GB2248731A - Coaxial electrical connectors - Google Patents

Abstract

A coaxial electrical connector comprises a shield and dielectric assembly (2) consisting of a metal shield (8) enclosing a dielectric body (12) inserted into the shield from its forward end and retained in the shield by means of a latching tongue (14) and frusto-conical parts (22 and 24) of the shield (8) and the dielectric body (12). A central signal conductor (40) which has previously been crimped to the stripped end portion of the signal wire (W) of a coaxial cable (CC) is snug inserted into a central bore (32) of the dielectric body (12) and a ferrule (10) on the shield (8) is crimped about the exposed end portion of the shield (S) of the cable (CC). The severed end of the dielectric (D) of the cable (CC) abuts the rear end (33) of the dielectric body (12) so that the signal conductor (40) is axially fixed in the bore (32). <IMAGE>

Description

COAXIAL ELECTRICAL CONNECTORS This invention relates to a kit of parts for a shielded, coaxial electrical connector and to a shielded coaxial electrical connector.

Such a connector usually comprises a tubular, elongate circular cross section metal shield in which is secured a dielectric body having a circular cross section bore therethrough coaxial with the shield and to which is preassembled an elongate circular cross section signal conductor secured in the bore by means of shoulders therein and shoulders on the signal conductor. The preassembled signal conductor has a crimping ferrule for crimping to the signal wire of a shielded coaxial cable. The shoulders tend to render the impedance of the connector uneven lengthwise thereof and the signal conductors of such connectors cannot be terminated by means of an automated system.

According to one aspect of the invention, a kit of parts for a shielded coaxial electrical connector, comprises a shield and dielectric assembly comprising a circular cross section, elongate tubular metal shield having snuggly fitted and secured therein an elongate, circular cross section dielectric body formed with a bore therethrough coaxial with the shield; and an elongate, circular cross section signal conductor for snug reception in the bore, and having at one end a mating end portion and at its opposite end a ferrule for crimping to the stripped end portion of the signal wire of a coaxial cable; wherein the shield has integrally formed therewith a second crimping ferrule for crimping about the stripped end portion of a shield of the coaxial cable and the dielectric body has an end face for abutment with a severed end of the dielectric of the coaxial cable whereby when the first ferrule has been crimped to the end portion of the signal wire of the coaxial cable, and the second ferrule has been crimped to the stripped end portion of the cable shield, the signal conductor is prevented from axial movement in the bore by abutment between the abutment end face of the dielectric body and the severed end of the cable dielectric.

Since the signal conductor of the connector is prevented from axial movement in this way, the bore can be of constant cross section throughout that part of the bore which is occupied by the signal conductor, whereby the impedience of the connector is constant throughout its length.

The signal conductor is crimped to the signal wire of the coaxial cable before the signal conductor is inserted into the bore, so that the signal conductors of any convenient number of connectors can be crimped to their respective signal wires by means of an automated system. Also, the signal conductors can be crimped to the signal wires by means of any appropriate method of crimping.

The dielectric body, may be insertable into the shield, from one end thereof, being retained in the shield by means of a retention tongue and a reduced cross section end of the shield.

A multiplicity of the shields may be produced in strip form, the shields being connected in side by side parallel relationships by mean of a carrier strip.

Before the insertion of the dielectric bodies into the shields, the shields may be immersed in plating baths for selectively gold plating the shields and the second ferrules. The shield may for example be gold plated where it is to engage the shield of a mating coaxial connector and the second ferrule may be tin plated.

