Title of Invention

"A WATERTIGHT INTEL DEVICE FOR INSERTING AN OPTICAL CABLE

Abstract

This invention relates to a watertight inlet device for inserting an optical cable (1) into a chamber (8). The device comprises a metal solepiece (16) for securing a plurality of strength members (5,6,7) of the optical cable, and which plugs into and fixes to a tubular sealing body (17) equipped with an external o-ring gasket (23) and having its rear portion shaped to form a sealing stuffing box (21,22) on the outer sheath of the cable. The rear of the nut (29) of the stuffing box (20) receives a clamp (30,31) for retaining the cable. Once the device has been fitted the resulting assembly is inserted into the inlet passageway (11) until it abuts against a shoulder (63) in the passageway (11). Then only the bead of the securing solepiece (16) and a groove (16a) in the body project inside the container (8), the groove (6a) then receiving a key (32) for retaining the assembly.

Full Text

1A. The present invention relates to a cable inlet device for inserting an optical fiber cable into a chamber or into a container, e.g. into a splice box containing an optical organizer and designed to be placed outdoors or in a buried duct. Currently the Applicant sells an elongate metal securing solepiece that is in the form of a rigid metal bar whose downstream end is provided with a clamping piece for securing the optical central strength member, and whose upstream end is 2 the optical cable against said bar, the upstream notches being followed downstream by two pairs of notches for receiving two securing collars for securing the peripheral strength members. Once the optical cable has been prepared, then put in place and clamped onto the securing solepiece, the resulting assembly is threaded into the container, and the securing solepiece is fixed by means of screws to a place provided for that purpose in the container Then, the cable inlet is sealed either by using a heat-shrinkable sleeve, or by pouring in a sealing resin, or else (in other known and analogous devices) by using a conventional stuffing-box sealing device Such known cable inlet devices suffer from the drawbacks of being quite voluminous in the longitudinal direction, and of being awkward to use because it is necessary to act positively in the container to fix the securing solepiece therein by means of screws, while access to the inside of the container is often difficult In addition, the cable inlet sealing is positioned before the place where the outer sheath is secured, so that any external stresses on the cable are applied initially to the sealing device (heat-shrinkable sleeve, sealing resin, stuffing box, etc ), and only then to the sheath securing device As a result, such a cable inlet device is not very reliable because the sealing device is not always designed to be capable of withstanding external stresses for very long An object of the invention is to remedy those drawbacks To this end, the invention provides a watertight inlet device for inserting a cable containing optical fibers into a chamber or into a container via an inlet passageway provided for this purpose, said device being characterized in that it is fitted to the cable and secured to the strength members thereof before the cable is inserted into the chamber or container, the outer sheath of the cable further being secured directly on the watertight inlet device and upstream from its sealing means, the watertight inlet device then being received by being threaded into the chamber or container, and being locked therein merely by keying The invention provides, in particular, a device as defined above, characterized in that it comprises at the front a rigid securing solepiece provided with orifices or slots into which central strength members and/or side strength members of the cable are inserted, each of these orifices or slots co-operating with a clamping member typically acting by a screw being rotated to clamp the strength member(s) that it receives; 3 at the rear a nut for clamping a stuffing box, which nut is also shaped to receive a retaining member for retaining the outer sheath of the optical cable, and between the front and the rear a sealing tubular body whose front portion engages telescopically into said securing solepiece, means being provided for fixing the sealing body to the securing solepiece in the engaged position, the rear portion of the tubular body co-operating with a sealing ring to form the sealing stuffing box that is complementary to said clamping nut, the stuffing box achieving the sealing by clamping on the outer sheath of the cable, the sealing body also receiving means for providing the sealing relative to the inlet passageway in the chamber or container, and further including an abutment member which is designed to co-operate with a complementary shape of said inlet passageway to limit