US1678752A - Insulating cap for the joints of electrical conductors - Google Patents

Description

July 31, 1928.

F. M. VAN GELDEREN INSULATING CAP 'r'on THE JOINTS OF ELECTRICAL cbnnuc'rons Filed Oct. 18, 1927 v If A HI" by the in no prior patent Patented July 31, 1928.

FREDERIK MARINUS VAN GELDEREN, OF ENSCHEDE, NETHEDLAN DS.

INSULATING CA1 FOR THE JOINTS OF ELECTRICAL CONDUCTORS.

Application filed October 18, 1927. Serial No. 226,974.

This invention relates to insulating caps for the joints of electrical conductors, and more particularly to caps for insulating the bare ends of said conductors.

In my prior Patent No. 1,460,624, I have shown an insulating cap of this type, said cap having an internally threaded cavity in which is located a conical coil of spring wire. \Vhen thecap with the spring therein is screwed on the bare ends of the con? doctors. the spring gradually expands in radial direction due to the introduction of the conductors, and this radial expansion brings more. or less of the intermediate portion of the spring into contact with the grooves of the threads of the insulating cap, the extent of the contact being determined size of the conductors upon which the cap and coil are threaded. Thus the conductors are firmly bound together and secured within the cap, in effective electrical connection with one another;

In the use of a cap of this type, unless care is exercised by the electrician to cut the ends of the wires exactly the right length, or if the tot. l diameter of the twisted wires is not suiliciently happens that the ductors protrude beyond the innermost turn of the coil when the latter has reached= the limit of its inward movement and strike the bottom of the cavity of the cap before the conductors are properly bound and tightly secured in the cap. As a result, further rotation of the cap on the conductors produces no tightening eflect'and it becomes impossible under such conditions to obtain a firm connection and reliable insulation.

It is an object of the present invention to avoid the aforesaid difiiculty, and I have found that this object may be accomplishedby the provision of a well or supplemental cavity at the bottom of the principal bore, or inner bore in case the cap is provided with inner and outer bores; a stop being provided for limiting the inward movement of the coil. 1

Another object of the invention is to provide a coil of such formthat it will more effectively engage both the thread of the cap and the surface of the united conductors than results from the use of the coil shown mentioned. This is accomp ished by employing for the coil metal great, it frequently extreme ends of the con- I sula-ted.

form of a double cone,

wire which in cross section is squareor rhombic.

The invention will be more readily understood upon reference tothe accompanying which the cap has been applied, and

1 1g. 4 15a longitudinal section through,

another form of cap.

ln the drawing the numeral 1 represents an lnsulatmg cap. of porcelain or other suitable insulating material. The cap is hollow as shown and is provided with an internal thread 2. As shown in Fig. 1, the thread 2 extends almost to the open end of the cap, whereit opens into the shallow recess 3. 1n the -lorm illustrated in Figs. 2 and 3, the outer threaded bore 3 is of substantial depth and its inner. end merges into the inner bore about midway the entire depth of the cavity. The cap shown in Fig. 4 is of the same general form as that shown in Figs. 2 and 3, but the outer conical bore 3" is not provided with screw threads.

lhe wire coil is indicated in Figs. 2 and 3 by the numeral 4, and as illustrated is of polygonal cross section. Conveniently the section may be square, but it may be rhombic or other form which will provide an outer angle on the coil for engagement with the thread of the cap and an inner angular portion for gripping the surface of the united conductors to be connected and in- As shown in Fig. 2, only the larger convolution at the inner end of the coil engages the threads 2 when the coil is threaded into the cap. The coil has the general and the portion ofsmallest diameter is preferably close to the inner end of the coil. The inner diameter at the smallest section must, of course, somewhat smaller than the external diameter of the thinnest conductor joint which movement of the wire coil by abutment thickest conductor therewith of the inner end of the coil. Other modes of effecting engagement of the coil.with the thread of the cap and for limiting the inward movement of the coil when the cap is applied to the conductor may be employed, but that illustrated is quite prac- *tical and inexpensive.

' In the use of the device described, the cap '20 is applied to thebare ends of the conductors to be united and rotated thereon. The wire coil engages the conductors and firmly unites, the same.

conductors progresses, the intermediate portion of the conical coil 4 becomes .expanded and may ultimately engage the thread within the cap to a-greater or less extent. In the absence of the well, should the complete binding efiect and' the tightemng of the cap on the conductors not be effected before the ends of the latter strike the bottom of the bore, further rotation of the cap on the conductors is useless andan efiicient joint and insulation cannot be secured. By the'provision of the supplemental bore, however, the protruding extremities of the conductors are .free to move inward the necessary dis tance to permit the coil to proceed .in its movement until interrupted by engagement of its inner end with the stop 5 and to expand as completely as it will into the groove in'the ca v; in other words, until the maximum bin ing effect is produced. i

As shown In Figs. 2 and 3, the outer bore 3 is-threaded for'engagement with the insulation (ion the separate conductors to provide a firm and substantially water-proof connection.

It willbe understood that the cap is useful for insulating the joints of electrical con ductors even if the wires happen to be cut so short that the well is not necessary, and it will be obvious, therefore, that. with the use of the device described itis not necessary for the electrician to be particularly careful as to the length of wire ba'red before applysaved. What I claim isi 7 ingthe cap, so that considerable time can be '1. An insulating cap'of the type including a body. of insulating material having a cavity-therein, and a metallic insert in said diameter extending laterall As the inward movement of the provided with a well below said cavity for receiving the ends of conductors which pro-,

trude beyond said cavity .and the metallic insert therein.

12. The combination with an insulating cap for the bare ends of electrical conductors, said .cap having a cavity therein provided with an internal thread, of a tapered coil of wire for receiving and binding the bare ends 'of the conductors when the cap is'applied thereto and rotated and having a free end below the. turn of smallest to engage and move along said thread, an a stop comprising the inner endof said thread for limiting .the inward movement of'sai'd coil, said cap having a well below said stop for receiving the ends of conductors which protrude beyond said cavity. 7

3. The combination with an insulating capv for the bare ends of electrical conductors, said cap having a tapered cavity there- -1n provided with an internal thread, of a conical coil of wire for receiving and bindingthe bareiends of the conductors when the cap is applied thereto and rotated, and having a freeend below the turn of smallest diameter extending laterally to engage and move along said thread, and a stop comprising the inner end of said thread for limitmg the inward movement'of said free end, sa d cap having a cylindrical well below sald stop and of smaller diameter than the lower end of the cavity for receiving the ends of conductors which protrude beyond said cavity. I

4. The combination with a hollow insulat mg cap for the bare ends of electrical cons ductors, said cap being internally screwthreaded, of a metal coil for receiving and bmdmg the bare ends of the conductors. when the cap is applied thereto and rotated and having means for the said coil being formed of wireof noncn cular cross-section which presents a sharp thread-forming edge at the interior of the 5. An insulating ca as set- 'forth in claim 4, wherein the wire fiirmin said coil is of polygonal cross-section an arranged to and at the exterior of the coil.

i -In testimony whereof, I atli xl my signature. V

'FRIiJDERIK M." VAN GELDEREN. Y

having an internally I10 engaging the thread,

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