Strain Relief Clamp For An Electrical Connector

Abstract

The strain relief clamp designed for use on general purpose multi-pin electrical connector assemblies to the plug or receptacle of the assembly and extending therefrom to terminate in a keeper element which includes apertures to facilitate retention of a band or tie string that secures to the clamp all the wires extending from the connector. The bundle of wires extending from the connector is thereby gripped in a firm and immovable position so that all axial and radial movement of the wires which might occur in operation is prevented from being transmitted to the point of connection of the several wires with the connector contacts. One or more apertures in the keeper element makes it possible to secure many or as few as one wire extending from the connector in the aforementioned manner to prevent breaking the connection point of a wire to a contact.

Description

BACKGROUND OF THE INVENTION

This invention relates to electrical connectors of the type having multiple attachment points for the connection of the ends of several wires and more particularly to a strain relief clamp adapted for attachment to the electrical connector to secure the wires extending from the connector as a bundle in substantially fixed position to prevent stresses from breaking one or more of the connection points of any of the several wires to the contacts of the connector.

Wires, connected to electrical connectors, are relatively flexible and are especially subject to wear and tear adjacent to their point of connection to the contacts of the connector. This is particularly true of the wires to the plug element of a connector assembly since the plug is movable as compared to the receptacle which in some cases remains in a fixed position when mounted to supporting structures such as a wall or bulkhead. During normal operation and use of the connector assembly, any one or more of the wire terminations may become impaired and/or broken. Stresses on the wires to the connector are aggravated by the fact that in many instances stresses are placed on the connections as the wires are forced into out-of-the-way places and small areas. To reduce the strain on the connections between the wires and the electrical connector the strain relief clamp was developed in the form of a generally tapered fitting which is secured to and projects from the connector, a smaller outer end of which is adjustable to clampingly engage and secure the wires into a bundle. Movement and flexing of the several wires along their lengths is thereby prevented from passing this clamp and being transmitted to the point of the connection of the wires to the contacts of the connector. Examples of a strain relief clamp for a single cable containing multiple wires may be found in U.S. Pat. No. 1,874,334 entitled "Locking Means for Separable Electric Fittings," issued August 30, 1932 to A. H. Nero; U.S. Pat. No. 2,276,818 entitled "Electrical Connecting Device," issued March 17, 1942 to B.C. Bellows, Jr.; and U.S. Pat. No. 3,603,913 entitled "Strain Relief Clamp for Electrical Wiring Connector," issued Sept. 7, 1971 to John M. Hasty, Jr.

For aircraft applications, these fittings have been lightened as much as possible by the removal of large portions of the material in the tapered section between fitting ends so that the ultimate part comprises in effect a pair of concentric rings. The larger of these rings is adapted to attach to a standard electrical connector (plug or receptacle) while the smaller ring is adapted to clampingly engage the wire bundle.

Unfortunately, the number and size of wires that comprise a bundle of wires varies so that the cross-sectional area of each bundle differs in an unpredictable manner. Therefore, the aforementioned type of strain relief clamp will not be able to accomplish its purposes in all instances.

SUMMARY OF THE INVENTION

This invention provides a strain relief clamp for an electrical connector that prevents stresses and strains from being transmitted to the junction of the incoming wires and electrical contacts regardless of the number of wires coming into the connector.

The invention is a strain relief clamp for an electrical connector characterized by a keeper element (40) that has a plurality of fingers (41,42,43) that in conjunction with a connecting member (44) define one or more openings (45,46) that receive a tying strap or the like for tying one or more wires to the strain relief clamp. Tying straps generally have a larger cross-section at one end and therefore when they are passed through an aperture (45,46) in the keeper section (40) the straps when opened are retained and are less likely to be misplaced or lost.

In one specific embodiment of the invention the strain relief clamp on electrical connectors of the type having multiple attachment points for the connections of the ends of several wires extending therefrom, comprises: an attaching member (10) for attaching the clamp to the connector, the attaching member including engagement means (11) for the connection of the clamp to the connector; and an arm (20,30), carried by and extending in a direction away from the attaching member, the arm terminating in a keeper element (40) which is formed by a plurality of spaced fingers (41,42,43) which extend from the arm in a direction away from the attaching member to terminate at a connecting member (44) which is connected to each of the fingers to define therewith at least one aperture (45,46) in said keeper element; a step (30) between the attaching member (10) and the keeper element (40); and a shoulder (49), on the connecting member (44), which faces in the direction of the fingers (41,42,43) whereby the step (30) and the shoulder (49) define a surface therebetween adapted to receive and confine the movement of a tying means for tying the wires to the strain relief clamp (1). The foregoing reference numbers are used for purposes of illustration and the invention is not limited to the specific structure shown in the drawings.

