EP0914689B1 - Method for connecting coaxial cables and connector therefor - Google Patents

Abstract

A connector for coaxial cables having an inner conductor (14) and an outer conductor (10) separated by a dielectric (16) includes a front body (4) to attach a coaxial cable in the connector and a rear body (8) adapted for connection to the front body (4), and a device for holding the cable in the connector in a manner that permits reproducible deformation of the outer conductor (10) during the connecting operation. The device for holding the cable in position is comprised of a ferrule (1) for holding the coaxial cable, and a bushing (2) that cooperates with the ferrule (1) to permit axial movement of the coaxial cable over a determined distance (L) in the connector during the connecting operation. The surfaces of ferrule (1) and bushing (2) cooperate to produce reproducible compression and/or deformation of the outer conductor (10) between said ferrule (1) and said bushing (2) during said connecting operation. The connector enables the coaxial cable to be deformed during the connection operation in an automatically reproducible manner without requiring precise measurements or special tools. The impedence fault value produced by the deformation of the outer conductor can be predetermined and is automatically reproduced during each connection operation.

Description

The subject of the invention is a connector for coaxial cables, especially for high frequency ones in use in telecommunications or cable television.

One of the conditions necessary to ensure the transmission of high frequency signals with a minimum losses in coaxial transmission lines, coaxial cables and connectors respectively, is keep a constant impedance over the entire length of the transmission line.

Impedance is directly related to dimensions of the central conductor, of the conductor outside and at the dielectric. If the cables have a constant section over their entire length, this section is sometimes modified where the connector is fixed, especially if the external conductor has to be deformed to ensure electrical contact and cable retention. Modifying cable dimensions introduces a defect impedance which must be compensated in the connector. This compensation is not adjustable. It is therefore not valid only for a value of the impedance fault well precise, difficult to achieve during assembly of the connector on the cable.

The object of the invention is a connector for coaxial cables which allows to fix the cable by deforming the external conductor (which provides electrical contact and fixing the connector) automatically reproducible without the need for precise measurements or subjective estimates during installation, or tools special.

The general principle of such a connector is known from the patent German 42 07 482 which describes a method of connecting coaxial cables with a corrugated outer conductor annually (rinfôrmig gewellter Mantelrohr). The cable is cut at a hollow of the corrugations and a piece intended to hold the cable is placed in the hollow of the next ripple. During the connection operation a front body and a rear body of the connector the ripple left free by the holding part is relatively reproducibly overwritten between the front body and the holding part. This type of connector known however has the disadvantage that it does not prevent the rotation of the cable in the holding part during the connection operation, which can affect the good reproducibility of the deformation of the external conductor. In addition, this type of connector is quite specific. coaxial cables with a corrugated outer conductor annularly. It is therefore not suitable for cables coaxial with smooth outer conductor or with conductor spiral exterior.

The object of the present invention is to provide a method of connection for coaxial cables which remedies these disadvantages and thanks to which the deformation of the conductor outside of the cable is always the same.

The method according to the invention, intended for the connection of coaxial cables provided with an inner conductor and an outer conductor separated by a dielectric, by connection of a front body intended to fix the cable and of a rear body, while a device keeps the cable in position so as to cause a reproducible deformation of the external conductor, involves the use of a ferrule intended to hold the cable, and of a socket which cooperate to allow axial movement over a distance determined of the ferrule and the cable relative to the socket.
Preferably, the deformation of the external conductor is caused and determined by a frontal plane of said socket.
This process uses a new connector which is also the subject of the invention

This connector according to the invention, for cables coaxial provided with an inner conductor and a external conductor separated by a dielectric, comprising a front body intended to fix the cable in the connector and a rear body intended to be connected to the front body, as well as a device intended to maintain the cable in position relative to the connector so that allow reproducible deformation of the conductor outside during the connection operation, this device intended to hold the cable in position being constituted at least two parts cooperating to maintain and guide the cable in a reproducible manner, including a ferrule intended to hold the cable, and a cooperating socket with the ferrule so as to allow axial displacement over a determined distance from the ferrule and the cable by relative to the socket during the connection operation.

According to a preferred characteristic of the invention, the socket comprises a frontal plane, the shape of which determines the deformation of the external conductor.
The connector according to the invention can also advantageously comprise a seal provided between the rear body and the parts cooperating to hold and guide the cable.

