US2832816A

US2832816A - Self-insulated two-way butt connector

Info

Publication number: US2832816A
Application number: US425638A
Authority: US
Inventors: Lawrence M Curtiss
Original assignee: Thomas and Betts Corp
Current assignee: ABB Installation Products Inc
Priority date: 1954-04-26
Filing date: 1954-04-26
Publication date: 1958-04-29
Anticipated expiration: 1975-04-29

Description

April 29, 1958 L. M. CURTISS 2,832,816

SELF-INSULATED TWO-WAY BUTT CONNECTOR Filed April 26, 1954 5 0 INVENTOR.

LAWRENCE M. CURTISS E T W' iww QTTORN EY SELF-lNSULATED TWO-WAY BUTT CGNNECTQR Lawrence M. Curtiss, Mountainside, N. 3., assignor to The Thomas & Betts Cot, Elizabeth, Fl. 3., a coir-norm tion of New Jersey Application April 26, 1954, Serial No. 425,638

5 Claims. (Cl. fi l- 84) The invention relates to a self-insulated two-way butt electric connector of the type which includes sleeves in telescopic relation adapted to secure conductors therein by means of a crimping operation and of which the outer sleeve is formed of a plastic insulating material and the inner metal sleeve is provided with a window or een hole through which the inserted ends of the conductors are visible when the outer sleeve covering the window is more or less transparent.

The present disclosure is a development of and includes some features disclosed in the Patent No. 2,769,965, is sued to John Nelson Frey, entitled Nylon-Jacketed Connector. In this prior patent there is featured three sleeves in telescopic relation, that is, an outer sleeve of nylon, an intermediate thin, easily deformed metal tube, not necessarily of conductive material, overlying the insulation of the cable, and an inner tube of highly corn ductive metal adapted to be crimped onto the conductive core of a cable. When a squeeze pressure is appliee through the outer face of the nylon sleeve in th area adjacent a free end of the intermediate tube, the tube is deformed into a biting engagement with the cable insulation and, on retreat outwardly of the nylon sleeve when released of such squeeze pressure, an insulatin air space remains between the tube so deformed and the outer plastic sleeve. incidentally, the same thing occurs in the disclosure of this application when the deforming pressure on the outer nylon sleeve has been removed.

It has been otherwise known in the prior art to provide such connectors with cables inserted into opposite ends and to crimp the inner sleeve onto the bare wire ends of the cables by crimping pressures applied through the outer sleeve. It has also been suggested to provide the bore of the inner sleeve of a connector of the type having an opaque sleeve with a stop or abutment located adiacent its mid-length and against which stop the inner ends of the bare wire ends abut and arranged to indicate by the fact that the cables can be intruded no bo her that the wire ends have been advanced sufficiently to pass beyond the point where crimping is to be had and thus permit the securing of the cables to the connector at the position intended when the connector is finally crimped onto the cables.

In actual practice, however, the outer sleeve, when formed of a plastic such as nylon or similar material which has highly desirable insulating properties, is more translucent than transparent, and as a result it is diliicuit for the operator to be assured, as he attempts to look into the window, to see that the cable wire ends have been inserted to the extent of meeting each other within the connector as desired.

Accordingly, it is an object of the present invention to provide such form of translucent jacketed connector as will permit a visual inspection of the cable ends through the window or peep hole when the intruded cable ends reach their desired position and thus assure the operator that the cable ends properly located therein to have the connector deformed into position to crimp the connector onto the cables as is usual in this art.

Broadly, this objective is attained by locating in the bore of the inner sleeve and opposite its window or peep hole, a change-direction obstacle which lies in the path of the advancing cable wire ends and which will operate thereon to bend the ends out of the bore and into or even through the window and eventually to locate the ends so bent sufficiently close to the transparent part of the outer sleeve covering the window that the cable ends are visible through the outer sleeve.

More specifically defined, the change direction obstacle features on opposite sides thereof cable-engaged bearing surfaces both inclined to the axis of the connector, both facing the covered window and disposed with one such surface facing one of the open ends of the connector and the other surface facing the other open end of the connector, and each surface adapted to turn its associated cable end as it bears on the same away from the obstacle towards the window and sufficient to expose the cable ends for inspection through the Window.

