U.S. patent number 3,569,608 [Application Number 04/757,047] was granted by the patent office on 1971-03-09 for splice case assembly.
This patent grant is currently assigned to Superior Continental Corporation. Invention is credited to Louis Ance.
United States Patent |
3,569,608 |
Ance |
March 9, 1971 |
**Please see images for:
( Certificate of Correction ) ** |
SPLICE CASE ASSEMBLY
Abstract
Disclosed herein is a cable splice assembly in which a stripped
end portion of the cable is enclosed in a plastic domelike
container, said domelike container being in sealing engagement by
means of a first type seal with a sealing chamber. This sealing
chamber encloses not only the unstripped portion of said cable but
also a plasticlike substance within a closed space to form a second
type seal. Provisions are made for producing compressive forces on
such plasticlike substance, to drive it thoroughly into engagement
with the unstripped cable surfaces as well as the interior surfaces
of the sealing chamber that encloses such plasticlike substance so
as to produce a tight and gasproof seal of a second type against
the unstripped cable surface and the inner surface of the sealing
chamber enclosure. By means of such a two seal assembly, ready
access can thus be had to the stripped cable portion through said
first seal means without breaking the last mentioned seal.
Inventors: |
Ance; Louis (Hickory, NC) |
Assignee: |
Superior Continental
Corporation (Hickory, NC)
|
Family
ID: |
25046138 |
Appl.
No.: |
04/757,047 |
Filed: |
September 3, 1968 |
Current U.S.
Class: |
174/93; 174/76;
174/91; 277/621; 174/22R; 174/77R |
Current CPC
Class: |
H02G
15/013 (20130101) |
Current International
Class: |
H02G
15/013 (20060101); H02G 15/00 (20060101); H02g
015/08 () |
Field of
Search: |
;174/91--93,88,76,77,75,22,21,87 ;277/(Inquired),58,102,51
;220/4 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Clay; Darrell L.
Claims
I claim:
1. A splice case receiving and protecting portions of cable
sections comprising:
a. a domelike container wherein there is formed at an open end
thereof an outwardly extending external face plate;
b. means defining a sealing chamber having two open ends, one end
having formed thereon a face plate complementary with the face
plate of said domelike container, said sealing chamber being formed
near its other end with an internal annulus protruding inwardly
from the internal surface of said sealing chamber and constituting
an abutment, said means defining said sealing chamber being in
removable, sealing engagement with said domelike container;
and,
c. a composite formed of first, second and third spaced apart disc
means all strung on a means adapted to move said first, second and
third disc means in a closer relationship one to another, said
first disc means being disposed on one side of said internal
annulus, said second disc means being disposed on the opposite side
of said internal annulus, said third disc means being spaced apart
from said internal annulus and forming a compression compartment in
combination with said second disc means and said sealing chamber,
wherein said compression compartment contains a body of deformable
sealing material, essentially filling said compartment, and each of
said disc means having openings therein through which said portions
of said cable sections extend, with said sealing material forming a
seal around the portions of said cable sections extending through
said compartment.
2. The splice case defined in claim 1 wherein the domelike
container, sealing chamber, and each of said disc means are
composed of polyvinyl chloride.
3. The splice case defined in claim 1, wherein the body of sealing
material comprises a material which has a high internal molecular
resistance, is deformable under compressive force, is substantially
nonelastic, and is of a high viscosity.
4. The splice case defined in claim 3, wherein the sealing material
comprises polyisobutylene.
5. The splice case defined in claim 4 wherein said sealing material
is highly self-adhesive, and when portions of such material contact
with each other under compressive forces, a substantially integral
body of material is produced.
6. The splice case defined in claim 1, wherein the domelike
container, said means defining sealing chamber, and each of said
disc means are composed of a plastic material.
7. The splice case defined in claim 1, wherein the plastic material
forming the sealing chamber is slightly adhesive to the body of
said sealing material disposed in the compression compartment, and
is more strongly adhesive to said body of said sealing material
under shear.
8. The splice case defined in claim 1, wherein said means defining
the sealing chamber and each of said disc means comprises polyvinyl
chloride.
9. The splice case defined in claim 1, wherein an O-ring made of
deformable material is disposed in U-shaped grooves formed in the
face plates of both said sealing chamber and said domelike
container to provide a seal therebetween.
10. The splice case defined in claim 1, wherein said means defining
said sealing chamber is removably attached to at least one bracket
means.
11. The splice case defined in claim 10, wherein said bracket means
extend beyond a terminal portion of said sealing chamber and is
removably engaged to at least one sheath of said cable
sections.
12. The splice case defined in claim 1, wherein said means adapted
to move said first, second and third disc means in a closer
relationship one to another is a nut and bolt combination in
engaging relationship, the head of said bolt being disposed on the
outermost surface of said first disc means and said nut being
disposed on the outermost surface of said third disc means,
whereupon advancement of said bolt through said nut, advances said
first disc means towards said third disc means.
13. The splice case defined in claim 1, wherein said openings in
each of said disc means are of different diameter.
14. A cable splice case receiving and protecting portions of cable
sections comprising:
a. a first cable portion receiving container having a first sealing
means circumscribing an opening in said container; and,
b. a second cable portion-receiving container having a first
opening circumscribed by a second sealing means, a second opening
structured to receive a third sealing means, an annulus protruding
inwardly from the inner surface of said second container, said
second sealing means being in sealing engagement with said first
sealing means of said first container and the third sealing means
forming a composite formed of a first, second and third
spaced-apart disc means strung on a means for moving said first,
second, and third disc means in a closer relationship one to
another, said first disc means being disposed on one side of said
inwardly protruding annulus, said second disc means being disposed
on the opposite of said inwardly protruding annulus and said third
disc means being spaced apart from said inwardly protruding annulus
to form a compression chamber in combination with said second disc
means and the sidewall of said second container, said compression
chamber containing a body of deformable sealing material, and each
of said disc means having openings therein through which said
portions of said cable sections extend, with said sealing material
extending around the portions of said cable sections extending
through said compression chamber.
15. The splice case defined in claim 14, wherein said first and
second containers are composed of a plastic.
16. The splice case defined in claim 14, wherein said first and
second circumscribing sealing means are complementary sections of
an O-ring-type seal.
17. The splice case defined in claim 14, wherein the body of
deformable material of said third sealing means has a high internal
molecular resistance, is deformable under compressive force, is
substantially nonelastic, and is of a high viscosity.
18. The splice case defined in claim 17, wherein the sealing
material comprises polyisobutylene.
19. The splice case defined in claim 14, wherein said second
chamber is removably attached to at least one bracket means.
20. The splice case defined in claim 14, wherein said first and
second containers are composed of materials selected from the group
consisting essentially of polyvinyl chloride, polyethylene,
polypropylene, and polystyrene.
Description
DETAILED DISCLOSURE
This invention relates to cable splicers, and the like. The splice
cases hereinafter to be disclosed have been designed especially to
meet the rigorous and severe conditions to which such units are
subject in normal and everyday use, and to meet other even more
severe and rigorous conditions sometimes imposed by severe weather
and temperature conditions. The splice cases herein disclosed have
also been designed to accommodate and meet such conditions
primarily where cables carry many pairs of conductors, either power
or communications type-- including such cables as are presently
being used in connection with telecommunications systems--for
example coaxial lines or signal lines.
