EP3878061B1 - Rear connection with electromagnetic protection - Google Patents

Description

TECHNICAL AREA

The invention relates generally to a back connector. More particularly, the invention relates to a back connector capable of connecting an overshielded harness comprising shielded cables to a connector in a reliable manner and in such a way as to minimize electromagnetic disturbances. The invention also relates to a harness with terminated shielding as well as a connection comprising this rear connector.

PRIOR ART

In aircraft, electrical connections are essentially made using electrical harnesses. During the flight of an aircraft, several constraints apply directly or indirectly to the electrical harnesses, in particular in the engine areas. These stresses can be of a mechanical, electrical or environmental nature.

Mechanical stresses (eg vibrations) can in particular damage the ends of the harness and/or lead to wear, cut or deterioration of the connection which can create an undesirable contact resistance.

In addition, the electrical installation of a system must comply with electromagnetic compatibility (EMC) constraints, i.e. be able to operate in an environment without disturbing the systems that are already there, and without being disturbed by these systems or by external disturbances such as lightning, a strong electromagnetic field (radar), etc.

To this end, the electrical connections generally have shielding which makes it possible to attenuate the disturbances received or emitted. Shields can be on an individual cable (shield) and/or on the entire strand/harness (overshield). To ensure the EMC protection of a system, the electromagnetic shielding must cover all the areas of the harness between the boxes containing the equipment. Use of these backshells, assembled to the electrical connectors, must be able to meet the electrical and mechanical requirements.

These fittings must perform both mechanical functions, namely be designed to withstand vibrations in the most severe areas, meet integration requirements such as the orientation of harnesses, but also perform electrical functions, such as cable shielding recovery, electromagnetic protection of the harness, efficient EMC, with the lowest possible transfer impedance.

Requirement US-A-5052947 discloses a rear connector (shield termination) for an overshielded harness having shielded cables. The rear fitting includes a sleeve and a fixing ring. The overshielding of the harness is connected to a pad at the back of the sleeve and is secured to the latter by a clamping collar. The cables pass inside the sleeve. The ends of the cables have their conductive parts exposed. However, the cable shield terminations pass through the through holes to the outside, and then join a land at the front of the sleeve to which they are secured by means of a cable tie. The rear coupling also comprises a fixing ring mounted so as to be able to rotate at the front end of the sleeve. The assembly forms a terminated shield harness for connection to a connector.

However, the local extra thickness of the shield terminations leaves “openings” between the back fitting wall and the clamp when tightening the latter. When this terminated shielded harness is mounted on a connector, electromagnetic disturbances can pass through these openings and then into the through holes of the sleeve and generate interference on the cables. The protective sheath (boot) provided does not make it possible to shield its disturbances. Consequently, the protection against EM disturbances is not satisfactory, this rear connection is not optimal in terms of EMC and the transfer impedance is relatively high.

Moreover, on certain rear fittings, to facilitate the resumption of the terminations of the shields on the sleeve, slots are provided, extending from the crown of teeth to the holes. As a result, the corona is not whole, therefore implying non-uniform electrical continuity and a resistance of high contact. Sometimes, the sleeve is made in several parts, which also has the consequence that the connection of the overshielding and of the shieldings (to the connector) does not have the desired electrical continuity uniformity.

There is therefore a need for a rear connector capable of connecting an overshielded harness, comprising shielded cables, to a connector in a reliable manner with good electrical continuity and therefore low electrical resistance, so as to minimize electromagnetic interference and guarantee low transfer impedance.

DISCLOSURE OF THE INVENTION

The object of the present invention is therefore to remedy the aforementioned needs and drawbacks by proposing a rear connector (for shielding termination) for connecting an overshielded harness comprising shielded cables to a connector, the rear connector comprising a sleeve and a ring fixing, the sleeve having a wall of substantially tubular shape defining an internal passage adapted to receive shielded cables, the wall of the sleeve comprising, from its front end towards its rear end, an engagement zone adapted to engage on a connector, circumferentially distributed through holes adapted to receive the terminations of the cable shields from the internal passage, a first external area adapted to receive the terminations of the shields, an external shoulder, and a second external area adapted to receive the overshielding of the harness , the attachment ring having a substantially tubular shaped wall defining a n annular passage adapted to receive the sleeve, the wall of the attachment ring comprising, from its front end towards its rear end, an attachment zone adapted for connection to a connector, a first internal area, and an internal shoulder, the rear coupling being arranged so that the fixing ring can slide above the sleeve in a direction going from the rear end towards the front end of the sleeve, up to an abutment position where the internal shoulder of the fixing ring comes into abutment with the external shoulder of the sleeve, the internal surface of the fixing ring covering the first external area of the sleeve in the abutment position, the fixing ring thus being arranged to cover the terminations of the shields, and the engagement zone of the sleeve comprising an entire crown of teeth adapted to engage on the connector .