the insertion of the device through said inlet passageway, the abutment position then being such that the head of the device emerges inside the chamber or container, keying means then being provided for locking the device in this position Advantageously, said clamping nut has an outside shape comprising a plurality of facets, while the rear portion of said passageway orifice is of the corresponding female shape Also advantageously, said keying means are constituted by a semi-rigid retaining fork which plugs into an outer annular groove in the cable inlet device, thereby holding it captive in part, the groove therefore emerging downstream relative to said inlet passageway when the device is inserted to its abutment position The invention can be well understood, and its various advantages and characteristics appear more clearly from the following description of a non-limiting embodiment given with reference to the accompanying diagrammatic drawings, in which Figure 1 is an exploded perspective view of a cable inlet device; Figures 2 to 9, together with their complementary Figures 4A, 4B, 4C, and 9A, which is a section view on IX-IX of Figure 10, diagrammatically show the successive stages in which the cable inlet device is fitted and then put in place, Figure 10 is a longitudinal axial vertical section view of the cable inlet device as fitted and put in place, and Figure 11 is a view similar to Figure 8, and showing a variant embodiment 4. In accompanying figure 1, which is described in more detail further on below, reference 1 designates an optical cable of known type. That cable 1 is provided with a strong semi-rigid outer sheath 2 which protects a set of small flexible tubes 3, each of which contains a few optical fibers 4 themselves often embedded in a protective and sealing grease-In addition, two semi-rigid strength membes 5 and 6, e.g. made of aramid fibers, are provided inside the sheath 2, and they are referred to as peripheral strength members' because they are positioned close to the sheath 2 on either side of the middle longitudinal axis of the optical cable 1. The free end of the cable 1 is stripped, i.e. the sheath 2, the small protective tubes, and the sealing grease are removed. The strong outer sheath 2, the strength members 5,6 the small tubes 3, and the grease coating the fibers 4 are mechanical protections for the optical fibers 4 and they are made necessary because optical fibers cannot withstand any mechanical stress. Instead of using side semi-rigid strength members 6,5 to imaprt strength to the optical cable 1, it is also possible, as shown diagrammatically by way of example in Figure 1 and in Figure 10, to use an axial and central semi-rigid strength member 7, and flexible side strength members (not shown), all this being well known to the person skilled in the art- 4A. In the art, the axial and central semi-rigid strength member 7 may be referred to as a 'central strength member, and the cable as stripped as shown in Figure 1 may be said to be 'prepared'. In view of the mechanical weakness of optical fibers, it is necessary for a watergitht inlet via which an optical cable can enter a chamber or a container to be provided not only with sealing means, but also with strong means for securing the outer sheath 2 of the cable and its strength members, such as the peripheral strength members 5,6 or the central strength member 7 and its associated flexible peripheral strength members. Reference is made firstly to Figures 1, 9A and 10, which show the make-up of this optical cable inlet device. In this example, the optical cable inlet device is assumed to constitute an inlet for inserting an optical cable into a splice box 8 made up of a recessed bottom 81 and of a lid 82, the bottom and the lid closing on each other with a peripheral sealing gasket 10 being interposed in conventional manner- All these elements of the cable inlet device are described briefly above The following description of the successive stages in which the device is fitted and then put in place will enable the missing details to be given. With reference to Figure 2, once the free end 33 of the cable 1 has been cut to the right length but before it has been stripped, the following are successively threaded onto the cable the very special stuffing-box nut 24, the annular gasket 23, and, if necessary, the compensation ring 25, then the tubular sealing body 17 pre-fitted with the O-ring gasket 19 The part 17 is made of a plastics material which, while being very rigid, nevertheless remains sufficiently flexible to enable the stuffing box fingers 22 to clamp the annular gasket 23 on tightening the stuffing-box nut 24 (whose inside section is conventionally frustoconical as shown in Figure 10) onto the nut-receiving thread 21 The plastics material used for said part may, for example, be a non-filled polyamide Then, as shown in Figure 3, the "preparation" of the cable 1 can commence For the purpose of preparing it, the cable is stripped of its outer sheath 2 and of its small protective tubes 3, starting from the chosen place 34 to release the length of optical fibers 4 desired inside the box 8, and the grease is then removed from the stripped optical fibers 4 The strength members 5, 6 are also cut off so that they extend beyond the transverse stripping plane 34 only by a length substantially equal to the length L of the securing solepiece 16 The metal solepiece 16 is made in one piece (see also Figure 1) comprising a head 35 which is designed, as explained below, to secure the peripheral strength members, e g the strength members 5 and 6, and the central strength member 7 (Figure 10) if such a central strength member exists, and a tail 36 in the form of a half cylinder of semi-circular section. As described below, the tail 36 plugs snugly into the tubular orifice formed in the front half 68 of the sealing body 17 As indicated by arrow 69 in Figure 3, and as shown in Figure 4, the securing solepiece 16 is then positioned contiguous with the non-stripped end of the cable 1, i e so that the transverse stripping plane 34 and the transverse plane 37 of the rear end of the tail 36 substantially coincide to form a single common transverse plane that is vertical as shown in the drawing As shown in Figures 4 to 4C, the two peripheral strength members 5 and 6 of the cable are then secured in the head 35 of the securing solepiece 16 To make such securing possible, the head 35 is provided with two side notches 38 and 39, in which the peripheral strength members 6 and 5 are inserted sideways (see, in particular, Figures 1, 4A to 4C) 6 A respective U-shaped metal clamping piece 40, 41 is mounted in each of the notches 38, 39 to slide downwards along a vertical guide recess 42 and along a vertical guide orifice 43 By tightening the two vertical screws 44 and 45 in their respective tapped vertical orifices 46 and 47, the clamping pieces 40 and 41 are caused to descend and to press strongly against but without damaging respective ones of the two peripheral strength members 6 and 5 that have been inserted into respective ones of the notches 38 and 39. It should be noted that the head 35 is also shaped to secure the optional central strength member 7 (Figure 10). For this purpose, the head 35 is provided with an axial orifice 49 extending along the middle longitudinal axis 48 of the device and of section that is oblong in the vertical direction, which orifice receives and holds another securing metal clamping piece 50 (Figures 1 and 10) The central strength member 7 is secured, as above, by clamping the central strength member between the clamping piece 50 and the wall of the oblong hole 49 into which the central strength member 7 has been inserted, the clamping also being actuated by means of a vertical clamping screw 51 The presence of the clamping pieces 40, 41, 50 is not essential, and it is possible, as is the case for copper wires, merely to lock the strength members 5, 6, and 7 by means of corresponding screws 44, 45, and 51 However, such clamping pieces are very useful in this example because they make it possible to secure the strength members 5, 6, 7 strongly without damaging them, which would be detrimental to the reliability of the securing Once the strength members 6, 5 have been secured in this way, the tubular sealing body 17 is grasped, and, as shown in Figure 5, it is plugged fully onto the tail 36 of the securing solepiece 16 In order to optimize and to guide this operation, the front periphery of the sealing body 17 is provided (Figure 1) with a longitudinal projection 52 which plugs into a longitudinal and corresponding female notch 53 in the head 35 of the metal securing solepiece 16 In addition, two side ribs 65, 66 (Figure 9A) on the cylindrical inside wall of the body 17 participate in guiding the body 17 as it slides over the tail 36 of the metal solepiece 16 The solepiece 16 is then fixed to the body 17 by means of the screw 18 which passes through a vertical orifice 54 in the projection 52 and screws into vertical tapping 55 in the head 35 (Figures 1 and 10), the tapping 55 and the orifice 54 then being in alignment After making sure that the annular sealing gasket 23 and the compensation washer 25 are properly in place, the next step is to tighten the special nut 24 of the 7 stuffing box, as shown in Figure 6 As mentioned above, sealing is obtained between the nut and the outer sheath 2 of the cable 1 once the nut 24 has been tightened until it comes into abutment against the compensation washer 25 It should be noted that the hexagonal outside shape of the nut, i e. it having six facets, enables it to be tightened by means of a wrench. Then (Figures 7 and 8), by means of the retaining clamp in two halves 30, 31, of the two nuts 29, and of the two associated