CABLES

DESCRIPTION

The present invention relates to an improved device for the ground connection of coaxial cables.

The field of the invention relates to coaxial cables, used for the transmission of electromagnetic signals in the telecommunications field.

For this purpose, the coaxial cables consist of a primary signal transmission conductor and a secondary shield conductor of the signal transmitted by the primary conductor, wherein the above-mentioned conductors are positioned reciprocally coaxial to each other .

In installations of this type, it is also usual to effect the grounding of the coaxial cables, in order to dissipate any possible parasite currents and also any possible electrical discharges such as lightning.

For this purpose, ground connection devices of the coaxial cables are used, positioned in contact with the secondary conductor and fixed to the outer sheath of the coaxial cable.

The known art represented by Italian patent 1,393,532 describes a ground connection device for coaxial cables in which a contact bar is electrically connected to an internal contact, which is in turn electrically connected with the secondary conductor of the coaxial cable. In particular, the fixing of the contact bar to the internal contact of the cable is effected by means of a protuberance, present on the same contact bar and suitable for being inserted inside a corresponding connection seat formed on the internal contact .

This known solution has the disadvantage of not guaranteeing a stable connection between the contact bar and the internal contact. During the manipulation of the earth cable, fixed to the contact bar, in fact, the movements to which it is subjected during the installation of the coaxial cable are also transmitted to the same contact bar. This often causes the detachment of the internal contact of the contact bar, by disengagement of the protuberance of the latter from its seat on the internal contact. Said disengagement in turn causes an interruption in the electrical connection between the coaxial cable and ground cable, thus neutralizing the functionality of the device.

US 5,562,482A describes a ground connection device of coaxial cables in which the contact bar is connected to the grounding cable.

The main objective of the present invention is to provide an improved device for the ground connection of coaxial cables, which guarantees the stability of the electrical contact between the ground cable and the coaxial cable.

These and other objectives are achieved with the device and coaxial cable according to claims 1 and 7 respectively. Preferred embodiments of the device of the invention are specified in the remaining claims.

With respect to analogous devices of the known art for the ground connection of coaxial cables, that according to the present invention offers the advantage of ensuring the stability of the electrical contact between the ground cable and the coaxial cable, at the same time maintaining the necessary coupling between the contact bar and the internal contact, effected without weldings and by means of mechanical connection.

These and other objectives, advantages and characteristics appear evident from the following description of some preferred embodiments of the device and coaxial cable of the invention, illustrated, for exemplificative and non-limiting purposes, in the figures of the enclosed drawings. n these: figure 1 illustrates the device of the invention in an overall perspective view;

figure 2 illustrates a first embodiment of the device of the invention in an exploded view;

figure 3 illustrates the detail of the connection system between the contact bar and internal contact of the device of figure 2;

figure 4 illustrates a sectional view of the device of figure 2 in an assembled position;

figure 5 illustrates an exploded view of a second embodiment of the connection system between the contact bar and internal contact of the device of the invention;

figure 6 illustrates a sectional view of the details of figure 5 in an assembled position; figure 7 illustrates a third embodiment of the device of the invention in an exploded view;

figure 8 illustrates the device of figure 7 in an assembled state;

figure 9 illustrates a further variant of the device of figure 1; - figures 10 and 11 respectively illustrate an exploded and horizontal sectional view of the device of figure 9; and

- figure 12 illustrates the coaxial cable of the invention with the ground connection device of the previous figures assembled thereon.

The device of the invention for the ground connection of coaxial cables is indicated as a whole with 1 in figure 1. It comprises a metallic outer shell 2, in which a gasket 3 is housed, made of an elastomeric material, such as a synthetic rubber such as, for example, an EPDM (Ethylene-Propylene-Diene Monomer) rubber. As better illustrated in figures 2 to 4, the device 1 also comprises a contact bar 4, at whose end 5 it is crimped onto the ground cable 6. The opposite end 7 of the contact bar 4, i.e. that facing the gasket 3, is, on the other hand, suitable for being inserted in the pocket seat of the same gasket, composed of a first pass-through inlet section 8 and a second section 9, the latter closed by a bottom 10. The above-mentioned sections 8 and 9 of the pocket seat for the contact bar 4 in the gasket 3 are interrupted by the seat 11 for the internal contact 12. The connection, with the formation of the necessary electrical connection between the contact bar 4 and the internal contact 12 of figure 3, is obtained by engagement of the hook 13 of the contact bar 4 inside the slot 14 envisaged on the internal contact 12.

