Non-Bulging Quick Snap-on Strain Relief Adapter

1. Field of the Invention

This invention relates to a strain relief adapter for an electrical connector, and is more particularly concerned with a non-bulging quick snap-on strain relief adapter for an elongate electrical connector.

2. Description of the Prior Art

In the past, strain relief for conductors which are connected to electrical contacts has been provided by a variety of structures. A tortious conductor path, for example, may be utilized to provide strain relief for flat multi-conductor cables, such as disclosed by D. J. Crimmins in U.S. Pat. No. 3,336,565.

For multi-conductor cables of circular cross section, a variety of strain relief clamps have heretofore been disclosed. One such strain relief clamp is disclosed by J. E. Caveney and Roy A. Moody in U.S. Pat. No. 3,638,169.

Although elongate electrical connectors may employ a strain relief clamp for the entire cable, the elongate structure of the connector requires removal of the outer protective jacket material of a cable so that the individual insulated conductors may extend individually to and be connected to respective contacts of the electrical connector, which contacts are usually aligned, spaced apart in rows on opposite sides of the electrical connector. In elongate electrical connectors of the type which employ insulation-opening contacts, it is highly desirable to provide strain relief for each of the individual conductors in order to prevent accidental and inadvertent dislodging of the conductors from the contacts. A strain relief adapter for use with an elongate electrical connector is disclosed by Istvan Mathe in his U.S. Pat. No. 3,959,868. This adapter includes an elongate member which carries a plurality of transversely extending members which engage and press against the individual conductors as the same are held in respective insulation-opening contact portions on one side of an electrical connector. A similarly constructed member provides strain relief for the opposite side of the electrical connector. Each of the strain relief adapters includes a pair of arms located at opposite ends of the elongate member which are hook-shaped and embrace the rear end of the electrical connector for anchoring the adapters to the connector. Also, each of the elongate members includes a transversely extending, notched member which receives the individual conductors in the notches and urges the conductors into the strain relief mechanism normally carried by the electrical connector so as to provide an additional strain relief for the conductors.

In his allowed patent application Ser. No. 679,091, Istvan Mathe discloses a similar elongate member in which the means for anchoring a pair of elongate members on opposite sides of an electrical connector includes a hook-shaped arm at one end of the member which is received in a recess of the other elongate member.

In U.S. Pat. No. 3,958,853, R. E. Wilson discloses an elongate member which carries a plurality of individual projections which bear against the individual conductors which are carried in insulation-piercing contacts of an electrical connector. The electrical connector has a pair of slots at each end thereof and each of the elongate members is provided with a flip-shaped element at each end for engaging respective slots at opposite ends of the connector.

In U.S. Pat. No. 3,920,306 M. E. Barnett Jr., G. H. Foster Jr. and G. A. Patton disclose the utilization of a pair of clamping bars on opposite sides of an electrical connector. The clamping bars each include a recessed arm at one end and a projection at the other end for interengagement with like structure of the other clamping bar. Each of the clamping bars also includes a transversely extending hook-shaped member and a rearwardly extending projection carried on the rear surface of the clamping bar. The hook-shaped member extends across the rear end of the connector to engage the projection of the other clamping bar.

Although various strain relief structures are known in the art, as noted by the examples referenced above, a number of problems have been encountered and have been solved, and advantages heretofore unknown have been realized, according to the primary object of the present invention, by providing a new and improved strain relief adapter.

One object of the invention is to provide a strain relief adapter of the type generally set forth above in which the end latches have been eliminated so that the adapter may fit in a standard right angle hood generally used with the elongate electrical connector.

Another object of the invention is to provide for a positive alignment between the adapter and the connector insert in order to shorten field assembly time.

Another object of the invention is to provide a strain relief adapter with a structure which positively controls ride-up of the adapter under force, that is displacement of the adapter in the rearward direction of the connector.

Another object of the invention is to provide a strain relief adapter which will hold insulation-opened conductors positively between the insulation-opening jaws and control bulging out, i.e. bending out of the adapter at the center, when an adapter is assembled to an electrical connector.

