US3123427A - Electrical connectors - Google Patents

Description

March 3, 1964 R. s. YOPP ELECTRICAL CONNECTORS Filed April 18. 1961 i0 33 34 I I 'IIIIIIIIIW/II'IIIIIIIIIII United States Patent 3,123,427 ELECTRICAL CONNECTORS Robert S. Yopp, Riverside, Ill., assignor to Amphenol- Borg Electronics Corporation, Broadview, Ill., a corporation of Delaware Filed Apr. 18, 1961, Ser. No. 103,866 1 Claim. (Cl. 339-252) The present invention relates to electrical connectors, and particularly to the contact elements of such connectors.

It is a primary object of the invention to provide an improved form of contact pin, having high performance characteristics yet of a mechanical design particularlyadaptable to high density contact placement wherein many contacts may be closely grouped within a comparatively small connector.

A further object is to provide a contact pin having the above characteristics yet which is relatively simple, quite rugged, inexpensive, and well suited to mass production manufacture by automatic machinery.

More specifically, it is among the objects of the invention to provide a contact pin adapted to telescope within a mating contact sleeve but so arranged that the resiliency usually provided between the contacts is derived wholly from the structure of the pin itself, rather than from the sleeve. This permits use of a completely rigid sleeve which, unlike the various split sleeves or resilient socket devices heretofore often provided, is quite immune to damage by spreading or enlarging, as frequently caused by careless use of a test probe, for example.

A further object of the invention is to provide an expansible, resilient pin contact for the purpose indicated above, so designed and constructed as to telescope within its mating sleeve with the exact pressure and frictional characteristics desired, whereby the contacts are capable of meeting exacting Government or commercial standards as to insertion and withdrawal forces. This not only requires that the contacts be capable of achieving an unusually high initial degree of uniformity in insertion and withdrawal forces between the several contacts of a given connector, but also that the individual pairs of contacts show specified uniformity of characteristics even after long repeated test cycles of coupling and uncoupling.

A further object of the invention is the provision of a contact as indicated above wherein the pin affords a plurality of smoothly rounded, convex contact slide surfaces, each adapted to engage the inner surfaces of a mating contact sleeve to provide a multiple-path electrical union between the contacts.

Obviously, the accomplishment of the objects enumerated above requires reconciliation of several conflicting considerations and the simultaneous provision of features usually regarded as incompatible with each other. The objects are accomplished in the present invention by provision of an improved pin-type contact wherein the pin consists of a plurality of individual spring wires, each resiliently biased in a manner to frictionally engage the inside of a mating contact sleeve, with adequate spring pressure between each of the several pin wires and the inner surfaces of the sleeve to achieve a positive multiplepath parallel connection.

Improved means of interlocking the forward ends of several U-shaped wire members are provided in a manner to hold the several spring wires thereof in a closely grouped cluster and to thus present a smoothly rounded tip at the end of the pin. This aids in the insertion of the pin within its mating sleeve as Well as maintaining the individual wires of the contact pin against lateral displacement. The several wires forming the pin are interlocked at their forward end in a manner to achieve a smoothly rounded tip, yet without the need of any turning, swaging ice or other manufacturing operations which might impair the surface finish of the wire.

The present invention also provides contacts of such design that they may be conveniently crimped to their conductors before assembly and thereafter rotatably mounted in the cavities of the connector dielectrics. The contacts may be soldered or crimped to their conductor as desired, with the design of the female sleeves and the mounting devices for the male pin contact of essentially the same design whereby economies of manufacture may be realized.

A preferred embodiment is illustrated in the drawings attached to and forming a part of the present specification, wherein:

FIGURE 1 is an enlarged fragmental cross-sectional view of the essential elements of an electrical connector employing contacts constructed in accordance with the present teaching;

FIGURE 2 is an enlarged cross-sectional view of one of the male contacts formed of a cluster of spring wire slides according to the present invention;

FIGURE 3 is a further enlarged detail cross-sectional View taken substantially on the plane of the line 33 of FIGURE 1 and illustrating the appearance of the forward end of the pin contact;

FIGURE 4 is a similarly enlarged detail cross-sectional view taken on the plane of the line 4-4 of FIGURE 1 and showing the multiple-path interconnection between the contact pin wires and their mating sleeve; and

FIGURE 5 is a detail sectional view taken substantially on the line 55 of FIGURE 3 and illustrating the crimped indentations by which the contact pin wires are interlocked with each other at the forward end of the pin.

Contacts according to the present invention are applicable to a wide Variety of electrical connectors, but in a typical installation will each be mounted in a cavity 10 formed in a dielectric body member 11 of the connector and adapted to telescope within the tubular metallic sleeve 12 comprising the female contact and carried within a similar cavity 13 in the dielectric member 14 of a mating connector.

