EP0010461A1 - Bei hoher Temperatur funktionsfähiges antimikrophonisches Koaxialkabel - Google Patents

Bei hoher Temperatur funktionsfähiges antimikrophonisches Koaxialkabel Download PDF

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Publication number
EP0010461A1
EP0010461A1 EP19790400610 EP79400610A EP0010461A1 EP 0010461 A1 EP0010461 A1 EP 0010461A1 EP 19790400610 EP19790400610 EP 19790400610 EP 79400610 A EP79400610 A EP 79400610A EP 0010461 A1 EP0010461 A1 EP 0010461A1
Authority
EP
European Patent Office
Prior art keywords
core
coaxial cable
beads
cable
cable according
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP19790400610
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English (en)
French (fr)
Other versions
EP0010461B1 (de
Inventor
Georges Melet
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Original Assignee
Commissariat a lEnergie Atomique CEA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Commissariat a lEnergie Atomique CEA filed Critical Commissariat a lEnergie Atomique CEA
Publication of EP0010461A1 publication Critical patent/EP0010461A1/de
Application granted granted Critical
Publication of EP0010461B1 publication Critical patent/EP0010461B1/de
Expired legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B11/00—Communication cables or conductors
    • H01B11/18—Coaxial cables; Analogous cables having more than one inner conductor within a common outer conductor
    • H01B11/1834—Construction of the insulation between the conductors
    • H01B11/1856—Discontinuous insulation

Definitions

  • the invention relates generally to coaxial cables which are used in electronics techniques for transmitting electrical signals of very low intensity and applies more particularly to those of these cables which operate in medium hostile and high temperature.
  • Such a coaxial cable known per se is shown in FIG. 1 and consists of two electrodes, namely a central core 1 and an outer braid 3 separated by a dielectric medium 2 surrounding the central core.
  • the central core 1 is generally made of sometimes tinned red copper
  • the dielectric 2 is made of a material with high resistivity such as Teflon
  • the external conductive braid 3 is generally made of sometimes silvery red copper.
  • This antimicrophonic protection in itself known, however, has the disadvantage that it does not overcome the electric charges induced by the friction phenomena developing between the core 1 and the dielectric 2; on the other hand, when it comes to making a coaxial cable working in the middle hostile with vibrations and in particular at a high temperature of the order of several hundred degrees Celsius as is the case for the transmission of measurements from a nuclear reactor core, it is then impossible to use such a intermediate plastic envelope and the problem of microphonic protection of the cable is then completely called into question.
  • the coaxial cables undergo a transformation essentially concerning their dielectric, which then consists of a number of high density ceramic beads, generally in pure alumina, strung on the core of the cable and covered by an outer stainless steel braid.
  • Fig. 1 shows such a coaxial cable for high temperature of a type known per se.
  • a coaxial cable comprising a central core 1 of stainless steel or copper covered with stainless steel on which beads 2, made of pure alumina, constituting the dielectric are strung.
  • the pearls 2 preferably have the shape of a portion of a cylinder limited by respectively convex and concave end surfaces so as to be able to fit perfectly into each other.
  • the second electrode of this cable consists of an outer braid 3, also made of stainless steel and which may comprise several layers.
  • the present invention specifically relates to an antimicrophonic coaxial cable which can operate in a hostile environment and in particular at high temperature, without having the drawbacks of the prior art.
  • the coaxial cable also includes a certain number of metallic intermediate pieces threaded on the core and placed between each of the consecutive beads, which gives it a certain complementary flexibility.
  • the metallic coating of the friction surfaces can be produced in two different ways.
  • the metallic coating of said surfaces is produced by means of a deposit made on the parts of the surface thereof which are in contact with the core, the braid and / or the intermediate pieces, said deposit possibly being constituted for example by an alloy of molybdenum and manganese obtained from a pulverulent solution in an appropriate solvent which is left to dry and which is fixed by a treatment at a high temperature oven to make the combination of the alloy with the alumina surfaces of the pearls.
  • the metallic coating of the friction surfaces consists of rings and metal sleeves which are crimped directly around the pearls or which are forced into their central orifice.
  • an advantageous variant of the invention consists in using said metallic sheaths threaded d ⁇ the central orifice of each pearl to constitute at the same time the spacers making the desired spacing between two consecutive pearls.
  • the cable further comprises intermediate pieces which consist of spherical stainless steel balls 4 two in number between two consecutive beads 2 of pure high density alumina provided with a central channel 5.
  • intermediate pieces consist of spherical stainless steel balls 4 two in number between two consecutive beads 2 of pure high density alumina provided with a central channel 5.
  • external lateral 6 and internal 7 surfaces as well as the hemispherical portions 8 of the entry holes of channel 5 are covered with a metallization with a thickness of 3 / 100th of a mm of an alloy of molybdenum and manganese deposited in the presence of a mask as follows.
  • the mixture of molybdenum and manganese is carried out in a solvent such as toluene or benzene in powder solution.
  • a solvent such as toluene or benzene in powder solution.
  • This mixture is then deposited by brush, spray gun or stencil on the surfaces to be covered and then allowed to dry for about a quarter of an hour until the solvent has completely evaporated.
  • the pearls thus treated are placed in an oven under humid hydrogen and the temperature is raised to 1500 ° C. to obtain the combination of the alloy with the constituting allumine of the pearls.
  • the operation of combining the alloy with alumina requires approximately 45 minutes on average.
  • the assembly can then take place with the pearl thus treated, of course taking the usual precautions to maintain the necessary insulation between the conductive parts.
  • the steel balls 4 are pierced with a diametrical orifice 0.85 mm in diameter which thus allows the passage of the core 1 and the positioning of the alumina beads 2 between them.
  • the dimensions of the different consecutive pieces provide great flexibility to the cable without causing, and this is very important, the slightest abrasion of the bearing surfaces of the balls 4 on the beads 2. It may also be noted that the core 1 does not touch the internal surfaces of the alumina beads 2 which further limits the risk of abrasion:
  • FIG. 3 there are also the main constituent elements of a coaxial cable according to the invention and the corresponding elements which carry the same numbers of reference as in the previous example.
  • the intermediate pieces 4 consist of small cylinders 4 of stainless steel pierced along their axis with an orifice allowing the passage of the steel core 1 and are thus threaded onto said core 1 alternately with the pearls 2.
  • the edges 10 of the intermediate cylinders 4 as well as the outer edges 11 of the beads 2 have a rounded or hemispherical shape, since the presence of sharp angles would deteriorate the metal coating deposited on the dielectric 2.
  • the different previous conditions mean that neither the intermediate pieces 4, nor the outer ringed tube 3 come into contact with the ceramic constituting the pearls 2. In this embodiment it may sometimes be desirable to divide the intermediate elements 4 into two parts to give more flexibility to the entire cable.
  • Fig. 4 shows an embodiment of the second embodiment of the invention in which the metallic coating of the pearls 2 is constituted, as regards the external surface, by a stainless steel ring 12 mounted hot or by any other known means on the dielectric and shown in more detail in FIG. 5; the metallic coating of the central orifices as well as the spacers 4 are produced using sleeves 13, one of which is more particularly shown in FIG. 6, the sleeves 13 being made of a stainless steel cylinder force-fitted at very low temperature (in liquid nitrogen for example) inside the central orifices 5 of the alumina beads 2.
  • the sleeves 13 are made of stainless steel and fitted after fitting the rings 12; they are drilled right through along their axis with an orifice 14 intended for the passage of the stainless steel core 1 of the coaxial cable (fig. 6).
  • the electrode external 3 is also constituted by a ringed tube made of stainless steel and each alumina pearl 2 is a disc pierced along its axis with a hole whose diameter is equal to the external diameter of the steel sheaths 13.
  • Fig. 7 finally shows a very interesting variant of the invention in which we manage to further improve the electrical qualities of the cable while eliminating the intermediate parts.
  • the dielectric 2 the form of spherical or (ellipsoidal) alumina balls which are metallized on all their surface portions in contact with the core 1 or the braid 2 of stainless steel as well as the neighboring pearls .
  • the metallized parts are shown in reinforced lines. This configuration, which is easier to manufacture since it requires only one component, offers, in addition to its antimicrophonic qualities, the advantage of eliminating any capacitive effect which occurs from the other variants between the metallized external faces of the spacers and the metallic sheath.
  • a coaxial cable according to the invention has been the subject of a comparative test with a cable of known type as shown in FIG. 1 in which the alumina beads had no particular metallic protection on their surface part in connection with the core and the outer braid.
  • the cable sample was placed in a shielded enclosure and rigidly fixed at two points.
  • a mechanical device gave the cable an alternating movement with an amplitude of 4 mm, the period of which was 2 seconds.

