WO2020104587A1

WO2020104587A1 - Repairable hermetically sealed connector for coupling optical fibres

Info

Publication number: WO2020104587A1
Application number: PCT/EP2019/082079
Authority: WO
Inventors: Yannick Pelletier
Original assignee: Safran Aerosystems
Priority date: 2018-11-21
Filing date: 2019-11-21
Publication date: 2020-05-28
Also published as: FR3088734B1; FR3088734A1

Abstract

This connector for the sealed coupling of optical fibres (20), able to couple fibres in a sealed manner, comprises a body of which the internal part comprises a cylindrical insert (27) equipped internally with longitudinal ducts, an optical-connection device comprising, for each optical fibre, a cylindrical ferrule (22) which is pierced for the passage of the core of the fibre, a ferrule-holder (28) intended to be connected to the end of the fibre, to be inserted into a longitudinal duct of the body and to provide the mechanical connection between the ferrule and the insert (27), and an assembly of at least one O-ring seal (31) provided between the ferrule-holder (28) and the insert, characterized in that the optical-connection device comprises, for each optical fibre, assembly means (34) for assembling the ferrule-holder on the body, the assembly means acting on each ferrule-holder separately.

Description

OF SCRIPTION

TITLE: HERMETIC ORDINATION CONNECTOR

REPAIRABLE FOR OPTICAL FIBERS

The present invention relates to a connector for optical fibers intended to ensure the functional connection of two respective ends of two optical fibers, and more particularly of two bundles of a multiplicity of optical fibers.

The invention relates more particularly to a waterproof / hermetic connection connector for optical fibers.

An optical fiber ensures the transmission of a light signal, carrying information, from one point to another.

When the distance between the emission and the reception of the light signal exceeds a given length, or even when the fibers pass from one medium to another which are separated by a partition, for example from a liquid to air, it is necessary to provide devices which ensure the functional continuity of the two sections of the fibers to be connected, these devices being called connectors.

Known connectors for optical fiber bundles include:

a generally cylindrical and hollow body, advantageously provided with a median disc and two threaded end parts;

- an insert formed of a cylindrical block, provided with longitudinal through holes; and

- At least one device intended to ensure the optical connection of one end of fiber with another end of fiber, this device comprising a cylindrical ferrule, generally made of silica, this ferrule being pierced for the passage of the fiber, and a holder ferrule to ensure the mechanical connection between the ferrule and the insert. It is understood that the connectors must not only ensure the functional connection between the fibers, but also provide a sealed or hermetic connection.

Airtightness is measured in terms of leakage rate, depending on the standards, applications and environments located on either side of the connector.

Sealing is measured as a "protection index" (known by the acronym IP).

The required tightness is generally between 1 x 10 ⁵ and 1 x 10 ⁹ atm.cm ³ / s.

The hermeticity of such a connector must be carried out in three zones or places, namely between:

- the partition and the connector, in a known manner by an O-ring provided at a median disc of the body of the connector;

- the optical fiber and the end of the ferrule, in known manner using an epoxy type adhesive or by messaging; and

- the ferrule and the insert.

Conventional connectors ensure sealing and airtightness at the level of the partition and of the connector, and at the level of the optical fiber and of the end of the ferrule, in a satisfactory manner by current standards.

To ensure sealing at the level of the ferrule and the insert, there are provided, in known manner, adhesive-type sealing means.

However, the known connectors, if they seal properly and satisfactorily, are however not removable and do not allow access to the ferrule or the ferrule holder, for example to perform maintenance or repair.

In the event of a malfunction, for example of a ferrule, a fiber or a ferrule holder, it is therefore necessary to replace the entire optical harness, with consequences for maintenance costs.

Reference may be made to document FR-A-3 050 287 which describes a waterproof and removable connector for optical fibers, ensuring the tightness or hermeticity of the connector and of the fibers relative to the respective media located on each side of the connector, while in allowing the latter to be dismantled, in particular the ferrule (s), for replacement or maintenance.

The connector body and the insert are made in one piece, two O-rings being provided between the ferrule and the conduit passing through the insert in order to guarantee airtightness.

The ferrule holders are held on the insert by a generally circular plate comprising a central hole intended for the passage of a screw for its fixing on the insert, the plate abutting against a flange provided on the ferrule holders , which are themselves in abutment against the insert of the connector body.

The connector achieves an adequate seal, meeting the standards, by positioning two O-rings on each ferrule, between them and the insert.

Disassembly of the connector is easy since it suffices to unscrew the screw to release the retaining plate, in order to have access to each ferrule holder.

However, during the disassembly of the connector, and more particularly during the unscrewing of the fixing screw of the retaining plate, a relaxation of the O-rings of the optical contacts is likely to occur, moreover after the removal of the retaining plate, which can potentially cause a lack of airtightness.

The object of the invention is therefore to overcome this drawback and to provide a connector for optical fibers capable of ensuring functional continuity between the fibers and the hermeticity of the connector and of the fibers with respect to the respective media located on each side of the connector. , even when the ferrule holder of one of the fibers of an optical fiber bundle must be removed.