In the case of communication lines and other lines for such use as
telecommunications, it is necessary to produce splices between
successive lengths of the cable reel-ends, i.e. usually a few
hundred or even a thousand feet of such construction, and in such a
manner that current leakages or short circuits between the numerous
pairs of conductors are avoided to a maximum degree. Not only is
the splicing of such reel-ends necessary, it is also necessary in
laying cable either above or below ground-- either unpressurized or
pressurized--to splice into said cable between such reel-ends
electrical apparatus such as loading coils and the like. Thus, the
instant invention is concerned not only with splicing the ends of a
reel of one cable to another, but also splicing into a cable
between reel-ends additional apparatus necessary in making up a
telecommunications system. Both of the embodiments of the instant
invention avoid current leakages or short circuits between the
numerous pairs of conductors. Furthermore, by use of the instant
invention a saving of skilled labor, time expended in locating and
repairing the defects, as well as losses due to "downtime" caused
by such defects are achieved. There is assured, by means of the
instant invention, near perfect transmission of the messages over
each of the pairs, and avoidance of "crosstalk" between pairs.
Aside from defects due to actual conductor contacts between the
conductors of a pair or between conductors of proximate pairs,
leakages may occur between such conductors, or between a conductor
and ground due to the presence of moisture within the splice case
unit. The presence of moisture within the splice case unit greatly
magnifies troubles such as mentioned above, especially when the
insulation on the conductors themselves is a paper product. The
moisture, in such cases, readily finds its way through the
insulation, due to capillary or similar water action. It is
therefore imperative that maximum precautions be taken to avoid the
presence of moisture within the splice case at and after the time
of sealing the splice case; and above all, to provide a structure
which shall, of itself, be practically impervious to incursion of
moisture through elements of the splice case itself after sealing.
Such incursions are largely due to successive changes in
temperature conditions inside and outside of the splice case, such
changes producing "breathing" which carries the moisture (water
vapor in most cases) into the enclosed space of the splice case
where condensation thereof takes place. Such conditions are
aggravated proportionally to the lapse of time since the splice was
completed, as well as the nature and severity of the weather to
which the splice is exposed.
It will be understood, however, that the features of the instant
invention hereinafter to be disclosed, are not limited to enclose
splices made in existing lines overhead, but are also useful in the
case of underground or buried lines and cables. In underground or
buried lines of cables as well as aerial lines, the instant splice
cases can be used in conjunction with either a pressurized or
nonpressurized system. Furthermore, in underground systems natural
electrical currents flow through the ground or other formations.
These currents may greatly aggravate the deterioration of a metal
splice case, especially when the cable is metal sheathed. In such
cases the presence of different metals in contact with each other
will cause production of local currents especially when water is
present, and even more especially when there's water carrying one
or more minerals in solution.
The recent introduction of cable sheaths formed of materials other
than metal (e.g., various plastic material), largely eliminates
some of the foregoing objectionable effects due to the use of metal
sheaths, but it is also highly desirable to form the splice case
itself of such a nonmetallic material, thus completely avoiding any
electrolytic conditions at all. It is one of the prime objects of
the present invention to provide a structure of such design and
construction that all portions of a splice case may be formed of
synthetic or plastic, nonmetallic materials, thus avoiding the
objections already referred to in the case of metal splice cases.
In this connection, there is also provided a splice case structure
which may be, if desired, used in the joining together of proximate
ends of lead or other metallic sheath cables, the elements of the
splice case itself being completely devoid of any metal which could
possibly produce or enter into an electrolytic and/or galvanic
action.
The larger telephone lines, which have cables carrying 100 or more
pairs, are conventionally provided with an inner and outer sheath
or covering. The inner sheath may be of paper or plastic
sheathing--the outer sheath being formed of material capable of
withstanding the elements and physical encounters to which the
cable may be subjected, including snow, sleet, ice, hail, etc. such
outer sheathing is thus intended to protect the communication
carrying lines against damage or physical encounters of severe
degree. It sometimes happens, however, that such outer sheath is
pierced, thus providing an entrance for water and water vapor. Even
without a rupture of the outer sheath, water sometimes by osmotic
pressure differential finds its way through such outer sheath and
to the outermost surface of the inner sheath. This inner sheath is
usually not made of material possessing the same or similar
physical strength as the outer sheath but it is designed primarily
to prevent entrance of moisture into the inner pairs. However, it
seldom happens that such inner sheath itself is itself pierced,
thus, it may retain its intended moistureproof characteristic. But
moisture, admitted through the piercing of the outer sheath or
otherwise, may arrive at the inner sheath notwithstanding, and then
gradually move largely by capillary action, either lengthwise along
the surface of the inner sheath to a location of lower pressure or
into and through the inner sheath itself by osmotic movement.
Furthermore, if in time such inner sheath loses much or even some
of its moisture resisting characteristics, it too may become a path
for free radial movement of such moisture inwardly, to the
core--the location of the conductors.
It is one of the objects of the present invention to provide a
splice case structure so constituted that when it is locked into
its final place it will protect the junctions of the ends of the
cable conductors and also form at least two different types of
seals of high moisture resisting ability. The first of these seals
is a positive seal between the surface of the cable's outer sheath
and the inner surface of a portion of the splice case. Another but
different type seal is an O-ring seal made between two flanged
surfaces of a dome and main sealing or compression chamber, these
two components making up the main portion of the splice case of the
instant invention.
Consistent with the aforementioned object of the instant invention,
the O-ring seal is so located that by breaking this seal, the dome
portion of the splice case of an incoming cable and its pairs can
be exposed where maintenance or construction work may be performed.
This dome can subsequently be sealingly replaced without disturbing
the integrity of the other seal operating around the cables coming
into or leaving the splice case enclosure. Even a resealed dome
develops such a strong seal that notwithstanding the fact that such
a seal is broken a plurality of times, each and every resealing
results in an airtight seal. Thus, the seal through which the
incoming and out going cables or drop wires pass need not be
disturbed when repair work in needed or additional cables added for
any purpose. Since the last mentioned non O-ring-type seal is the
most sensitive to the development of leaks therethrough, by
providing an additional O-ring type seal that is readily restored
in a quick and easy manner without fear of leaks developing through
loss of seal integrity a most desirable combination is
constructed.
Another object of the instant invention is to provide bracket means
attachable to the external surface of the splice case, these means
being so adapted as to provide mechanical support for arriving or
departing sections of wire or cable. This support is attached at
the splice case itself. One function of these support means
(brackets) is to resist lateral displacement of the cable (as by
bending) and thus preventing any disruption of lateral shift of the
more sensitive non-O-ring-type formed between the outermost surface
of the cable sheath and the innermost surface of the splice case
container. Such a support means preserves the aforementioned seal
even when there is swaying and swinging of the cable. Such motion
usually results, in the absence of these supports, in a gradual
grinding or deforming of the outer jacket and breaking of the
non-O-ring seal integrity thereby producing leaks.