Another feature of the invention is to provide a solderless form of insulated coupling for electrically connecting the bare ends of a pair of cable conductors inserted into cylindrical end portions forming opposite ends thereof and integrally connected through a Wide bridge forming a conductive electric path spanning the gap betweenthe end portions and on which bridge the conductors bear and are turned by reason of being inserted into the connector as above outlined.

Various other objects and advantages of the invention will be in part obvious from an inspection of the ace-ornpanying drawings and in part will be more fully set forth in the following particular description of two forms of self-insulated two-part butt connector, each embodying the invention, and the invention also consists in certain new and novel features of construction and combination of parts hereinafter set forth and claimed.

in the accompanying drawings Fig. l is an axial sectional view of an empty connector forming a preferred embodiment of invention as it exists when first molded and designed subsequently to have a pair of cables inserted into its opposite open ends;

Fig. 2 is an end View of the connector shown in Fig. 1;

Fig. 3 is an axial sectional view of the connector of Fig. l with two cables inserted into opposite ends with the connector crimped onto the cables and with the ad jacent ends of the cables in the window and close to the translucent sleeve, and showing the outer nylon sleeve less deformed than in Fig. 1;

Fig. 4 is a View looking down on the midmortion of th disclosure as shown in Fig. 3, and showing the cable ends radially distended and visible through the outer sleeve;

Fig. 5 is an axial sectional View of a modified form of connector with the cables inserted therein, prior to the connector being crimped onto the cables; and

Fig. 6 is a plan View looking down on the showing in Pig. 5 and showing exposed the end of the left cable.

in the drawings and referring first to Fig. 1, there is disclosed a straight through connector 10 comprising two preformed sleeves in telescopic relation and both formed of ductile materials. The outer sleeve 11 is formed of a thermoplastic insulating material and is initially pro-molded to a hollow cylindrical form. In the case illustrated the outer sleeve is formed of a synthetic condensation amide commonly known on the market as nylon. The inner sleeve 12 is formed of a highly conductive metal and in the case illustrated is formed of soft copper.

A bore 13 extends axially through the inner sleeve from end to end. Opposite ends of the bore are enlarged to form

cylindrical pockets

14, 15, in which are fitted the insulated end portions A of cables B and C. The pockets are outlined respectively by cylindrical, thinwalled

shrouds

16 and 17 for protecting the insulated portions of the cables, and shoulders 18 at their inner ends limit the intrusion of the insulated portions of the cables. Stripped-back, bare wire ends D of the cables extend thereheyond through the inner ends of the bore. Directions which come with the connector advise the user as to What should be the length of the strippedback, bare ends D to fit in the connector and this is ascertained by measuring the distance between the shoulder 18 and the point where the ends D become visible through the outer sleeve, as hereinafter described.

It is a feature of this disclosure that the inner sleeve has a mid-length portion of one side thereof cut away to form a window 1E. The portion of the bore of the inner sleeve which faces the window is provided with a change-direction extension 20 disposed in the path of the inserted wire ends and with the window particularly forming the novel feature of this disclosure. This extension in the form illustrated in Fig. l is a dimple of somewhat conical form and in the case illustrated was formed by indenting the inner sleeve as shown by a suitable pressure tool acting through the outer tube at 31 to deform the outer sleeve at the point so indicated into the extension M3. The dimple projects into the bore 13 to a point slightly above the axis of the inner sleeve and terminates in a well-rounded point. The inclined sides of the dimple provide surfaces 21 ancl-22, both facing the window with surface 21 facing the left end of the connector and surface 22 facing the right end of the connector.