Preferably, the wall of the sleeve comprises at the front end a flared part on which the engagement zone and the through-holes are formed.

Preferably, the through holes are located immediately behind the engagement zone, on a part of the wall up to 20% of the length of the sleeve from its front end.

Preferably again, the first outer range of the sleeve has a larger outer diameter than that of the second outer range.

Advantageously, the wall of the sleeve comprises a flared intermediate section between the first external area and the second external area.

Preferably, the outer shoulder of the sleeve and the inner shoulder of the attachment ring are ring-shaped.

Preferably again, the sleeve is in one piece.

Preferably, the rear connector comprises at least one clamp adapted to secure the terminations of the shields by tightening them around the sleeve.

The present invention also proposes a harness with terminated shielding comprising a rear connection as described above as well as an overshielded harness comprising shielded cables, the shielded cables being received by the internal passage of the sleeve, the terminations of the shieldings of the cables passing towards the outside of the sleeve by through holes and received on the first outer region of the sleeve while the overshielding is received on the second outer region of the sleeve, and the fixing ring being mounted so as to slide above the sleeve.

The present invention also proposes a connection between a harness with a terminated shield as described above and a connector, the cables being electrically connected to the connector, the engagement zone of the sleeve being engaged on an engagement zone of the connector, and the fixing ring being connected to a connector attachment zone, the sleeve and the attachment ring of the rear connector being in an abutting position.

BRIEF DESCRIPTION OF DRAWINGS

• la figure 1 présente une vue en coupe (partielle) d'un harnais à blindage terminé monté sur un raccord arrière selon un premier mode de réalisation de l'invention ;
• la figure 2 présente une vue éclatée en perspective du raccord arrière, et
• la figure 3 présente une vue en coupe transversale du raccord arrière.

There is described below, by way of non-limiting examples, preferred embodiments of the invention, with reference to the appended drawings, in which:

• the figure 1 shows a (partial) sectional view of a completed shielded harness mounted on a rear connector according to a first embodiment of the invention;
• the figure 2 shows an exploded perspective view of the rear fitting, and
• the figure 3 shows a cross-sectional view of the rear fitting.

In all these figures, identical references can designate identical or similar elements. In addition, the various parts shown in the figures are not necessarily shown on a uniform scale, in order to make the figures more readable.

DETAILED DISCUSSION OF PARTICULAR EMBODIMENTS

The figure 1 illustrates a first embodiment of the rear connector 50. It makes it possible to terminate the shielding of a harness 16, forming together with the latter "a terminated shielding harness", 70, adapted to be connected to an electrical connector 80 to achieve a connection 100. The connector 80 is of a known type, often used in an aircraft.

The figure 2 and 3 illustrate only the main elements of the rear connector 50, namely a sleeve 20 and a fixing ring 40, in perspective and in cross-section respectively, to facilitate the understanding of the invention.

The rear connector 50 is connected to an overshielded harness 16 comprising shielded cables 12. It comprises a sleeve 20 and a fixing ring 40, illustrated with the fixing ring 40 slipped over the sleeve 20.

The sleeve 20 comprises a wall 25 of substantially tubular shape (of circular cross section) extending along a longitudinal axis, and defining an internal passage 27. The wall 25 of the sleeve comprises, from its front end 21 (left side in the figures) towards its rear end 29, an engagement zone 22, circumferentially distributed through holes 24, a first outer land 26, an outer shoulder 28, an intermediate section 32, a first flange 34, a second land external 36, and a second flange 38. The sleeve 20 is in one piece, and made of an electrically conductive material, typically metal. The sleeve 20 is linked to a harness 16.