According to the invention, a strain relief adapter is provided for an electrical connector of the type which includes an elongate dielectric rear member, a plurality of insulation-opening contact portions which are supported spaced apart by the dielectric rear member for receiving respective insulated conductors, and a front member which is connected to the rear member and adapted to mate with another electrical connector, the adapter comprising an elongate member, pressure means in the form of a plurality of spaced apart blades carried by the elongate member for pressing against the conductors to urge the conductors into the insulation-opening contact portions, and anchoring means for securing the elongate member to the connector, the anchoring means being in the form of a plurality of spaced hook-shaped members which engage a flange near the juncture of the front member and rear member and a plurality of spaced apart hook-shaped members which engage a shoulder formed in the rear surface of the dielectric rear member.

More specifically, a strain relief adapter for an electrical connector of the type generally mentioned above comprises a pair of elongate members for engagement with respective sides of the dielectric rear member, each of the elongate members including a forward edge and a rear edge, referenced to the front and rear of the connector, pressure members between the forward edge and rear edge for engaging and pressing against the conductors in the insulation-opening contact portions, a plurality of hooks for engaging a respective flange on the respective side of the electrical connector and constituting a pivot for rotating the elongate member toward the rear member and at least one latch surface for engaging at least one shoulder in an elongate groove in the rear surface of the elongate dielectric rear member of the electrical connector.

In one embodiment of the invention the latch surface is constituted by a plurality of forward extending projections which extend from a transversely directed member carried by the elongate member. In this embodiment, the projections extend forward in an area between the blade-shaped pressure members over the entire extent of the elongate member.

In another embodiment of the invention, the latch surface is formed by a plurality of spaced forwardly extending projections, similar in structure to the projections mentioned above, but being fewer in number and terminated at each end so as to form pockets, each of which pockets surround a group of barriers which extend transversely of the dielectric rear member forming channels in which the insulation-opening contacts are mounted.

In another embodiment, a pair of projections extend transversely from the elongate member and carry a cross member at the distal ends thereof, the projecting members and the cross member forming an opening for receiving the end of a barrier therein.

Other objects, features and advantages of the invention, its organization, construction and operation will be best understood from the following detailed description taken in conjunction with the accompanying drawings, on which:

FIG. 1 is a pictorial representation of an elongate electrical connector with the protective hood removed and with a pair of strain relief adapters constructed according to the present invention mounted thereon;

FIG. 2 is a top plan view of one of the strain relief adapters of FIG. 1, shown partially in section;

FIG. 3 is a side elevation view of the strain relief adapter;

FIG. 4 is a sectional view of the strain relief adapter taken generally along the line IV--IV of FIG. 3;

FIG. 5 is a side elevation of the strain relief adapter showing the side opposite to that illustrated in FIG. 3;

FIG. 6 is a side elevation view, similar to that of FIG. 5, showing a different latch mechanism for the strain relief adapter;

FIG. 7 is a transverse section of an elongate electrical connector with a protective hood thereon and the strain relief adapters of FIGS. 1-5 mounted thereon, showing the relationships between the connector, the insulation-opening contacts of the connector, the insulated conductors and the strain relief adapters and the relationships between the connector, the strain relief adapters and the protective hood;

FIG. 8 is a fragmentary pictorial illustration of a portion of an elongate electrical connector with a strain relief adapter thereon, the strain relief adapter including portions of pressure members for extending into the strain relief of the connector and a latch construction which is different from that illustrated in FIGS. 5 and 6.

Referring to FIG. 1, an elongate electrical connector having a pair of strain relief adapters mounted thereon is generally illustrated at 10 as comprising a forward end 12 having a hollow front housing 14 which is adapted to mate with a complementary electrical connector, and a rear member 16 which supports a plurality of insulation-opening contacts, such as found on the Amphenol Connector designated 157-82500-3. The connector 12 includes an end flange 18 at one end thereof and an end flange 20 at the other end thereof which supports a cable strain relief structure 22. A pair of strain relief adapters 24 is mounted on the rear end 16 of the electrical connector. As illustrated, the electrical connector includes a pair of components, which may be formed sheet metal components, which are secured together to hold the dielectric insert which carries the rear member 16, one of which components includes a flange 44 which is directed inwardly of the connector.