A further object of the instant invention resides in the provisions
of a structure which lends itself admirably to production of many
or all of its elements for molded, e.g. injection or extrusion
molded, plastics or other readily formed and produced materials,
especially from materials of a nonconductor (plastic) quality, In
this connection it is a further object to provide a design of the
various elements, such that they may be produced to a desired or
predetermined tolerance and substantially without need of high cost
machining or other finishing operations.
A further important object of the instant invention resides in the
provisions of a splice case of such a construction that it will
make possible the sustained existence of continuous air conducting
ducts through the successive cables and the splice cases. This
feature will be better understood from the following brief
explanatory statement: Many multipaired cables have cores that
contain gas under pressure. This pressurized gas aids in preventing
incursion of moisture to the conductors, even when leads do occur
at positions intermediate between successive splices-- that is,
along the length of the cable itself. Such air pressure systems,
when used, necessarily includes provisions for maintaining a supply
of the compressed air (usually of a few pounds to above
atmospheric) input at successive locations along the length of the
cable. Such inputs may be many miles apart. Any minor leakage along
such a length of cable will necessarily result in a small but
significant flow of the air from the proximate input stations
towards the point of loss. It is evident that such flow of air
axially through the cable, small though it may be, requires flow
through one or many of the splice cases present between such points
of input. Accordingly, it is needful that the seals, which are
provided at the junction of the proximate cable ends or at the
points of junction of the proximate telecommunications additional
apparatus (load coils) within a splice case, be of such form and so
produced that they will not hinder the free exit of the moving air
from one cable end, into the dome of the splice case, and from said
dome of the splice case into the proximate end of the next cable
section, it will be understood that such a slow flow or movement of
the air lengthwise of the line of cable is possible through the
inner core of the cable which is within an inner sheath. Air flow
is possible because the core is formed of numerous pairs of lines,
but its core construction is not solid to the extent sufficient to
forbid such air flow lengthwise of the cable. To meet this
condition, the seal contact with the cable itself obviously does
not extend down into the pairs of the outer cable sheath. Such a
seal is in contact only with the innermost surface of the splice
case itself and the outermost surface of the cable sheath.
Another feature of the instant invention relates to an inherent
provision of the disclosed structure in which the piece parts
making up the composite splice case are of such a nature that when
necessary the splice case may be readily opened and dismantled to
the extent necessary to repair a broken pair, or a pair which may
have become leaky or cross-connected to adjacent pairs, or to
repair other damage while the splice case remains open. Such
repair, as well as additional construction, can be carried out with
substantial subsequent ability to restore such splice case to
service under its original sealing ability, without any damage to
such splice case itself or to its original seal contacting the
cables involved. In other words, the instant splice case may be
opened up and the cable and its pairs therein may be worked on by a
workman--either for repair purposes or for further addition or
construction-- and the case itself then subsequently closed without
disturbing the seal between the cable carrying conductors outer
sheath and the splice case itself. The ability to affect such
emergency or nonemergency operations is enhanced by the nature of
the splice case construction itself, including as one of its
features two opposing face plates removable but sealingly secured
one to another, the innerface created by the adjacent face plates
being sealed from outside conditions by use of an O-ring-type
seal.
A further important feature of the instant invention is a provision
whereby a grounding harness connection is made between two cables
just out-by the entrance of these cables into the splice case
itself, this grounding means being electrically connected to an
inner metal cable jacket which lies nested inside the outer plastic
sheath of the cable. It is this grounding harness that maintains
metal shield continuity throughout the cable trunk.
A further feature of the instant invention is a structure whereby a
composite means is used to seal the outermost surface of the outer
cable sheath to the innermost surface of the splice case itself,
this composite being fixed and not free to move upon the
application of varying mechanical, pneumatic, or gaseous pressures
on the inside of the splice case itself.
The junction of the proximate cable ends within a splice case is of
such form, and so produced, that there is no hindrance to the free
exit of moving air from one cable end, into the body of the splice
case, and the air while in the splice case can and does flow into
the proximate end of the next cable section and thus out of the
splice case via the cable. It will be understood that such slow
flow of movement of the air lengthwise of the line of cable is
possible through the inner core of the cable, within the inner
sheath, since such core, formed of numerous pairs of lines, being
not solid to the extent sufficient to forbid such air flow
lengthwise. To meet this condition, the seal against the outer
sheath of the cable, and the inner surface of the splice case
itself is airtight. Thus, air traveling into the splice case by
means of the cable sheath itself and therein being discharged into
volume of the splice case is forced by the pressure built up in the
splice case back into the proximate end of an outgoing cable length
and thus into the core of said outgoing cable. Thus, the air flows
lengthwise of the outgoing as well as the incoming cable.
A last, but not by any means least, feature of the instant
invention is a structure whereby not only end portions of two
different cables may be placed in a splicing means and spliced
therein, but also additional cable stubs can be led into the
instant splice case and electrically connected to the
aforementioned two cable ends. Additionally, provisions are made
for drop wires to be spliced to incoming and outgoing cables and to
be let out through the splice case into appropriate installations
or homes as the case may be. Furthermore, provisions are made to
accommodate differing diameters of cables or drop wires
notwithstanding a wide variance in diameter of drop wire cable or
trunk cables used in actual service.
Other objects, advantages and features of the present invention
will become apparent from the following detailed description, one
embodiment which is present in conjunction with the drawings in
which:
FIG. 1 shows an outside surface view of an assembled splice case
embodying the features of the instant invention, the companion
cable lengths joined together in the splice case, are shown broken
off for the sake of convenience;
FIG. 2 shows a splice case with its dome removed exposing cable
sections for ready access, splicing and/or maintenance;
FIG. 3 shows disc means strung on a bolt, this composite forming
part of one of the seals of the instant splice case;
FIG. 4 shows the thus strung disc means of FIG. 3 assembled with
cable portions and sealing tape laid adjacent to the cables to fill
up unused or unwanted space in the holes of the discs;
FIG. 5 shows the disc means of FIG. 3 perspective, said disc means
having more than just two complementary holes in each disc;
FIG. 6 shows the disc means of FIG. 4, along with an additional
disc, assembled in a section surrounding of the sealing chamber of
the splice case surrounding a deformable packing material not yet
under pressure;
FIG. 7 shows a section view of the sealing chamber of FIG. 6
wherein the deformable packing is under pressure through the
coaction of the discs, bolt, nut, and sealing chamber sidewalls.
FIG. 7 also shows a locking of the aforementioned sealing composite
to the sealing chamber itself through the compressive action of the
composite sealing assembly;
FIG. 8 shows in perspective the basic components of the splice case
depicting specifically the mode of assembly of the components to
create an O-ring-type seal;
FIG. 9 shows a typical disc means of FIGS. 3 and 4 showing how an
unwanted space is filled in the disc holes to accommodate various
sized of cable diameters;
FIG. 10 is a front elevation of the disc of FIG. 9; and
FIG. 11 and 12 are perspective views of various types of plastic
tapes used to accommodate cables of varying diameters in the disc
holes shown in FIGS. 9 and 10.
Turning now to FIG. 1, numeral 1 indicates generally the overall
assembly of the splice case as disclosed. Basically the splice case
of the instant invention is made up of three basic portions:
compression or sealing chamber 9, splice case dome 10, and a
sealing means composite not shown in FIG. 1 because its normal
assembled position is inside of compression or sealing chamber 9.