According to a first particular embodiment of the invention, the connector can more specifically be provided for use with coaxial cables with a spiraled outer conductor. In this case, the ferrule can advantageously be provided with a special thread allowing the spiral conductor to be screwed into it, while the ferrule and the socket have a geometry preventing rotation of the ferrule and the socket relative to each other. and relative to the cable.
In this embodiment, the ferrule and the socket are preferably each provided with zones with mutually matching plates, preventing rotation of the ferrule and the socket relative to each other, and of grooves intended to housing a ring allowing the ferrule to move relative to the socket with a determined stroke.

According to another particular embodiment of the invention, the connector can more specifically be provided for use with coaxial cables with a smooth outer conductor. In this case the ferrule can advantageously be provided with a longitudinal slot allowing a clamping of the diameter of the ferrule, and an internal thread or profile allowing to hang the smooth outer conductor during the clamping of the ferrule. In this embodiment, the ferrule is preferably provided, on the side of the socket, with a cone outside and inside, and the socket with a cone at the inlet and in the bottom, the cone outside of the ferrule being intended to cooperate with the cone at the inlet, the socket to cause the tightening of the slotted ferrule, and the cone of the bottom of the socket being intended to cause the determined deformation of the external conductor, in cooperation with the cone inside of the ferrule.
In this embodiment, the parts cooperating to hold and guide the cable in a reproducible manner, may usefully further comprise a ring intended to advance the ferrule during assembly of the rear body of the connector, making it possible to wedge the ferrule between the socket. and the ring.

Other details and properties will become apparent from the description of a connector for coaxial cables according to the invention, illustrated by the drawings appended hereto.

• la figure 1 représente une vue en perspective des pièces de maintien (ferrule et douille, montrées séparées) d'un connecteur selon un premier mode de réalisation de l'invention (connecteur pour câbles à conducteur extérieur spiralé) ;
• la figure 2 représente une vue en perspective des pièces de la figure 1, montrées assemblées;
• la figure 3 représente une vue en élévation, partiellement en coupe, d'un connecteur selon l'invention utilisant les pièces de maintien des figures 1 et 2;
• la figure 4 représente une vue correspondant à la figure 3, montrant le connecteur avec un câble coaxial, avant l'opération de déformation du conducteur extérieur;
• la figure 5 représente une vue correspondant à la figure 4, après l'opération de déformation du conducteur extérieur;
• la figure 6 représente une vue en perspective des pièces de maintien (ferrule et douille, montrées séparées) d'un connecteur selon un deuxième mode de réalisation de l'invention (connecteur pour câbles à conducteur extérieur lisse) ;
• les figures 7 à 9 représentent des vues en coupe d'un connecteur selon l'invention utilisant les pièces de maintien de la figure 6, disposé sur un câble coaxial, montrés à des phases successives de l'opération de capture et de déformation du conducteur extérieur.

In these drawings,

• FIG. 1 represents a perspective view of the holding pieces (ferrule and socket, shown separate) of a connector according to a first embodiment of the invention (connector for cables with spiraled outer conductor);
• 2 shows a perspective view of the parts of Figure 1, shown assembled;
• 3 shows an elevational view, partially in section, of a connector according to the invention using the holding parts of Figures 1 and 2;
• FIG. 4 represents a view corresponding to FIG. 3, showing the connector with a coaxial cable, before the operation of deformation of the external conductor;
• FIG. 5 represents a view corresponding to FIG. 4, after the operation of deformation of the external conductor;
• FIG. 6 represents a perspective view of the holding pieces (ferrule and socket, shown separate) of a connector according to a second embodiment of the invention (connector for cables with smooth outer conductor);
• Figures 7 to 9 show sectional views of a connector according to the invention using the holding parts of Figure 6, arranged on a coaxial cable, shown in successive phases of the conductor capture and deformation operation outside.

