US2279794A - Electrical connector - Google Patents

Description

April 14, 1942. E. R. oLsoN ELECTRICAL/ CONNECTOR Filed Jan. a,v 19.41

INVENTOR. Osofb UNiTll-:D s'm'rr-:sV PATEN ELECTPICAL CONNECTOR Einar- B. Olson, Richmond, Ind., assignor to Belden Manufacturing Company, Chicago, Ill.,

a corporation of Illinois Application January 8, 1941, Serial No. 373,529 4 Claims. (C1. 173-269) fr. OFFICE My invention relates generally to mono-cord electrical connectors of the plug-in type, as for example, the jack plug connectors used in conjunction with electrically operated business and tabulating machines, switchboards, and the like. The invention is. particularly concerned with the provision of an improved electrical and mechanical connection for the terminals and conductors of connectors of this general type, this connection reducing breakage and extending the service life of these devices.

Connectors of the subject type'usually comprise a cylindrical, metallic, terminal or contact member of the plug-in type, a flexible, insulated lead wire or cord having a stranded conductor which is attached to the rear portion of the contact member, and a suitable grip or sleeve, preferably of resilient rubber, enclosing the rear portion of the contact member and the adjacent portion of the lead wire. This resilient grip or sleeve serves to enclose the electrical and mechanical connection between the terminal and the lead wire, and facilitates the grasping of the connector during its use. The grip or sleeve may also provide a certain amount of strain relief support for the lead wire.

Although connectors of this type now in use are generally satisfactory for the purposes intended as long as they remain in good condition,

the breakage and failure thereof due to the repeated flexing, bending, and tension stresses which accompany the ordinary use oi these connectors is relatively high. v

The principal object oi my invention is to provide plug-in connectors of this type which have a much greater service life than that of connectors heretofore available in the art. An additional object of my invention is to provide improved long-life connectors which can be manufactured at little or no greater cost than the present connectors intended for the same purposes.

Accordinggto my invention, the usual fabric or thread separator which overlies the conductor o f the lead wire portion of the connector, contrary to the prior practice, is not removed when the connector is assembled. A clip of thin metal,

overlies the end of the lead wire and the separator which is left in place thereon. Projections provided on the inside of the clipextend through the serving to engage the strands of the lead wire conductor. crimped or pressed onto this end of the lead wire with the metal clip thereon. The separator, which is left on the end of the conductor, serves both to support the conductor, and as a sleeve The terminal or, contact member is housing or retainer for the ends of any o! the conductor. strands' which may become broken through extended use. trasts with the usual connector assembly and construction wherein the end of the lead wire conductor is completely bared and stripped of all insulation, including the inner separator, and a terminal is then fastened to the bare end.

For a more complete understanding of the nature and scope of my invention, reference may now be had to the following detailed description taken in connection with the drawing, in which:

accompanying Fig. l1 shows a lead wire -with the diiierent layers or parts of the insulation stripped therefrom so as to show the construction thereof;

Figs. 2, 3, and 4 are sectional views taken on A lines 2 2, 3 3 and 6 8, respectively, of Fig. 1; Fig. 5 is a perspective view of'a thin metal clip member before it is applied to the end of the leadv wire;

Fig. 6 isa viewvshowing the metal clip applied over the stripped end of a lead wire;

Fig. 7 is a sectional view taken on line 1 1 of Fig. 6;

Fig. 8 is a fragmentary'view of a terminal or,

contact member which is to be applied tothe end of a lead wire;

Fig. 9 is a side view of a completely assembled electrical plug-in connector; and,

Fig. l0 is a sectional view taken on line it-l@ of Fig. 9.

Referring now to Figs. 1 through 4 of the drawing, a lead wire or cord is indicated generally at 5 having'a flexible, central, stranded conductor it. The conductor i@ is covered with a separator il made up of threads woundin long spirals of relatively few turns per unit length, around the conductor. This type of covering, when thus formed, by winding threads around a conductor, is referred to in the art as a serving or serve.