The harness 16 is of a known type and comprises individual shielded cables 12 which are grouped together in a strand, the latter being surrounded by an additional shielding 17 to protect it from EM disturbances. The cables 12 and the harness 16 can also include layers of insulation in a manner known per se. To connect a harness with a rear connector 50, then an 80 connector, this harness must be prepared. In a known manner, the harness 16 is stripped and unshielded towards one end, which consists in locally removing the outer insulation and the over-shielding 17 of the harness 16. Then, the shielded cables 12 of the harness 16 are stripped and unshielded at a location still closer towards the end in order to then expose the conductive part 13 of the cables 12, while keeping the terminations of the shields 14 of the unshielded cables (/pigtails) attached to the harness 16.

As you can see on the figure 1 , shielded cables 12 of the harness 16 are received in the internal passage 27 of the sleeve 20. The conductive parts 13 of the cables 12 visible towards the end of the harness 16 are intended to be plugged into the contacts of the connector 80 to electrically connect the cables 12 to connector 80. However, the terminations of the shields 14 are inserted through the through holes 24 to the exterior of the sleeve, and are then returned to the rear of the sleeve, and laid on the first outer pad 26 in a generally aligned manner. substantially with the longitudinal axis.

The first range 26 of the sleeve 20 is intended for the resumption of terminations of the shields 14. It has a generally cylindrical outer surface extending parallel to the longitudinal axis. The terminations of the shields 14 are secured there with a fastening element 33, for example a clamp 33. It is possible that axial grooves are provided to better receive the terminations of the shields 14. Towards the rear of the first range 26 is the external shoulder 28, which is in the form of a ring, projecting radially from the wall 25 of the sleeve 20. This external shoulder 28 is intended to come into abutment with the fixing ring 40 to prevent it from exceeding it. , as discussed later in the description.

The second outer area 36 of the sleeve 20 is intended to take up the additional shielding 17 of the harness. Like the first pad, it has a generally cylindrical outer surface on which the overshield can be received. This second outer area 36 also extends parallel to the longitudinal axis, and allows the securing of the additional shielding 17 with a fastening element, for example a clamp. The additional shielding 17 of the harness 16 is not received in the internal passage 27 of the sleeve 20, but directly on the second external area 36.

The first rim 34, located in front of the second outer range 36, is mainly designed as an abutment for the additional shielding 17, so that it does not exceed it. A second flange 38 is provided behind the second range 36, and more precisely at the rear end 29 of the sleeve 20. When the overshielding 17 is fixed around the second range 36 with a fastening element, these two flanges 34 , 38 prevent it from easily dissociating.

The first outer pad 26 has an outer diameter larger than that of the second outer pad 36. In this embodiment, the diameter of the first pad 26 is approximately 1.5 times that of the second pad 36. In order to integrate these outer pads, the wall 25 of the sleeve comprises a flared intermediate section 32 between the first land 26 and the second land 36, increasing in diameter towards the front end 21 of the sleeve 20.

The wall 25 of the sleeve 20 comprises another flared part 23 at its front end 21, of increasing diameter from the first outer region 26 towards the front end 21 of the sleeve 20. The engagement zone 22 as well as the through holes 24 are located on this flared part 23.

The through holes 24 being located on the flared portion 23 are therefore angled, facing forward and are also of a larger diameter than the first land 26. As a result, not only is it easier to handle the terminations of the shields 14 insertion into the through holes 24, moreover, they lie more naturally on the first range 26 in alignment with the longitudinal axis. This therefore allows a more uniform distribution of the terminations of the shields 14 on the sleeve 20.

Furthermore, it can be seen that the through holes 24 are located just behind the engagement zone 22, that is to say just behind the crown of teeth 22. This is in a region starting at the front end 21 of the sleeve 20 up to 20%, even just 10% preferably, of the length of the sleeve 20. The first advantage of being located on this region is that the shields can be left on each cable 12 closer to the connector 80. In other words , only the parts of the cables 12 to be plugged into the connector 80 are unshielded, which limits the crosstalk between the conductive parts 13 of the harness 16 as much as possible, ensuring good EMC.

The second advantage is that the terminations of the shields 14 surround the sleeve 20 up to its connection with the connector 80, thus improving the EM protection of the cables 12 within the latter. Finally, being closer to the front end 21 of the sleeve 20 the terminations of the shields 14 are also easier to see and handle during insertion into the through holes 24, compared to the case where the holes are deeper in the muff.

Since these through-holes 24 are distributed circumferentially and evenly on the wall 25 of the sleeve 20, the terminations of the shields 14 are consequently also distributed evenly around the sleeve 20. Although it is not mandatory, the through-holes 24 are advantageously located in the same plane perpendicular to the longitudinal axis. For practical reasons of inserting the terminations of the shields 14, a small part of each of these through holes 24 can be formed in the first range 26.