The first two of these major components, i.e. compression chamber 9
and splice dome 10 are made out of plastic such as polyvinyl
chloride, polyethylene, polypropylene, polystyrene, and the like.
Both the splice case dome 10 and compression chamber 9 have at
least one complementary opening therein. At this particular opening
there is a sealing means attached to or integral with both the
compression chamber 9 and splice dome 10. Such is shown at 11 and
12. This sealing means is a conventional and well-known O-ring-type
seal means employing two face plates 11 and 12, which are mirror
images of each other. Both face plates 11 and 12 have a U-shaped
groove disposed therein (not shown here, but see element 25 of FIG.
8) in which there lies an O-ring. This O-ring is made up of
elastomeric (resilient) material. It is this O-ring-type seal means
formed by elements 11 and 12 and its associated resilient O-ring
that provides a ready means for access into the splice case without
disturbing the sealing means that seals the surfaces of cables 5 to
the inner surfaces of the sealing or compression chamber 9. One
need only to loosen the bolt or fastening means 8 so as to permit
removal of the dome splice case 10 from the sealing or compression
chamber 9. Once this removal operation is performed, a stripped
segment of cable--see element 14--is exposed as shown in FIG.
2.
Cable reel-ends or any portion between such ends are represented by
elements 5. These cable portions are mechanically supported by
bracket 3 and removably attached to cable 5 by clamp means 4.
Bracket means 3 is secured to the compression chamber 9 by means of
bolts 2. It will be noted that in FIG. 1, just out-by the terminal
portion of the compression or sealing chamber 9, there is shown by
element 6 a wrapping of tape around the cable portions 5. During
the installation of the cables 5 into the assembly 1, cable sheath
5 is broken and the cable sheaths 5 peeled away to expose an inner
metallic jacket or shield (not shown). A separate insulated
electrical conductor 7, hereinafter referred to as a grounding
harness, essentially a metallic conductor (not shown) surrounded by
some form of electrical insulation such as a plastic. The metal
means or conductor of the grounding harness 7 is attached to the
metal shield of the cable 5 as the cable either goes into or comes
out of, whichever the case may be, the splice case assembly 1. As a
result of this grounding harness 7 being in electrical contract
with the metal shield means of cable 5, a metallic path is created.
Thus, the continuity of the cable metallic shield means is
preserved from one reel end to another reel end or through any
breaks in the cable 5 such as is shown in FIG. 2 by the exposed
conductors 14 and cable 5.
As will be hereinafter disclosed and discussed, there is an
additional (second) sealing means disposed inside of sealing or
compression chamber 9. This sealing means terminates at one end
generally near the attached end portion of bracket means 3 and
terminates at its other end just in-by the terminal end of a
compression chamber 9. This second sealing means, disposed on the
inside of the sealing chamber 9, is one that crates a seal between
the surface of cable 5 and the inner surface of sealing or
compression chamber 9. Inasmuch as bracket means 3, acting in
concert with cable clamps 4 and cables 5, hold cables 5 in a rigid
predetermined and fixed position, any swaying, "singing", or
vibration of cable 5 due either to wind movement or to manmade
causes will not have a harmful effect on the seal between the
cables 5 and the innermost walls of sealing or compression chamber
9. If such brackets were not used in the disclosed combination, the
swinging and swaying of cables 5 would gradually erode and loosen
the seal that seals the incoming and outgoing cables to the splice
case inner surface.
Primarily what is shown in FIG. 1 is a hermetic splice case, which
provides a volume in which there can be no entry of water, either
liquid or vapor. The splice case is easy to install and after
installation the cables therein are readily accessible to workmen
who may need to repair or add apparatus thereto. Basically, a
splice case of the instant invention as shown in FIG. 1, must
maintain air pressure in order to exclude water or water vapor.
Obviously, if it maintains air pressure within reasonable
tolerances, then any water vapor existing in the outside ambient
atmosphere will not find ready access to the interior of the splice
case itself.
So as to achieve the above mentioned watertight splice case, use is
made of a hole, in which plug 13 normally is disposed, during
installation and/or after any reentry of the splice case assembly
1. This plug is a means used to fill up a small hole in the butt
end of the dome splice case 10. The hole normally filled by plug 13
is used for the purpose of "flash testing" the splice case assembly
1. For example, once the instant splice case is assembled and
attached to the cables as shown in FIG. 1, but before any form of
superatmospheric pneumatic gas pressure is applied inside the
splice case, a flash testing procedure takes place. This procedure
entails the introduction of gaseous pressure to the inside of the
splice case by means of the hole otherwise filled up by plug 13.
Such a flash testing procedure detects leaks in the splice case
before it is placed in its in-service condition (pressurized).
Approximately 20 or 25 pounds p.s.i.g. are introduced into the
splice case 1 through the hole normally filled by plug 13. Because
of the constrictive air passages in cables 5, a temporary back
pressure is created preserving much of the introduced 20 to 25
p.s.i.g. for a time used to test the splice case assembly 1 for
leaks. To detect for such leaks one need only to "soap" down the
outer surface of the splice case assembly 1 with a liquid
containing a soaplike material. Any leaking air, if any, can thus
be detected as bubbles will be formed by escaping air. Repairs can
then be made to remedy such sources of leaks.
It is in the dome portion of the splice case, i.e. item 10, where
stripped-away portions of cable 5 are disposed thereby exposing
electrical conductors 14 as shown in FIG. 2. It will be noted from
FIG. 2 that the cable sheath 5 extends through compression or
sealing chamber 9 and partly into the dome splice case 10 before
terminating and thus exposing the insulated electrical conductors
14. It is here in this volume created by dome splice case 10 where
either reel-ends are spliced one to another or where electrical
apparatus such as load coils and the like are introduced into a
cable means either at or other than at the reel-ends. In other
words, a length of cable can be cut at any predetermined or chosen
point and inserted into the splice case of the instant invention.
After removing a portion of the cable sheath 5 exposing electrical
conductors 14, additional apparatus such as load coils can be
spliced into the telecommunications system by selecting
predetermined pairs and splicing in the aforementioned load coil.
Load coil assemblies usually are made up with a predetermined
length of cable stub attached to the load coil, and the load coil
itself is usually encapsulated inside of a separate container.
Either the entire encapsulated load coil assembly including its
cable stub can be disposed outside of the splice case assembly or,
in the alternative, the dome splice case can contain not only the
encapsulated load coil assembly itself, but also its associated
cable stub as well. Obviously if the encapsulated load coil
assembly were not also encased in the dome splice case 10, then
such coil assembly would either have to be buried along side of the
splice case assembly 1, or placed in a housing. Such housings may
be either flush with or below the soil surface. Furthermore,
microwave amplifiers can be disposed inside the splice case dome
and spliced into the telecommunications system through exposed
electrical conductors 14, much as in the same manner as load coil
assemblies can be spliced into a telecommunications trunk line.
Shown in FIG. 5 is a portion of a sealing assembly composite used
to seal the outer surfaces of the cable sheath 5 to the inner
surface of the compression or sealing chamber 9. Also shown in FIG.