Accordingly, it is an object of the invention to provide a strain relief clamp that is lighter in weight than like strain relief clamps while maintaining the same degree of strain relief.

It is another object of this invention to provide a strain relief clamp that includes one or more apertures therein for retaining a wire tie or the like which has been passed through the aperture.

It is another object of this invention to provide an inexpensive strain relief clamp which is a single unitary integral structure.

It is a further object of this invention to provide a versatile strain relief clamp that accomplishes its purposes whether one wire or twenty or more wires pass therethrough.

The above and other objects and features of the invention will become apparent from the following detailed description taken on conjunction with the accompanying drawings and claims which form a part of this specification.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic view of a strain relief clamp which utilizes the principles of this invention.

FIG. 2 is a side view of a strain relief clamp shown in FIG. 1.

FIG. 3 is an end view of the strain relief clamp shown in FIG. 1.

FIG. 4 is an alternate embodiment of the invention.

FIG. 5 is a diagrammatic view of the alternate embodiment shown in FIG. 4.

FIG. 6 illustrates how the objects of this invention are achieved when the strain relief clamp is used in combination with an electrical connector.

FIG. 7 is an alternate embodiment of the invention where the wires leaving the connector element are required to turn at a 90-degree angle.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring now the drawings, FIG. 1 illustrates a strain relief clamp having an attachment member 10, for connecting the strain relief clamp to the electrical connector; an arm which includes a root end 20, and a converging portion 30 which extends away from the attaching member 10; a plurality of fingers 41, 42, 43 extending away from the attaching member; and a connecting member 44 which is connected to each of the fingers to define therewith apertures 45, 46. The fingers 41, 42, 43 and the member 44 combine to form what is called a keeper element 40 which receives a strap or the like which is used for tying one or more electrical conductors to the strain relief clamp.

FIG. 2 illustrates another view of the strain relief clamp shown in FIG. 1. This view illustrates that the keeper element 40 includes a shoulder 49 that faces in the direction of the attaching member 10. The shoulder 49, together with the step formed between the attaching member 10 and the keeper element 40 operate to confine a strap or the like therebetween which has not passed through one of the apertures 45 in the keeper element 40. Confinement of a strap (not shown) prevents a strap, tied to the clamp, from sliding off the strain relief clamp and thereby losing the benefit of the strain relief clamp.

FIG. 3 is an end view of the strain relief clamp shown in FIG. 1 that illustrates the arcuate shape of the arm.

FIG. 4 illustrates an alternate embodiment of the invention wherein the arm 20, extending from the attaching member 10 does not include a step before the keeper element 40. In this embodiment the arm 20 has a relatively wide root end that narrows outwardly to terminate in a keeper element 40 that includes one or more apertures 45 and a shoulder 49 facing in the direction of the attaching member 10. The arm 20 is an arcuate member that extends around a portion of the ring-shaped attaching member 10 a sufficient distance to give the arm 20 radial rigidity.

FIG. 5 is another view of the strain relief clamp shown in FIG. 4 and illustrates how the keeper element 40 would confine a strap or other tying means between the shoulder 49 and the junction of the fingers 41, 42, 43 with the arm 20.

FIG. 6 illustrates how the strain relief clamp 1 is used in combination with an electrical connector to accomplish the objects of the invention. In this illustration the electrical connector 50 receives a large number of wires 70 therefore the tying means or strap 60 is not placed through one of the apertures in the strain relief clamp but instead is wrapped around the keeper element and the wires to retain the wires in a relatively fixed position. Once the strap 60 is tied to the strain relief clamp it is restricted from moving off the strain relief clamp by the shoulder 49 and the inwardly extending portion 30 of the arm. The attaching member 10 is ring-shaped to match the configuration of the electrical connector 50 and includes a plurality of threads 11 that engage the threads on the electrical connector 50 for attaching the ring 10 to the electrical connector 50. To facilitate the threading of the attachment member 10 to the electrical connector 50 a plurality of ridges, knurles or the like 12 are disposed around the periphery of the attaching member 10.

