US2475787A

US2475787A - Termination for coaxial cables

Info

Publication number: US2475787A
Application number: US601651A
Authority: US
Inventors: Le Roy W Kelsay
Original assignee: Bell Telephone Laboratories Inc
Current assignee: AT&T Corp
Priority date: 1945-06-26
Filing date: 1945-06-26
Publication date: 1949-07-12
Anticipated expiration: 1966-07-12

Description

Juy M? 1949. LE Roy w. KELSAY TERMINATION FOR COAXIAL CABLES Filed June 26, 1945 /Nl/sA/TOR L. W KEA 5,4 Y

ATTORNEY Patented July 12, 1949 UNITED STATES PATENT OFFICE Telephone Laboratories,

Incorporated, New

York, N. Y., a corporation of New York Application June 26, 1945, Serial No. 601,651

7 Claims. 1

This invention relates to under-water signaling systems and more particularly to systems of this type in which under-water cable connections must be severed to permit removal of apparatus for repairs or replacements.

It is an object of the invention to provide in a system of this kind suitable connecting means between cable sections which, when raised above the Water surface, may be disassembled and again restored to operating condition in a simple and effective manner and without impairment of the equipment.

It is a more specific object of the invention to provide a simple and effective seal for a signaling cable which has two insulated and coaxially arranged conductors.

It is a particular object of the invention to provide a seal of the type referred to, which may be readily assembled and tightened to seal the end portions of the coaxial conductors and their intervening insulation against penetration of sea water when placed near the sea bottom for service during long periods of time, and which may be opened or disassembled and again assembled without destruction of its parts.

The invention is particularly useful in certain under-water signaling systems of a type in which a submerged listening post is placed in the sea at some distance from the shore to pick up sounds whereby signal indications may be transmitted over a cable to a shore station that a ship or other sound producing source is in the region of the listening post. The listening post is provided With a microphone or equivalent sound responsive device preferably supported above sea bottom at a depth sucient to be clear of passing craft and in a position which exposes it to waterborne sounds. In order that the sound detecting equipment may receive occasional inspection for replacement or repair the listening post is provided with a flexible cable section extending from the sound responsive device to'a junction box or apparatus housing which serves as a detachable couplingI between the flexible cable section at the listening post and the armored cable section which extends from the junction box to the shore station at which the sound indications or signals are to` be observed.

The necessity for providing a coupling or connection whereby the ilexible local cable at the listening post may be detached from the armored cable extending out to the shore gives rise to a problem of insulation and of preventing the ingress of sea water. Moreover the connecting device should be of such character that it readily may be hoisted at sea, disassembled and reassembled without impairment of the electrical transmission properties of the system or of the insulating and water excluding properties of the reassembled coupling. Thus the operation of replacement or repair of the listening post apparatus and of the flexible cable section which connects it to the armored section may take place without the difliculties which would be involved were it necessary to open up the armored cable section itself.

In accordance with a feature of the invention the sound responsive device is connected through a flexible water-impervious cable of the coaxial type to the circuit from the armored cable, and the flexible cable is led through a water-tight seal or stuing box into the water-tight apparatus housing in which the armored cable is terminated, the seal being constructed so that it may be taken apart during service for disconnection of the flexible cable from the apparatus housing and removal of the sound responsive device without impairment of the sealing elements.

In accordance with a more specific feature of the invention the end portion of such a flexible cable is prepared by exposing the various concentric layers in the usual staggered or stepwise manner and a disc is placed around and in contact with the outer conductor which is soldered to the disc. The disc carries a connecting post or wire near its rim for soldering to an external circuit connection and the central conductor has its end portion bared of insulation to permit soldering to a second external circuit connection. Before attaching the external connections, semihard insulating bushings are placed about the exposed portions of the cable end and the connecting post and on both sides of the said disc, and the entire assemblage is ultimately placed within a rigid tube and clamped tight by endwise pressure to insure a water-tight packing about the cable elements by compression of the insulating bushings. The central conductor and the connecting post project beyond the bushings and the tube for attachment to the external connections.

This type of water-tight seal may be used either as a termination for a coaxial cable or, by combination with another similar seal for another coaxial cable, it may be used in a joint between two coaxial cable sections, in which latter case both seals would be placed in a common tube and clamped tight.

