Title: Solderless electrical connector for connecting a plurality of insulated wires

Description: FIELD OF THE INVENTION

This invention relates to solderless electrical connectors and particularly to such connectors utilized to interconnect or splice two or more insulated wires together.

BACKGROUND OF THE INVENTION

One type of solderless connector is made up of a base, a contact, and a cap. This type is exemplified in the teaching of J. P. Pasternak U.S. Pat. No. 3,511,921. The base consists of an insulating material and functions to position and retain the wires to be interconnected. The contact is made of an electrically conductive metal having slots for each of the conductors to be spliced. The slots are of a configuration such that when the wire is forced into the slot, the insulation is pierced and the inside surfaces of the slot bear into the surface of the conductor. Consequently, a plurality of wires forced into respective slots of the contact will interconnect the wires. The cap is also made of an insulating material and is mated with the base to protect and insulate the splice.

In the noted prior patent 3,511,921 of Pasternak, the slots used in the contact had parallel inner walls culminating with a bottom wall perpendicular to the two parallel inner walls, thus forming two sharp corners. When a wire is forced into this slot, the stresses are focused on these corners. It has been realized that these corners have a tendency to tear or distort and under certain conditions cause the posts of the slot to lose their resiliency.

Another slot configuration used in the prior art is disclosed in J. P. Pasternak U. S. Pat. No. 3,718,888. This connector utilizes a pair of cantilevered posts for each wire to be connected. The adjacent sidewalls of each pair taper continuously together toward the fixed ends of the posts. It has now been determined that this slot has to be quite long relative to the height of the contact. Otherwise, the inner walls of the tapered slot will cut unduly into larger sized conductors and risk conductor weakening or breaking.

Furthermore, it is essential in posts of this type that they remain elastic in order to maintain efficient reliable contact with the wire conductor. Post configuration of the above-mentioned prior art would in certain instances evidence a small but still undesirable plastic deformation.

The base in the Pasternak U.S. Pat. No. 3,718,888 teaching has a plurality of adjacent openings for receiving the wires to be interconnected. The guidance which these openings provide is in some circumstances not as adequate as would be desired. Specifically, more than one wire could inadvertently be inserted into the same opening --which would, of course, prevent interconnection. Further, after the wires were inserted, but prior to effecting the splice, wires could possibly stray from their proper position and prevent the cover from mating with the base.

The prior art system of Pasternak 3,718,888 discloses basically passive reactions between the cap and the body to maintain conductor strain relief. But because there is a tendency of the cap to "rebound," the passive clamping action of the base and the cover is not always fully adequate.

SUMMARY OF THE INVENTION

In overcoming some of the prior art problems noted above, pursuant to one aspect of the invention, a wire contact element is provided which utilizes generally keyhole-shaped wire receiving slots. These slots can be made smaller than prior art designs and yet accommodate the same range of wire sizes. Also, the contact does not significantly warp or distort since stresses are distributed more evenly by virtue of the keyhole slot shape. Hence, elasticity of the contact is maintained and longevity of the connection is enhanced.

Another facet of the invention involves the adding of ribs to the base which form easy-to-use channels to guide the wires to be interconnected into retaining tunnels.

Pursuant to a further aspect of the invention, highly enhanced strain relief is achieved by adding bumpers on the cap which cooperate with fins that extend from the ribs of the base, to grip the wires more firmly. In a further embodiment, an offset gripping slot is provided for protecting the connection from torsional and tensional stresses.