The hook 13 of the contact bar 4 is kept in a blocked position in the slot 14 of the internal contact 12 thanks to the elastic thrust exerted, in the direction of the arrow Fl of figure 4, by the bottom 10 of the section 9 of the pocket seat of the gasket 3 made of an elastomeric material, in response to the force insertion of the end 7 of the contact bar 4 inside the same section 9.

The internal contact 12 of the device of the invention is, in turn, kept in a stable position with respect to the contact bar 4, thanks to its housing inside the above-mentioned seat 11 envisaged in the gasket 3.

For the assembly of the device of the invention, the contact bar 4 is pushed inside the pocket seat 8,9 of the gasket 3 in the direction of the arrow F2 of figure 3, until the hook 13 is completely brought beyond the edge 15 of the slot 14 of the internal contact 12. In this position, the bottom 10 of the gasket 3 made of an elastomeric material, is elastically deformed generating, on the end 7 of the contact bar 4, an elastic thrust Fl (figure 4).

In this state, the elastomeric material of the gasket 3 also generates an upward pushing component F3 (figure 3) , which causes the hook 13 to become inserted inside the slot 14. In this way, a coupling is formed which is kept in a stable position thanks to the thrust Fl exerted by the bottom 10 of the section 9 of the pocket seat of the gasket 3 against the end 7 of the contact bar 4, which in turn causes an analogous thrust of the hook 13 against the edge 15 of the slot 14 of the internal contact 12.

In this way, the stress generated by the manipulations on the ground cable 6, which is transmitted onto the coupling between the tooth 13 and the edge 15 of the slot 14 and which operates in the direction of the opening of the same coupling, is opposed by the stress Fl, F3 generated by the elastomeric material of the gasket 3 on the contact bar 4.

In the variant of the invention illustrated in figures 5 and 6, the internal contact 12 is provided by a hook 16 suitable for being engaged, with the procedures already described with reference to the previous figures, inside a slot 17 formed on the contact bar 4.

In the version of the device of the invention illustrated in figures 7 and 8, the hook 13 of the contact bar 4 is directly engaged on the edge 18 of the internal contact 12, again thanks to the thrust exerted by the elastomeric material of which the gasket 3 is formed.

A notch, not illustrated, suitable for guiding the coupling of the hook 13 on the above-mentioned internal contact, can be advantageously envisaged on the portion of the edge 18 of the internal contact 12, which receives the engagement with the hook 13.

In the variant illustrated in figures 9 to 11, the device 19 of the invention again comprises a gasket 3 made of an. elastomeric material, ^" and an internal contact 12, suitably shaped so as to house the contact bar 4, no longer on a horizontal plane as in the previous figures, but on a vertical plane or rotated by 90° with respect to the previous plane. For the rest, the coupling solutions are the same as those already represented in figures 4, 6 and 8, the first of which is reproduced, according to the variant under examination, in figure 11.

The coaxial cable provided with the device of the invention is illustrated in figure 12. It consists of a primary conductor 21 and a secondary conductor 22, separated by a dielectric material 23. An outer sheath

24 is also present.

Thanks to the closing action exerted by the metallic shell 2 of the device of the invention, the gasket 3 of the latter guarantees a sealing action on the outer sheath 24. Furthermore, in correspondence with the position of the internal contact 12, the corresponding portion 25 of outer sheath 24 is removed, so as to create the necessary electrical contact between the secondary conductor 22 of the coaxial cable

20 and the internal contact 12 of the device of the invention .-

Further modifications can be applied to the device and coaxial cable of the invention, to form variants which, however, are included in the scope of the following claims, when the elastic action of the gasket is exploited for stably coupling the contact bar and the internal contact inside the earthing system.