The invention will now be described more in detail as embodied in a preferred form and reference will be made to the accompanying drawing in which:

Fig. 1 shows a typical signaling station or listening post located on the sea bottom;

Fig. 2 is a longitudinal sectional view showing a terminal casing or junction box containing electrical apparatus and adapted for termination bothzof the armoredishorecable and-of the flexible connecting cables;

Fig. 3 is a cross-sectional View of the casing4 to a reduced scale taken on line 3 3 in Fig. 2;

Fig. 4 is an exploded view of; thefseal'for; oneI of the coaxial ilexible cables;

Fig. 5 is a detail view of the seal; showing the disc connected to the outer conductor.; and

Fig. 6 shows an end portion of the co'axialcable as prepared for forming of the`seafl;

Whereas the more specific features of the invention will be described as used in a specific under-water system it should be understood that it isapplicable to other types of` systems and under other conditionsf-t'han'those described. in detail" hereinafter.

As shown in Fig. 1- the signaling station on the sea bottom may comprise a` mounting structure such as the* tripod' 5`witlf cross-pieces Si between' itslegs and weighted' by concrete blocks. An armoredfshore cable I-2-"is `terminatedinthe'appa-- ratus-l housing' or junctionv boxl III.` andf thel connections arev continued through flexible stub cables I3 and I4 to two signal producing or listeningA devices'Y I-I attached by any desired means 8 to: the tripodI near its top; The casing I- may be securely fastenedbymean'sIo clamps'l' to the` cross-piece 6 of"the=tripod'.

Asshown' more in detail iniFi'g. 2 theztubular apparatus housing". Ill:v enoloses a` centrall watertight chamber 2-0=spaced between tWo/ end'pieces 3:1 and-y 322 of' thel housingz by means of tubular' spacing memb'ers33and. 341 The spaces Within the housingbetween thechanrberv 2II1and4 the endr plates 3I and32f' arefopento the seawater.

The hermetic'all'yf sealed chamber- 20- comprises atubeV 2|` with endzpiecesl 22': andy 2.3 solderedl in position. In. thea chamberf ai longitudinalv m'ounting. plate 24 carries. al` plurality of* different elec.- trical` apparatus:r 2.5` andi thef. chamheris lled with aneutral: oil.

rIhefshorexcable I.2\is of conventional type and has four insulated conductors; 42x encased'. injute` and' protected`v byf armor wires; having: an outer layer' of jute. The endf platey 32 of the housing supports: a cable clampi 401 and? thefarmoring ofi the. cable I2 i's brought.about the`- clampingplate 4I bolted to the` plate.: 3'2'. thev tripod with the housing' attachedthereto may be'loweredk with' the cable I2 anchoredi in' the-end plate. of the-housing IU. 'Ehey conductorsr42 are spliced to other conductors, such: as 43; and 44,

leading out from permanent-water-tight outlets 45and46 from the chamber. 20. Details. of. these splices and outlets-are=omitted becausethey form` no part of the invention.

At the opposite. end. of. thelhousing.. IIJ the two flexible stub cables l'3' and |41 from the listening devicesy I'I' are clamped` in position. by meansv of the clamp 5U' with sufficient bedding material 5I to insure against strain being( transmitted from the` cables'to the seals orst'uin'gboxes 60 and 6I leading into thel oil4 chamber. The two cables pass through the detachable-seals 6'0 and' 6I and thetwo' conductors of each cable are connected in a similar manner to the electrical apparatus 2-5 within the chamber 2Ul from' which the circuit extendsinto the shore cable` I2?.

By this` arrangement f As shown in Figs. 2 and 3 the housing I 0 is placed in two suitable mountings 1 which are clamped about the cross-tube 6 of the tripod, thereby securing the housing in a fixed position.

As shown in Fig. 3 the seals 60 and 6I are placed on a diameter at an angle with the vertical so that the conductors extending from the seals within the chamber 2U: will appear at opposite sides of the partition 24.

Referring now more particularly to the sectional view of the seal 6I included in Fig. 2 and the more detailed views of the seal shown in Figs. 4 and 5 and to the View in Fig. 6 of the prepared endi portion of the cable, it will be noted that the cable I4 comprises a central conductor I5 surrounded by insulation I6, which may be vulcanized rubber. particularlytreated to resist penetration of sea water during years of service; the outer conductor is in the form of a braid I'I of copper wires i8 placed tightly about the insulation I6 andislin turnI surrounded by theouter insulation I 9; whichimay be similar to the insulation I8 or whicnmay differ from theinsulation I6 by being more abrasionresistant. The cable end is bared as shown in Fig. 6 by removing the different layers in afr stepwise formation, so that an end portion ofv each layer will be'exposed.

