Note: Descriptions are shown in the official language in which they were submitted.
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A PLASTIC SLEEVE FOR PROTECTING SPLICES OF ELECTRIC
CABLES OR TELEPHONE CABLES AND A METHOD FOR
ACHIEVING FLUID-TIGHTNESS OF SAID SLEEVE
BACKGROUND OF THE IMVENTION
Field of the Invention
The present invention relates to a sleeve of
plastic material for protecting splices of electric
cables or telephone cables.
The invention is also directed to a method for
achieving fluid-tightness of a sleeve of this type.
Description of the Prior Art
French patent N 2,469,782 and the Certificates
of Addition N 2,479,545, N 2,492,151, N 82 11467 and
N 83 02641 related to the patent aforesaid and filed by
the present Applicant all describe a sleeve for protect-
ing splices of cables and especially telephone cables,
said sleeves being constituted by two half-shells
assembled together along their adjacent edges. In the
assembly position, said adjacent edges deEine between
them a perlpheral channel into which a sealing produc-t
in paste form is introduced by injection, for example.
At the opposite ends of the sleeve, the cable is
clamped between a series of jaws which are removably
fitted withln the sleeve.
In the French patent and the Certificates of
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Addition cited earlier, the present Applicant described
difrerent means for obtaining excellent fluid-tightness
between the adjacent edges of the two half-shells of the
sleeve and also between the cable and the clamping jaws
which are Eitted in the end portions of said sleeve.
Although the solutions described in the afore-
mentioned patent and certificates of Addition are all
satisfactory, they call for equipment which is complicated
to use such as cartridges for the injection of sealing
material into the peripheral channel defined between the
adjacent edges of the pre-assembled half-shells.
The aim of the present invention is therefore to
produce a cable protection sleeve which makes it possible
to obtain excellent fluid-tightness between the adjacent
edges of the half-shells of said sleeve, the means
employed for the achievement of this result being both
inexpensive and simple to use.
SUMMARY OF THE INVENTION
The protective sleeve contemplated by the
invention comprises two half-shells assembled together
along their adjacent edges, the edge of one of the half-
shells being provided with a longitudinal rib engaged
within a groove formed in the adjacent edge of the other
half-shell and sealing means being provided between said
edges.
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In accordance with the invention, said sleeve is
distinguished by the fact that the groove has an inner
side wall of sufficiently small thickness to be flexible,
that the height of the rib which is engaged in said groove
is slightly smaller than the depth of the groove, that the
rib face which is adjacent to the inner face of said
flexible wall forms with said inner face an angle of a few
degrees having a vertex located at the extremity of said
wall, the space defined by said angle being filled by a
strip of putty which is deformed and compressed between
said faces of the rib and of the wall.
In accordance with the method contemplated by
the invention, in order to form a tight seal between the
two half-shells of the protective sleeve aforesaid, a
strip of putty is applied against the inner face of the
flexible wall which extends on one side of the groove of
one of the two half-shells, the rib of the other half-
shell is engaged in the groove, the two half-shells are
tightly applied against each other, whereupon the
interior of the sleeve is put under pressure.
By virtue of the angle of a few degrees formed
between the adjacent faces of the rib and of the flexible
wall, when said rib is engaged within the groove, the
strip of putty is accordingly compressed between these
two faces and is progressively deformed by creepage flow.
Compression of the putty between these two faces tends to
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cause the flexible wall to bend towards the interior of
the sleeve.
When the half-shells have been assembled
together in interengaged relation, the pressure which is
applied within the sleeve by means of clamping screws,
for example, tends to thrust the flexible wall towards
the rib, which has the effect of compressing the putty
and thus increasing the tightness of the seal. By virtue
of the wedge formed between the adjacent faces of the
flexible wall and of the rib under the action of com-
pression, the putty tends to creep more readily towards
the space formed between the summit of the rib and the
bottom of the groove and thus to produce a favorable
effect in regard to fluid-tightness but does not tend to
creep towards the summit of the flexible wall and towards
tlle interior of the sleeve.
BRIEF DESCRIPTION OF THE DRAWINGS
Other features of the invention will be more
apparent to those skilled in the art upon consideration
of the following description and accompanying drawings,
wherein :
- Fig. 1 is a longitudinal sectional view of a
sleeve in accordance with the invention, said sleeve
being mounted around the splice of a telephone cable ;
- Fig. 2 is a sectional view to a larger scale
and taken a]ong the plane II-II of Fig. 1 ;
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- Fig. 3 is a sectional view to an even larger
scale and taken along the plane III-III of Fig. 2, it
being assumed that the upper half-shell has been removed ;
- Fig. 4 is a large-scale view showing the
detail IV of Fig. 2 ;
- Fig. 5 is a view which is similar to Fig. 4,
which shows the half-shells in a partially interengaged
position, and which illustratles the practical application
of the method in accordance with the invention.
lQ DETAILED DESCRIPTION OF THE INVENTION
In the embodiment of Figs. 1 and 2, the plastic
sleeve 1 which is mounted around the splice 3 of the
telephone cable 2 comprises two half-shells la, lb (as
shown in Fig. 2), said half-shells being assembled one
against the other along their adjacent edges 2_, 2b by
means of clamping screws 4.
