Coaxial Cables

Abstract

A plug connector fitting for coaxial cable comprises contact lugs arranged to contact the bared outer sleeve conductor of the cable. The lugs are pressed radially inwards by cam faces on a sleeve of the fitting.

Description

BACKGROUND OF INVENTION

Field to Which Invention Relates

The invention relates to cable plug connectors for fully insulated coaxial cables.

In accordance with a previously proposed arrangement such cables comprising an external conductor made up of a thin copper layer, supported by a dielectric, and surrounded by a protective casing of insulating material were provided with a radial contact between the external conductor, freed of the protective casing, and there was also a rigid contact sleeve, surrounding the external conductor, a floatingly mounted spring contact ring being provided.

The advantage of this construction was that the spring ring lay against the external conductor with a predetermined radial contact pressure and it was not turned in relation to the external conductor, so that damage owing to a sliding or fretting action was out of the question. Furthermore, no force is transmitted via the external conductor foil, because contact is only made with the latter via the external conductor contact ring. The only difficulty in the case of this plug connector was that of sliding the contact sleeve with the inserted spring ring axially onto the external conductor. In the case of clumsy carrying out of this operation damage of the external conductor could occur, more particularly if the conductor was surrounded with easily damaged copper fabric.

SUMMARY OF INVENTION

One aim of the present invention is therefore that of constructing a cable connector in such a manner that the spring contact ring does not need to be slid axially at all and is only placed radially on the external conductor.

In accordance with one aspect the invention provides, in order to achieve this aim, that the spring contact ring is so gripped at its one edge portion in the sleeve surrounding the cable at its radial face that it is raised from the external conductor and the resilient contact ring is pressed by a sleeve, which is conically shaped internally, radially onto the external conductor. Preferably the spring contact ring is clamped and soldered or brazed in the end side of the screw threaded sleeve and the latter is screwed by means of a self-cutting internal screw thread on the protective casing of the cable. The resilient contact ring, which is preferably constructed in the manner of a comb, is spaced radially owing to its being clamped, from the external casing or external conductor so that the screw threaded sleeve can be screwed onto the protective casing without the contact ring coming into contact with the external conductor. The radial pressing of the spring contact ring against the external conductor occurs on sliding on or screwing on the contact sleeve because the free edge portion of the spring contact ring runs onto the conical surface and thus passes with a certain amount of radial resilient deflection into contact with the external conductor. In this manner it is possible to ensure that even in the case of the presence of copper wire braiding or in the case of very thin foil conductors damage or displacement does not occur. In the case of a suitable construction of the spring or resilient ring and the contact sleeve it is also possible to ensure that the transfer of current occurs at the front end edge of the external conductor via the contact ring directly following the contact sleeve, while in the case of the previously proposed arrangement the making of electrical contact occurs via the spring contact ring in its middle section and the external conductor extends beyond this contact position to some degree. In order to ensure such a transfer of current the spring ring is preferably so arranged that its free edge portion extends axially somewhat beyond the end of the external conductor.

In accordance with a further form of the invention the contact sleeve is provided with a self-cutting internal screw thread and the front end of the cable dielectric, which has been bared by removing protective casing and external conductor has the contact sleeve screwed on it. This leads to a particularly firm and mechanically reliable attachment or connection. In some cases the screwing on of the contact ring onto the protective casing can be dispensed with.

While in the case of the previously mentioned proposed construction a twisting of the contact ring must be avoided in order to ensure that there is no unnecessary fretting between the contact ring and the external conductor, in accordance with the present invention this screwing movement of the contact ring can certainly be allowed because the spring contact ring is prevented from turning owing to its connection with the screw sleeve and its contact lugs can accordingly only bend radially inwards and lie against the external casing.

LIST OF SEVERAL VIEWS OF DRAWINGS

In what follows embodiments of the invention will be described with reference to the drawing.

FIG. 1 is an axial section of a coaxial plug connector mounted on a coaxial cable.

FIG. 2 is a view, corresponding to FIG. 1, of a coaxial plug connector according to the invention with additional screw means for connecting the contact sleeve with the cable dielectric.

FIG. 3 is a developed view of the spring contact ring.

FIG. 4 is a partial sectional view of the position at which electrical contact is made with the contact spring ring projecting beyond the external conductor.

DESCRIPTION OF PREFERRED EMBODIMENTS

The cable comprises an internal conductor 10, a cable dielectric 12, an external conductor 14, carried by the latter, in the form of a thin copper layer, and an insulating material casting 16 for protective purposes. The internal conductor 10 extends to the front beyond the cable dielectric. The front part of the external conductor is bared by removing the protective casing 16 and in this part the external conductor makes electrical contact with a spring contact ring 18. The construction of the spring contact ring will become apparent on referring to FIG. 2. It comprises a cylindrical wound piece of resilient sheet metal with cut away portions 20 extending from one side, and between these cut away portions 20 contact arms 22 are left. The edge portion 24 of the spring contact ring 18 is inserted into a slit provided in the front side of the flange 32 of the screw sleeve 30 and is held in this position by soldering or brazing. The screw sleeve 30 is provided with a self-cutting internal screw thread and by means of this is screwed onto the protective casing 16. In the screwed on condition the flange 32, which is drawn inwards, lies against the end of the protective casing 16.