On the front end 21 of the sleeve 20, there is an engagement zone 22 in the form of a crown of teeth 22. The teeth allow a better engagement over a wider surface with the connector 80, which is itself provided with an engagement zone 82 in the form of a crown of teeth 82. Moreover, this engagement prevents rotation between the sleeve 20 (and therefore the harness 16) and the connector 80 once the connection has been made.

Importantly, it is noted that the ring of teeth 22 is whole, that is to say that it makes a complete circle. No splits are present, and no missing teeth. When this crown of teeth 22 is engaged on that of the connector 80, a good connection is obtained with minimum electrical resistance and uniform electrical continuity.

The fixing ring 40 comprises a wall 45 of substantially tubular shape extending along the longitudinal axis, defining an annular passage 47. The wall 45 of the fixing ring 40 comprising, from its front end 41 towards its rear end 49, an attachment zone 43, an internal area 46, and an internal shoulder 48. The attachment ring 40 is in one piece, and made of an electrically conductive material, typically metal.

Referring again to the figure 1 , the fixing ring 40 is mounted around the sleeve 20, the two being oriented in the same direction with the sleeve 20 received in the annular passage 47 of the fixing ring 40. It is arranged so that it can slide above the sleeve 20, in a direction going from the rear end 29 towards the front end 21 of the sleeve, this up to an abutment position (illustrated) where the internal shoulder 48 of the fixing ring 40 abuts with the outer shoulder 28 of the sleeve 20. The inner shoulder 48 is in the form of a ring, projecting radially from the wall 45 of the fixing ring 40. The fixing ring 40 is illustrated in front of a connector 80 for its connection to it.

It can be seen that in the abutment position, the internal area 46 of the fixing ring 40 covers the first external area 26 of the sleeve 20. Consequently, the terminations of the shields 14 are entirely covered by the fixing ring 40, this which provides protection against EM disturbances. Unlike the prior art, EMI cannot enter through openings or through holes in the sleeve. The assembly comprising the internal range 46, the internal shoulder 48 and the fixing zone 43 of the fixing ring 40 surrounds the terminations of the shields 14, and beyond the front end 21 of the sleeve 20. Indeed, the rear connector 50 is arranged in such a way that a Once connected to the connector 80, the fixing ring completely surrounds the terminations of the shields 14, the engagement zone 22 of the sleeve 20 and the engagement zone 82 of the connector 80 as well as its fixing zone 83.

It should also be noted that the fact that the securing ring 40 can slide relative to the sleeve 20 allows it to be removed when the terminations of the shields 14 are inserted into the through holes 24 and then replaced.

In order to ensure/improve the seal, O-rings 44 are advantageously used. They are provided just next to the internal shoulder 48, and in front of the internal area 46 of the fixing ring 40. If necessary, circumferential internal grooves can be provided to accommodate the O-rings 44. These O-rings 44 are arranged to be interposed between the fixing ring 40 and the sleeve 20, and between the fixing ring 40 and the connector 80. In addition, a protective sheath (boot) 54 can cover the sleeve 20 from its first edge 34, beyond its rear end 29 as far as part of the harness 16. The assembly comprising the O-rings 44 and the protective sheath 54 make it possible to seal the connection.

The rear connector 50 of the invention is more efficient than the known rear connectors, above all by making it possible above all to make a reliable connection 100 between an overshielded harness 16 comprising shielded cables and a connector 80. The terminations of the shields 14 of the cables 12 are distributed uniformly around the sleeve 20 and arrive very close to the front end 21 of the sleeve 20. What is more, they are completely covered by the fixing ring 40 when it is in the abutment position. Furthermore, the rear connector 50 is made of two main elements which are each in one piece. Additionally, sleeve 20 includes an entire crown of teeth 22.

The overshielding 17 and shielding terminations 14 on the sleeve 20 prevent the forces from being applied directly to the conductive parts 13 plugged into the connector 80. The distribution as well as the positioning of the shielding terminations 14 on the rear connector 50 provide better continuity electrical power and reduced transfer impedance. Having only two main elements, the rear connector 50 is easier to install on a harness 16, and less likely to be lost. Moreover, the connection of the overshielding 17 and the shieldings 14 (to the connector) is ensured by a single conductive part, having a much better electrical continuity than a sleeve in several parts. As a result, the rear connector 50 is more efficient in terms of EMC.