Referring to FIGS. 2-5, each strain relief adapter 24 is illustrated as comprising an elongate member 26 having a transversely extending end member 28 at one end and a transversely extending end member 30 at the opposite end thereof. On one side, the inner side, the elongate member 26 has a pressure means in the form of a plurality of inwardly extending pressure members or pressure blades 32 which are spaced apart corresponding to the spacing of the insulation-opening contacts of the electrical connector. As best seen in FIGS. 4 and 7, each pressure member 32 has a forward surface for engaging and pressing against a conductor mounted in the respective contact and a projection 36 which deflects upon engagement with the respective conductor and presses the conductor further inwardly at a point adjacent the end of the terminating portion of the contact in a constricted-opening strain relief which is normally a part of the electrical connector. This construction of the electrical connector is best seen at reference 104 in FIG. 8.

As illustrated in FIGS. 3, 4, 5 and 7, some of the pressure members 32 may be provided with an extension 38 which carries a transversely extending projection 40 to form a hook-shaped member which engages beneath the longitudinally extending, inwardly directed flange 44. This structure provides several features. First of all, when the adapter is mounted in place, the projections 40 bear against the flange 44 to prevent an up-riding, that is a rearward movement, of the adapter, thereby resisting tensile forces on the conductors which could cause dislocation of the conductors. Secondly, a center bulging effect is obviated when such hooks are provided in the central portion of the adapter. This feature is also provided by the latching mechanism which is discussed below. Thirdly, the provision of such a hook at each end of the adapter corresponding to the positions of the end contacts, provides for easy positive alignment of the adapter and quick connection of the adapter to the rear end of the electrical connector.

Referring for a moment to FIG. 8, the electrical connector is illustrated as comprising a plurality of protective barriers 60 with the electrical contacts disposed therebetween. In FIG. 1, the end barriers are illustrated as having a surface 48 which also aids in aligning the adapter on the connector. The adapter ends 28 and 30 carry respective inner surfaces 45 and 46 which slidingly engage the end surfaces of the barriers, such as at 48, to locate the end barriers between these surfaces and the adjacent pressure member 32. The end members 28 and 30 which extend from the elongate member 26, and a top transversely extending member 50 which joins the elongate and end members, and the one-piece molding of these members, along with the pressure blades as a single unit, provides rigidity for the adapter.

As is evident from the drawings, particularly FIGS. 1, 2, 5, 7 and 9, the disposition of the pressure member 32 in the contact channels and the engagement of the surfaces 45, 46 with the end surfaces of the barriers, as at 48, stabilizes the adapter in the longitudinal direction.

The top member 50 carries a plurality of projections 52 which extend in the forward direction of the connector. The projections 52, as best seen in FIG. 5, are also connected to the elongate member 26 by a pair of members 54 which extend forwardly from the top member 50 and transversely from elongate member 26 to form pockets which receive the ends of a plurality of the barriers 60 when the adapter 24 is rotated into its final mounted position. Each of the projections 52 therefore carries a latch surface 53 which engages the opposite facing surface of a plurality of the barriers 60. It should be noted that the barriers 60 extend above the end surface of the dielectric insert to form an elongate slot or groove 61 therein, and it is in this slot or groove 61 that the conductors enter the connector body for termination to the insulation-opening contacts. In order to facilitate removal of the adapter, a plurality of openings 55 are provided to receive a tool 57, such as a screwdriver (shown in phantom), which may be rotated, as indicated by the arrow, against a surface 51 of the top member 50 to lift the latch surface 53 out of engagement with the barriers 60.

The anti-bulge feature discussed above is also provided by the latch mechanism and it is therefore preferable that a latch projection 52 be provided in the central portion of the adapter 24.

Another embodiment of a latch is illustrated in FIG. 6 in which the top member has been referenced 50', and which top member has a plurality of forwardly extending latch members 56 projecting therefrom and with a spacing corresponding to the spacing of the barriers 50. In this embodiment, each latch member 56 engages the oppositely facing surface of a respective barrier and the cross sectional view thereof is the same as illustrated in FIG. 4. The latch members 56 may be provided in spaced groups as in FIG. 5, or the same may be provided along the entire length of the adapter. Here again, it is preferred that the latch members be provided in the central portion of the adapter to prevent bulging at the rear end of the adapter, that is in the area of the top member 50'.