5 is a plurality of discs 15 and 16, containing complementary holes
of varying sizes 18 and 19, strung on a bolt means 14. Larger holes
18 are usually provided for cables of large diameter whereas
smaller cables or drop wires can be led through holes 19. Cable
sections 5 are inserted into holes 18 in both discs 15 and 16 much
like that as shown in FIG. 4. in this particular embodiment there
is shown two cable sections 5 along with bolt means 14 and discs 15
and 16. Usually the holes 18 are as large as the geometric area of
discs 15 and 16 will permit. However, such is not always the case
when different size cables are sought to be placed in the holes 18,
i.e. the diameter of cable 5 may differ (be significantly smaller
than) from that provided for in discs 15 and 16 by holes 18. That
space not otherwise occupied by the cable 5 in hole 18 is generally
filled up by a L-or tongue-and-groove-shaped tape means shown at
17. See also FIGS. 11 and 12. In FIG. 4 number 17 denotes an
L-shaped tape means by showing a cross section thereof. Item 17 is
a tape of indefinite length, which can be wrapped around cable 5
and the thus formed composite inserted inside of hole 18 in discs
15 and 16. These tape wrappings tend to fill up the majority of
space not otherwise occupied by the cable 5 in holes 18. Such a
taping technique could be used for small holes 19, in see FIG. 5.
However, the smaller holes are normally provided for drop wire and
as usually is the case the drop wire is of such a diameter that it
virtually fills all of the volume represented by smaller hole
19.
FIG. 3 shows in section view the discs 15 and 16 strung on a bolt
means 14 without the cable means inserted through the holes 18.
Actually, there are three such discs making a sealing means
composite used in combination with the cable 5 outer surface and
the inner surface of compression or sealing chamber 9. However, for
the sake of simplicity only two disc means are shown in FIGS. 3 and
4.
Bolt 14 as shown in FIGS. 3, 4, and 5 has a nut (not shown)
threadedly engaged on its terminal portion. When said bolt 14 is
rotated in a proper direction, disc means 16 and 15 are brought
closer and closer together as a result. The second sealing means
composite, previously made reference to and which is disposed on
the inside of sealing or compression chamber 9, is made up
primarily of cable 5, a sealing compound, and disc means 15 and 16.
A sealing compound (preferably a polyisobutylene), which has a high
internal molecular resistance, deformable under compressive force,
is substantially nonelastic and of high viscosity as well as being
highly self adhesive, and possess the characteristic that when
portions of such material contact with each other under a
compressive force a substantially integral body of the material is
produced, is generally disposed between discs 15 and 16. As stated
previously, the second sealing means composite is disposed on the
inside of sealing or compression chamber 9. This second sealing
means is a composite, which in its entirety is composed of at least
two of the disc means 15 and 16 plus an additional disc, the cable
sheath 5, the polyisobutyl plastic 21 disposed between discs 15 and
16, an internal surface of sealing or compression chamber 9 shown
by the numeral 22, and internal shoulder means noted by number 23
in FIG. 6. All of the aforementioned units act in concert with each
other to form the compression seal.
Turning now for description of such a sealing composite, attention
is directed to FIGS. 6 and 7 where it can be immediately
appreciated that the sealing or seal composite, previously
mentioned, is placed inside of the sealing or compression chamber 9
with the stripped portion of cable 5, exposing electrical
conductors 14, being extended outside of the compression or sealing
chamber 9. In FIGS. 6 and 7 it can be immediately noted, in
contradistinction to FIGS. 3 and 4, that there are shown three disc
means, elements 15, 16, and 20. In FIGS. 6 and 7, a first disc
means 15 is disposed on one side of and inwardly protruding
shoulder means 23 and still another identical disc means 20 is
shown disposed on the opposite side of said shoulder means 23. This
shoulder means 23 is used primarily to fix or anchor the sealing
composite in a predetermined or fixed position inside of the
sealing or compression chamber 9. The reason for this fixation will
become apparent hereinafter in more elaborate detail. A third disc
means 16, like unto that disc means 15 and 20, is disposed in a
spaced part relationship from the internal shoulder means 23.
Between disc 16 and 15 there is disposed packing material 21, which
is normally a polyisobutylene or B-sealing tape.
In FIG. 6, which shows the sealing composite made up of discs 20,
15, and 16 strung on bolt means 14 associated with cable 5, there
is also shown a packing material 21. The composite with the packing
material 21 is loosely laid into the sealing or compression chamber
9 as shown in FIG. 6, with the discs 20 and 15 disposed on their
respective sides of inwardly protruding shoulder means 23. Upon
rotating bolt means 14 or its associated nut 14a in a manner such
that disc means 20, 15 and 16 are brought closer together, the
packing material 21 is compressed. This compressive action forces,
in a sandwichlike fashion, disc 15 to the left and against shoulder
means 23. Concomitantly with this compressive force, disc 20 is
moved to the right and it too engages shoulder means 23, but on an
opposite side thereof. In effect then, shoulder 23 acting in
concert with discs 20 and 15, bolt means 14, and interacting with
the packing 21, which is being placed under a compressive force,
anchors the disc 20, shoulder means 23, disc 15 in a sandwichlike
construction to the sidewall of compression or sealing chamber 9 by
biting action on shoulder means 23. The sidewall innermost surface
of compression or sealing chamber 9 has a nonsmooth surface. That
is to say, there is no need to have the innermost surface of
sealing or compression chamber 9 finely machined or smooth for any
purpose. In fact, during the molding of sealing or compression
chamber 9, the innermost surface of this particular chamber is
purposely roughened, knurled, scratched, or otherwise rendered
nonsmooth so that the packing material 21 will have engaging
crevices in which it will intrude and perfect the desired seal
between the sealing compound 21 and the sidewalls of sealing or
compression chamber 9. In like manner, the cable sheath 5 may also
be roughened, nicked, or scratched--but in no manner completely
penetrated--so as to form a rough surface into which the sealing
material 21 may intrude and perfect a seal between the innermost
innersurface of sealing or compression chamber 9 and the outermost
surface of the cables 5.
FIG. 6, as previously stated, shows the sealing composite loosely
laid on the compression or sealing chamber 9 as a first step
towards complete assembly. On the other hand, FIG. 7 shows the
sealing composite under its compressive force brought about by bolt
14 acting in concert with its corresponding nut 14a shown in both
FIGS. 6 and 7 on the lefthand terminal portion thereof. One
immediately will observe that discs 16, 15 and 20 have been brought
in a closer relationship by the rotation of bolt 14 and its
complementary or corresponding nut 14a on its opposite side.