The spring contact ring 18 is so mounted in the flange 32 that, as shown in broken lines in FIG. 2, it is spread and its contact making arms are raised from the external conductor. This ensures that there is no fretting of the contact making arms on screwing on onto the protective casing 16. The arms 22 of the spring contact ring are pressed radially inwards on sliding on of a contact sleeve 28, because the front ends of the arms run along the internal conical surface 29 of this contact sleeve and are accordingly pressed inwards. The two sleeves 28 and 30 are held together by means of a shoulder nut 34, whose rear flange 36 supports the sleeve 30 axially and the nut is screwed on an external screw thread 38 of the sleeve 28. In an external annular groove of the contact sleeve 28 a sealing ring 40 is laid, which ensures that the shoulder nut 34 is sealed. The internal conductor 44 of the plug connector is carried via an insulating support 42 and the conductor 44 has a spring contact bush 46 at its rear end. The spring lugs of this contact bush are provided with fingers 48 extending inwards, which make electrical contact radially with the internal conductor 10. Centering is carried out using a rigid internal conductor bush 50, into which the front end of the internal conductor 10 extends. Between the internal contact bush 46 and the sleeve 28 a ring 52 of foam material is fitted so as to leave an annular gap 54. Between the internal flange 36 and the screw sleeve 30 a sealing ring 56 is placed.

The embodiment of the invention in accordance with FIG. 2 differs from the plug connector in accordance with FIG. 1 in that the cable dielectric 12 in a front section 13 extends over the external conductor 14, that is to say in this front section the cable dielectric is bared because there is no external conductor. The correspondingly extended contact sleeve 28a is provided in this respect with a self-cutting internal screw thread 31, which is screwed on the front part 13 of the cable dielectric. In other respect the cable plug connector in accordance with FIG. 2 corresponds to that described with reference to FIG. 1.

In the case of the embodiment of the invention in accordance with FIG. 2 the contact arms lie like the arches of a bridge within the free space 26 enclosed by the contact sleeve and make electrical contact with the external conductor 14 approximately in the middle. In the case of the embodiment in accordance with FIG. 4 the arms 22 of the spring contact ring extend into the section 23 beyond the end of the external conductor 14 and are accepted by an annular groove 29a, which adjoins the conical surface 29 and the end of the resilient arms are pressed thereby against the cable dielectric 13. This ensures that the front edge 15 of the external conductor is contacted electrically by the spring arms 22 so that the current can flow in one direction from the external conductor via the contact making arms to the contact sleeve.

Claims

I claim:

1. A cable plug connector for insulated coaxial cable:

the cable comprises an internal conductor, a dielectric layer outside said internal conductor, a thin metal layer external conductor positioned around and supported on said dielectric layer and an external protective casing of insulating material around said external conductor; an annular section of said casing is removed to facilitate electric contact with said external conductor;

said connector comprises

a first sleeve positioned around said external protective casing of said cable; said first sleeve having a first end;

a resilient spring contact ring around said exposed annular section of said external conductor; said ring having one edge portion which is supported said first sleeve at its said first end; said ring having a free edge portion opposite its said one edge portion; said ring is so shaped and oriented in said first sleeve that its said free edge portion is normally raised above said annular section of said external conductor and is radially deflectable inwardly against said annular section of said external conductor;

a second sleeve with a first end that faces toward said first sleeve first end and having a bore near said second sleeve first end; said second sleeve bore is shaped to cause said ring free edge portion to deflect radially inwardly and to cause said ring to engage said external conductor annular section, and is shaped to cause such deflection of said ring as said second sleeve first end is moved toward said first sleeve first end.

2. The connector of claim 1, wherein said second sleeve bore tapers conically radially inwardly away from said first sleeve.

3. The connector of claim 2, wherein said first sleeve has a self cutting internal thread therein, which is screwed onto said protective casing.

4. The connector of claim 1, wherein said front end of said first sleeve is slotted and in the slot is soldered said contact ring.

5. The structure as set forth in claim 1, in which said spring contact ring is constructed in the manner of a comb and is divided by cut away portions into individual resilient lugs.

6. The connector of claim 5, wherein each said lug is curved radially outwardly to form an arch and is so shaped and oriented that said lugs are forced inwardly by said second sleeve bore to cause their center portions to engage said external conductor.

7. The connector of claim 6, wherein said external conductor has a front edge which is included in said annular section and is located so as to extend out of said first sleeve; said lugs extend past said external conductor front edge and make contact therewith; said second sleeve bore receives said ring free edge portion and biases said lugs radially inwardly.

8. The connector of claim 6, wherein an annular section of said external conductor is removed to expose said dielectric layer; said second sleeve having an internal thread therein which is screwed onto said exposed annular section of said dielectric support.