The invention, its further features, objects, and advantages are more fully described in the following detailed description of the illustrative embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view showing the elements of the connector;

FIG. 2 is a partial section perspective view of the connector base;

FIG. 3A is a cross section of the connector base showing the wire end prior to insertion;

FIG. 3B is a partial cross section of the connector base and cap with the wire inserted into splicing position;

FIG. 3C is a partial cross section of the connector in a closed position with the splice implemented;

FIG. 4A is a cross section of the connector prior to the interconnection of the wires;

FIG. 4B is a cross section of the connector with the cap snap-locked to the base and the interconnection of the wire implemented;

FIG. 5 is a perspective view of the contact of the connector showing a wire in its connected position;

FIG. 6 is a perspective view of the butt-splice type connector;

FIG. 7 is a perspective view of the bridge-splice type connector; and

FIG. 8 is a perspective view of the base of the bridge-splice type connector.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The three basic components of the solderless connector denoted 10, consist of a base 20, a contact 40, and a cap 60 as depicted in FIG. 1. The base 20 is equipped with vertical rib extensions, for example, the three ribs 21. These, with associated wire-gripping means such as fin pairs 29 illustrated in FIGS. 2 and 8, form two channels 22.

FIGS. 3A, 3B and 3C show assembly sequence. On insertion, a wire 90 is guided into a channel 22 aided by the entrance-flanking ribs 21. The wire then encounters ramp 27 seen in FIGS. 2 and 3A. The wire 90 passes through wire-receiving tunnels 23 until they touch the rear closed ends of the tunnels.

The base 20 interior has an interior chamber generally denoted 24, which includes a central riser 24-a. The tunnels 23 are formed in part through riser 24-a. The top of riser 24-a ends beneath the top edge of base 20.

Just within each tunnel opening, a ramp 27 is formed, so that the passage for the conductor leads upwardly to the level of the tunnel floor. In this distance, the passage makes a transition from rectangular at the entrance, as seen in FIG. 8, to circular at the first interruption point adjacent to the recess 24-1. The ramp 27 is contoured to the curvature of this transition zone.

Advantageously, because the ramp changes direction more rapidly than the associated wire, the space denoted 23a in FIG. 3C is created beneath the wire. Encapsulating sealant thus may be placed or provided within this space to provide an initial blocking medium against moisture seeking to enter the connector interior.

The U-shaped contact 40 contained in cap 60 and depicted in FIG. 5 electrically interconnects two insulated conductors inserted into the body 20, by intersecting the tunnels and engaging each conductor in two separate places. Engagement is aided by anvil 26.

Contact 40 receives a given wire in two sets of jaws, each jaw set being defined by a pair of opposing posts 48. Each pair of posts 48 forms a wire slot 41 consisting of an open mouth entrance 45, which tapers to closely spaced and substantially parallel wire-contacting walls 46 and thereafter widens out in a bulbous configuration 47. The latter is smoothly contoured to have no sharp inside corners. The entire wire slot as defined is seen to have a keyhole shape.

As seen in FIGS. 4A and 4B, during insertion of the wire into the slot, the insulation is penetrated, pierced, and stripped away from the conductor, and the conductor penetrated by slot entrant details resulting in bearing contact of the inner walls of the slot on the conductor.

By virtue of the keyhole slot 41, stresses created by placement of wires between the walls 46 are more evenly distributed which helps minimize splitting or warping of the contact. Contact elasticity is thus maintained. The bulbous configuration 47 also permits maximizing the range of conductor sizes with a minimum length of the slot 41.

The central expansion slots 42 are substantially coextensive in length with the slots 41, and serve to further permit resilient movement of the posts 48 as they spread to accommodate a wire. Each post 48 has a shoulder 43 transverse to the walls 46 and located at the base of entrance 45. As seen in the sequence depicted in FIGS. 3A, 3B, 3C, the insulation is pierced and then shoulder 43 strips away insulation.

Cap 60, seen in FIGS. 1, 4A and 4B has two nubs 61 which mate with the holes 44 in contact 40, thus providing a means for indexing and subsequent fastening the contact to the cap. Grooves 25 are located on each side of the base 20 for loosely snap-fitting with inwardly extending tongues 64 of cap 60. This secures the cap to the base in an initial, ready-to-splice position as seen in FIG. 4A. In this position the contact posts 48 are noninterruptive with respect to the tunnels. Advantageously, the connector is supplied to the field with the body and cap in this position.