Figures 1 and 2 show the ferrule (1) which holds the cable and the sleeve or guide piece (2) of the first embodiment of the invention, thus than all of these two parts with ring (3). For this example, the cable is a coaxial cable with conductor spiral exterior (10). The ferrule (1) is provided with the inside of a special thread (12) which allows you to screw inside the outer conductor of the cable and has a geometry which prevents its rotation around its axis while keeping the possibility of axial displacement which can in this case be an area with two dishes which matches the two socket plates (2). In addition, the ferrule is provided on the outside with a groove in which is housed the ring (3). The sleeve (2) is in turn provided with a groove on the outside, to accommodate the ring (3) when it is fitted into the ferrule (1). The socket (2) has the groove wider than the thickness of the ring (3) which holds at the ferrule (1), which allows movement of the ferrule (1) with a limited stroke, always the even.

Figure 3 shows a coaxial connector subject of the invention. The body (4) contains the dielectric (5) which maintains the central contact (6). Still in the body (4) and integral with it is fixed the sleeve (2) forming a guide piece, which is assembled with the ferrule (1) using the ring (3).

On the side of the rear part (8) of the connector, the ferrule (4) is provided with a tubular zone which can engage in the rear (8) and which houses the seal (7) which seals on the outer conductor and the sheath of the cable. The seal between the body (4) and the rear (8) is provided by the seal (9).

Figures 4 and 5 illustrate the operation of the connector. In Figure 4, we can notice that by screwing the connector on the cable, the central contact (6) of the connector receives the central conductor (14) of the cable. The ferrule (1) accepts the outer conductor (10) of the cable by moving away from the guide piece (2) at a maximum distance (L) limited by the ring (3). The seal (7) is located around the outer conductor (10) and the cable sheath (11).
In Figure 5, we see that by screwing the rear (8) it advances the ferrule (1) and compresses the seal (7) which is molded around the outer conductor and the cable sheath. In a second step, the rear (8) comes to touch and push the ferrule (1) which advances towards the socket (2) by deforming the outer conductor (10) of the cable to ensure good contact. Depending on the shape of the front plane (13) of the socket (2) on the side of the ferrule (1) and the shape of the latter, the outer conductor of the cable can be compressed or flared. In the embodiment shown, the outer conductor (10) is deformed against the front plane (13) of the socket (2), while the dielectric (16) which is located between the outer conductor (10) and the central conductor (14) enters the socket (2); the conductor (10) undergoes a final deformation (17) illustrated in FIG. 5. As the deformation of the external conductor of the cable, determined by the length (L), is strictly reproducible, a reproducible impedance fault is created which can be electrically compensated by the correct sizing of the connector.

Figure 6 shows the ferrule (1) and the socket (2) of the second embodiment of the invention. The ferrule (1) has a longitudinal slot and is provided inside with a thread or profile which allows the external conductor of the cable to be hooked. In addition, the ferrule (1) is provided on the side of the sleeve (2) with a cone (a) on the outside and a cone (b) on the inside.
The socket (2) is provided with a cone (c) at the inlet and a cone (d) at the bottom.

FIG. 7 represents a coaxial connector for cables with a smooth outer conductor, subject of the invention. Inside the body (4) is the central contact (6) and behind it the guide (26) for the central conductor (14) of the cable. Still in the body (4) and integral with it is fixed the sleeve or guide piece (2). The ferrule (1) is wedged between the sleeve (2) and the ring (20).
Behind the ring (20), there is the O-ring (27) and the rear (8) which is provided with the O-ring (9) in the groove of the thread.

The cable is inserted into the connector. The central conductor (14) of the completely cleared cable is inserted in the central contact (6). Dielectric (16) and the outer conductor (10) of the cable are cut in the same plane and will come up against the cone (d) which is in the bottom of the socket (2). The outside conductor (10) of the cable is released from the sheath (11) as far as behind the smallest bore in the ring (20).

Figures 8 and 9 illustrate how it works of the connector. In Figure 8, we can notice that screwing the rear (8) the seal (27) engages in the bore of the ring (20). The ring (20), pushed from behind (8) advances the ferrule (1) which is clamped in the cone inlet (c) of the socket (2) and flu on the conductor outside (10) of the cable.