In. operation the insulation on the ends of the cables to be intruded into the connector are cut back as usual to form the bare wire ends D. First one and then the other cable with its bare ends in advance is inserted into opposite ends of the connector until the insulated portion A engages and fits against and is stopped by the associated shoulder 18. In the act of inserting the 'cable in place the bundle of wires forming its ends D first bear on the

inclined surface

21 and 22, as the case may be, and are bent slightly out of their initial straight line and are turned laterally to project more or less into the window 19. The extreme ends E are stopped by engaging with the inner surface of the part of the outer sleeve which forms a covering for the window. As the ends E are crowded between the projections 20 and the outer sleeve they tend to enlarge, that is, the strands spread apart. As the ends E approach the translucent covering formed by the outer sleeve they become more and more clearly visible. When the conductors are formed of stranded wire, as illustrated, the exposed ends E of the wires form a dotted appearance which becomes quite noticeable when viewed through the outer sleeve, so that all the operator need do is to advance each cable into the connector until he sees its dotted or stippled end in the window. The operator is thus assured when he sees the ends E within the window, as indicated in Fig. 4, that the cables have been fully inserted to the desired extent and are in position selected by the manufacturer as the proper location to have the connector crimped thereon.

The connector is then deformed into a crimping engagement with the two cables, as, for instance, by applying a squeeze pressure through the outer sleeve at 23 to secure cable A, and at 24 to secure cable B, and in both cases to deform the

shrouds

16 and 17 into a binding engagement with the insulation portions of the two cables.

Referring to the modified form of the invention shown in Figs. and 6, there is disclosed an outer substantially transparent sleeve 25 similar to the sleeve 11 and within which is fitted an inner copper sleeve 26. The sleeve 26 is formed of two

cylindrical end portions

27 and 28 spaced apart to form an opening 29 therebetween. The end portions are integrally connected by a bridge 30 which extends from one to the other as a broad, solid blade. The blade extends across the axis of the opening 29 and is inclined thereto at an angle of about 45 degrees.

Gpposite sides of the bridge are disposed to be engaged by the intruded ends D of the cables A and B, with the end D of the cable B turned upwardly and the and D of the cable C turned downwardly, in both cases into such close proximity to the outer sleeve that the extreme ends E are visible when viewed respectively through the top side and through the bottom side of the outer sleeve, as shown in Fig. 5.

r the cable ends are so located the connector is yd, say, aiong squeeze lines as suggested in Fig. 3, to secure the parts together following conventional practices in this respect.

in Fig. l the bore is constricted at its inner ends. That is, the cross section of the bore as measured in the plane of the sheet between the

faces

21 or 22 of the projection 26) and the adjacent edge of the window forms a throat which is of less cross section than the cross section of the bare ends D. This tends to flatten the ends D as they are forced through the throat so narrowed.

in both the Fig. l and Fig. 5 forms of the invention the cross section of the opening formed between the projection and the inner periphery of the outer sleeve as measured in the plane of the sheet is less than the diameter of the conductor or cable ends E.

In other words and referring to Fig. 3, the cross section of the opening is less than the diameter of the conductor D. Referring to Fig. 5, the distance 37-38 similarly measured is less than the diameter of the conductor D. In either casethe conductor ends E are jammed between the outer sleeve and the projection 20 in Fig. 3, or the bridge 30 in Fig. 5. In both cases the ends E are substantially flattened as they are forced against the inner wall of the outer sleeve and take the form some what that of an ellipse, as viewed in Figs. 4 and 6.

The fact that the ends E show up as ellipses rather than straight lines advises the operator as he looks through the outer sleeve that the wire strands have been bent; that they have contacted the outer sleeve; and thus, in general, that the two cables A and B have been advanced as far as possible and the parts are in position ready to be crimped.

It is noted that in Fig. 3 the several indents along the

lines

23 and 24 are visible. However, as taught by the above-identified Frey Patent, the outer nylon sleeve tends to recover its initial molded form as shown in Fig. 1, by virtue of its plastic memory, and the depressions formed in the outer sleeve, both externally and internally thereof, tend to disappear or substantially so.

The recovering of the outer nylon sleeve tends in its movement away from the permanently deformed inner metal sleeve to form insulating air pockets between the outer nylon sleeve and the inner copper sleeve, as more fully described in the said Frey patent. This also applies to a less extent to the larger indentation 31 which tends to fill up in time, leaving an insulating air pocket between the outer nylon sleeve and the deformed inner sleeve. The metal parts so crimped remain in their positions interlocking with the cables.