Furthermore, it will also be noted in FIG. 7 that the discs 20 and
15, disposed on opposite sides of shoulder means 23, actually place
shoulder means 23 in compression. As previously mentioned, this
compressive force or biting action actually acts as an anchor which
fixedly positions the sealing composite, shown in FIG. 6 and 7, to
the sidewalls of the sealing or compression chamber 9. The packing
material 21 shown in FIG. 6 is essentially a tape or bits and
pieces, either granular or strips, of what is known in the sealing
trade as "B-sealing tape." This sealing tape is normally a
polyisobutylene and has the characteristic of being highly
self-adhesive when portions of such material contact with other
portions under compressive forces. As previously noted, materials
suitable for use as a sealing compound would naturally have to have
a high internal molecular resistance, be deformable under
compressive force, substantially nonelastic, and possess a high
viscosity. Most, if not all of the polyisobutylenes possess such
properties. Viewing now FIG. 6 in comparison with FIG. 7, one will
note immediately that the packing material 21 here at this stage of
assembly is composed of substantially integral, discreet elements,
whereas after compressive forces are added as depicted in FIG. 7,
the resinous polyisobutylene is essentially homogenous, possessing
no discreet particles at all. This is shown in cross section as
21a. In FIGS. 6 and 7, disc 20, 15, and 16, as well as the cables 5
were not shown in cross section for the sake of simplicity and to
avoid confusion. Whereas on the other hand, in FIG. 6, the packing
material 21 was not shown in cross section because when this
packing material is initially introduced into the composite sealing
assembly previously described, it is particulate in nature and not
yet integral. However, on the other hand, one only needs to observe
FIG. 7, especially that element denoted by numeral 21a to
understand that the packing material 21 in FIG. 6, after having
been subjected to compressive forces, is compressed and made
integral with all of the particulate particles heretofore unjoined
and discreet as shown by element 21. It will be further appreciated
that the innerface created between the contacting surfaces of discs
15 and 16 with the innermost sidewalls of compression or sealing
chamber 9 are not exactly airtight, absent the polyisobutylene or
sealing material 21 or 21a. However, upon compression of the
polyisobutylene material 21 into its integral state as shown in
21a, the polyisobutylene tends to intrude into the innerface
created by the contacting surfaces of discs 15 and 16 and the
innermost sidewalls of compression or sealing chamber 9. This
intrusion into this specified innerface creates an airtight seal,
thus keeping out all water vapor and other unwanted gases as well
as water in the liquid state.
One feature of the instant invention upon which there cannot be
placed too much emphasis is the fixing means or anchoring
combination created by the coacting elements of discs 20, 15 and
shoulder 23. Although a perfectly usable and viable sealing means
can be created using only discs 15 and 16, absent any disc 20 or
shoulder means 23, such a sealing combination is subject to being
disturbed by subsequent high levels of gaseous pressure being
disposed against disc 16 and acting in a manner in which said disc
16 would be urged in a leftward manner. It has been previously
pointed out, during the discussion of FIG. 1, the primary function
of plug means 13 disposed in the dome splice case of the instant
invention. When 20--25 lbs. p.s.i.g. are introduced into the splice
dome 10 through the hole occupied by plug means 13, this particular
high amount of pressure is obviously applied against disc means 16.
This pressure subsequently urges the disc means 16 in a leftward
manner. If it were not for shoulder means 23, then it would be
quite possible under certain circumstances that the composite lying
between disc means 16 and disc means 15 could be moved in its
entirety in a leftward fashion. Such movement would obviously
disturb the integrity of the thus formed seal and invite the
leakage of air, water, and water vapor from outside of the splice
case to the inside.
The foregoing discussion shows how seal integrity can be disturbed
when there is no shoulder means 23 such as that shown in FIGS. 6
and 7. Thus, the seal integrity is important so as to insure the
exclusion of moisture from the splice case itself or the loss of
air pressure from within the splice case to the outside ambient
atmospheric pressure. Wheat has been previously described is the
loss of seal integrity by moving the composite from an original
sealing position in a leftward manner. Obviously if the original
seal is moved in a rightward fashion the sealing integrity is also
broken and the same invitation to moisture entrance is initiated.
Thus, it is quite obvious that neither leftward or rightward
movement of the sealing composite is desired. Absent disc 20 and
inward protruding shoulder means 23, the sealing composite made up
then only of discs 15 and 16 are associated components could then
be moved in a rightward fashion by an intentional or even an
inadvertent force acting on disc 15 and emanating from outside the
sealing or compression chamber 9. Consequently, the anchoring or
fixing action of discs 20 and 15 biting or compressing shoulder
means 23 anchor the sealing composite in a fixed, but nonetheless
removable, position inside the sealing or compression chamber 9. By
this anchoring action, the sealing composite may move neither to
the left nor to the right, thus maintaining complete seal integrity
between the composite sealing means and the innermost surfaces of
sealing or compression chamber 9.
Turning now to FIG. 8, there is shown in this delineation the
coaction between O-ring 24 and face plates 11 and 12 with the
associated U-shape groove 25. It is to be understood that the
U-shaped groove 25 is not a singular groove being only in face
plate 11, but has a counterpart in faceplate 12. In the well-known
manner, O-ring 24 lies partly in groove 25 and a corresponding
U-shaped groove in faceplate 12 when the faceplates 11 and 12 are
joined in a seating engagement as shown in FIG. 1.
The O-ring used in the instant invention obviously must be an
O-ring of outstanding sealing properties. Ordinarily, just any kind
or elastomeric material would not be appropriate for the
temperatures that are anticipated to be encountered when the splice
case is underground or in buried service. However, generally
speaking the O-ring 24 can be made out of most any kind of silicone
rubber. Specifically, however, any silicone rubber that possesses
the specifications and qualities of military specification 58470
(MIL-R-58470) and/or Aeronautical Material Specification 3303E
(AMS-3303E) would be sufficient for practical purposes. The O-rings
used in the instant invention not only live up to and conform to
the aforementioned government specifications but were purchases on
the commercial market from Prevision Rubber Products bearing the
catalog number 113076.
Still focusing attention on FIG. 8, there is shown in this
particular FIG. in the upper right-hand corner thereof, three
cables all identified by the numeral 5. Furthermore, these cables
are shown, deliberately so, as cables of varying diameters. For the
sake of clarity and delineation in the instant drawing, the
associated continuing portions of cable 5 as they would obviously
extend through the compression or sealing chamber 9 through O-ring
24 and terminate in the dome splice case 10 are not shown. FIG. 8
should be viewed along with FIG. 5 because the combined teachings
of these FIGS. are used to point out that not only cables of a
singular diameter can be used in the instant splice case but also
cables of a number higher than two and of all varying diameters.
FIG. 5, as it will be remembered, shows three large holes 18 in the
disc means 15 and 16. Also three smaller holes indicated by the
numeral 19 are also shown in discs 15 and 16. Normally, cables of
larger diameter occupy the holes indicated by the numeral 18
whereas on the other hand drop wires or cables of a much smaller
diameter are led out of he splice case through holes 19. If holes
19 are not desired to be used when the splice case is being
installed, then the sealing composition identified as
polyisobutylene can be used to fill these holes and prohibit the
entry of air or water vapor into the interior of the splice case.
Obviously, the filling of small holes 19 is accomplished by the
compressive force being applied to discs 15 and 16 and thus
transferred from these discs to the packing material
(polyisobutylene) initially shown as uncompacted in FIG. 6 by
numeral 21 and ultimately shown as compacted and in sealing
engagement in FIG. 7 as item 21a.
