple means tor causingl a retraction of the wire to seat the insulating body tirmly in the elbow; and to provide simple and effective means for preventing an excessive retraction oit the wire aiter it has thus drawn the` insulator' to its seated posiA tion. Furthermore, my invention aims to provide a connector plug of the cl described which will readily lend itselt to both single-pole and double-pole constructions and which will readily pred-etermine the medial plane ot the elbow when the plug` is in use.

ln their immediate commercial aspects, the connector plugs otl my invention are particularly suited tor use in connection Y-yith autoinobile lamps carried by sorkets having their shells equipped Afor interlockingl with laterally projecting pins on tl e plugs and having spring-pressed contact elements adapted to engage the wire terminals ou the plugs when the latter are thus interlocked with the shells ot the sock-k l ain therefore illustrating and deseribino' the connector plugs of my invention in 2liornis adapte Vl i'or these purposes, although do not wish to be limited to any particular uses of the same. v

Referring tirst to the connector plug ot' Figs. l, 2 and fl, these ligures show an angle Y plug designed lor use with a lamp socket having a cylindrical shell l equipped near its end with diametrically opposite bayonet slots adapted to engage lateral pins 2 projecting trom the angle plug. The socket shell l houses the usual insulating' body f3 supporting a springpressed plunger et which is disposed axially oi the casing 1 and is continuously urged by the spring associated with-ittowards the rear end ot the socket shell,V atter'the general manner of the plunger shown in U. S. Pat-entNo. 1.083542 ot January 6, 1914i to George C. Knanft'. To cooperate with the plunger 4 which :terms parts ot the connection within the socket to the lamp, I provide a screw 5 which extends through an axial bore in a cylindrical insulator 6 and which is threaded into the shank 7 ot a wire terminal equipped at its rear end with a loop 8 through which the tip portion of the corresponding wire 9 is adapted to be hooked. The threaded shank '4" of vthe wir-e terminal is slidably disposed in a bore ot larger diam` eter than the shank ot the screw 5 and eX- tending into the insulator G 'troni the rear ot the latter-,so that upon tightening the screw 5 the shank 7 will be drawn torwardly ot the insulator and will therefore double the tip 9 ot the wire into a loop and draw this tip into the borel() within which the shank 7 is slidably disposed. In so doing, the screw kinks the wir-e into an anchoring loop bet'ore the tip ot' the screw engages the wire and clamps the latter against the rear part ot' the loo-p S.

The insulator 6 in turn is merely sl'ldabl-e in the 'forward end ot the metal elbow ll, vwhich elbow is desirably oit' diecast metal and desirably has the anchoring pins 2 cast upon the same. This elbow has its bore contracted to 'form an interior annular shoulder 13 spaced from the forward end ot' the elbow by a distance shorter than the length ot the insulator 6, so that the entry ot' this insulator into the elbow will be limited by this shoulder to a position in which the Aforward end portion ot the insulator 6 projects beyond the torward end ot' the elbow. Moreover, the inet-al elbow also desirably has int-egralwvith it a web lll extending longitudinally along its interior ttor some distance toi-ward ot' the said shoulder l2', and adapted to enter a correspending longitudinal recess ou the surface oi the insulator (S after the manner shown in Figs. 2 and 4, so as to prevent the i.n sulator troni rotrtinn` within the bore ot the elbow. The rear end ot the elbow, which end in the illustrated embodinuint extends atright angles to the forward end, dcsirablv is threaded on its exterior'to tit a cap lb 'tor the purposes hereafter desruibed. A

l/Viththe parts thus arranged, the cap l5 is first left off the elbow but slipped over the free end ot' the wire, while the insulator 6 together with the wire terminal carried by the latter are lel't out of the metal elbow. Then the wire l1 is slid through this elbow after the manner shown in Fig. 3, which can readily be done while imparting a relatively slight curve to the wire, and this wire is attached to the wire terminal after the manner shown in Fig. 2. Then the wire is pulled back, and the insulator 6 is slid into the forward end of the metal elbow during this retracting of the wire until the insulator engages both the web 14 and the annulaishoulder 13. After this has been done, the cap 15 can be brought up from its previous loose position of-Fig. 5 and can readily be screwed upon the rear end of the elbow so as to afford a handsome finish for this end, while also providing means for securing the metal of the elbow tightly to a metal sheath 16 on the wire if the wire was metal sheathed. In either case, I also desirably employ this cap for relieving the wire of any strains which might tend to pull its tip out of the fastening of the latter` to the wire terminal, such as a downward pull on the wire in Fig. 2. For this purpose, I may simply wrap the wire adjacent to the rear end of the elbow with a few layers of tape 17, thereby providing an enlargement of greater diameter than that of the bore of the cap l5, so that the contracted tail end of this cap will engage the tape when the cap is screwed into position (as shown in Fig. 2) and thereby will relieve the wire of undue strains.

With the parts thus arranged and assembled, it will be obvious that the metal shell of the installed plug will afford a strong mechanical protection; that the general arrangement will facilitate the wiring, and that the ability to attach the wire to this terminal while the latter is out of the elbow will insure the making of a connection which will be both mechanically and electrically ample. Moreover, the position of the an choring pins 2 with respect to the medial plane of the elbow will readily determine the position of the plug when used in connection with a lamp-socket having bayonet catch formations in any given position. For example, if the socket has its axis horizontal and has its bayonet catch formations in a vertical plane through that axis, and the angle plug having its anchoring pins in the medial plane of the elbow will present its rear end in a vertical position after the manner of Fig. l.

However, while I have heretofore described the connector plug of my invention in a single-pole embodiment and have illustrated the same as including a rightangled elbow, I do not wish to be limited to these or other details of the construction and ar- 2. So also, the relative position of the crosspins 2 might be altered, as for example after the manner indicated in dotted lines in Fig. 3 which shows an elbow designed for use at right angles tothe position of Fig. 1.

I claim as my invention:

In an electric fitting, an elbow-shaped casing having its forward arm counterbored to provideV an inner annular shoulder spaced from the mouth of the said arm and having a iin projecting radially inward into the said counterbored portion adjacent to the said shoulder, the shoulder being disposed forwardly of the bend of the casing; a tubular insulator socketed in the said counterbored arm and abutting at its rear end against the said shoulder and having a notch fitted over the said fin to prevent the insulator from rotating in the said arm, the forward part of the bore of the insulator being contracted in diameter; a wire terminal member slidably inserted in the insulator bore from the rear of the insulator and having a forward threaded end and presenting an eye adjacent to the rear end of the insulator; a screw eX- tending through the contracted bore portion of the insulator and having its head engaging the forward end of the insulator and its shank threaded into the said threaded end of the wire terminal member; and an insulated circuit wire extending into the casing through the other arm of the casing and having a bared end extending through the eye of the terminal member and clamped against and kinked into the rear end of the insulator bore. v

Signed at Chicago, Illinois, December Y THOMAS J. KERWIN.

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