U.S. patent number 3,571,486 [Application Number 04/797,490] was granted by the patent office on 1971-03-16 for pressurized communication cable and system.
Invention is credited to Walter T. Kennedy.
United States Patent |
3,571,486 |
Kennedy |
March 16, 1971 |
PRESSURIZED COMMUNICATION CABLE AND SYSTEM
Abstract
Disclosed herein is a pressurized communication system and a
novel-type cable forming a significant component of the pressurized
system. Such a system is composed of a plurality of spaced-apart
enclosures, which may contain means for transmitting, modifying,
amplifying or repeating an electrical signal. Each of the
enclosures is connected one to another by a novel-type cable, which
comprises a plastic sheath surrounding and defining a first cable
portion containing electrical conductors and a second cable portion
containing a longitudinally disposed cavity adapted for the
transport of a fluid (dry gas). The electrical conductors of the
cable are in electrical connection with a transmitter, repeater,
modifier, or amplifying means and the fluid carrying cavity portion
of the cable may be in pneumatic communication with the inside of
the enclosure and physically separable either in whole or in part
from that portion of the cable containing the electrical
conductors.
Inventors: |
Kennedy; Walter T. (Newton
Square, PA) |
Family
ID: |
25170971 |
Appl.
No.: |
04/797,490 |
Filed: |
February 7, 1969 |
Current U.S.
Class: |
174/11R; 174/47;
174/70R |
Current CPC
Class: |
H01B
11/1895 (20130101); H01B 7/0072 (20130101) |
Current International
Class: |
H01B
11/18 (20060101); H01B 7/00 (20060101); H01b
007/00 () |
Field of
Search: |
;174/8,11,14,15 (C)/
;174/16,18,24,41,47,68,70,70.1,70.4,115,113.2,12,13 ;340/320
;339/15,16 ;179/170,179 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
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129,667 |
|
Sep 1932 |
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OE |
|
916,363 |
|
Aug 1946 |
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FR |
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285,920 |
|
Sep 1968 |
|
AU |
|
1,222,734 |
|
Jan 1960 |
|
FR |
|
902,988 |
|
Feb 1954 |
|
DT |
|
206,441 |
|
Jan 1968 |
|
SU |
|
Primary Examiner: Askin; Laramie E.
Claims
I claim:
1. A cable comprising an essentially impervious plastic sheath of
indefinite length which surrounds at least two spaced-apart,
longitudinally disposed cavities, one of said cavities being
occupied by a center conductor circumscribed longitudinally by a
dielectric material which is in turn circumscribed by a second
conductor and the other cavity being essentially unoccupied and
adapted for the longitudinal transport of a fluid therethrough,
that portion of the plastic sheath lying between and connecting the
plastic surrounding said first and second cavities being
configurated so as to permit division of said plastic sheath into
at least two such sheaths each containing one of said cavities.
2. A cable as defined in claim 1 wherein said sheath defines a
third cavity in which is disposed a means for structurally
supporting the entire weight of said cable.
3. A cable as defined in claim 1 wherein that cavity adapted for
the longitudinal transport of a fluid contains a tubular means
longitudinally disposed therein.
4. A cable as defined in claim 3 wherein said tube is constructed
of a plastic of a composition differing from the plastic
sheath.
5. A cable as defined in claim 3 wherein said tube is constructed
of a metal.
6. A pressurized communications system comprising a plurality of
spaced-apart enclosures containing means for modifying an
electrical signal connected one to another by a cable comprising a
plastic sheath defining a first cable portion containing electrical
conductors and a second cable portion containing a longitudinally
disposed cavity adapted for the transport of a fluid, the
electrical conductors being in electrical connection with said
modifying means and said cable second portion being in pneumatic
communication with the inside of said enclosure.
7. A communications system as defined in claim 6 wherein said
second cable portion is physically separated from said first cable
portion just before it reaches the outside surface of the sidewalls
of the enclosure and terminates just after passing into the
interior of said container.
8. A cable comprising an essentially impervious plastic sheath
defining a first cable portion having a first longitudinally
disposed cavity, in which a plurality of insulated electrical
conductors are contained, and a second cable portion having a
second cavity adapted for the longitudinal transport of a fluid and
a valve means disposed in said first cavity adapted to establish
communications between the interior of said first cavity and that
atmosphere in contact with the outside surface of said plastic
sheath.
