EP0458237B1 - Coaxial cable connector - Google Patents

Description

The present invention relates to a coaxial cable connector, in particular for video communication. This connector must retain the electrical characteristics of the cable and have good mechanical strength on the cable (see US-A-4408822).

The present invention aims to provide these two functions simultaneously and thereby allow rapid and simple mounting on a coaxial cable.

It relates to a coaxial cable connector, with said coaxial cable comprising a central conductive core, a dielectric coating on said core and an external conductor on said dielectric coating and the connector comprising, held coaxially and isolated from one another , a central conductor and an external conductive structure with respect to this central conductor, for contacting the core and the external conductor of the cable, respectively, characterized in that said conductive structure consists of a ferrule and an external conductive body connector, substantially cylindrical in shape and having a so-called rear section, for receiving said cable, in which the ferrule is on the one hand integral with the body and on the other hand provides, between itself and said body an annular space for tightening said outer conductor of said cable, and a front section, in which said central conductor is mounted prisoner in an insulating support ring, itself made integral with said body.

According to another characteristic, said ferrule comprises, on the one hand, a front shoulder, of diameter substantially equal to the inside diameter of the rear section of the body, by which the ferrule is integral with the body inside the rear section according to the length of the body, and peripheral anchoring means along the annular space which it defines with the rear section of the body.

According to another characteristic, the shell can initially be independent of the body and then be blocked by any suitable method in the rear section of the body, or be obtained directly with the body. Advantageously, the anchoring means presented on the ferrule are a thread making it self-tapping for the external conductor of coaxial cable with smooth and self - tapping outer conductor for the outer conductor of coaxial cable with fluted outer conductor.

• La figure 1 représente en coupe un connecteur coaxial selon la présente invention.
• La figure 2 et la figure 3 représentent en coupe un premier et un deuxième câble coaxial, qui sont équipés du connecteur selon la figure 1.
• La figure 4 représente en coupe un autre câble coaxial équipé d'un connecteur selon une variante de la figure 1.

The characteristics and advantages of the present invention will appear more clearly during the description given below of an embodiment given by way of non-limiting example and illustrated in the attached drawings. In these drawings

• Figure 1 shows in section a coaxial connector according to the present invention.
• FIG. 2 and FIG. 3 show in section a first and a second coaxial cable, which are equipped with the connector according to FIG. 1.
• FIG. 4 represents in section another coaxial cable equipped with a connector according to a variant of FIG. 1.

The coaxial connector shown in FIG. 1 is said to be of the monobloc type. It comprises a central conductor 1 and a conductive ferrule 2 in a body 3 also conductive. The central conductor 1 and the ferrule 2 are both made integral with the body 3 and are isolated from one another.

The body 3 has a generally cylindrical shape. It has a front section 3A for the central conductor 1 and a rear section 3B in which is the ferrule 2. It also has an internal shoulder 3C between its rear section 3B and its slightly smaller front section 3A.

The ferrule is directly integral with the body 3. It is produced independently of the body and is blocked therein or alternatively belongs to the body and obtained with it. It is generally cylindrical in shape, with a front shoulder 2A of diameter corresponding to the inside diameter of the rear section 3B of the body 3 and coming against the inside shoulder 3C of the body 3. The central conductor 1 is made integral with the body by an insulating support ring 4, in which it is mounted prisoner and which is blocked in the front section of the body. This central conductor is thus made prisoner longitudinally on the axis of the body.

Being at the start independent of the body 3, the ferrule 2 is made integral with the body 3 and locked in its rear section against the shoulder 3C by force fitting, crimping, screwing, necking or any other suitable process. The support ring 4 carrying the central conductor 1 is likewise made integral with the body 3 by any suitable method.

A spacer washer 5, made of insulating material, is preferably mounted with the ferrule 2 and locked with it in the rear section of the body. It is partially housed in the front face of the ferrule and locked with its shoulder 2A against the internal shoulder 3C of the body 3. This insulating washer receives centered in the hole which it presents in its middle the rear end of the central conductor 1, the two end parts of which protrude from its support ring 4. The front end of the central conductor is substantially level with the end of the front section of the body and is centered there.

In this so-called monoblock coaxial connector, the ferrule 2 cleans, at the rear of its shoulder 2A, between it and the body 3, an annular space 6. This annular space is intended for the external conductor of coaxial cable possibly coated with a sheath protective exterior. It maintains it tightly, while the inner conductor or core of the cable is simultaneously in intimate electrical contact with the central conductor 1.