The invention therefore relates to a waterproof connection connector for optical fibers, the connector being able to ensure the connection of the fibers in a sealed manner to external environments and comprising:

- a body, the internal part of which comprises a cylindrical insert and fitted internally with longitudinal conduits; - an optical connection device comprising, for each optical fiber, a cylindrical ferrule pierced for the passage of the fiber core, a ferrule holder intended to be connected to the end of the fiber, to be inserted in a longitudinal duct of the body and to ensure the mechanical connection between the ferrule and the insert; and

- a set of at least one O-ring provided between the ferrule and the insert.

The optical connection device comprises, for each optical fiber, means for assembling the ferrule holder on the body, the assembly means acting separately on each ferrule holder.

Thus, each ferrule can be independently dismantled from the other ferrules of the connector, so that the hermeticity is guaranteed with regard to the ferrules which are not dismantled.

According to another characteristic, the assembly means comprise a nut and a complementary thread provided on the ferrule holder, the ferrule holder further comprising a flange abutting against the insert when the nut is screwed.

A seal is advantageously interposed between the collar and the insert.

In another embodiment, the assembly means are snap-on assembly means.

In this case, the assembly means comprise retractable latching tabs provided on the ferrule holder and coming to bear on the edge of a longitudinal duct in which the ferrule holder is inserted.

According to yet another characteristic, the connector comprises two successive O-rings arranged at a distance from one another along the axis of the ferrule holder.

Advantageously, one of the joints is made of material corresponding to a first medium situated on one side of the connector, the other joint being made of a material corresponding to a second medium situated on the other side of the connector. Other objects, characteristics and advantages of the invention will appear on reading the following description, given solely by way of nonlimiting example and made with reference to the appended drawings in which:

[Fig.l]

is a partial sectional view along a diametrical plane of a connector according to the state of the art, associated with optical fibers;

[Fig.2]

is a partial sectional view along a diametrical plane of a connector according to the invention;

[Fig.3]

is a detailed view of the connector of Figure 2;

[Fig.4]

is a sectional view of a ferrule holder assembly, ferrule, and assembly means of the ferrule holder according to the invention;

[Fig.5]

is a perspective view of the assembly of Figure 4;

[Fig.6]

illustrates another embodiment of a connector according to the invention; and

[Fig.7]

illustrates yet another exemplary embodiment of a connector according to the invention.

Reference will first be made to FIG. 1, which illustrates an exemplary embodiment of a sealed connection connector for optical fibers according to the state of the art.

This connector, designated by the general reference numeral 1, is associated with a bundle 2 of optical fibers mounted at the rear of the connector while the front face of the connector 1 has a wall from which protrude ferrules 3 constituting male elements intended to ensure, with a set of ferrules disposed on another associated connector (not shown), the functional optical connection of the respective ends of the fibers. The connector 1 comprises a body 4, of generally cylindrical shape and including a central ring 5, a median disc 6 of larger diameter than the central ring, a threaded front sleeve 7 and a rear cylindrical sleeve with teeth 8 intended for indexing of the connector.

The body 4 internally comprises a cylindrical insert 9 with an outside diameter corresponding to the inside diameter of the central ring 5.

The insert 9 is traversed by longitudinal holes or conduits, parallel to the longitudinal axis of the connector, which are capable of receiving and being traversed by cylindrical ferrule holders 10.

Each ferrule is, at the rear, associated and linked to an optical fiber and, on the front side, associated with a ferrule which protrudes from the front face of the insert 9.

At the rear, each ferrule has a collar 1 1 which abuts against the rear face, on the side of the optical fibers, of the insert 9.

Furthermore, each ferrule has two O-rings 12 and 13 spaced longitudinally from one another which are respectively made of materials corresponding to environments located on either side of the connector.

The ferrule holders are also held on the insert by a plate 14 of generally star-shaped circular shape, comprising a central hole intended for the passage of a screw 15 intended to be screwed onto the insert.

The ferrule holder holding and fixing plate includes peripheral notches each intended to receive the ferrule holder portion located just behind the flange.

The disassembly of this connector is easy, since it suffices to unscrew the screw 15 to release the retaining plate, in order to have access to each ferrule holder.

However, as indicated above, the replacement of one of the optical contacts can cause relaxation of the O-rings 12 and 13, which potentially can cause a hermeticity defect. There is shown in Figure 2 an embodiment of a connector according to the invention, designated by the general reference 17, to overcome this drawback.

As can be seen in this figure, the connector 17 also includes a body 18 of generally cylindrical shape comprising a rear face 19 by which the body 18 is linked to a bundle 20 of optical fibers and a front face 21 from which the ferrules protrude 22 intended to cooperate with corresponding ferrules (not shown) to ensure the functional optical connection of the respective ends of the fibers to be connected. Each ferrule has a cylindrical shape and includes an axial passage for the insertion of a stripped end of the fiber core which is also embedded in an external conduit.