9. A pressurized communication system comprising a plurality of
spaced-apart means for modifying an electrical signal, each of said
means being enclosed in a container having sidewalls and connected
one to another by a cable composed of a plastic sheath defining a
first cable portion having a first longitudinally disposed cavity
in which a plurality of insulated electrical conductors are
contained and a second cable portion having a second longitudinally
disposed cavity adapted for the longitudinal transport of a fluid,
the electrical conductors of said cable first portion being in
electrical connection with said modifying means and said first and
second cable portion being in pneumatic communication with the
inside of said container so that pressurized fluid may be
introduced into said container from said first and second cable
portions.
10. A communication system as defined in claim 9 wherein a valve is
disposed in said second cable portion between the container means
adapted for the expulsion of water accumulated in that space of
said first cavity not otherwise occupied by the insulated
electrical conductors.
11. A communications system as defined in claim 10 wherein said
valve is responsive to open at a predetermined pressure.
12. A communications system as defined in claim 10 wherein said
valve is responsive to open at a predetermined moisture content.
Description
This invention relates to pressurized communication systems and
more particularly to the structure of a novel-type cable and its
use in a pressurized communication system. Such cable as disclosed
herein is normally used in low voltage level applications as in
connection with voice transmission lines (telecommunication lines)
or television signal transmission.
In the main, it is the primary purpose and one of the fundamental
objects of the instant invention to provide a cable structure that
can be used either aerially or underneath the soil, which can give
rise to a unique pressurized system. For example, within the scope
of coaxial cable transmission systems using either an expanded or
unexpanded polyethylene dielectric, conventional cable construction
precludes a pressurized system that uses any part of the cable for
gas passage. In view of the fact that the instant invention
visualizes a tube addition integrally fixed to a coaxial cable, dry
air or gas can be forced under pressure into, through and out of
equipment enclosures connected together by the cable itself. Such a
system, using the novel type cable disclosed herein, enables the
creation and maintenance of a stabile atmosphere and pressure
within enclosures housing such devices as CATV amplifiers,
telephone repeater units, and any pole mounted or underground
equipment whose proper operating characteristics are stabilized or
enhanced by dry gas pressurization.
In the area of multiconductor communication cables, as
distinguished from coaxial cable, the structure of the novel-type
cable allows the transmission of dry gas through that part of the
cable carrying the electrical conductors as well as that cable part
especially designed for such transport to and into desired
enclosures. Thus, gas may be used to pressurize such enclosures,
but the gas also may be used to purge water that may collect in a
cavity where insulated electrical conductors are confined. Gas can
be forced from each enclosure into that longitudinal cavity in
which a plurality of insulated conductors are disposed; therefore,
water collecting in said last-mentioned cavity is forced towards
the middle of each cable section between enclosures. A valve
adapted to open and close automatically by the degree of moisture
or pressure within that cavity of the cable enclosing insulated
electrical conductors may be inserted in the cable between any two
enclosures. Such a valve is optimumly placed at the point in the
conductor carrying portion of cable section where pneumatic
pressure is equal from both directions. Thus, each cable section
can be automatically purged of moisture when such moisture reaches
an undesirable level. Furthermore, enclosures that need to be
bypassed and not pressurized can be in a simple and inexpensive
manner.
The foregoing delineates the objects of the instant invention,
other objects, advantages and features of the present invention
will become apparent from he following detailed description, one
embodiment of which is present in conjunction with the drawings, in
which:
FIG. 1 shows a cross section of a figure "8" Cable, wherein the
plastic sheath of the cable describes two cavities, one such cavity
being longitudinally disposed and essentially unoccupied and the
other such cavity containing an outside and inside conductors
separated by a plastic dielectric;
FIG. 2 shows essentially the same subject matter as FIG. 1 except
that FIG. 1 discloses a metal tube disposed in the essentially
unoccupied cavity whereas FIG. 2 uses a plastic tube disposed in
that cavity;
FIG. 3 is a fragmentary view of a cross section of a FIG. "8"
Cable, wherein there is shown two cavities longitudinally disposed
in the plastic sheath, one such cavity containing a metal tube and
the other such cavity containing a plurality of electrical
conductors;
FIG. 4 shows a plastic sheath containing three longitudinally
disposed indefinite length cavities, the plastic portion of an
integral sheath surrounding said cavities being connected one to
another by a plastic web, one of said cavities being essentially
unoccupied but containing a metal tube longitudinally disposed
therein, another of said cavities being occupied by a centrally
disposed electrical conductor nested inside of a tubular outside
electrical conductor, these conductors separated one from another
by a plastic dielectric, and the third cavity being essentially
occupied by a messenger cable which is adapted to support the
entire cable;
FIG. 5 shows a pressurized communication system that includes
spaced-apart enclosures containing amplifying or repeater means
pneumatically and electrically connected together by a means of the
novel-type cable disclosed herein; and,
FIG. 6 shows a cross section along lines 6-6 of FIG. 5.
