GB1563851A - Device for fixing the covering of a cable extending through a wall - Google Patents

Description

(54) DEVICE FOR FIXING THE COVERING OF A CABLE EXTENDING THROUGH A WALL (71) We, CAPRI-CODEC S. a French body corporate of 24 a 32 rue Ernest Renan 92700 Colombes, France do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement :- The present invention relates to a device for fixing the covering of a cable extendng through a wall.

In the electrical equipment industry, in order to ensure the passage of a cable through a partition wall, a tubular stuffing box is used, the interior of which is provided with a screw-threaded cap which serves to locate the cut end of the tubular envelope which proteots the cable, whilst a ring of flexible material also ensures the fluidtightness between the stuffiing box and the envelope of the cable. This tubular envelope is, in general, essentially formed by a flexible metal covering, formed by threads or bands, which may be plaited., and covered by an exterior protective sheath of plastics material.

An object of the present invention is to provide a device in which in use the flexible metal covering of a cable can be secured without damaging the cover.

According to the present invention there is provided a device for securing the covering of a cable extending through a wall, comprising an annular stuffing box and a screw member having two annular parts which are interconnected so as to be held against relative axial displacement but rotatable relative to each other, one of the parts being screw-threaded externally and screwable into the stuffing box, and the other part having an external diameter smaller than the internal diameter of a corresponding part of the stuffing box, the stuffing box having an internal shoulder arranged to co-operate with said other part in use to lock between them the covering of the cable.

Preferably, the device has a sealing ring and a screw cap, the cap being screwable into the stuffing box to press the sealing ring against an end portion of the stuffing box.

In a stuffing box provided with a fixing device according to the invention, the end of the covering, preferably stripped of its sheathing, is folded outwards on itself, and a screw member is engaged between the covering or its sheathing and the folded-back part of the covering, until the latter is locked against an internal shoulder of the stuffing box. However, the screw member is formed in two annular parts, secured against axial movement but rotatable one relative to the other, namely a rear screw-threaded part to be screwed into the stuffing box and a front part which has an external diameter smaller than the internal diameter of the portion of the stuffing box in which it engages, and of which the end comes against the shoulder of the stuffing box to lock against the latter that end of the covering which is folded outwards.

This device avoids damage to the covering which would otherwise be entrained by rotation of the screw member upon its contact as is frequently the case with conventional stuffing boxes.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which :- Fig. 1 shows a part-sectional side view of a device for securing a cable covering in a stuffing box according to the invention ; Fig. 2 is a part sectional view of the two members which form the screw cap of said device; Fig. 3 shows in section a detail of the assembly of the members of Fig. 2; and Fig. 4 shows, partly in section, the sealing ring of the device of Fig. 1.

The device in this particular embodiment of the invention has a stuffing box which secures the passage of a cable 2 through a partition wall 1. The cable 2 is provided with a plaited metal covering 3 which itself is covered by a protective sheath 4 of plastics material. Adjacent the partition wall 1, the cable is stripped of its protective envelope, the latter bemg formed by the covering 3 and the sheath 4 and ensuring external protection of the cable 2.

The body 5 of the stuffing box is formed in two tubular parts of different diameters connected by a ring portion 6. The front part 7, which has the smaller diameter, passes through the wall I and is screwthreaded externally to receive a nut 8, by which the stuffing box is fixed to the wall 1.

The ring portion 6 has an external circular protuberance 9 which ensures a fluid tight seal against the wall 1.

The rear part of the body 5 of the stuffing box is screw-threaded internally and exter nally, and its rear face has a circular recess with a flat base against which the front edge of a sealing ring 12 abuts. It receives internally a screw-threaded fixing cap for securing the end of the covering 3 in the stuffing box. It also receives externally a screw cap 10 which, as well as acting as a protector, effects compression of the sealing ring 12.

! The fixing cap is formed by two annular members 13, 15 which are fixed against axial movement, but are independently rotatable.