The seal IIl is so constructed that it may be disassembled Without destruction of its parts.` Thel seal comprises'asemihard rubber-Washer 62 tting. slidably4 on the insulation I9; a metal washer 63 and a threaded compression :bushing Gllofmetal; The elements 62;,63'and (i4-are temporarily placed somedistancebackron the insulation I 91 before the seal is assembled. The seal further comprises the conducting disc 65 which iitsabout1 the braiding' I"I:I and which carries the connecting wire or rod 66; the Wire 66 may be fastened inl any desired mannernear'the peripheryfof the disc, such;y as by riveting and soldering. The disc 65' ismounte'd against the shoulder of insulationA I9 with the-wire 66; extending parallel with" the central conductor I5; For the purpose of: establishing a reliable electrical connection with the braiding I'Ifthe-wires I8` of the braiding extendingA beyond the disc 65 are unbraided and tanned out against the free side of Vthe disc and soldered thereto; thisv arrangement is shown in detail inI Fig. 5. The seal further comprises an insulating

bushings'l having openings

68 and 69 tting slidably upon the insulation I6 and the wire.6`6`; the length ofthe bushing 61 is the same as= thel protruding portion of the insulation IB beyond the washer. 65. A metal tube 'Ill of suitable length to extend slightly beyond` the end of the seal is placed` over the central conductor I5 for reinforcement' and' is soldered thereto near the free end. The seal'further comprises an insulating bushing 'il having openings 'I2 and 'I3 fitting slidably. about the tube 'I0 and the wire 66. The insulating end bushing I4 has openings 'I5 andTB a-lsotting slidably on the tube I0 and the wire 66'; the'bushing 'II has a shoulder portion `I`I for' tak-ing up the longitudinal pressure on the sealing elements.

Whereas the bushings 62, 61 and 'II maybe of semihard rubber and therefore capable of slight deformation under pressure, ther bushing I4 is ofahard-insulating material whichwill not materially change its shape under appreciable pressure; A suitable material for this purpose is a commercially available glassA having mica dust dispersed' throughout the body thereof to reduce its brittleness;

The outerw casing of they seal is in the form of a metal tube or sleeve with an outer shoulder portion 8| for seating against the end plate 22 of the chamber 2D. The end extending into the chamber 28 has an inner shoulder 82 for seating of the bushing 'I4 and the general dimension of the inner diameter is such that the tube 80 ts slidably over the elements 53, 62, 5l, 'H and T4. The end of the tube remote from the shoulder 82 is threaded to match the thread of the clamping plug 64 and a longitudinal groove 83 is cut through the thread to accommodate a projection on the washer 63 to lock the washer against rotation while the seal is being tightened up. The tube 80 is seated in the end plate 22 and soldered thereto.

The seal may be assembled by forcing the various bushings from both sides against the disc 55 and inserting this assemblage into the tube 8! followed by the washer 63 and the compression plug B4. The plug is screwed tight until its hexagonal head engages the end of tube 3U. The dimensions of the semisoft bushings 62, 61 and 'll should be such as to secure a tight packing against both their inner and their outer surfaces when the plug 64 is screwed in position. The washer 63 serves to protect the bushing 62 against friction with the plug 64.

The chamber 20 is so arranged that a unit is formed of the two end plates 22 and 23 and the mounting plate 24, so that upon completion of the seals in both end plates the connections may be made to the various apparatus 25. Thereafter the cylindrical wall 2l is passed over the end plates 22 and 23 and locked in position by rolling the edges of the tube down over the edges of the end plates and hermetically sealing the seams as by soldering. The chamber may thereafter be lled with oil to replace the entrapped air, through suitable plugs il and 48.

When desired the housing l0 and chamber 20 may be taken apart for purposes of repairs or replacements, in which case the seals 63 and Bl may readily be disassembled for disconnection of the cables I3 and i4 from the apparatus 25. Thereafter the seals may again be assembled and tightened to make them water-tight. In fact the two ends of the coaxial cables i3 and M with attached parts of the seals may be interchanged in the two seals 6l) and 6l, if desired, or one of listening devices with its stub cable may be replaced by another and the water-tight connection through the seal reestablished to the new device.

What is claimed is:

1. A water-tight end-seal for a water-impervious coaxial cable capable of being disassembled and reassembled and comprising in combination a terminal portion of the cable having end portions of the two coaxially disposed conductors bared, a conducting member connected and at tached to the outer conductor and disposed in parallel relation to the bared portion of the inner conductor of the cable, an outer tubular casing enclosing said terminal portion and said conducting member and having clamping plugs at opposite ends thereof, and a plurality of solid bodies of insulating material disposed within said casing and being diierently shaped to lill the spaces about said terminal portion and said conducting member, to be clamped water-tight against them by said clamping plugs, said parallel conducting portions extending beyond said seal for connection to an external circuit.

