GB2177268A

GB2177268A - Strain relief for electrical connector cable

Info

Publication number: GB2177268A
Application number: GB08616417A
Authority: GB
Inventors: Friedrich Schauer
Original assignee: Kabelmetal Electro GmbH
Current assignee: Kabelmetal Electro GmbH
Priority date: 1985-07-05
Filing date: 1986-07-04
Publication date: 1987-01-14
Also published as: IT8648223A0; CH669690A5; IT1195075B; GB2177268B; GB8616417D0; DE3524105C2; DE3524105A1

Abstract

A non-conducting strain relief cord (15) of a cable (only the stripped end of the cable is shown) is joined to a conical metal sleeve (7) firmly joined to the termination end (5) of the metallic body of the connector, so as to facilitate removal of the relief cord/sleeve from the body for reuse of the body. Conducting wires are joined to terminals (14) and potted (9) before an outer insulating layer (8, Fig. 1 not shown) is moulded over the termination ends of the connector and the cable. <IMAGE>

Description

SPECIFICATION Coupling component for an electric plugconnection system This invention relates to a coupling component for an electric plug-connection system, the coupling component having connected to it an electric line which has in its core at least two insulated electric wires and an elongate strainrelief element; the coupling component comprising a metallic body accommodating a plastics material contact carrier carrying a plurality of electric contact members, the number of the latter being at least equal to the number of wires; the metallic body having a grippable portion and a projection portion, the latter being at the lineward end of the metallic body (i.e. that end of it nearer the said electric line) and having radial dimensions smaller than those of the said grippable portion, which is at the connection end of the metallic body (i.e. that end of it further from the said electric line) and which is engageable with a second coupling component, this being provided with counter contact members; the coupling component also comprising a metallic sleeve which is attached in a closely fitting manner to the said projection portion of the metallic body and which projects therefrom over the electric line, narrowing in the lineward direction with a substantially conical taper; and an insulating-material grip body being moulded around the lineward end of the metallic body and an adjacent portion of the said electric line.

In the present field, German Offenlegungsschrift 3034415 is of interest.

A coupling component within the context of the invention can be a plug or a socket, the contact members incorporated being pins or sleeves respectively. The coupling component should be usable both for unshielded lines and for lines whose wires are surrounded by a common shield. Electric lines comprising a strain-relief element are needed, for example, for portable radio sets, as tension-proof telephone lines, or in coiled lines for stationary electro-acoustical systems; moreover they are needed for vehicles, ships and aircraft. The coupling components should be moisture-tight, and a safeguard against twisting is also required for most cases pf application. In addition, the shielding in the coupling component in the case of shielded lines must be at least as good as the shielding of the line itself, and there must not be any interruption of the shield in the coupling component.

These requirements are met in coupling components of the above-mentioned German Offenlegungsschrift 3034415, which are intended for shielded lines. However, their pro duction is relatively elaborate, since both the strain-relief element and the shield of the line have to be fixed in an undercutting of the projection portion of the metallic body specified. For this purpose, the projection portion has been provided with two axial grooves into which are inserted the strain-relief element and the shield, the latter being twisted together.

The ends of both are bent over. They lodge in the undercutting and are held there by the sleeve, which fits closely against the projection portion. In this known coupling component, it is also disadvantageous that the expensive metallic body specified cannot be reused. When the electric line connected was no longer usable, the moulded coupling component had also to be thrown away, since the moulded grip body could not sufficiently easily be completely removed from the metallic body and components associated with it. This applied particularly to contact member ends projecting from the contact carrier, which are easily damaged when dismantling is attempted.

It is an object of the present invention to provide a coupling component as first mentioned herein which is simple to produce and whose metallic body can be readily re-used.

According to the present invention, there is provided a coupling component for an electric plug-connection system, the coupling component having connected to it an electric line which has in its core at least two insulated electric wires and an elongate strain-relief element; the coupling component comprising a metallic body accommodating a plastics material contact carrier carrying a plurality of electric contact members, the number of the latter being at least equal to the number of wires; the metallic body having a grippable portion and a projection portion, the latter being at the lineward end of the metallic body (i.e. that end of it nearer the said electric line) and having radial dimensions smaller than those of the said grippable portion, which is at the connection end of the metallic body (i.e. that end of it further from the said electric line) and which is engageable with a second coupling component, this being provided with counter contact members, the coupling component also comprising a metallic sleeve which is attached in a closely fitting manner to the said projection portion of the metallic body and which projects therefrom over the electric line, narrowing in the lineward direction with a substantially conical taper; and an insulating-material grip body being moulded around the lineward end of the metallic body and an adjacent portion of the said electric line; in which coupling component: the end of the said strain-relief element is secured to the said metallic sleeve, at a lineward end portion thereof; and the contact members carried by the contact carrier have ends projecting therefrom which are surrounded by an insulating body composed of a material which is flowa ble when heated but becomes brittle upon cooling, this insulating body in turn being surrounded by the said metallic sleeve.