Turning now to FIG. 1, this drawing shows in cross section the
structure of an indefinite length cable indicated by element 1. A
tubular conduit 3 is surrounded by an impervious plastic sheath 2
forming an essentially unoccupied cavity 4 longitudinally disposed
in the cable sheath and adapted to transport a fluid. A web 19
connects this fluid-carrying portion of the cable with that portion
of the plastic sheath 2 that surrounds electrical conductors 5 and
7, which are, in this particular embodiment, a tubular outer
conductor 5, usually made of metal such as aluminum or copper and
the like, and center conductor 7, centrally disposed inside of
tubular electrical conductor 5. Center conductor 7 is insulated
from outer electrical conductor 5 by dielectric 6, which can be
either expanded or unexpanded plastic, the composition of which can
be the same as or different from that of plastic sheath 2. In
effect, elements 5, 6, and 7 make up a coaxial cable surrounded by
an outer plastic sheath 2, this outer plastic sheath being joined
by web 19 to the same plastic sheath 2 which surrounds a metal
conduit or tubular means 3, the latter being adapted to carry a
fluid in the longitudinal direction. It is to be understood,
however, that metal tube 3 of FIG. 1, as well as plastic tube 3' of
FIG. 2, can be deleted. In this case, cavity 4 formed by plastic
sheath 2 is used to transport a fluid in a longitudinal
direction.
The figure "8" Cable shown by element 8 of FIG. 2 is essentially
the same as that shown by element 1 in FIG. 1, except for the fact
that the metal tube 3 of FIG. 1 has been replaced by a plastic tube
3'. Usually, but not absolutely necessary, this plastic tube 3' is
of a different composition from that forming web 19 and plastic
sheath 2. For example, tube 3', as well as plastic sheath 2, can be
made from polyethylene, either of the high or low density type,
polyvinyl chloride, polycarbonates, fluorinated hydrocarbons
(Teflon) and nylon. In some instances, it may be desirable to have
plastic tube 3' filled with a finely divided filler such as metal
or a silica material (quartz, ground rock and the like) in order to
make this particular plastic tube abrasive and resistant to attack
from outside elements, such as gophers, tools of careless workmen,
and intentional vandalism.
Elements 1 and 8 of FIGS. 1 and 2 are made from a coaxial cable
portion composed of elements 5, 6, and 7 integral, via sheath 2 and
web 19, with a cable containing a longitudinally disposed cavity 4,
adapted for the transport of a fluid, created by elements 3 or 3'.
Heretofore, there has been a need for such a cable like 1 and 8,
but cable fabricators have always attempted to position the
fluid-carrying, longitudinally disposed cavity 4 in the dielectric
6. Such a positioning of this cavity 4 in that particular area 6
disrupts the electrical characteristics of the coaxial cable. Thus,
complicated electrical design problems were created in an effort to
recoup those electrical properties normally incident to coaxial
cable structure.
Shown in FIG. 3 is a figure "8" Cable having a structure much like
that of the figure "8" Cables in FIGS. 1 and 2. In fact, from web
19 upwards, the structure of the cable 9, shown in FIG. 3, is the
same as the cable 1, shown in FIG. 1. Thus, no further discussion
of this particular structure is deemed necessary. The balance of
cable 9 of FIG. 3, from web 19 downward, resembles the balance of
the cable 1 and 8, shown in FIGS. 1 and 2 respectively, only in the
sense that there is a cavity in which electrical conductors are
disposed. This cavity 20 is filled with three elements, namely
metal tape 10, plastic tape 11, and insulated electrical conductors
18. The metal tape, the extremities of which overlap one another to
form a circular configuration, can be either a metal tape per se
made from steel, aluminum or copper or alloys thereof or it can be
a plastic-coated tape much like that shown in the U.S. Pat. to
Jachimowicz (No. 3,233,036). Plastic tape 11 can be either a
noncorrugated polyethylene terephthalate tape or corrugated tape
such as that shown and described in Roberts' U.S. Pat. No.
3,244,799. Of course, the polyethylene terephthalate composition of
plastic tape 11 is exemplary only and other compositions could be
used as equivalents such as polyethylene, PVC, polycarbonate,
halogenated hydrocarbons, and nylon.
Cable 13, shown in FIG. 4, is a variation of that cable structure 1
shown in FIG. 1. An additional web 19 has been added to the cable
structure 1 of FIG. 1 and this additional web is integral with
plastic sheath 2, which completely surrounds a messenger cable 12.