And, when the threads are wound in long spirals so as to be nearly lengthwise with the conductor, the covering is referred to as a long serve. Such a serving has considerable longitudinal strength. It will be understood that the separator il, instead of being in the form of a serving as shown may also be in other forms such as a long single braid. The threads making up theseparator Il are preferably formed of long, staple cotton fibers. However, certain other iibrous materials such as wool fibers, silk, synthetic bers, spun glass, etc., may be used. g

A sheath of rubber insulation I2 is extruded over the separator or serving Il. Ordinarily the This construction conlarly available on of tin, iron, copper,

shown iny Fig. 6.

' linder that would be onto or over the en'd of shown in Fig. 10.

crimping also serve to securely port for the lend lead wirewill be providedwith an outer woven or4 braided fabric'sleeve rubber insulation I2, vas shown. However, the braided sleeve I3 is vnot essentiaL- andv may be omitted. The lead wire o'r cord 5 shown and described is representative of diilferent types and grades of wire or conductor cord that arezregu- Figs. 5 through 10 of the drawing to show the assembly and construction of. one form -of electrical plug-in connector which embodies the features of my invention. In Fig.' 5 a thinmetal clip Il is shown having I5 punched out and turned up therefrom, as shown. The clip or member IImay be formed zinc, attaching a terminal or connector to thevend of a lead wire, the braided sleeve I3 and rubber insulation I2 are stripped away from one end of the lead wire, leaving the separator II 'intact thereon.' The clip Il is then wrapped around I3 over the outside of the` strain relief su the market, in large quantities.

show 'the ruggedness ,and

four projections or points cuprous alloys, etc. :In z

the stripped or trimmed end of the lead wire, as

'I'he rear ofthe clip -II should preferably tagainst the end of the rubber insulation I2, and the edges 'of the clip I4 should be spaced apart, or separated, as indicated at Il (Fig. 6). By having the edges ofthe clip Il thus spaced apart, the clip Il may be readily pressed and crimped without having to distort the c'yformed if the edges of the clip Il abutted each other. This same result may be obtained by I4 overlap eachother'. Thefprongs or projections I5 on the inside of the clip I4 project into the strands of the central conductor I0 as shown in Fig. 7. When a terminal member, such as the 2| shown in Fig. 8, is crimped the lead wire, the projecterminalv member having the edges of the clip tions I5 will be furtherpressed or, forced into the center-of the conductor III.

The terminal or contact member 20 comprises a solid end portion 2l with alarger diameter tubular or from the rear'thereof. After the clip I4 is' placed on the prepared or stripped end of a lead wire, as shown in Figs. 6 and "I, the terminal 20 is slipped over this end"of the lead wire and the tubular portion is squeezed or crimped thereto as Finally, a resilient grip or sleeve 23, which may have been previously slid back on the lead wire, is pulledover the ltubular portion 2 2 of `the terminal 20, as shown. The grip 23 iits tightly or snugly around the rear end 22 of the terminal 20 and the adjacent end of the lead wire, and covers readily made.

A good electrical 20 and the central conductor I0 is made through the clip I4 and the prongs or projections I5 projecting deeply into the heart of the conductor. The indentations 24 in the tubular portion 22 provide good electrical contact with the clip Il. The indentations 23 and fasten the terminal 20 to the end of the lead wire.

Although the grip 23, braid I3 and insulation I2 provide a certain amount of strain relief supof the central flexible conductor I0, the'same as in prior constructions, it must still withstand repeated ilexure stresses at the end to which the terminal 20 is attached. Ex-

hollow section 22 extending integrally and mechanical'connection between the terminal 60.

tended tests and observations of my improved connectors have shown that the strong separator or serving II, which extends clear out to the end of the conductor Il, gives a material amount of rt to the end of the conductor I0 whereit is fastened to the terminal 20.

In order to obtain an indication of the longevity of service to be obtained from connectors of this type, theymaybesubjected to repeated bendnectors without theseparator II failed at only 80,000 cycles of bending.