The invention has been described in relation to an overshielded harness comprising shielded cables. However, it is also suitable for other cables, for example an unshielded harness with shielded cables, or even a single shielded cable.

Of course, the invention can be used at the same time as other known means of protection against EM disturbances. Also, the rear connector of the invention can be retrofitted (or "retrofitted") to the connections already existing in the aircraft.

Alternatively, the intermediate section may be a flange perpendicular to the axis and incorporate, where appropriate, the outer shoulder of the sleeve.

Claims (10)

1. Backshell (50) for connecting an overall-shielded harness (16) comprising shielded cables (12) to a connector (80), the backshell (50) comprising a sleeve (20) and an attachment ring (40),

   the sleeve (20) having a wall (25) with a substantially tubular shape defining an internal passage (27) for receiving the shielded cables (12),

   the wall (25) of the sleeve (20) comprising, from the front end (21) to the back end (29) thereof, an engagement area (22) configured for engaging with a connector (80), through-holes (24) distributed circumferentially for receiving the terminations of the cable shielding (14) of the shielded cables (12) from the internal passage (27), a first external area (26) for receiving the terminations of the shielding (14), an external shoulder (28), and a second external area (36) for receiving the overall-shielding (17) of the harness,

   the attachment ring (40) having a wall (45) with a substantially tubular shape defining an annular passage (47) for receiving the sleeve (20), the wall (45) of the attachment ring (40) comprising, from the front end (41) to the back end (49) thereof, an attachment area (43) for connecting to a connector (80), a first internal area (46), and an internal shoulder (48),

   the backshell (50) being arranged in such a way that the attachment ring (40) can slide over the sleeve (20) in a direction going from the back end (29) to the front end (21) of the sleeve (20), to an abutment position in which the internal shoulder (48) of the attachment ring (40) abuts against the external shoulder (28) of the sleeve (20),

   characterized in that, in the abutment position, the internal area (46) of the attachment ring (40) covers the first external area (26) of the sleeve (20), the attachment ring (40) being thus arranged to cover the terminations of the shielding (14),

   and the engagement area (22) of the sleeve (20) is a full toothed ring for engaging with the connector (80).
2. Backshell (50) according to claim 1, characterized in that the wall of the sleeve (20) has, at the front end thereof, a flared portion on which are formed the engagement area (22) and the through-holes (24) are made.
3. Backshell (50) according to claim 1 or 2, characterized in that the through-holes (24) are located immediately behind the engagement area (22) on a portion of the wall up to 20% of the length of the sleeve (20) from the front end thereof.
4. Backshell (50) according to one of the preceding claims, characterized in that the first external area (26) of the sleeve (20) has an outside diameter that is greater than that of the second external area (36).
5. Backshell (50) according to claim 4, characterized in that the wall of the sleeve (20) comprises a flared intermediate section (32) between the first external area (26) and the second external area (36).
6. Backshell (50) according to one of the preceding claims, characterized in that the external shoulder (28) of the sleeve (20) and the internal shoulder (48) of the attachment ring (40) are in the shape of a ring.
7. Backshell (50) according to one of the preceding claims, characterized in that the sleeve (20) is a single part.
8. Backshell (50) according to one of the preceding claims, characterized in that the backshell (50) comprises at least one clamping ring (33) for securing the terminations of the shielding (14) by clamping them around the sleeve (20).
9. Terminated shielding harness (70) comprising a backshell (50 according to one of the preceding claims as well as an overall-shielded harness (16) including shielded cables (12), the shielded cables (12) being received into the internal passage (27) of the sleeve (20), the terminations of the cable shielding (14) going to the outside of the sleeve (20) through through-holes (24) and received on the first external area (26) of the sleeve (20), whereas the overall-shielding (16) is received on the second external area (36) of the sleeve (20), and the attachment ring (40) is movably mounted so as to slide over the sleeve (20).
10. A connection (100) between a terminated shielding harness (70) according to claim 9 and a connector (80), the cables (12) being connected electrically to the connector (80), the engagement area (22) of the sleeve (20) being engaged in an engagement area (82) of the connector (80), and the attachment ring (40) being connected to an attachment area (83) of the connector (80), the sleeve (20) and attachment ring (40) of the backshell (50) being in an abutment position.

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