In the event there had been less wires 70 than shown the strain relief clamp 1 could have achieved the same purposes as illustrated by passing the strap 60 through one of the apertures and tying the wire 70 to one of the fingers of the strain relief clamp. Examples of straps 60 or other tying means ideally suited for this application are disclosed in U.S. Pat. No. 3,186,047 issued to D. P. Schwester et al., June 1, 1965; and U.S. Pat. No. 3,197,829 entitled "Binder Strap" issued Aug. 3, 1965 to J. E. Caveney et al. The latter patent illustrates a binder strap that has one end of a larger cross-section than the other end which therefore allows the binder strap, when placed through one of the apertures, to be retained by the keeper element. This feature is quite practical because it prevents the binder strap from being mislaid when maintenance has been performed on the electrical connector, which occurs frequently.

FIG. 7 illustrates an alternate embodiment to the invention shown in FIG. 1. In this embodiment the wires (not shown) would leave the clamp at a right angle as the arm 20 extends at a right angle away from the attaching member 10. Alternately, the arm 20 could extend across the attaching member 20.

When a preferred embodiment of the invention has been disclosed, it will be apparent to those skilled in the art that changes may be made to the invention as set forth in the appended claims, and, in some cases, certain features of the invention may be used to advantage without corresponding use of other features. For example, the attaching ring 10 may include a slot therein so that the attaching member extends less than 360.degree.. This feature would allow the passage of a wire through the ring-shaped attachment member 10 without necessitating the removal of the strain relief clamp and all the wires from the connector when adding an additional wire. In this regard it is suggested that any slot in the attaching member can be approximately equal to the wire diameter so as not to unduly weaken the strain relief clamp structurally when threaded onto the electrical connector. Further, the arm may have portions cut away completely so as to lighten the structure. Also, although the arm is shown extending inwardly the strain relief clamp arm could extend outwardly at right angles to the attaching member 10 and still perform its function. Accordingly, it is intended that the illustrative and descriptive materials herein be used to illustrate the principles of the invention and not to limit the scope thereof.

Claims

Having described the invention, what is claimed is:

1. A strain relief clamp for an electrical connector of the type having multiple attachment points for the connection of the ends of several wires extending therefrom, comprising:

an attaching member for attaching said clamp to said connector, said attaching member including engagement means for the connection of said clamp to said connector; and

an arm, carried by and extending in a direction away from said attaching member, said arm terminating in a keeper element which is formed by a plurality of spaced fingers which extend from said arm in a direction away from said attaching member to terminate at a connecting member which is connected to each of said fingers to define therewith two apertures in said keeper element; a step between said attaching member and said keeper element; and a shoulder, on said connecting member, which faces in the direction of said fingers whereby said step and said shoulder define a surface therebetween adapted to receive and confine the movement of a tying means for tying said wires to said strain relief clamp.

2. The strain relief clamp as recited in claim 1 wherein said keeper element includes a shoulder on the member defining the free end of said keeper element, said shoulder facing in a direction towards said fingers.

3. The strain relief clamp as recited in claim 2 wherein said attaching means includes demountable engagement means for the connection thereof to one end of said connector.

4. The strain relief clamp as recited in claim 1 wherein said arm includes said step therein.

5. The strain relief clamp as recited in claim 2 wherein said arm includes said step therein.

6. The combination as recited in claim 1 wherein said strain relief clamp is a unitary integral structure.

7. The dombination as recited in claim 1 wherein said strain relief clamp is a unitary integral structure comprised of plastic.

8. A strain relief clamp for an electrical connector of the type having multiple attachment points for the connection of the ends of several wires extending therefrom, comprising:

an attaching member for attaching said clamp to said connector, said attaching member including engagement means for the connection of said clamp to said connector; and

an arm, carried by and extending in a direction away from said attaching member, said arm terminating in a keeper element which is formed by a plurality of spaced fingers which extend from said arm in a direction away from said attaching member to terminate at a connecting member which is connected to each of said fingers to define therewith at least one aperture in said keeper element, at least one of said spaced fingers having a shape substantially the same as at least one wire extending from said connector, whereby said wire may be tied to one of said fingers, or if more than one wire is attached to said connector they may be tied to at least two said fingers; a step between said attaching member and said keeper element; and a shoulder, on said connecting member, which faces in the direction of said fingers whereby said step and said shoulder define a surface therebetween adapted to receive and confine the movement of a tying means for tying said wires to said strain relief clamp.