Connector for coaxial cable with friction locking arrangement

Abstract: Cable connector for coaxial cable, comprising a bushing (2) for providing an axial displacement of parts (4, 5, 6, 7, 8) in the connector, whereby these parts are brought into mechanical and/or electrical engagement with the coaxial cable. The axial displacement is provided by screwing a thread (10) provided on the bushing (2) onto a corresponding thread (9) provided in the main body (1) of the connector. The axial displaceable parts in the connector comprising a ferrule (4) for engaging the outer conductor or screen of the coaxial cable, said ferrule (4) comprising a locking arrangement for preventing rotation of the ferrule and cable. The ferrule (4) comprises a conical surface (11) and the main body (1) of the connector comprises a corresponding conical surface (12), said surfaces (11,12) being brought into locking engagement when axially displaced by the bushing (2), whereby the ferrule (4) and cable are prevented from rotating in the connector. By this construction an improved locking arrangement is provided. By further inserting a friction reducing disc (7) between the bushing (2) and the inner bushing (6) the forces acting on the locking arrangement are reduced.

Description: The present invention relates to a cable connector of the kind set forth in the preamble of claim 1. In cable connectors of this kind it is known to use axially displaceable components with conical formations cooperating to provide the radial compression of connecting parts to provide the electrical and mechanical connections between the connector and the coaxial cable. The axial displacement of parts in the connector is effected by a bushing provided with a thread which is screwed onto a corresponding thread provided in the main body of the connector. In such cable connectors it is known to provide a non-rotational locking arrangement between the main body of the connector and a ferrule for engaging the outer conductor or screen of the coaxial cable and/or the outer insulating jacket of the coaxial cable. WO 97/22162 describes a connector for coaxial cable, in which the main body comprises a shoulder forcibly contacting a truncated conical exterior surface on the ferrule in order to radially compress the ferrule to engage the isolating jacket and conductive sheath of the coaxial cable. This compression presupposes a sliding movement of the shoulder relative to the conical surface, thus not preventing a corresponding sliding rotational movement of the ferrule and cable relative to the main body. It is the object of the present invention, to provide a cable connector of the above kind, with an improved locking arrangement. This object is achieved with a connector of said kind, which according to the present invention is characterized by the features set forth in the characterizing clause of claim 1. With this arrangement the ferrule is prevented from rotating by simple engagement between conical surfaces on the ferrule and the main body of the connector. A further advantage with this construction is that the electrical contact between the ferrule and the main body of the connector is achieved circumferentially continuous along the conical engagement surfaces, whereby the shielding effectiveness is improved and the intermodulation distortion, return loss and insertion loss are reduced compared to similar connectors of traditional construction. Preferred embodiments of the connector are revealed in the subordinate claims 2-4. Claim 2 indicates a friction reducing disc between the bushing and the ferrule, whereby the load on the locking arrangement, when rotating the bushing, is reduced. Claim 3 indicates the provision of O-rings for providing a liquid and moisture tight connector. Claim 4 indicates provision of threads in the bushing and the main body of the connector as multiple-start threads, whereby the assembly time for assembling a connector with a coaxial cable will be substantially reduced, the final mounting position being reached with only a few rotations of the bushing and the threading is almost instantanously brought into engagement whereas the single thread of the prior art, having only one start, may have to be rotated up to approximately 360° before it is brought into initial engagement. In the following detailed portion of the present description, the present invention will be explained in more detail with reference to the exemplary embodiment of the cable connector for coaxial cable according to the invention shown in the drawing, in which: Fig. 1 shows an axial cut through a cable connector for coaxial cable in accordance with the invention. The cable connector for coaxial cable shown in the figure comprises a main body 1, which, as shown to the left in the drawing, is provided with a plug part in the form of a BNC, TNC or the like. This plug part is not part of the invention and any suitable connection may be provided in this place. The main body 1 is provided with threads 9 for engagement with corresponding threads 10 on a bushing or collar 2. Centrally placed in the main body 1 is an axially slotted tube 3 for connection of the central conductor of the coaxial cable. The axially slotted tube 3 will be radially compressed by an axially displaceable insulating part 5 which is provided with a conical formation for engaging the axially slotted tube 3. An axially slotted ferrule 4 for electrical connection to the outer conductor of the coaxial cable and possibly for mechanical connection to the outer insulating jacket of the cable is placed behind the axially displaceable part 5 and the axial displacement of the ferrule 4 and the axially displaceable part 5 is provided by screwing the bushing 2 onto the main body 1 whereby the bushing moves an axially displaceable inner bushing 6 acting upon the ferrule 4. In the embodiment shown a friction reducing disc 7 and a O-ring 8 is placed between a step on the bushing 2 and the inner bushing 6. A further O-ring 13 is provided on the main body 1 for providing a sealing between the bushing 2 and main body 1 when the bushing 2 is brought into its final position. The cable connector shown in the drawing functions in the following way: A prepared coaxial cable is inserted into the connector, the cable being prepared in such a way, that the inner conductor can be inserted into the axially slotted tube 3 and the outer conductor and outer isolating jacket can be positioned inside the ferrule 4. The bushing 2 is screwed onto the main body 1 using the threads 9 and 10, whereby the bushing moves the friction reducing disc 7, the axially displaceable inner bushing 6, the axially slotted ferrule 4 and the axially displaceable part 5 whereby the axially slotted tube 3 is compressed radially into contact with the central conductor of the coaxial cable. The ferrule 4 is provided with a conical locking surface 11 which is brought into engagement with a corresponding conical locking surface 12 provided on the main body 1. The engagement between the two conical locking surfaces 11,12 prevents the ferrule 4 from rotating relative to the main body 1. The axially movement of the bushing 2 will provide an axial movement of the inner bushing 6, whereby the axially slotted ferrule 4 will be radially compressed due to appropriate conical formations on the ferrule 4 cooperating with the inner bushing 6, whereby the ferrule 4 is brought into engagement with the outer conductor and the outer isolating jacket on the coaxial cable. In the embodiment shown part of the radial compression of the ferrule 4 is provided by engagement between the front of the inner bushing 6 and a conical formation of the ferrule and other part of the radial compression of the ferrule is provided by engagement between a conical formation on the inner bushing 6 and the back part of the ferrule 4. A friction reducing disc 7 is positioned between the inner bushing 6 and the O-ring 8 and bushing 2, in order to reduce the torque forces transferred from the bushing 2 to the ferrule 4 and its conical locking surface 11, whereby the forces during assembly of the connector on the locking function of the conical locking surfaces 11, 12 are reduced. Above the present invention has been described in connection with a specific embodiment of the invention, however it will be clear for a man skilled in the art, that many alterations can be made without departing from the following claims.