-In addition to the above'ileizure tests, sample connectors both with and without the. separator removed from -the ends thereof have been tested 'for tensile strength.. In making these tests, the force required-to "pulllou the lead-wire from the connector is measured. Samples of con-4 nectors having a construction as shown in Eig. l0, wherein the vseparator extends to the end of found to have an average Apull ou strength of about 23 pounds. Similar plug-in lconnectors havingthe separator removed from the trimmed end had an'average pull ou strength of about 15 lbs. It -is thus apparent from these exure and pull outf strength tests that velectricalconnectors made according to my invention will give much longer service in use.

Besides the above outlined advantages and improvedwear and strength properties of my connector constructions 'given by retaining the separator or servingat the end of the lead wires,

the elimination of the additional step of remov foregoing construction and -diilerent embodi- 'v ments of my invention may be made without departing from the scope that all matter shown in the accompanying drawing, or described heretofore, shall be interpreted as illustrative and not in a limiting sense, and that the claims shall be given a construction as broad as is consistent with the state of the prior art.

I claim as my invention: 1. Electrical connector means comprising, in combination; a lead wire having, a central, flexible conductor, a fibrous covering over said conductor, and a sheath of insulation over said brous covering; a thin of said lead wire from which said rubber insulation has been removed, said clip enclosing said flbrous'covering and portions of said clip being in electrical conductive relationship with said flexible conductor; and a contact member having a tubular portionfor .receiving the end of said lead'wire having 'said clip thereon, said tubular portion of the terminal being crimped onto the clip at the end of the lead wire to provide a mechanical and electrical connection between the lead wire andthe terminal.

2. Electrical connector'means comprising, in combination; a lead wire having, a central stranded conductora separator enclosing said stranded conductor, and a sheath of rubber inisulation over said-separator; a thin metal clip tests'have been made to was an additional cost item in thereof, it is intended metal clip on one end envases least a portion thereof projecting into said.

stranded conductor; and a plug-in terminal member havmg a tubular portion on the rear thereof for receiving the stripped end of said lead wire having said clip thereon, said tubular portion of the terminal being crimpedfonto said clip at the end oi said lead wire to provide a mechanical and electrical connection between said lead wire and the terminal: said separador providing both e, strength support and housing for the end of said stranded conductor 3. In an electrical connector, in combination; a lead wire having, a central stranded conduc tor, a :fabric separator' enclosing said stranded conductor with the threads of said separator extending generally longitudinally of the length of the conductor, and a sheath of rubber insulaton extruded over said separator; a thin metal clip around one end of said lead wire from which said rubber ins ation lies ineen removed, said clip enclosing the ends oi said separator and conductor; e plmality or integral projections on the inside ,of clip projecting into said strand ed conductor providing,p electrical Contact therewith; and a ping-in terminal member having a tubular portion' on the rear thereof for receiving the stripped end of said lead wire having said clip thereon, said tubular portion of the terminal being crimped onto the clip and the stripped end of the lead wire therein so as to fasten the terminal thereto and provide a goed electrical connection with the clip; said separator providl ing both a support for the end of said stranded conductor in fiexure stressing and a retaining cio@l sure for broken ends of the conductor strands.

d. Aplug-in electrical connector construction adapted to'withstand repeated iiexing comprising, in combination; a lead wire having, a central stranded conductor, a serving around said stranded conductor in which the threads of said serving are in long spirals of relatively few turns per unit length oi the conductor, a sheath of rubber insulation extruded over said serving, and a braided sleeve over said rubber sheath; a thin metal clip pressed around one end of said lead Wire from which said rubber insulation and braided sleeve have been stripped, the edges of said clip' being apart, said clip enclosing the ends of said serving and conductor, a plurality of integral projections on the inside of said clip projecting into said stranded conductor to provide electrical contact between the clip and conductor; s. plug-in terminal member having a tubular portion on the rear thereof for receiving said stripped end of the lead wire having said clip thereon, said tubular portion of the terminal be ing crimped onto the stripped end of the lead wire therein so as to fasten the terminal thereto and provide a good electrical connection with said clip; and s. resilient grip tting over the tubular portion of said terminal member and 'the .adjacent portion of said lead Wire; said serving providing 'looth e support for the end or' said stranded conductor in dorure stressing and a retaining closure for breiten ends or tire condeci'or strands adjacent the rear end of said clip. iS-INAH lt. @USUN

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