The connector 17 is intended to be mounted on a partition, for example between two media, such as liquid / air, to ensure the sealed connection of the optical fibers.

The body 18 comprises, as in the connector of FIG. 1, a central ring 23, a median disc 24 intended to be tightened against the separating partition, of larger diameter than the central ring 23, a cylindrical front sleeve 25 threaded intended to the coupling of the reverse connector and a rear cylindrical sleeve 26 threaded capable of receiving a rear connector. The holes 38-are intended for screwing the connector against the separating partition.

Internally, the body has an insert 27 which is traversed by holes parallel to the general axis of the connector which are capable of receiving and being traversed by ferrule holders 28.

In the illustrated embodiment, the insert 27 is integrally formed with the body 18 of the connector, the insert 27 constituting a part of the body of the connector.

Each ferrule holder is associated and linked at the rear with an optical fiber and connects the end of this optical fiber to a ferrule 22.

Referring to Figure 3, each ferrule has two grooves 29 and 30 spaced longitudinally in each of which is placed an O-ring, such as 3 1. The joints are spaced apart from each other longitudinally. One of the seals is made of a material corresponding to the first medium located on one side of the connector, while the other seal is made of a material corresponding to the second medium located on the other side of the connector.

Thus, there is no leakage between the insert and the ferrule holder, and it is not necessary to provide a sealing by glue or welding, between the various parts of the connector, which allows access to the ferrule holder and make them removable.

Thus, each joint is made of a material capable of optimally ensuring airtightness with regard to the medium with which it is in contact.

In addition, each ferrule has a flange 32, of larger diameter, which abuts against the rear face, on the side of the optical fibers, of the insert 27.

Referring also to FIGS. 4 and 5, on the other side, that is to say on the front side of the insert, each ferrule holder has a thread 33 which cooperates with a nut 34 corresponding to so that each ferrule can be immobilized in a conduit of the insert by being tightened by the flange and the nut 34.

Thus, each ferrule can be removed without changing the preload of the joints of the other ferrules and, therefore, without altering the hermeticity of the other optical contacts.

For example, the connector body is made of stainless steel, aluminum, titanium, a material designated by the trade name Arcap® or a composite material. However, preferably stainless steel will be used.

The ferrules are for example made of ceramic, the ferrules being for example made of stainless steel or Arcap®.

As for the O-rings, these are of course made of a material corresponding to the medium with which they are in contact.

We could, for example, use a fluorosilicone or fluorocarbon seal.

Inside the ferrule holder, hermeticity is obtained by embedding the end of the ferrule holder in glue. The heart of the fiber is also immobilized inside the ferrule by gluing. The hermeticity in the heart of the fiber with respect to the longitudinal duct of the ferrule holder is ensured by a glass preform after fusion.

Finally, it should be noted that the invention is not limited to the embodiments described. Indeed, it is also possible, as visible in FIG. 6, to interpose a flat seal 35 between the collar of the ferrule holder and the rear end of the insert in addition to the seals 3 1 or in replacement of these seals .

Furthermore, in the embodiment described, the assembly of the ferrule holders, which is carried out separately for each ferrule holder, is carried out by means of a nut.

It is also possible, as a variant, as shown in FIG. 7, to use assembly means by clipping, by providing, at the front part of each ferrule, retractable latching tabs 37, these tabs coming to bear on the front edge of the longitudinal duct into which the ferrule is inserted. Of course, this embodiment can also be combined with the embodiment of FIG. 6.

Claims

1. Waterproof optical fiber connection connector (20), the connector being capable of sealing the fibers, and comprising a body the internal part of which comprises a cylindrical insert (27) fitted internally with longitudinal conduits, a connection device optic comprising, for each optical fiber, a cylindrical ferrule (22) pierced for the passage of the fiber core, a ferrule holder (28) intended to be connected to the end of the fiber, to be inserted in a conduit longitudinal of the body and in ensuring the mechanical connection between the ferrule and the insert (27), and a set of at least one O-ring (3 1; 35) provided between the ferrule holder (28) and the insert, characterized in that the optical connection device comprises, for each optical fiber, means (34; 37) for assembling the ferrule holder on the body, the assembly means acting separately on each ferrule holder.

2. Connector according to claim 1, in which the assembly means comprise a nut (34) and a complementary thread provided on the ferrule holder, the ferrule holder further comprising a flange abutting the insert (27) when tightening the nut.

3. Connector according to claim 2, comprising a seal interposed between the collar and the insert (27).

4. Connector according to claim 1, in which the assembly means are snap-on assembly means (35).

5. The connector of claim 4, wherein the assembly means comprise retractable latching tabs (35) provided on the ferrule holder and coming to bear on the edge of the longitudinal duct in which the holder is inserted ferule.

6. A connector according to any one of claims 1 to 5, comprising two successive O-rings (3 1) arranged at a distance from one another along the axis of the ferrule holder.

7. The connector of claim 6, wherein one of the joints is made of material corresponding to a first medium located on one side of the connector, the other seal being made of a material corresponding to a second medium located on the other side of the connector.