The metallic body of this coupling component consisting of a grippable portion and a projection portion and accommodating a contact carrier carrying contact members, can be used without alteration for unshielded and for shielded lines. Since neither the strain-relief element nor the shield, if present, are directly attached to the metallic body, the production of the coupling component is very simple.

After attaching the sleeve to the projection portion, it only remains to secure the strainrelief element to the sleeve, and, if necessary, to clamp the shield to the sleeve. After that, the grip body can be moulded on. This encloses all the other parts and also fills the cavities remaining inside the sleeve.

Before applying the sleeve, the stripped wires of the line are connected to the ends of the contact members projecting from the contact carrier, and the above-mentioned insulating body is moulded around the ends of the contact members and wires. Its material, which is flowable when heated becomes brittle upon cooling, so that, if necessary, it can be easily removed, for example by hitting it or shaking it lightly. The insulating body, moulded before the moulding of the grip body, covers the contact members so that no grip body material penetrates to or into them.

Thus, the metallic body of the coupling component is re-usable since all parts moulded to it can be very easily removed without residues. The brittleness of the insulating body does not affect the use of the coupling component since the insulating body is firmly surrounded by the sleeve and the material of the grip body.

The invention will be more fully explained with reference to the accompanying diagrammatic drawings, in which: Figure 1 is a partially sectioned side view of a coupling component according to the invention, and Figure 2 is a similar view on an enlarged scale snowing the coupling component without its grip body.

In Figure 1, a coupling component for an electric plug-in connection is shown which is permanently injection-moulded on to the end of an electric line 1. For the sake of simplicity, the contact members of the coupling component and the strain-relief means for line 1 are omitted from Figure 1 (also, no shield is shown). Two insulated electric wires 2 of the line 1 are diagrammatically indicated, but the number of wires 2, and thus also the number of contact members, is arbitrary. In preferred embodiments, the line 1 is provided with seven or ten wires 2.

The coupling component has a metallic body 3 which consists of a grippable portion 4, used for accommodating another coupling component having counter contacts, and of a projection portion 5 the diameter of which is smaller than that of the grippable portion. A groove-like recess 6 intervenes between the portions 4 and 5. The coupling component also includes a metallic sleeve 7, and a grip body 8 which is injection-moulded around the end of line 1 and the projection portion 5.

The grip body 8 can consist, for example, of polyvinyl chloride or polyurethane. For the grip body 8, a material should preferably be used which fuses to the sheath of the line 1.

An insulating body 9 surrounding the ends of the contact members and of the wires 2 abuts against the surface of the projection portion 5. In addition, ribs 10 can also be moulded on the grip body 8, to facilitate the plugging-together of the coupling components in the correct position.

As previously mentioned, the body 3 consists of the portions 4 and 5. As can be seen from Figure 2, the grippable portion 4 encloses a cavity 11 into which another coupling component comprising counter-contacts can be inserted for interconnection. At the bottom of the cavity 11 is an annular sealing member 12, which is preferably an 0-ring. The body 3 includes a contact carrier 13 of insulating material in which the contact members 14 of the coupling component are permanently embedded. The contact members 14 may for example be sleeves into which connector pins can be inserted from the cavity 11. They project from the contact carrier 13 on the side facing away from the cavity 11.

The procedure for applying a coupling component as shown in Figure 2 to the end of an electric line is, for example, as follows: The sheath is removed from the end of an electric line 1 so that the wires 2 and a strain-relief element 15 are exposed. In Figure 2, only two wires 2 are shown, again for the sake of simplicity. The strain-relief element 15 may for example be a wire rope. The ends of the wires 2 are subsequently stripped and an enlargement 16 is applied to the end of the strain-relief element 15, which enlargement may for example be a compression-type socket.