According to another aspect of the invention, a shielded, coaxial electrical connector comprises a shield and dielectric assembly having a forward mating end and a rear end, a circular cross section elongate tubular metal shield and snuggly fitted and secured therein an elongate circular cross section dielectric body formed with a bore therethrough opening into both ends of said body and being coaxial with said shield; and an elongate, circular cross section signal conductor snuggly received in said bore and having therein a first crimping ferrule extending therein to the rear end of said assembly and being crimped to the stripped end of a signal wire of a coaxial cable, the shield having formed integrally therewith, a second crimping ferrule projecting rearwardly from the rear end of said assembly and being crimped about the stripped end portion of the shield of the coaxial cable, with a severed end of the dielectric of the cable in firm abutment with a rear abutment end face of the dielectric body so that the signal conductor is fixed axially in the bore, the rear end of the second crimping ferrule also being in abutment with the severed end of the cable dielectric.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which; Figure 1 is a top plan view of a shield and dielectric assembly for a coaxial electrical connector, the assembly being part of a strip of such assemblies joined together in side by side relationship by means of a carrier strip; Figure 2 is an exploded, axial sectional view a coaxial electrical connector comprising the assembly shown in Figure 1; Figure 3 is an isometric view of the assembly; Figure 4 is a rear end view of the connector; Figure 5 is an isometric view of the connector when crimped to a shielded electrical cable; and Figure 6 is an enlarged axial sectional view of the connector when crimped to the cable.

As shown in Figure 1, a shield and dielectric assembly 2 is connected to a carrier trip 4 by way of a metal slug 6 thereof. The assembly 2 comprises an outer, elongate, circular cross section metal shield 8 formed integrally with a U-cross section crimping ferrule 10 which is in turn formed integrally with the slug 6. A multiplicity of further and identical assemblies 2 (not shown) are similarly connected to the carrier strip 4 in side by side relationship. The shield 8 which has been stamped, formed and rolled up from sheet metal stock as a longitudinal seam 9.The assembly 2 also comprises an elongate, circular cross section dielectric body 12 which is snuggly received in the shield 8 and is latched against forward movement therein by means of a resilient retention tongue 24 having a free end engaging a forwardly facing shoulder 16 defined by a circumferential groove 18 in the body 12. Rearward movement of the body 12 in the shield 8 is restrained by means of a collar 20 proximate to the forward end of the body 12 and by a peened down marginal rear end portion 22 of the shield 8 which engages a rearwardly tapered frusto-conical rear end portion 24 of the dielectric body 2. Diametrically opposite to the tongue 14, the shield 8 is formed with a rearwardly, and radially outwardly, inclined retention lance 26 and rearwardly of the lance 26, with an over-travel and orienting pip 28.Forwardly of the collar 20, the body 12 has a forwardly tapered frusto-conical nose 30. The body 12 is formed with a through central bore 32 which is coaxial with the shield 8 and opens into the flats 33 and 35, respectively of both the portion 22 and the nose 30. At its forward end, the bore 32 has a reduced cross section part 34 which opens into a flared, in guiding mouth 36. A dielectric body 12 is assembled to the shield 8, by inserting it through the forward end thereof, with the portion 24 of the body 12 leading, until the tongue 14 which has been raised by the inclined surface of the portion 24 resiles to snap against the shoulder 16 and the collar 20 abuts against the forward end of the shield 8.

A tubular, circular cross section, centre signal conductor 40 in the form of an elongate pin receptacle, for reception in the bore 32, comprises an axially divided mating forward end portion 42 and a rear crimping ferrule portion 44 which has been indent crimped to the signal wire W at the stripped end portion of a shielded coaxial cable CC. As shown in Figure 2, the ferrule portion 44 has been crimped at 46 to the wire W in such a way that the rear end of the ferrule portion 44 is tightly engaged against the severed end E of the dielectric D of the cable CC. The jacket J of the cable CC has been stripped back from the severed end E to expose a length of the cable shield S.

In order to provide a complete shielded coaxial electrical connector 48 electrically connected to the cable CC, the signal conductor 40 is inserted into the bore 32 of the assembly 2, in the direction of the arrow A in Figure 2, with the portion 42 of the conductor 40 leading, until the severed end E of the cable dielectric D butts firmly against the flat 33 of the portion 22 of the body 12. The ferrule 10 is then crimped by means of an O-crimp about the exposed portion of the shield S, as shown in Figures 5 and 6.

Since the end E of the cable dielectric D is fixed by the 0-crimp infirm abutment with the flat 33 of the dielectric body 12, and since the crimped ferrule 10 is fixed to the shield 8, the signal conductor 40 can, under no circumstances, back on from the bore 32 and is, indeed, fixed axially with respect thereto. Since the bore 40 is uninterrupted over the length of the signal conductor 40, and the signal conductor 40 is also uninterrupted, the impedance of the connector 48 is substantially constant throughout its length.