In particular, the internal diameter of the rear section 3B of the body 3 and the dimensions and the shape of the ferrule 2 are adapted to the type of coaxial cable concerned in order to obtain the desired tightening of the external conductor with or without its external protective sheath and consequently obtaining intimate electrical contact with the external conductor. To this end, the ferrule 2 has a thread 2F or the like, making it self-tapping or self-tapping depending on the type of external conductor, smooth or not, of the cable. It thus anchors firmly in the outer cable conductor, under which it is inserted. It also has a chamfer 2C on its rear edge, facilitating its insertion under the outer cable conductor, when the connector is screwed at the end of the cable.

An annular seal 7 is mounted in the rear edge of the shoulder 2A of the ferrule. It comes on the periphery of the shoulder 2A, to be compressed against the shoulder 2A and the body 3 by the end of cable mounted in this connector. It provides transverse sealing of the connector when it is thus fully compressed.

The body also has externally on its rear section 3B 3P dishes, or alternatively notches or holes, which facilitate the screwing and tightening of the connector on the end of a coaxial cable using a key.
On its front section 3A, the body carries a threaded terminal nut 8, for screwing the connector on a coaxial connector complementary to another coaxial cable, of equipment, of apparatus or of a circuit board. This complementary connector is not illustrated. It has a front end fitting complementary to that illustrated and threaded and has a rear section similar to that of the connector illustrated or connected to the equipment, device or circuit in question.

On the coaxial connector, the nut 8 is mounted with a limited stroke possible on the front section 3A, being trapped between a rear stop shoulder 3D and a retaining circlip 9. On this section before another joint 10 inside the nut provides transverse sealing of this connector when it is connected to a complementary connector.

In addition, advantageously one or more screws such as 13 can be used for locking in rotation in the rear section of the body 3 of the cable end, once in place in this connector.

For this coaxial connector according to the invention, it is indicated by way of example that the body 3 and the ferrule 2 are for example made of brass, or of bronze, or else of a conductive alloy known under the name Zamac. The support ring 4 will for example be made of polytetrafluoroethylene. In addition, the central conductor is as such of a known type. It is for example with longitudinal elastic deformation slots, on its rear end part, as illustrated, or with a compression spring or contact piston in its rear end part. Its front end part is of common type, as illustrated.

Figures 2, 3 and 4 show the coaxial connector according to the present invention mounted on different coaxial cables. In these figures, the main elements of the connector have been identified by the references used in figure 1. Only the possible differences compared to figure 1 are specified below.

In FIG. 2, the coaxial cable has a central conductor or core 21 surrounded by a dielectric coating 22 and an external conductor 23 mounted on the dielectric 22 and covered with an external protective sheath 24. The external conductor 23 is counter glued or overlapped. It is made of copper or aluminum. For this type of cable, the coaxial connector is mounted on the cable end, with its relatively thin outer conductor 23 kept coated with its protective sheath. The ferrule 2 is inserted under the outer conductor 23 and anchored firmly in this outer conductor 23; the latter is clamped with its sheath 24 between the ferrule and the body 3 of the connector while the central conductor 21 of the cable and that 1 of the connector have been brought into intimate electrical contact.

In FIG. 3, the coaxial cable comprises a central conductor or core 31, a dielectric coating 32 on this central conductor and an external conductor 33. This external conductor is a smooth conductor, made of copper or aluminum, it is extruded or welded. It has no protective outer sheath. It is therefore alone between the ferrule 2, which is anchored therein, and the body 3 of the connector, while the central conductors of the cable and of the connector are also in intimate electrical contact.

In the two examples illustrated in these two Figures 2 and 3, the ferrule 2 is self-tapping with the screwing of the connector on the cable end. The resulting anchoring guarantees excellent electrical contact between it and the outer conductor of the cable and the ferrule, itself in intimate contact with the body 3, as well as excellent mechanical strength of the connector on the cable end.

In FIG. 4, the coaxial cable is with central conductor or central core 41, with dielectric coating 42 around the central conductor and with external conductor 43. This external conductor 43 is a grooved conductor, the grooves are on its internal face and are designated by 43A. It is made of aluminum or copper. It is with an outer protective sheath 44. For this type of cable, the coaxial connector is with a threaded ferrule 2, the 2F ′ threads of which are rounded and no wider than in the above examples. These 2F ′ threads are not slightly greater than that of the splines, but remain slightly smaller in height. This ferrule is also given a slightly conical shape, better suited for its insertion under this grooved conductor 43, while its end chamfer can be eliminated, as illustrated.