These two members are constructed and assembled as is shown more particularly in Figs. 2 and 3, respectively. The rear member 13 is formed by a ring which is screwthreaded externally to engage with the internal screw-threading of the body 5 of the stuffing box. Tt is castellated so as to provide gaps 14 which allow it to be gripped easily d, uring screwing. The front member 15 is formed by a rotatable socket member. Inter nally, said socket member 15, like the screwthreaded ring 13, has a diameter greater than the external diameter of the envelope 3, 4 of the cable, to permit passage of the latter axially. Externally, the socket member has a diameter smaller than the internal diameter of the body 5 of the stuffing box. At the end 16 by which it is attached to the ring 13, the socket member 15 has slits 17, which give it some degree of elasticity to permit attachment to the ring 13, and an internal annular recess 18 in which an annular boss 19 on the ring 13 engages to ensure a good joint between the two members (Fig. 3).

As shown in Fig. 1, the rotatable socket member 15 terminates at its opposite end in a bearing surface which, when the cap 13, 15 is screwed into the stuffing box, abuts a shoulder 20 formed by the internal face of the crown 6.

The method of assembling the stuffing box is obvious from the preceding description and from the illustration in Fig. 1. The cap formed by the two members 13 and 15 being engaged on the cable, in the zone still having the envelope 3,4, the strands of the covering 3, which extend beyond the sheath 4, are turned back outwardly, and the whole is clamped in the stuffing box. When the cap 13, 15 is screwed into the stuffing box, the reduced diameter of the socket member 15 permits the latter to jam between the bent back parts of the strands of the covering and the part of the covering still covered by the sheath. During screwing, only the screwthreaded ring 13 turns, so that damage to the strands of the covering is thus avoided.

After screwing, the strands of the covering are pressed between the end of the socket member 15 and the shoulder 20 of the stuffing box, and are thus held firmly in the latter.

With the covering thus anchored in the stuffing box, the cap 10 is screwed to lock the sealing ring 12. The latter consists of an elastic material such as rubber or resilient plastics material. Out-of-use, it has the shape shown in Fig. 4. Its rear portion 22 has an inwardly directed flanc,, 23 having an inter nal diameter smaller than the external diameter of the envelope of the cable. When the ring is fitted to the envelope, the flange 23 resiliently engages in fluid-tight contact with the sheath 4 of the covering. It thus ensures a water-tight seal. The front portion 24 of the sealing ring has an external diameter greater than the part 22, and such that when the cap 10 is in position, it is pressed by an internal abutment 25 on the latter against the walls and the base of the recess of the rear face of the body 5 of the stuffing box. The sealing ring has at its front end a conical enlargement 26. When it is compressed by the cap, it forms a completely ftuid-tight joint between the cable and the body of the stuffing box.

The invention is not limited to the embodiment described and shown; it is open to various modifications which are available to a person skilled in the art, in accordance with the applications envisage, and without departing from the scope of the invention as claimed.

Claims (5)

WHAT WE CLAIM IS :-

1. A device for securing the covering of a cable extending through a wall, comprising an annular stuffing box and a screw member having two annular parts which are interconnected so as to be held against relative axial displacement but rotatable relative to each other, one of the parts being screwthreaded externally and screwable into the stuffing box, and the other part having an external diameter smaller than the internal diameter of a corresponding part of the stuffing box, the stuffina box having an internal shoulder arrange to co-operate with said other part in use to lock between them the covering of the cable.

2. A device according to claim 1, having a sealing ring and a screw cap, the cap being screwable onto the stuffing box to press the sealing ring against an end portion of the stuffing box.

3. A device according to claim 1 or claim 2, in which the two annular parts are interconnected through an annular recess cooperating with an annular boss.

4. A device according to any one of claims 1 to 3, in which the screw-threaded part is castellated to facilitate screwing.

5. A device for securing the covering of a cable extending through a wall, substantially as hereinbefore described with reference to and as shown in the accompanying drawings.