clamping screws 28, the cable 1 is retained on the two rear tabs 26, 27 specially designed for this purpose on the special nut 24 of the stuffing box. For this purpose, the two square nuts 29 are inserted sideways into their respective nut-receiving cavities 56 in the bottom half of the retaining clamp 31, the two halves of the retaining clamp 30, 31 are put in place so that their orifices 57, 58 through which respective ones of the two screws pass 28 coincide with the orifices 59 through which the screws also pass, and which are provided in respective ones of the rear tabs 26, 27 on the stuffing-box nut 24 The two clamping screws 28 are then tightened until the nut 24, the retaining clamp 30, 31, and the cable 1, via its outer sheath 2, are clamped together strongly It should be noted that the retaining clamp 30, 31 is made of a very rigid plastics material, e g a polyamide filled with glass fibers For example, the body 17 and its associated nut 24 may be made of optionally-filled polyamide, imparting slight flexibility to them, which is essential to stuffing box operation As shown in Figure 8, the resulting assembly is then fully prepared, secured, and sealed, all this having been advantageously performed outside the splice box 8 As shown in Figures 8 and 9, the following step consists in inserting the assembly into the box 8 via its inlet passageway 11 provided for this purpose, until it comes into abutment in a position (Figure 9) in which only the head 35 of the metal solepiece 16 and a front groove 60 in the body 17 project beyond the inlet passageway 11 into the box 8, the inlet sealing in the passageway 11 being provided by the above-mentioned O-ring sealing gasket 19 For this purpose, the inlet passageway 11 has a special shape, corresponding to the shape given to the body 17, this special shape being imparted to it in this embodiment, and therefore in a manner that is in no way limiting, by the shape of the above-mentioned adapter piece 12 As can be seen in the drawings (in particular in Figure 8), at its front end, the inlet passageway 11, ie the inside wall of the adapter piece 12 in this example, is provided with a reduced outlet section portion 61 which, while enabling the head 35 8 and the groove 60 to pass through it easily, defines a circular shoulder 62 which, in cooperation with a corresponding annular shoulder 63 on the body 17, positioned slightly upstream from the groove 60 as shown in the drawings, serves as an end-of-stroke abutment on inserting the assembly into the orifice 11 The O-ring gasket 19 is positioned in an annular groove 64 in the body 17, which groove is, in this example, situated just in front of the abutment shoulder 63, and when the body is in the abutment position as shown in Figure 9, the gasket 19 is pressed between said groove 64 and the inside wall of the passageway 11, and thus of the adapter piece 12, whose section is matched accordingly at this place Very advantageously, the rear half 70 of the inlet passageway 11, i e the rear inside surface of the adapter piece 12, is hexagonal in shape, i e it has the female shape corresponding to the hexagonal outside surface of the stuffing box nut 24 In the abutment position shown in Figure 12, the nut 24 is inserted at least in part into the hexagonal inlet 70 of the passageway 11, thereby preventing it from rotating, so that the cable inlet device is then effective in withstanding any external torsion stresses that are exerted subsequently on the cable 1 All that then remains to be done, as shown in Figures 9, 9 A, and 10, is to put the above-mentioned locking fork or key 32 in place by clipping it into the groove 60 The cable inlet is then fully put in place, clamped, locked, and sealed, without it being necessary, as it is in the prior art, to act inside the box, e g to perform often difficult tightening operations, and without sealing on the outer sheath of the cable being performed upstream from the point at which it is secured, with the resulting weakening of the sealing. The device is particularly simple and user-friendly to fit and to put in place, thereby greatly facilitating the task of the user, and, in addition, the amount of longitudinal space that it takes up inside the chamber or container is reduced significantly Naturally, the invention is not limited to the above-described embodiment For example, the adapter piece 12 could be omitted or simply replaced with a corresponding shape on the inside surface of the inlet passageway 11, which is then made in one-piece with, typically by being integrally molded with, the box 8, as shown diagrammatically in Figure 11 9. WE CLAIM; 1. A watertight inlet device for inserting an optical cable (1) into a chamber (8) via an inlet passageway (11), the optical cable (1) comprising an outer sheath (2) accommodating a plurality of flexible tubes (3) each containing a number of optical fibres (4), at least two strength members (5,6,7), characterized in said device is fitted to the cable (1) and secured to the strength members (5,6,7) thereof before the cable (1) is inserted into the chamber (8), the outer sheath (2) of the cable (1) further being secured directly on said device and upstreeam from its seal ing means (20,23,19) , said device then being received by being threaded into the chamber (8), and being locked therein by keying (32). 