2. A Water-tight end-seal for termination of two concentric conductors of a water-impervious coaxial cable and capable of being disassembled and reassembled, said seal comprising in combination a terminal portion of the cable having end portions of said conductors bared, a conducting member attached to the outer conductor and disposed in parallel relation to the inner conductor of said cable, an outer casing enclosing said terminal portion of the cable and said conducting member except short tip portions of the inner conductor and of said conducting member adapted for attachment of external connections thereto, said casing having at one end an end stop member with openings for passing said short tip portions and a clamping plug at the other end, said seal further comprising a plurality of solid insulating bodies substantially lling the spaces within said casing about said terminal portion of the cable and said conducting member and being compressible, said clamping plug being detachably attached to said casing and adjustable to clamp said insulating bodies tight against the surfaces internal of the seal including those of said terminal portion, conducting member, casing, stop member and clamping plug.

3. A water-prooi" seal for the terminal portion of a cable having a central conductor, an inner layer of insulation, an outer stranded conductor, and an outer layer of insulation arranged concentrically and being terminated in stepped relation along the terminal portion of the cable, said seal comprising an annular conducting member placed against the end of said outer insulation and about said outer conductor and connected to said outer conductor and having an eccentrically attached connecting wire disposed parallel with the terminal portion of said central conductor, an outer casing including a tubular member for enclosing the terminated cable parts and clamping means at opposite ends of said tubular member, and insulating material substantially completely lling the space within said casing about said terminated cable parts and connecting wire and adapted to be compressed into tight contact with all the surfaces within said casing by the clamping action of said clamping means, said casing having passages and being shortl enough to permit said central conductor and connecting wire to extend beyond said seal.

4. A water-proof seal in accordance with claim 3 in which said annular conducting member is disk-shaped and has one of its faces soldered to the flared strand ends of said outer conductor, said strand ends being flared.

5. A water-proof seal in accordance with claim 3 in which said tubular member has an internal shoulder at one end and an internal thread at the other end, in which said clamping means at one end comprises a hard insulation bushing adapted for engagement with said internal shoulder and having said passages for said central conductor and said connecting wire, and in which said clamping means at the other end comprises a threaded plug adapted to be screwed into said internal thread for the compression of said insulating material.

6. A water-proof seal in accordance with claim 3 in which said insulating material comprises a plurality of semihard bushings with passages for the different terminated cable parts and for said connecting wire and adapted to substantially completely ll the spaces within said casing when compressed.

7. A detachable terminal seal for a coaxial 1 cable having; a central: conductor:l and a concentric layer. of.. conducting strands separated by insulation from said central, conductor and hav ing; an outer sealing.L envelopeabout saidlayer, saidseal comprising a metallic disk with a central passage tting snugl'ynabout said layer and having one of its at sides in engagement with an end surf-ace of said envelope, and having its other side. in contact. with the flared end, portions of said conducting strands and soldered thereto, said central conductor and insulation passing throughl and, beyond.y said disk, aconnectingwire fastenedto said disk near its periphery and extending parallel tov said central conductor, ai packing ring of insulating material in engagement with; theA first saidilat side of said disk and having: a snug tting passage for said envelope,l a. packing of*` insulating material in engagement with said other flat side and having snugfitting passages for said central conductor and connecting Wire, and a clamping tube extendingv over and beyond said packing ring and packingv and having an inside. shoulder at one end, said clamping tubevcontaining arigid clamping bushing in engagement with said shoulder with openings-for passingfsaid central conductor 81 and, connecting wire; anda clamping plug with an opening for. passingv said cableand in threaded engagement and cooperating with the other end portion of saidtube for clamping said packing ringl about said envelope and against said disk and for clamping said packing against said disk andiaboutsaid central conductor and connecting Wire and against said clamping bushing.

LE ROY W. KELSAY.

REFERENCES CITED The followingy referenlces are of record in the file ofthis patent:

UNITED STATES PATENTS Number` Name Date 793,896 Mundyr July 4, 1905 935,750 Gale Oct. 5, 1909 1,411,949 Williams Apr. 4, 1922 1,746,424 Hecht'et al Feb. 11, 1930 11,780,686 Proos Nov. 4, 1930 1,893,741 Hechtet al. Jan. 10, 1933 2,110,457; Wentz Mar. 8, 1938 2,147,418 Bahls Feb. 14, 1939 2,419,592 Richardson Apr. 29, 1947