The connector 48 is intended to mate with a female, shielded coaxial electrical connector (not shown) the mating part of which comprises a signal conductor in the form of a central pin surrounded by the forward end of a metal shield of the female connector. When the connectors are mated, the pin conductor enters the mating end portion of the signal conductor 40 guided by the mouth 36, the forward end of the shield of the female connector sliding over the shield 8 at the forward end of the connector 48. Before the dielectric bodies 12 are assembled to the shields of the strip of assemblies 2, the carrier strip 4 can be used to immerse the shields 8 in plating baths for selectively plating the external forward surfaces of the shields 8, with gold and the crimping ferrules 10 with tin, for example.

Since the signal conductors 10 are not preassembled to the assemblies 2, signal conductors 40 can be crimped to the cable conductors C by means of a fully automated system and any suitable form of crimp can be employed.

In order to provide a strip of conriectors 48 for winding about a storage reel (not shown) for application to a stitching machine for stitching the connectors 48 into cavities in insulating housing (not shown) the carrier strip 4 can be fed through a crimping press (not shown) for crimping the connectors to their cables CC. The pips 28 on the shields 8 serve to limit the insertion of the connectors into their housings and the retention lances 26 serve to latch them therein. Alternatively, the crimping press may be arranged to shear out the slugs 6 to provide loose piece connectors 48.

Claims (7)

1. A kit of parts for a shielded coaxial electrical connector, the kit of parts comprising a shield and dielectric assembly comprising a circular cross section, elongate tubular metal shield, having snuggly fitted and secured therein an elongate circular cross section dielectric body formed with a bore therethrough coaxial with said shield; and an elongate, circular cross section signal conductor for snug reception in the bore and having at one end a mating portion and at its opposite end a first crimping ferrule for crimping to a stripped end portion of the signal wire of a coaxial cable; wherein the shield has integrally formed therewith a second crimping ferrule for crimping about the stripped end portion of the shield of the coaxial cable and the dielectric body has an end face for abutment with a severed end of the dielectric of the coaxial cable, whereby when the first ferrule has been crimped to the end portion of the signal wire of the coaxial cable, and the second ferrule has been crimped to said shield end portion of the coaxial cable, the signal conductor is prevented from axial movement in the bore, by abutment between the abutment end face of the dielectric body and the severed end of the cable dielectric.

2. A shielded, coaxial electrical connector comprising, a shield and dielectric assembly having a forward mating end and a rear end, an elongate tubular metal shield and snuggly fitted and secured therein an elongate, circular cross section dielectric body formed with a bore therethrough opening into both ends of the body and being coaxial with said shield; and an elongate, circular cross section signal conductor snuggly received in said bore and having a first crimping ferrule extending to the rear end of said assembly and being crimped to the stripped end of the signal wire of a coaxial cable, the shield having formed integrally therewith a second crimping ferrule projecting rearwardly from the rear end of said assembly and being crimped about the stripped end portion of the shield of the coaxial cable, with a severed end of the dielectric of said cable in firm abutment of a rear abutment end face of the dielectric body so that said signal conductor is axially fixed in said bore, the rear end of the second crimping ferrule also being in firm abutment with the severed end of the cable dielectric.

3. A kit of parts, or an electrical connector as claimed in claim 1 or 2, wherein the second crimping ferrule is connected to a carrier strip to which a multiplicity of further and identical shield and dielectric assemblies are also connected in side by side parallel relationship.

4. A kit of parts, or an electrical connector, as claimed in claim 1, 2 or 3, wherein the dielectric body is assemblable to the shield, by inserting it through an open end thereof, snap action means being provided for securing the dielectric body in the shield.

5. A kit of parts for a connector, as claimed in any one of the preceding claims, wherein the tubular metal shield is secured to the dielectric body by means of a resilient retention tongue engaging an external shoulder defined by an opening in said body and facing away from the second crimping ferrule, and a peened over margin of the tubular metal shield engaging a frustoconical end portion of the dielectric body, which end portion defines said abutment end face.

6. A kit of parts for a shielded, coaxial electrical connector, substantially as hereinbefore described with reference to the accompanying drawings.

7. A screened, coaxial electrical connector substantially as hereinbefore described with reference to the accompanying drawings.