Once the wires 90 have been inserted into the body 20 the cap and body are pressed together. During this operation, a number of things take place. First, tongues 64 are forced out of the grooves 25. Next, the mouths 45 of the contact 40 pierce the insulation of the wires 90. The wires at this point yield downwardly a distance dependent on wire gauge size, and also on whether the wire is copper as illustrated in FIG. 4B, or aluminum. If aluminum, the wire will deflect significantly more, but not beyond the supporting anvils 26 which act as a secondary stuffing surface in that event. The anvils 26 in serving this purpose advantageously extend fully across the recesses as illustrated, but terminate in a flat top surface situated slightly below the floors of tunnels 23 -- the distance being shown somewhat exaggerated for illustrative purposes. As the slots 41 move over the wires, the wide areas created by the shoulders 43 pierce and strip away the insulation, thus permitting the walls 46 to receive the bared conductors and yieldingly engage the surfaces thereof.

Meanwhile, two bumpers 62 located on the underside of cap 60, as seen in FIGS. 3A, 3B, 3C, and equipped with staircase-shaped insulation contacting and gripping teeth 63 come in contact with the insulation. In the closed position, when the cap 60 and base 20 are mated, as in FIG. 4B, the bumpers 62 extend into the channels 22. The wires 90 are thereby forced or stuffed between yieldable members such as fin pairs 29 seen in FIGS. 2 and 8. The gripping teeth 63 now bear against wires 90 and the lower wire-contacting edge of bumpers 62 even further snubs and holds the wires down, as seen in FIG. 3C. This function pursuant to one aspect of the invention secures the wires and protects the splice from tensional and torsional stresses. The tongues 64 slide over retaining steps 28, advantageously with an audible click, indicating that the splice is effected. The cap 60 is now secured to the base 20, as seen in FIGS. 3C and 4B. The completed connection is shown in FIG. 6.

In order to minimize oxidation of aluminum conductors, it is advisable to include a globule of sealant, such as polyethylene-polybutene within the connector assembly to protect the connection from moisture and corrosive gases.

The above-illustrated embodiment accommodates a two-wire splice. However, the invention also contemplates connectors of the same wire-receiving and gripping configurations but with capacity extended to three or indeed many more, i.e., 100 wires. Here bridging between pairs or any adjacent two or more wires is achieved by expanding the contact element.

Practical experience has determined that approximately seventy-five percent of the usage of this type of connector is in two-wire butt splicing. As noted, the first embodiment relates to a two-wire butt splice connector. However, a bridge-splice version is depicted in FIGS. 7 and 8 as the connector 50. FIG. 8 indicates an angled slot 31 comprising an open wire-receiving side in the tunnel, which provides a means for inserting a continuous wire 91 into the connector body 30. An extension 32 is provided with a gripping slot 33 for securing the respective side of the wire and providing strain relief. This gripping area is offset from the wire and tunnel center line to prevent relative rotation of the connector with respect to the wire. The offset also makes it very difficult for a through wire to twist out of the slot 31 after insertion. The cap 70 of the connector 50 is so modified as to correspond with the extension 32 of the body 30.

The spirit of the invention is embraced in the scope of the claims to follow.
Other info:


Inventors: D'Annessa, Anthony Thomas (Marietta, GA, US)
Gustin, Paul Rudolph (Baltimore, MD, US)
Smith, Donald Tolman (Norcross, GA, US)
Zalmans, Janis John (Atlanta, GA, US)

Application Number: 545816
Filing Date: 1975-01-31
Publication_date: 1976-02-03
Assignee: Bell Telephone Laboratories, Incorporated (Murray Hill, NJ); Western Electric Company (New York, NY)
Primary Class(es): 439/399
Other Classes:
US Patent Ref:

3511921	May, 1970	Pasternak	174/88.
3718888	Feb, 1973	Pasternak	339/98.
3890029	Jun, 1975	Izraeli	339/98.

Other Refs:
Primary Examiner: McGlynn, Joseph H.
Assistant Examiner:
Attorney: Graves; C. E.