The cable 2 is secured axially to the end
portions 5, 6 of the sleeve by means of a series of jaws
7, 8, 9, 10 fitted within the sleeve 1 and tightly
applied against an adhesive tape 11 having a base of
elastomer and wound around the cable 2.
Fig. 4 shows in greater detail that the edge
2a of the half-shell la comprises a longitudinal rib 12
engaged in a groove 13 which is formed in the adjacent
edge 2b of the other half-shell lb ~as also shown in
Fig. 3).
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The thickness or the inner wall 14 of the groove
13 is sufficiently small to ensure flexibility of said
wall.
As indicated in Fig. 4, the rib 12 which is
engaged within the groove 13 has a height H which is
slightly smaller than the depth P of the groove. Moreover,
the face 12a of the rib 12 which is adjacent to the inner
face 14a of the wall 14 forms with said inner face an
angle (a) or a few degrees (2 to 5 degrees, for example),
the vertex 15 of which is located at the extremity 14b of
the wall 14. The space defined by said angle (a) is
filled with a strip of putty 16 which is deformed and com-
pressed between the face 12a of the rib 12 and the face
14a of the wall 14.
The space E located between the summit 12b of
the rib 12 and the bottom of the groove 13 is filled with
the material produced by creepage flow of the strip of
putty 16 which is compressed between the faces 12a and 14a.
As can also be seen in Fig. 4, the wall 14, the
groove 13 and the rib 12 have a trapezoidal cross-section
and the large base B of the trapezoidal cross-section of
the groove 13 coincides with that of the rib 12 which is
engaged within this latter.
In addition, the faces 17 and 18 of the rib 12
and of the groove 13 which are opposite to the flexible
wall 14 are applied against each other and are substantial-
ly perpendicular to the plane of assembly M of the two
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half-shells la, lb.
In accordance with the invention, in order to
form a tight seal between the two half-shells la, lb of
the sleeve 1 described in the foregoing, the procedure
is as follows (see Fiq. 5) :
A strip of putty 16 is applied against the inner
face 14a of the flexible wall 14 which extends on one side
of the groove 13 of the half--shell lb, the rib 12 of the
other half-shell la is engaged in the groove 13, the two
half-shells la and lb are tightly applied against each
other by means of screws 4, whereupon the interior of the
sleeve 1 is put under pressure. The internal pressure of
said sleeve can be of the order of a few bar.
The thickness of the strip 16 of putty is at
least equal to the distance d between the summit 12b of
the rib 12 and the inner face 14a of the flexible wall 14
when said rib is fully engaged in the groove.
Preferably, the volume of the strip 16 of putty
is at least equal to the volume of the space formed
between the adjacent faces 12a, 14a of the rib 12 and of
the flexible wall 14 and between the summit 12b of the
rib 12 and the bottom of the groove 13.
At the time of assembly of the half-shells la,
lb of the sleeve in accordance with the invention, the rib
12 of the half-shell la engages in the groove 13 of the
half-shell lb as indicated in Fig. 5. During this
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engagement, the strip of putty 16, the volume of which is
initially greater than that of the available space between
the wedge formed by the two opposite faces 12a and 14a, is
progressively deformed and compressed in a downward move-
ment of creepage flow, with the result that the excessputty fills the space E. This compression of the putty 16
has the effect of thrusting the rib 12a against the face
18 of the groove 13 and of subjecting the flexible wall 14
to a light outward thrust (as shown by the arrow F in
Fig. 5).
After clamping by means of the screws 4, the
putty 16 is trapped and compressed within the space
located between the two faces 12a and 14a and between the
summit 12b of the rib and the bottom of the groove 13.
After pressurization of the interior of the
sleeve, no outleakage is found to occur.
This internal pressure guards against any danger
of penetration of moisture into the sleeve. Moreover,
said internal pressure has the effect of thrusting the
flexible wall 14 in a direction opposite to the arrow F of
Fig. 5 and of compressing the putty 16 to an even greater
extent, thus achieving enhanced fluid-tightness and re-
moving any risk of creepage flow of putty at the level of
the junction between the summit 14b of the flexible wall
and the base of the rib 12.
The strip of putty 16 can be applied by hand on
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the face 14a of the wall 14. Preferably, however, said
strip 16 is extruded directly and automatically onto the
face 14a of the wall 14 by means of a suitable extruder.
The putty 16 can have an elastomer base of a
type commonly employed in sealing operations. The putty
must be sufficiently soft to enable it to assume the wedge
shape defined between the surfaces 12a and 14a while at
the same time ensuring that such deformation is not liable
to exert an unduly high pressure on the flexible wall 14
since this would in turn be liable to subject the wall to
excessive flexural deformation in the outward direction.
There thus exists a certain correlation between deform-
ability of the putty 16 and flexibility of the wall 14,
this correlation being determined by experience.
As will readily be apparent, the invention is
not limited to the examples described in the foregoing
and any number of modifications may accordingly be
contemplated without thereby departing either from the
scope or the spirit of the invention.