In Figure 8, we see that by continuing to screw the rear (8), the ferrule (1) advances with the cable in the socket (2). The outer conductor (10) of the cable is flared by the cone (d) which is at the bottom of the socket (2) and is clamped between this cone (d) and the cone inside (b) of the ferrule (1) ensuring contact electrical and cable retention. Dielectric (16) of the cable advances below the cone (d) which is in the bottom of the socket (2). The O-ring (27) is compressed to seal between the rear (8) and the cable sheath (11). The O-ring (9) ensures the seal between the body (4) and the rear (8). As the deformation of the outer conductor (10) of the cable, determined by the length (L), is rigorously reproducible, a reproducible impedance fault is created which can be electrically compensated by the good connector sizing. In addition, we eliminate the recess of the dielectric which for certain cables is necessary to keep the characteristic impedance following the introduction of a tubular mandrel below the outer conductor of the cable to tighten it.

It should be noted that the specific details described above in relation to the two embodiments individuals of the invention illustrated in the figures do not are that as preferred examples of the general purpose of the invention and should in no way be interpreted as limiting the scope of this invention as stated above above and in the claims which follow.

Claims (11)

1. Connector for coaxial cable with an internal conductor (14) and an external conductor (10) separated by an insulating material (16), said connector has a front part (4) for fixing the cable to the connector, a rear part (8) intended to be connected to the front part (4) and movable with respect to the front part (4), and a device for keeping in position the cable with respect to the connector in a way to allow a reproducible deformation of the external conductor (10) when making the connecting operation, characterised by a device for maintaining the cable in position, composed of at least two co-operating parts for maintaining and guiding the cable in a reproducible way, comprising a ferrule (1) shifting into the rear part (8) for maintaining the cable, and a sleeve (2) fixed in the front part (4) and operating together with said ferrule (1) in order to allow an axial shift of the ferrule and the cable on a certain distance (L) in respect to the sleeve when making the connection.
2. Connector according to claim 1, characterised by a sleeve (2) with a flat front (13), (d) determining the deformation of the external conductor .
3. Connector according to claim 1 or 2, characterised by a gasket-ring (7), (27) located between the rear part (8) and the parts co-operating for maintaining and guiding the cable.
4. Connector according to any claim 1 to 3, for use with coaxial cables with spiral external conductor, characterised by a ferrule (1) having a special thread (12) on which can be screwed the spiral connector, and by the fact that the ferrule and the sleeve have a geometry to prevent the ferrule and the sleeve from rotating in respect to each other and in respect to the cable.
5. Connector according to claim 4, characterised by the ferrule and the sleeve (2) each having flat areas matching each other, preventing a rotation of the ferrule and the sleeve in respect to each other and having slots for receiving a ring (3) in order to allow the shift of the ferrule in respect to the sleeve on a certain distance.
6. Connector according to any claim 1 to 3, for use with coaxial cables with flat external conductor, characterised by a ferrule (1) having a longitudinal slot allowing the compressing of the diameter of the ferrule and having a thread or internal profile allowing the fastening of the external flat conductor when fastening the ferrule.
7. Connector according to claim 6, characterised by a ferrule (1) having, at the sleeve side, an external cone (a) and an internal cone (b), and by a sleeve having a cone at the top (c) and a cone at the bottom (d), the cone (a) of the ferrule is intended to function together with the cone (c) of the sleeve in order to realise the fastening of the splitted ferrule and the cone (d) in the bottom of the sleeve is intended to realise the deformation of the external conductor in cooperation with the cone (b) of the ferrule.
8. Connector according to claim 6 or 7, characterised by the fact that the parts working together to maintain and to guide the cable in a reproducible way , have in addition a ring (20) intended to move forward the ferrule when mounting the rear part (8) of the connector, allowing to pinch the ferrule between the sleeve and the ring.
9. Connecting process for coaxial cables with an internal conductor (14) and an external conductor (10) separated by an insulating material (16), by connecting a front part (4) intended to fix the cable and a rear part (8) while a device maintains the cable in a position to realise a reproducible deformation of the external conductor (10), the mentioned process involves the use of a ferrule (1) intended to maintain the cable, and a sleeve (2), working together to allow an axial shift on a certain distance (L) of the ferrule and of the cable in respect to the sleeve.
10. Process according to claim 9, characterised by the fact that the deformation of the external conductor is realised and fixed by a frontal surface (13) , (d) of the mentioned sleeve (2).
11. Process according to claim 9 or 10, characterised by the fact that the mentioned process involves the use of a connector according to any of the claims 1 to 8, or the use of ferrules (1) and/or sleeves (2) intended for such connectors.

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