Claims: Cable connector for coaxial cable, comprising an outer bushing (2) for providing an axial displacement of parts (4, 5, 6, 7, 8) in the connector, whereby these parts are brought into mechanical and/or electrical engagement with the coaxial cable, the axial displacement being provided by screwing a thread (10) provided on the bushing (2) onto a corresponding thread (9) provided in the main body (1) of the connector, the axial displaceable parts in the connector comprising a ferrule (4) for engaging the outer conductor or screen of the coaxial cable by radial compression, said ferrule (4) comprising a locking arrangement for preventing rotation of the ferrule and cable, the ferrule (4) comprising a conical surface (11) and the main body (1) of the connector comprising a corresponding conical surface (12), said surfaces (11, 12) being formed separately from the conical formations for providing the radial compression of the ferrule (4), and said surfaces (11, 12) providing a locking engagement when axially displaced by the bushing (2), said locking engagement preventing the ferrule (4) and cable from rotating in the connector, the ferrule (4) comprising a further conical surface, characterised by an inner bushing (6) provided with a conical surface for engaging the corresponding conical formations on the ferrule (4) for providing said radial compression. Cable connector in accordance with claim 1, characterised by further comprising a friction reducing disc (7) between the bushing (2) and an inner bushing (6), transferring the axial displacement of the bushing (2) to the ferrle (4), said inner bushing (6) being positioned between the bushing (2) and the ferrule (4), for providing the radial compression of the ferrule (4) by means of suitable conical formations on the inner bushing (6) and/or the ferrule (4). Cable connector in accordance with any of the preceding claims, characterised by further comprising O-rings (8, 13) between the bushing (2) and the cable and between the bushing (2) and the main body (1) of the connector for providing a liquid and moisture-tight connector. Cable connector in accordance with any of the preceding claims, characterised by said threads (9, 10) in the bushing (2) and the main body (1) of the connector being provided as multiple-start threads.

Inventors: HENNINGSEN JIMMY CIESLA, HENNINGSEN,JIMMY CIESLA
Applicants: CABEL CON AS, CABEL-CON A/S
Application year: 1998
Main classification: H01R9
IPC codes: H01R9