Landscapes

  • Communication Cables (AREA)
  • Insulated Conductors (AREA)
  • Measuring Temperature Or Quantity Of Heat (AREA)
EP19790400610 1978-09-08 1979-09-04 Bei hoher Temperatur funktionsfähiges antimikrophonisches Koaxialkabel Expired EP0010461B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR7825844 1978-09-08
FR7825844A FR2435787A1 (fr) 1978-09-08 1978-09-08 Cable coaxial antimicrophonique pouvant fonctionner a haute temperature

Publications (2)

Publication Number Publication Date
EP0010461A1 true EP0010461A1 (de) 1980-04-30
EP0010461B1 EP0010461B1 (de) 1983-08-24

Family

ID=9212448

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19790400610 Expired EP0010461B1 (de) 1978-09-08 1979-09-04 Bei hoher Temperatur funktionsfähiges antimikrophonisches Koaxialkabel

Country Status (3)

Country Link
EP (1) EP0010461B1 (de)
DE (1) DE2966090D1 (de)
FR (1) FR2435787A1 (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003054891A1 (en) * 2001-12-20 2003-07-03 Koninklijke Philips Electronics N.V. Rf system for an mri apparatus, provided with bead-shaped spacers
CN100357747C (zh) * 2004-03-22 2007-12-26 摩托罗拉公司 柔性测试电缆

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB397081A (en) * 1932-05-10 1933-08-17 Telefunken Gmbh Improvements in or relating to electric cables for use for conveying radio and other very high frequency energy
DE702951C (de) * 1932-12-21 1941-02-20 Porzellanfabrik Kahla solierten Hochfrequenzkabeln

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB397081A (en) * 1932-05-10 1933-08-17 Telefunken Gmbh Improvements in or relating to electric cables for use for conveying radio and other very high frequency energy
DE702951C (de) * 1932-12-21 1941-02-20 Porzellanfabrik Kahla solierten Hochfrequenzkabeln

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003054891A1 (en) * 2001-12-20 2003-07-03 Koninklijke Philips Electronics N.V. Rf system for an mri apparatus, provided with bead-shaped spacers
CN100357747C (zh) * 2004-03-22 2007-12-26 摩托罗拉公司 柔性测试电缆
CN101067636B (zh) * 2004-03-22 2010-08-18 摩托罗拉公司 柔性测试电缆

Also Published As

Publication number Publication date
FR2435787B1 (de) 1981-11-06
EP0010461B1 (de) 1983-08-24
DE2966090D1 (en) 1983-09-29
FR2435787A1 (fr) 1980-04-04

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