The body 3 is prefabricated with the contact carrier 13 located on the inside. The exposed conductors of the wires 2 are then connected to the contact members 14, for example by push-fitting or soldering. The line end prepared in this manner is then inserted into a mould in which the insulating body 9 is produced. For this purpose, for example a heated and therefore flowable hot-melting adhesive composition is applied to the contact carrier 13 in such a quantity that the ends of the contact members 14 and of the connected wires 2 are embedded into the insulating body 9. After the hot-melting adhesive composition has cooled down, the line end is removed again from the mould.

The sleeve 7 is then applied to the line end; it is preferably bent from a strip of sheet steel to form a sleeve which is closed all around, but it can alternatively be pressed from a tube section. The sleeve 7 is fixed, for example by localised pressure, to the projection portion 5, so that it is secured against twisting. The sleeve 7 can be secured against movement in the axial direction by bending its end around the end of the projection portion 5. The circumferential surface of the projection portion 5 is preferably provided with corrugations.

The sleeve 7 closely encloses the insulating body 9, so that it is protected during further processing.

Now the strain-relief element 15 is attached to the sleeve 7. For this purpose, the sleeve 7 is provided for example with a projection 17 which is stamped out of its wall and is bent inward. Due to the presence of the enlargement 18, the strain-relief element 15 is secured in the axial direction in the position shown in Figure 2. The grip body 8, not shown in Figure 2, is then moulded on in an injection moulding apparatus.

In principle, it is possible to produce the insulating body 9 when the sleeve 7 is already fixed to the projection portion 5. The sleeve 7 could then additionally be used as a mould.

However, this procedure is more difficult than the method just described, since the sleeve 7 at its free end encloses the wires 2 and the strain-relief element 15 so closely that the material for the insulating body 9 could be introduced into the sleeve 7 only with difficulty.

If the coupling component is to be used for a shielded line 1, its construction as described does not need to be altered. After removal of the sheath of the line 1, the shield (not shown), which may comprise mesh or circumferential stranding, is widened at its end and pushed over the sleeve 7 before the grip body 8 is moulded. The shield is fixed on the sleeve 7 by means of a clamping ring 18 which has a conical aperture matching the conical contour of the sleeve 7.

It will be understood that the invention has been described above purely by way of example, and that various modifications of detail can be made within the ambit of the invention.

Claims

1. A coupling component for an electric plug-connection system, the coupling component having connected to it an electric line which has in its core at least two insulated electric wires and an elongate strain-relief element; the coupling component comprising a metallic body accommodating a plastics material contact carrier carrying a plurality of electric contact members, the number of the latter being at least equal to the number of wires; the metallic body having a grippable portion and a projection portion, the latter being at the lineward end of the metallic body (i.e. that end of it nearer the said electric line) and having radial dimensions smaller than those of the said grippable portion, which is at the connection end of the metallic body (i.e. that end of it further from the said electric line) and which is engageable with a second coupling component, this being provided with counter contact members; the coupling component also comprising a metallic sleeve which is attached in a closely fitting manner to the said projection portion of the metallic body and which projects therefrom over the electric line, narrowing in the lineward direction with a substantially conical taper; and an insulating-material grip body being moulded around the lineward end of the metallic body and an adjacent portion of the said electric line; in which coupling component: the end of the said strain-relief element is secured to the said metallic sleeve, at a lineward end portion thereof; and the contact members carried by the contact carrier have ends projecting therefrom which are surrounded by an insulating body composed of a material which is flowable when heated but becomes brittle upon cooling, this insulating body in turn being surrounded by the said metallic sleeve.

2. A coupling component according to claim 1, wherein the strain-relief element is provided at its end portion with an enlargement, and is secured by means of this enlargement, the enlargement engaging a projection projecting inwardly from the wall of the sleeve.

3. A coupling component according to claim 1 or 2, wherein the projection portion of the metallic body has a corrugated circumferential surface, and the metallic sleeve is pressed, at least at some points, into the corrugations of this surface.

4. A coupling component according to claim 1, 2 or 3, wherein the said electric line is a shielded line comprising a shield in the form of mesh or in the form of circumferential stranding, and the shield is fixed to the outside of the metallic sleeve by means of a clamping ring which has a substantially conical internal surface complementing the external surface of the metallic sleeve.

5. A coupling component according to claim 1, substantially as described with reference to the accompanying drawings.