Shield Termination For Electrical Connectors

Abstract

Shield termination including clamp means are used for connection to a connector shell and for clamping engagement with an end portion of an outer flexible metallic shield of a cable, such clamp means being operable independently of strain relief means engaged with a portion of the cable shield spaced from the end portion. The clamp means comprises a first metallic member arranged to fit within the cable shield and including a thin wall having axially extending angularly spaced slots and a second metallic member surrounding the cable shield and coupled to the connector shell through a threaded ring. The second member has an inner surface portion of frustospherical shape while the wall of the first member is of complementary shape, resulting in a wedge enegagement and resilient deformation of the weall of the first member. Ground lugs are provideded on the first member for connection to contacts and conductors to be grounded.

Description

This invention relates to a shield termination for electrical connectors and more particularly to a shield termination which provides a durable and reliable connection and which is easily installed while facilitating the connection of cable conductors to connector contacts.

This invention was evolved with the general object of overcoming disadvantages of prior art arrangements and of providing an improved shield termination which is readily installed on a connector while firmly holding the cable shield and providing a reliable ground connection.

The shield termination of this invention is designed for use at the connection of one end of a cable to an electrical connector, wherein the cable includes an outer flexible metallic shield and conductor means therewithin, the conductor means being connected to contact means insulatingly supported within a shell of the connector. In accordance with this invention, the shield termination comprises clamp means arranged for connection to the connector shell and for clamping engagement with an end portion of the cable shield. Preferably, the clamp means comprises a first metallic member arranged to fit around the cable conductor means and within the end portion of the cable shield, a second metallic member arranged to surround the end portion of the cable shield and connection means for connecting the second metallic member to the connector shell. With this arrangement, the end portion of the cable shield is firmly clamped between the first and second members engaged with the inner and outer surfaces thereof. At the same time, the conductors of the cable can be readily connected to the connector contacts.

According to the specific feature of the invention, the connection means is arranged to move the second metallic member axially during connection thereof to the connector shell and the second member has a tapered inner surface portion for wedging the end portion of the cable shield into tight engagement with the first member. Preferably, the tapered inner surface of the second member is of generally frustospherical shape and the first member has an outer surface of a shape generally complementary to the frustospherically shaped inner surface of the second member. The second member is preferably relatively rigid while the first member has a relatively thin wall resiliently formable in effecting the clamping engagement. To further increase the flexibility of the first member, it is preferably provided with a plurality of axially extending angularly spaced slots therein.

Another specific feature of the invention relates to the provision of lug means on the first member for ground connection to conductor means of the cable, such lug means being preferably positioned in at least one of the slots of the first member.

A further feature of the invention relates to the provision of strain relief means for effecting clamping engagement with the cable and operable independently of the shield termination clamp means, the strain relief means being preferably associated with the second metallic member and being arranged to effect clamping engagement with a portion of the cable shield spaced axially from the end portion thereof.

This invention contemplates other objects, features and advantages which will become more fully apparent from the following detailed description taken in conjunction with the accompanying drawings which illustrate a preferred embodiment and in which:

FIG. 1 is an expanded view of an electrical connector incorporating a shield termination according to the principles of this invention, showing the parts before assembly;

FIG. 2 is a view partly in cross section and showing an assembled connector connected to a cable; and

FIG. 3 is an end elevational view of a member forming part of the shield termination.

Reference numeral 10 generally designates an electrical connector incorporating a shield termination constructed in accordance with the principles of this invention. The connector 10 comprises a main connector shell 11 within which contacts are supported in an insulating body for connection to mating contacts of another connector shell, not shown. An auxiliary shell 12 is provided arranged to be secured to the main shell 11 by means of a coupling ring 13 having an internally threaded portion 14 which is threaded on an externally threaded portion 15 of the shell 11. The coupling ring 13 is held on the shell 12 by means of a snap ring 16 engaged in annular grooves provided in the outer surface of the shell 12 and in the inner surface of the coupling ring 13, the coupling ring 13 being rotatable relative to the shell 12. An annular groove 17 is provided on the inside surface of the shell 12, adjacent the end thereof connected to the shell 11, for receiving a conventional O-ring seal member 18 which is compressed against an outer surface portion of the shell 11.

To prevent relative rotation of the shells 11 and 12, the internal surface of the shell 12, between the end thereof and the notch 17, is formed with equiangularly spaced notches 19 which receive equiangularly spaced projections 20 on the portion of the outer surface of the shell 11 which is adjacent the threaded portion 15. A knurled disc 21 is provided at the end of shell 11.

The shell 12 is arranged to receive an end portion of a cable 22 which includes an outer flexible metallic shield 23, of a conventional woven or braided construction, and a plurality of conductors 24 therewithin, the ends of the conductors 24 being connected to contacts within an insulating body in the shell 11. In accordance with this invention, a shield termination is provided including clamp means arranged for clamping engagement with an end portion 25 of the shield 23. The clamp means comprises the auxiliary shell 12 and a member 26 which is arranged to fit around the conductors 24 and within the end portion 25 of the cable shield 23, the end portion 25 being clamped between the outside of the member 26 and the inside of the auxiliary shell 12. The member 26, the auxiliary shell 12, the coupling ring 13 and the snap ring 16 are made of metal, i.e., a highly conductive material, to provide a good ground connection between the shield 23 and the shell 11, also of metal.