This last-mentioned messenger cable is usually made up of a
plurality of metal strands so designed, woven, and structured so as
to be adapted to carry the entire weight of the cable. Thus, cable
3 in service is strung using the messenger cable 12 in an aerial
disposition, the messenger cable 12 being structurally adapted to
carry not only its own weight, but the weight of the balance of the
cable as well. This messenger portion of cable 13 shown in FIG. 4
is essentially the same as the messenger cable portion shown in
U.S. Pat. to Pusey, No. 3,267,201 and can be formed in the same
manner as disclosed in this particular prior art disclosure.
FIG. 5 shows a portion of a pressurized telecommunications system
with elements 15, 15' and 15" representing enclosures in which
there are disposed amplifying, modifying, repeating, or splicing
means, which either amplify repeat, or connect the signal
transmitted along electrical conductors inside of the cable
represented by component 22. The line 6--6 indicates a cross
section through the cable and valve means 17, which is located
approximately midway between two enclosures 15 and 15'. As
previously indicated, the cable connecting enclosures 15, 15', and
15" are interconnected one to another by means of a cable, that
cable having two portions indicated by fluid-carrying portion 21
and electrical-carrying portion 22.
In FIG. 6, element 16 shows the cross section along line 6--6,
which passes through valve 17. The cable structure shown in 16 is
essentially the same as that of element 9 of FIG. 3, except for the
addition of valve 17. This particular valve can be either pressure
or moisture sensitive in the sense that it will respond, i.e.,
open, when a given pressure is achieved or when a predetermined
moisture content has been detected. In the cable system 14, of FIG.
5, cable 16 of FIG. 6 is used. Both cavity 4, [cable portion 21]
and that cavity created by metal tape 10 not otherwise occupied by
insulated electrical conductors 18, [cable portion 22] are under
pressure and are thus used to transmit longitudinally a fluid (dry
gas for example). Thus, in this embodiment, both cavities 4 and 23
would carry a dry gas under pressure.
Gas pressure in cavity 4 is envisioned to be greater in most
circumstances than that in cavity 23. Assuming for example that the
air or gas under pressure flows from left to right (FIG. 5), the
total pressure in enclosure 15 would be the sum of the pressures in
cavity 23 plus 4 and thus would be greater than that in the
individual cable portions 21 and 22 defining respectively cavities
4 and 23. Therefore, that in cavity 23 upstream therefrom. Hence,
some of the dry gas in enclosure 15 will flow to the left,
consequently forcing any condensed water in cavity 23 towards cable
valve 17. When a predetermined pressure or moisture content is
detected by valve 17, this valve opens and cavity 23 is thus purged
of collected moisture. Gas pressure in enclosure 15' forces dry gas
in the rightwardly direction in cable 22 [cavity 23] consequently
forcing moisture condensation towards valve 17 and its subsequent
expulsion in an automatic manner from the cable system 14.
In FIG. 5, it will be noted that cable portion 22 carrying the
electrical elements of the cable is separated from cable portion 21
just before cable portions 21 and 22 enter enclosures 15 and 15'.
Usually, separation takes place in web 19 and is for ease of
attachment of the cable to the enclosures. Previous discussion of
FIG. 5 employed that cable structure 16 shown in FIG. 6 as the
cable portion of the pressurized system; however, cable structures
[13, FIG. 4]; [9, FIG. 3]; [8, FIG. 2]; and [1, FIG. 1]can all be
used as that cable portion of the pressurized system as shown in
FIG. 5, it being understood that pressurized gas would exist only
in cavity 4 in these specific embodiments.
One of the great advantages of the cable structure shown by
elements 1 and 8 of FIGS. 1 and 2 respectively, is that
fluid-carrying cavity 4 can be used to pressurize enclosures such
as 15, 15' and 15" in which amplifiers, repeaters, modifiers,
splitters, or splices are located. In the technological area of
telecommunications, enclosures 15, 15' and 15" may be what is
called a "splice case" and they contain load coils and other
well-known apparatus incident to telecommunications systems.
Therefore, a splice case which is an enclosure, can be pressurized
suing this cable with relative ease.
Previous discussion has emphasized the use of the cable structures
for purposes of transmitting data from one point to another;
however, the cables shown in the drawings, can be used in
conjunction with electrical power transmission and the cavity
integral with such power-conveying electrical conductors can be
used to moderate temperature and/or moisture control of remote
transformers, breakers and other power system facilities. Such an
application of the instant cable structure to the field of power
transmission is quite obvious from the instant disclosure and one
of only ordinary skill in the art only need the disclosure
previously set forth before him to construct a power-transmitting
facility that can be and is pressurized for various and sundry
purposes.
From the foregoing, it is believed that the invention may be
readily understood by those skilled in the art so that further
descriptions are unnecessary. It being born 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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