It is envisioned that one may take advantage of smaller holes 19 by
employing foresight when the splice case is being installed. If at
the time of splice case installation there is no immediate need for
any drop wires to be spliced into the cable and let out of the
splice case into the installation nearby, but, there may be some
reasonable expectation that in the somewhat distant future that
such a need may occur, a length of drop wire may be installed for
just such a purpose in the manner that will be described. Taking a
length of drop wire long enough to extend from the exposed
electrical conductors 14 out of the splice dome case into the
sealing or compression chamber 9 and out of the chamber 10 into the
surrounding atmosphere for a predetermined length and then returned
by a parallel path, this wire is looped in a fashion to where the
two ends are brought in side-by-side relationship. Thus, a loop is
formed. Still maintaining the loop configuration thus made, the two
ends of the wire are pushed through two different holes 19 in disc
15 and corresponding holes in disc 16 as well as disc 20 as shown
in FIGS. 6 and 7. The loop thus threaded in the aforementioned disc
is then pushed further bringing the side-by-side ends of the loop
closer and closer to the exposed electrical conductors 14 as shown
in FIG. 2. When the ends have been extended far enough to where
they can be and are spliced into appropriate electrical conductors
14, then the thus looped and spliced in wire is ready for final
assembly in the same manner as the cables 5. This manner of sealing
is the same as that shown and described in previous discussions
relating to FIGS. 6 and 7.
After following the foregoing procedure the resulting assembly has
a loop of wire extending from the compression or sealing chamber 9,
one portion which comes out of the sealing chamber and the other
end naturally going back into the sealing chamber. Both ends of
this loop, as previously discussed, extend into the splice dome 10
where the ends of the wire are spliced into appropriate electrical
conductors 14 as shown in FIG. 2. Also in this assembly there
extends from the compression chamber 9 cables 5 in the same manner
as that as been previously discussed. Consequently, when there is a
need for a drop wire service, a workman need only dig up the splice
case--if indeed the splice case is buried--cut the loop formed
during initial installation thereby creating two drop wire stubs.
Either one or both of these stubs may be used, whichever the case
may be. Obviously if only one stub is used then the terminal end of
the unused stub should be sealed up with sealing tape or
encapsulated with an epoxy as is well known. Such a procedure forms
no part of the instant invention and will not be further discussed.
In the same manner, a looped cable stub--that is a cable carrying a
multiplicity of pairs--can be installed with the splice case much
in the same manner as that previous description running to the drop
wire loop. Obviously, neither one of these loops of cable or drop
wire are in immediate service but can be placed into service by a
very simple expedient of cutting and resplicing employing unskilled
labor.
The advantage of the foregoing looping of either drop wire or cable
in the manner just disclosed is that no disruption of the seal
existing between cable or wire outer surfaces and the innermost
surface of compression or sealing chamber 9 is necessary to
activate the looped wire or cable. Once this seal is achieved, it
is better practice not to disturb its integrity as it is this seal
that is the most sensitive to the possibility of leaks of both air
and water vapor.
Attention should now be focused on FIG. 9 wherein there is shown a
disc means 15 having eight holes therein. In this particular FIG.
the disc means is shown as 15, but it will be understood that discs
16 and 20 would also be of like configuration. As it has been
previously noted, the larger holes 18 in disc means such as 15 are
normally used for cables carrying a multiplicity of electrical
conductor pairs. It has also been previously stated that the
manufacture of disc means 15 with the holes 18 therein, must
encompass a procedure whereby the largest hole possible is formed
in disc means 15 as shown by the numeral 18. Of course the overall
design (size) and number of holes 18 and 19 are commensurate with
the physical strength necessary for disc means to carry out its
intended function. Nonetheless, consistent with the foregoing
structural requirements, holes 18 are designed to carry the largest
cable anticipated to be used for a particular splice case.
Obviously this does not prima facia take care of or account for the
use of cables that have a diameter smaller than that of the hole
18. To take care of this possibility, a "taping" of the hole 18 is
used in order to take up the space not otherwise occupied by the
cross-sectional area of the cable that is used and disposed in hole
18.
Once a determination is made that the cable used in holes 18 will
be smaller than the holes 18, then tape 25 as shown in both FIGS. 9
and 10 is used to take up the space not otherwise occupied by the
cable in hole 18. This tape is usually a plastic tape and it can be
made out polyvinyl chloride. Polyvinyl chloride is given as an
exemplary only and is not to be construed as limiting because the
tape obviously can be made out of polyethylene, polypropylene,
polystyrene and the like. Also, such a tape can be made out of
elastomeric material such as silicone or natural rubbers. In
essence the tape 25 is made into a washer or a packing that merely
takes up space and tends to lock itself into mechanical engagement.
It also can and does help contain the sealing material
(polyisobutylene) which it disposed on one side of the disc 15. In
FIGS. 9 and 10, the tape used here is an L-shaped tape. Each
revoultion--shown as 25a and 25b--is cut so that terminal end
portions abut one another and essentially create an entire
revolution forming a gasket or washerlike insert. Such a revolution
as shown in 25a and 25b are inserted into the holes 18 until there
is enough space taken up by the tape that the cable passing through
the reduced diameter of the hole will be in touching engagement
with the innermost surface created by the tape 25 gasket or
washerlike configuration.
Attention is called to the assembly as shown in FIG. 10 where the
tape, as previously mentioned, more clearly shows its L-shape.
Number 26 shows one leg of the L-shaped portion whereas number 27
of the tape more or less indicates the shank portion or other leg
forming the L-configuration. Obviously, tape 25b is also of the
same shape since its shank portion is fully extended and the flange
or horizontally protruding L-forming portion of this particular
tape being flush with the proceeding tape. Tape 25b's particular
overall L-shpaed configuration is not shown as well as its
preceding tape 25a, this latter tape configuration being indicated
by the numerals 26 and 27. FIG. 10 completes the disclosure of how
the tape is used in combination with cable 5 and disc 15. Viewing
this FIG., one can see how the disc 15 acts in concert with the
space occupying tape 25 with the cable nesting inside of the
individual revolutions of tape 25. In passing, it might be well to
note that ordinarily the space occupying tape is not usually used
in combination with drop wires and smaller holes such as 19.
However, this is not to say that the tape is never used with such
smaller holes, the use of this tape being dependent largely on the
size of hole, the size of the cable to be disposed in the hole,
along with the overall economics of the splice case installation
method.
In further amplification of the specific plastic tape discussed
above, attention is drawn to FIGS. 11 and 12. In these two FIGS.
two different embodiments of the aforementioned tapes are shown.
The first embodiment, is shown in FIG. 11. This embodiment is the
previously mentioned L-shaped tape and its L-shape cross section
can be readily appreciated from this particular FIG. The second
embodiment of the tape employed is shown in FIG. 12 which is not an
L-shaped tape. This tape is a tongue-and-groovelike tape as shown
by its characteristic cross-sectional configuration with the
tongues on one side of the tape being complementary and fitting
into the grooves on the opposite side of the tape. Thus, it can be
readily appreciated that a revolution of such a tape nesting inside
of a tape made of the same material can be used to form a tongue
and groove seal. As a result of the tongue-and-groove configuration
on both sides of the tape, the outermost surface of the first
revolution would be in complementary engagement in a
tongue-and-groove fashion with the innermost surface of the second
tape revolution. Experience has shown that it makes no difference
which one of the particular tape embodiments is used, i.e.
tongue-and-groove or L-shaped tape. The tongue-and-groove
embodiment is just as efficient as the L-shaped tape. Thus, the use
of either one is arbitrary and a mere matter of choice.