The male contact, to which the present invention is particularly directed, includes a pair of elongated hairpin loops A and B formed of resilient material such as pretempered beryllium copper wire, with the paired leg portions 15 and 16 of the loop A interconnected by a return bend 17 at the extreme forward (left) end of the contact and with the opposed leg portions 18 and 19 of the loop B interconnected by a return bend 20 closely encircled by the portion 17 described above (FIGURE 2). The leg portions 15, 16, 18 and 19 thus coact to form two opposed pairs of spring-pressed contact members, each having a normally bowed contour as best illustrated in FIGURE 2, but presenting an over-all tapered appearance so that the individual wires are resiliently yieldable and may be simultaneously flexed toward each other upon insertion of the male contact in the mating sleeve 12, Whereupon the parts assume the position of engagement illustrated in FIGURES l, 3 and 4.

The forward ends 17 and 18 of the loops A and B are interlocked with each other by inwardly crimped indentations 21 and 22 formed between the forward ends of the leg portions 15 and 16 and the returns bend 17, so that the indented portions of the wires come close to or contact each other at 23 in a manner to substantially encircle the return bend portion 20 of the loop B.

From the above it will be apparent that the interlocked ends of the loops form a smoothly rounded tip portion which may be only a few thousandths of an inch less than the interior diameter of the sleeve 12 (FIGURE 3), yet which may be easily and conveniently inserted into the tapered forward portion of the sleeve upon coupling movement of the connector. The rearward ends of the interlocked wire loops are mounted in a conductive metallic sleeve 25 which, in the preferred practice of the invention, has its forward portion 26 crimped around the several contact wires and is provided with a central neck portion 27 of reduced diameter and a rearward sleeve into which flexible insulated conductors 2% may be secured by soldering, if desired, or by crimping of the sleeve as indicated at 29 (FIGURE 1).

Since the sleeve 25 may be similar to or identical with the female sleeve 12 except as to length, it is obvious that manufacturing economies may be achieved in the manufacture of connectors having male and female contacts according to the present design. Also, the form of sleeve illustrated lends itself to cooperation with the mounting shoulders within the cavities of the inserts 11 and 14, each of which may be provided with a reduced diameter neck 32 having an abrupt shoulder 33 at its forward end and a gradually tapered portion 34 extending rearwardly thereof so that the contacts, after being attached to their respective conductors 28, may be easily snapped into position within their cavities.

From the foregoing it should be apparent that the teachings of the present invention achieve advantages over the prior art in that they provide a resilient, expansible contact pin capable of establishing low resistance electrical contact with a mating contact of simple tubular form. The contact pin is composed of a compact cluster of separate wire legs presenting several smoothly rounded convex slides to the interior surfaces of the sleeves, yet the forward extremities of each of the wires of the pin are interlocked in a manner to provide a smoothly rounded tip capable of easy insertion in a tubular sleeve. The contacts may be of unplated wire if desired, but since the pin may be formed without the necessity of welding, turning or other operations which would roughen or otherwise damage the surfaces of the metal during manufacture it is also possible to use Wire having a preplated layer of silver, gold or other metal so that all operating surfaces of the finished contact are highly conductive and corrosion resistant. The interlocking of the wire loops in the manner shown prevents spreading or misalignment of the several wires of the pin makes it practicable to use relatively large contact wires within a comparatively small contact sleeve, thus achieving the greatest possible physical strength for any given size contact, and assuring adequate spring pressure and maximum current carrying capacity,

Having thus described my invention, what I claim as new and desire to secure by United States Letters Patent is:

A pin contact for electrical connectors consisting of a pair of resilient spring Wires of substantially equal circular cross-sectional area, each wire being doubled back upon itself to provide a generally U-shaped loop having a pair of relatively long legs including slide portions of generally outwardly bowed configuration interconnected by a sharp return bend portion, each wire at the return bend portion being doubled back upon itself degrees or more, the return bend portions of the two wires overlying each other in perpendicular relationship, with one outside the other at the end thereof, the inside of the outside return bend portion being in direct contact with the outside end of the inside return bend portion along the periphery thereof, whereby the wires are restrained against lateral shifting with respect to each other and the return bend portions thereof extend longitudinally to a point where the slide portions begin to coact to form a compact smoothly rounded tip of lateral dimension adapted to be received within a cylindrical sleeve before engagement of the slide portions with said sleeve.

References Cited in the file of this patent UNITED STATES PATENTS 2,563,713 Frei et al Aug. 7, 1951 FOREIGN PATENTS 196,953 Great Britain Jan. 4, 1923 458,969 Germany Apr. 26, 1928 711,998 France July 8, 1931

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