While the showing in Figs. 3 and 4 indicates that the wire ends E are not in abutting relation, the disclosure does not prohibit that possibility.

The stripped-back ends D of the wires, particularly if the wires are stranded and sufiiciently flexible, may contact, even before they engage the outer sleeve, and thus the cables are mutually stopped from any further advance into the connector. The line of contact so formed by the meeting ends of the cables is elevated towards the window, as herein featured, and is thus caused to be visible through the window.

I claim:

1. A straight through connector comprising highly conductive cylindrical sleeve members coaxially and integrally jointed by a bridging member defining with the adjacent ends of said sleeve members an aperture affording visual access to the axis of the sleeve members between its adjacent ends, said bridging member extending fixedly and at an angle across the axis or" the bore, projected, of both ends of the sleeve members, and a translucent sleeve coaxially surrounding said members and extending beyond them at both ends, said translucent sleeve and said sleeve members being radially deformable into mutually interlocked relationship to constrict the sleeve members into electric contact with bare ends of wires inserted therein.

2. The combination of a connector formed of two sleeves in telescopic relation, the outer sleeve formed of a translucent thermoplastic material, the inner sleeve formed of a conductive metal, provided with an opening in one side thereof and with a projection integral therewith and facing the opening and projecting into the bore of the inner sleeve, the sides of the projection which face the ends of the inner sleeve being inclined inwardly towards each other and meeting adjacent the axis of the inner sleeve, the outer ends of the bore of the inner sleeve being enlarged to form shrouds, two insulated cables, one inserted into each shroud, each cable having bare wire ends projecting inwardly beyond its associated shroud, with the wire end portion bent sharply at the projection and with the extreme ends of the bare wires located close to the translucent outer sleeve and visible therethrough.

3. The connector defined in claim 2, wherein the shrouds are deformed into a crimping engagement with the insulated parts of the cable therein.

4. An electrical connector adapted for receiving there in bare end portions of insulated electric conductors in spaced, coaxial relation for crimping said connector at spaced points thereon, said connector comprising a cylindrical member of conductive metal having a portion thereof cut away on one side thereof midway of its length to form a slot therein to the depth of its axial center, said cylindrical member having an axial bore extending inwardly of each of its opposite ends terminating short of its midlength within said slot in a pair of oppositely facing, inclined shoulders extending transversely of said bores to provide abutments for respectively engaging the intruded bare ends of said conductors, said cylindrical member having its opposite open end portions counterbored concentric with said bores for receiving the insulation end portion adjacent the bare end portion of said conductors, and an outer sleeve of substantially transparent thermoplastic material having a length greater than said cylindrical member telescoped thereon in tight fitting relation with its opposite ends extending uniformly beyond the open ends of said cylindrical member.

5. An electrical connector adapted for receiving therein bare end portions of insulated electric conductors in spaced, coaxial relation for crimping said connector at spaced points thereon, said connector comprising a ferrule of conductive metal having an internal projection formed therein midway of its length in intersecting rela tion with the axial center thereof, said internal projection presenting oppositely facing inclined shoulders transversely of said ferrule to provide abutments for respectively engaging the intruded bare ends of said conductors, a portion of the peripheral wall of said ferrule being cut away midway of its length to expose said inclined shoulders, said ferrule having its opposite open end portions counterbored concentric therewith for receiving the insulation end portion adjacent the bare end portion of said conductors, and an outer sleeve of substantially trans parent thermoplastic material having a length greater than said ferrule telescoped thereon in tight fitting relation with its opposite ends extending uniformly beyond the open ends of said ferrule.

References Cited in the file of this patent UNITED STATES PATENTS 433,948 Leib Aug. 12, 1890 1,559,668 Brown et al. Nov. 3, 1925 2,370,725 Gordon Mar. 6, 1945 2,396,725 Thomasm Mar. 19, 1946 2,478,082 Broske Aug. 2, 1949