In accordance with a specific feature of the invention, the end portion 25 of the shield 23 is wedged between the outside of the member 26 and the inside of the shell 12 when the shell 12 is installed and moved axially by rotation of the coupling ring 13. Preferably, the shell 12 has a tapered inner surface portion 27 of generally frustospherical shape and the member 26 has outer surface portions 28 of complementary shape. The shell 12 also has an internal surface portion 29 of cylindrical shape adjoining the outer end of the surface portion 27, and the member 26 has curved surface portions 28 inside the surface portion 27.

The shell is relatively rigid while the member 26 has a relatively thin wall which is resiliently deformable in effecting the clamping engagement. To increase the resiliency of the member 26, it is provided with a plurality of axially extending angularly spaced slots 30, four equiangularly spaced slots being provided in the illustrated structure. The slots 30 at one end could terminate at points spaced radially outside a central opening through which the cable 22 extends but, as illustrated, so extend as to form four independent resilient fingers 32. The opposite ends of the slots 30 terminate at points relatively close to a radial wall 34 having a central opening 35 through which the conductors 22 extend. The cylindrical wall sections 32a of the resilient fingers 32 project radially outwardly beyond the curved surface portions 28 which are pressed against the surface portion 27 of the shell 12, through the fact that after assembly the radial wall 34 is clamped between the disc 21 and the shoulder 36 of the shell 12.

A further feature is in the provision of the lug means on the member 26, preferably in the form of integral portions 38 positioned in each of the slots 32 and having openings 39 for receiving the ends of conductors of the cable 22 or of conductors connected to contacts of the connector 11, to provide a reliable ground connection.

Strain relief means are provided for effecting clamping engagement with the cable 22, the shield termination being operable independently of the strain relief means. The illustrated strain relief means comprises a tubular member 40 arranged to be moved into an end portion 41 of the shell 12 and to force two forms of compressible means into tight engagement with the outer surface of the cable shield 23. One of such compressible means comprises an annular member 43 of elastomeric material, such as a relatively soft natural rubber or an equivalent material, which is axially compressed between an internal annular shoulder 44 of the shell 12 and an inner end surface 45 of the member 40. An annular metal member 47 is provided of generally L-shaped cross section having a first wall 48 between an end surface of the member 43 and the end surface 45 having a second wall 49 surrounding an end portion of the member 43. The member 47 thus serves to contain the member 43 and to apply the axial compressive forces thereto.

The second form of compressible means comprises a generally C-shaped resilient metal member 54 which is engaged by an internal surface 55 of the member 40 and of generally frustoconical shape to wedge the member 54 into tight engagement with the cable 22 when the member 40 is moved into the end portion 41 of the shell 12. The C-shaped member 54 preferably has a curved cross-sectional shape to provide a rounded convex outer surface 56 engageable by the surface 55 and to provide a pair of relatively sharp side edges 57 and 58 arranged to bite into the cable at axially spaced points.

The tubular member 40 has an externally threaded portion 59 threaded into an internally threaded portion 68 of portion 41 of shell 12.

In the assembly of the connector, the shell 12 and the members 40, 43, 47 and 54 are slid onto the end of the cable 22 and the end portion 25 of the shield 23 is expanded while the member 26 is slipped therewithin. Before or after installation of the member 26, the ends of the conductors 24 may be stripped of insulation and connected to contacts of the connector 10. After installation of the member 26, any conductors to be grounded may be connected to the lugs 38. The shell 12 is then moved toward the shell 11 and the ring 13 is threaded onto the threaded portion 15 of the shell 11. The end portion 25 of the shield 23 is then firmly clamped between the outside of the member 26 and the inside of the shell 12.

Next, the annular member 43 of elastomeric material together with the member 47 are moved within the end portion 41 of the shell 12 and the member 54 is moved to abut the wall 48 of the member 47. Finally, the tubular member 40 is threaded into the end portion 41 of the shell 12 which serves to axially compress the member 43 and to force the inner surface thereof into tight sealing engagement of the outer surface of the shield 23. At the same time, the member 54 is wedged by the surface 55 into tight engagement with the cable jacket with biting engagement between the edges 57 and 58 and the cable jacket. It is noted that the strain relief arrangement is thus operable independently of the shield termination.

It will be understood that modifications and variations may be effected without departing from the spirit and scope of the novel concepts of this invention. I claim as my invention:

Claims

1. A shield termination for use at the connection of one end of a cable to an electrical connector, the cable including an outer flexible metallic shield and conductor means therewithin, and the connector including a shell and contact means therewith connected to the conductor means of the cable, said shield termination including clamp means arranged for connection to the connector shell and for clamping engagement with an end portion of the cable shield, said clamp means comprising a first metallic member having a plurality of axially extending angularly spaced slots therein, and arranged to fit around the cable conductor means and within said end portion of the cable shield, a second metallic member arranged to fit around said end portion of the cable shield, and means connecting said second metallic member to the connector shell.

2. A shield termination as defined in claim 1, wherein said first metallic member has terminal lug means positioned in at least one of said slots.