FIG. 7 is offered to place the foregoing in a better perspective and to illustrate the advantageous features with respect to the relationships between the connector, the adapter and the protective hood. As seen in FIG. 7, the dielectric insert 58 extends from the rear end of the connector to the forward end of the connector and carries, on each side thereof, a plurality of spaced apart barriers 60. An insulation-opening contact, such as the type disclosed in the aforementioned Mathe patent, is mounted between adjacent barriers and includes an insulation opening portion 62 which is electrically and mechanically connected to a respective conductor, conductors 64 and 66 being illustrated in FIG. 7. The insulation-opening contact also includes an intermediate portion 66 which has a rearward facing shoulder 68 and a forward facing shoulder 70 which engage opposite sides of a projection 72 of the insert to prevent movement of the contact in the rearward and forward directions, respectively. Each contact also includes an active portion 74 which extends into the forward portion of the connector for mating engagement with a complementary electrical connector. The forward end of the electrical connector has a first shell portion 76 and a second shell portion 78, each with engaging flange portions which extend outwardly of the connector and form a flange 80. The shell portion 78 carries the inwardly directed flange 44 which is spaced, as indicated at 82 from a rearwardly facing surface 84 of the dielectric insert. As mentioned above, the pressure member portion 38 and the transverse projection 40 engage the flange 44 and pivot thereabout as the adapter 24 is moved into its mounted position.

An important feature of the invention resides in the provision of an adapter which can be used with the protective hood normally provided with the electrical connector. In FIG. 7 a protective hood 86 includes a pair of spaced side walls 94 and 96, a top wall 92 and an end wall 90 which define a chamber 88 for receiving the rear end of the electrical connector with a pair of adapters mounted thereon. The end of the hood 86 which is opposite the end wall 90 is normally open to receive a cable therein, which cable is supported on the cable strain relief 22 in FIG. 1. The side walls 94 and 96 include a bottom edge 98 which slidingly engages and is supported by the flange 80 and the hood 86 is slid onto the rear end of the connector. Each of the sidewalls 94 and 96 also includes a transversely, inwardly extending rib 100 which is received between the flange 44 and a forwardly facing surface 102 which prevents removal of the hood in the rearward direction.

Referring to FIGS. 8 and 9, an enlarged and more detailed view of the rear end of the electrical connector is illustrated in conjunction with another embodiment of the invention. As seen in FIG. 8, the dielectric insert 58 is provided with a plurality of constricted openings 104 which form a strain relief mechanism for the connector even without the provision of a strain relief adapter. In FIG. 8 a plurality of conductors 106, 108 and 110 are illustrated as the same would be electrically and mechanically terminated in an insulation-opening contact portion 62. The strain relief adapter 24' illustrated in FIGS. 8 and 9 has substantially the same construction as the previously discussed strain relief adapters and corresponding parts have been given similar, but primed, reference characters. There are two major differences, however, which will be discussed herein. First of all, the projection 36 of the pressure member 32 does not exist. Instead, the pressure member 32 includes a narrowed portion 112 which enters the constricted opening 104 of the strain relief mechanism to press against the respective conductor. Secondly, the top member 50" includes at least one pair of transversely extending members 114 and 116 which have a cross member 118 at the distal ends thereof. The members 114, 116 and 118 form a recess for receiving the end of a barrier 60 therein and the cross member 118 carries a latch surface 119 for engaging the oppositely facing surface of the barrier 60, as illustrated in FIG. 9. Preferably, this latch is centrally located and, of course, a plurality of such latches may be provided on the strain relief adapter 24'.

Although the strain relief adapters constructed in accordance with the present invention are substantially rigid, the same are also reasonably flexible in the area of the latches to provide for releasable engagement of the latches. The desired rigidity with the desired flexibility can be provided by molding the adapter from a resilient plastic material, such as NORYL, SE-O 225.

In summary, the objects of the invention have been accomplished and adapter constructions have been provided which permit the utilization of a conventional right angle protective hood, which have positive alignment of the pressure members, which do not ride up and do not suffer from center bulging, and which do not have end latches, but releasably engageable rear latches which aid in preventing center bulging.

Although the invention has been described by particular illustrative embodiments thereof, many changes and modifications of the invention may become apparent to those skilled in the art without departing from the spirit and scope of the invention. It is therefore intended that the patent warranted hereon cover all such changes and modifications as may reasonably and properly be included within the scope of this contribution to the art.