From the foregoing disclosure one can be readily appreciate that
there has been described a splice case of novel and unusual
characteristics that meet the needs currently plaguing the
telecommunications industry. Presently, this is the only known
splice case that has been able to stand the rigorous tests of the
Rural Electrification Administration identified as Phone Equipment
(PE) 70 (1967). There is no other known test, either ASTM or
otherwise that is designed to test the viability of splice cases
adapted to be used in conjunction with a pressurized
telecommunications system. The forementioned REA PE 70 test is one
that requires that a self-contained splice case be charged with at
least 25 p.s.i.g. air pressure. What is meant by self-contained is
that the cables used during this test create a short circuit. That
is to say, any cables led out of a splice case are immediately
looped around and brought back into the same splice case. A splice
case thus assembled, and charged with the necessary internal
pressure of 25 p.s.i.g. is then put through 50 cycles of severe
temperature changes. A cycle is defined as four clock hours at
-40.degree. F and then while at that temperature, the cold splice
case is plunged into an oven set at 140.degree. F and maintained at
that temperature for four hours. After 50 of the above described
cycles have been completed, a test is made to determine how much
air pressure still remains inside of the splice case. The Rural
Electrification Administration requires tat a minimum of 4 p.s.i.g.
must remain inside of the splice case at the end of the 50 cycles.
That is to say, if after the forementioned 50 cycles, a splice case
still contains 4 p.s.i.g. of pneumatic pressure, then it is to
receive the seal of approval from the Rural Electrification
Administration. When the instant splice case was put through its
paces using the REA PE 70 (1967) splice case testing procedure as
previously described, the amount of air pressure left inside of the
splice case after the 50 cycles was not 4 p.s.i.g. but two times
the minimum required for satisfactory approval by the Rural
Electrification Administration. In other words, after the 50 cycles
the instant splice case exhibited an 8-pounds per square inch gauge
internal pressure. Obviously, there was a loss of 16 p.s.i.g.
during the 60-cycle testing procedure. It is anticipated by both
the Rural Electrification Administration as well as those in the
industry that cable sheaths currently being used in
telecommunications system are the prime source of air pressure
loss. It is thought that the pressure is lost through the cable
sheaths by osmotic action. Since the temperatures encountered by
the splice case assembly and the cable looped into and out of the
splice case are rather severe, i.e. -40.degree. F to +140.degree.
F, there is a definite osmotic effect which argues for the escape
of gases from the pores of the cable sheath. This kind of osmotic
effect is known in the telecommunication pressurized industry, and
this phenomena was built into the Rural Electrification
Administration's test devised for splice cases. That is to say,
there was expected to be a pressure loss from the original 25
p.s.i.g. introduced into the splice case. In retrospect, one can
see that there was to be an expected loss from 25 p.s.i.g. down to
4 p.s.i.g. Such a loss of 21 pounds during the cycling period was
considered by the Rural Electrification Administration to be normal
and to be anticipated through the forementioned osmotic effect.
Thus, even a 21-pound loss would still render a splice case
suitable for Rural Electrification Administration's approval.
Almost in contradistinction to the expectancy of the Rural
Electrification Administration Phone Equipment test 70, the instant
splice case had a residual pressure of 8 p.s.i.g. and lost not 21
pounds during the cycling process but only 17 p.s.i.g.
One feature of the instant invention that has not been discussed is
the effect of the compression seal which seals the outermost
surfaces of the cables of the splice case assembly to the innermost
surface of the compression or sealing chamber 9. When it is
realized that the cores of most cables contain electrical
conductors that are also covered with an extruded covering of
plastic insulation, it can be anticipated that such a plurality of
electrical conductors--otherwise known as pairs--may cross one
another. That is to say, one electrical conductor may physically
lie across the path of another electrical conductor or a plurality
of electrical conductors for that matter. When compression is
created by bringing discs 15, 16, and 20 closer and closer together
and thereby putting polyisobutylene 21 under compression, this
compressive force is correspondingly transmitted from this
polyisobutylene material to the cable sheath 5 and obviously into
the core of the cable. Initially, it was feared that such a
continued, long sustained, and high compressive force would be of
such a nature that "cold flow" of the plastic surrounding the
electrical conductors in the core would take place. If cold flow
would take place as a result of this compression, then the
insulation surrounding the electrical conductors would be reduced
at the point where one electrical conductor contacted (crossed) and
adjoining an electrical conductor. This cold flow phenomena was not
observed in the cables used in designing the instant splice case
invention. It may be said in speculation that the compressive
forces generated by the sealing means composite in the sealing or
compression chamber 9 is of such a magnitude to accomplish the job
of sealing the cables to the innersurface of the sealing or
compression chamber 9 without transmitting the necessary cold flow
forces into the interior of the cable 5. Thus, in the absence of
any cold flow of the insulation surrounding the particular
electrical conductors in the core of the cable, short circuits,
attenuation loss, and crosstalk are virtually eliminated.
Viewing the foregoing disclosure in its entirety, one can come to
the conclusion that the instant disclosure sets forth a splice case
assembly of unique and outstanding features. Other innovators in
this particular field, namely, G.E. Peterson, in his patent
disclosure 3,381,082 (C1.174--93) approaches the same problem as
the instant disclosure in a radically different manner. As with
Peterson as well as other investigators in the particular area of
concern, no provision whatsoever was made for reentry into the
splice case without disturbing the compression seal formed in a
chamberlike compression or sealing chamber 9. The prior art all
requires that reentry into a chamber containing conductor pairs
must be accomplished by breaking the compression seal and thereby
disturbing its integrity. The only other way one could achieve
entrance into a chamber containing conductor pairs without breaking
the compression seal would be to actually destroy the splice case
itself by a cutting operation. Obviously this cutting operation is
undesirable as is the breaking of the compression seal. Thus, it
can be immediately appreciated that the instant invention discloses
a splice case assembly that permits ready access to a chamber that
contains the conductor pairs without disturbing a seal that seals
the outermost surface of the cable surfaces to the innermost
surface of the splice case itself. The instant invention requires
only that an O-ring-type seal be broken so as to expose the
conductor pairs. Once the conductor pairs are exposed, then work
can proceed in any manner desired for any purpose required. Once
such work is completed the O-ring-type seal can be reactivated
using the same O-ring that was previously installed with the splice
case itself, the sealing tested and the splice case placed back
into service without any disturbance of the seal between the cable
surfaces and the splice case sealing or compression chamber 9 inner
surface. Consequently, using this particular structured splice case
has many unique advantages over that of prior art splice cases.
Furthermore, prior investigators, such as G. E. Peterson, have all
used a threaded seal and attempted to extend this threaded seal
concept to plastic splice cases. As is commonly known, threaded
portions on plastic structures are not well adapted to maintain
seal integrity, especially seal integrity of the high order
required in pressurized splice cases. It will be immediately noted
that there is no such threaded seal concept in the instant
invention, the sealing concept used in the instant invention
depending entirely on compression which lends itself admirably to
the basic structural strength of plastic materials.
From the foregoing, it is believed that the invention may be
readily understood by those skilled in the art without further
description, it being borne in mind that numerous changes may be
made in the details disclosed without departing from the spirit of
the invention as set forth in the following claims:
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