2- The watertight inlet device as claimed in claim 1, comprising: - a rigid securing sole piece (16), positioned at the front of said device, provided with orifices (38,39,49) into which a central strength members (7) and/or side strength members (6,5) of the cable are inserted, each of these orifices cooperating with a clamping member (50,40,41) typically acting by a screw (51,44,45) being rotated to clump the strength members (7,6,5) that it receives; 10. - a sealing tubular body (17), positioned between the front and the rear of said device, having a front portion (68) engaging telescopically said securing sole piece (16), means (18) being provided for fixing the sealing body (17) to the securing sole piece (16) in the engaged position, and having a rear portion (20) cooperating with a seal ing ring (23) to form a seal ing stuffing box (21,22) which is complementary to a clamping nut (24), the stuffing box achieving the sealing by clamping on the outer sheath (2) of the cable; - a nut (24) positioned at the rear of said device, for clamping the stuffing box (20), which nut (24) is also shaped (26,27) to receive a retaining member (30,31) for retaining the outer sheath (2) of the optical cable (1); and the sealing body also receiving means (19) far providing the seal ing relative to the inlet passageway (11) in the chamber 11. device (16,17,24) through said inlet passageway (11) , the abutment position (62,63) then being such that the head (35.60) of the device emerges inside the chamber (8,9) key, means (32) then being provided for locking the device in this position. 3. The watertight inlet device as claimed in claim 2, wherein said nut (24) has an outside shape comprising a plurality of facets, the rear portion (70) of said inlet passageway (11) being of the corresponding female shape. 4. The watertight inlet device as claimed in any one of claims 1 to 3, wherein said keying means comprises a semi—rigid retaining form (32) which plugs into the front groove (60) thereby holding the sealing body (17), the groove (60) emerging downstream relative to said inlet passageway (11) when the device is inserted to its abutment position. 5. The watertight inlet device as claimed in claim 2 or 3, wherein said nut (24) is provided with two rear tabs (26,27) which are designed to receive a retaining member (31,32) for retaining the outer sheath (2) of the optical cable (1). 6. The watertight inlet device as claimed in claim 5, wherein the retaining member is configured in two halves (31,32). 12. 7. The watertight inlet device as claimed in any one of claims 2 to 6, wherein said sealing body (17) receives a rigid compensation ring (25) which is designed as a function of the diameter of the optical cable S. The watertight inlet device as claimed in any of claims 1 to 7, wherein said inlet passageway (11) comprises an intermediate piece (12) which adapts to an inlet orifice (67) of the chamber 3. 9. The watertight inlet device as claimed in any one of claims 1 to 7, wherein said inlet passageway (11) is made in one piece with the chamber (8). This invention relates to a watertight inlet device for inserting an optical cable (1) into a chamber (8). The device comprises a metal solepiece (16) for securing a plurality of strength members (5,6,7) of the optical cable, and which plugs into and fixes to a tubular sealing body (17) equipped with an external o-ring gasket (23) and having its rear portion shaped to form a sealing stuffing box (21,22) on the outer sheath of the cable. The rear of the nut (29) of the stuffing box (20) receives a clamp (30,31) for retaining the cable. Once the device has been fitted the resulting assembly is inserted into the inlet passageway (11) until it abuts against a shoulder (63) in the passageway (11). Then only the bead of the securing solepiece (16) and a groove (16a) in the body project inside the container (8), the groove (6a) then receiving a key (32) for retaining the assembly.

Documents:

00636-cal-1999 abstract.pdf

00636-cal-1999 claims.pdf

00636-cal-1999 correspondence.pdf

00636-cal-1999 description (complete).pdf

00636-cal-1999 drawings.pdf

00636-cal-1999 form-1.pdf

00636-cal-1999 form-18.pdf

00636-cal-1999 form-2.pdf

00636-cal-1999 form-26.pdf

00636-cal-1999 form-3.pdf

00636-cal-1999 form-5.pdf

00636-cal-1999 letters patent.pdf

00636-cal-1999 others document.pdf

00636-cal-1999 priority document others.pdf

00636-cal-1999 reply f.e.r.pdf