Under these conditions, the ferrule 2 is screwed into the outer conductor 43, coated with its outer sheath, when the connector is screwed onto the cable end. The terminal grooves received on the ferrule are slightly deformed, which ensures good anchoring of the ferrule for the required intimate electrical contact and good mechanical strength.

In the three examples of FIGS. 2, 3 and 4, the dielectric coating 22, 32 or 42 can be removed over a short terminal length, equal to or less than the length of the shell. The dielectric coating, partially removed, or not removed, along the length of the ferrule, is in correspondence inserted around the central conductor of the cable inside the ferrule. This central cable conductor remains largely remote from the ferrule and isolated from it.

The present invention has been described with reference to the examples illustrated. We can obviously make changes to it in detail without departing from the scope of this invention. In particular, the shape of the self-tapping or self-tapping ferrule and the diameters of the ferrule and of the rear section of the connector body are such that they allow firm tightening at the end of travel, between the ferrule and the body, of the cable wall, that is to say its outer conductor or the latter with its outer protective sheath, depending on the type of cable.

Claims (12)

1. Coaxial cable connector, with said coaxial cable including a central conductive core (21), a dielectric covering (22) over said core and an external conductor (23) over said dielectric covering and the connector including, held coaxially and insulated from each other, a central conductor (1) and a conductive structure (3) external to said central conductor for contact with the core (21) and the exterior conductor (23) of the cable, respectively, characterised in that said conductive structure comprises a cylindrical member (2) and a conductive exterior connector body (3) of substantially cylindrical shape and having a rear section (3B) adapted to receive said cable and in which the cylindrical member is fastened to the body (3), leaving between it and said body an annular space (6) for gripping said exterior conductor (23, 33, 43) of said cable, and a front section (3A) in which said central conductor (1) is trapped in an insulative ring (4) fastened to said body (3).
2. Connector according to claim 1 characterised in that said cylindrical member (2) includes a front shoulder (2A) whose diameter is substantially equal to the inside diameter of the rear section (3B) of the body by which the cylindrical member is fastened to the body (3) inside the rear section lengthwise of the body and peripheral anchor means (2F, 2F′) lengthwise of the annular space which it defines with the rear section (3B) of the body.
3. Connector according to claim 2 characterised in that said body (3) has an internal shoulder (3C) between its rear section and its front section with which the front of the shoulder (2A) of the cylindrical member (2) is in contact.
4. Connector according to claim 3 characterised in that said cylindrical member is initially independent of the body (3) and is wedged in said rear section (3B) of the body (3) abutting against said interior shoulder (3C).
5. Connector according to claim 4 characterised in that it further comprises an insulative spacer washer (5) partially housed in the front of the front shoulder of the cylindrical member (2) and abutted with the cylindrical member against said interior shoulder (3C) of the body (3).
6. Connector according to claim 3 characterised in that said cylindrical member (2) is part of said body (3) and is manufactured with said body.
7. Connector according to any one of claims 2 to 6 characterised in that said anchor means (2F, 2F′) comprise a screwthread for screwing the cylindrical member under the exterior conductor (23, 33, 43) of the cable.
8. Connector according to any one of claims 3 to 7 characterised in that it further comprises a first peripheral seal (7) housed partially in the rear of the front shoulder (2A) of the cylindrical member (2).
9. Connector according to any one of claims 2 to 8 characterised in that said body (3) further has exterior means (3P) for clamping the connector onto a cable end by means of a wrench.
10. Connector according to any one of claims 2 to 9 characterised in that it includes at least one screw (13) through the rear section (3B) of the body (3) for preventing rotation of the end of the cable in the connector.
11. Connector according to any one of claims 2 to 10 characterised in that said annular space (6) has dimensions adapted to receive and grip said exterior conductor (23) of the coaxial cable, which is optionally covered with a protective exterior jacket (24).
12. Connector according to any one of claims 2 to 11 characterised in that it further includes a nut (8) and a seal (10) inside said nut mounted around the end of said front section to lock it to a complementary coaxial connector and provide a seal between them.

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