EP0059272B1 - Cryogenic refrigerator with improved thermal-coupling device - Google Patents

Cryogenic refrigerator with improved thermal-coupling device Download PDF

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Publication number
EP0059272B1
EP0059272B1 EP19810200646 EP81200646A EP0059272B1 EP 0059272 B1 EP0059272 B1 EP 0059272B1 EP 19810200646 EP19810200646 EP 19810200646 EP 81200646 A EP81200646 A EP 81200646A EP 0059272 B1 EP0059272 B1 EP 0059272B1
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EP
European Patent Office
Prior art keywords
probe
cooled
cooling device
heel
cryostat
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EP19810200646
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German (de)
French (fr)
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EP0059272A1 (en
Inventor
Gérard Jaecques
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ABG Semca SA
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ABG Semca SA
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
    • F25J1/0243—Start-up or control of the process; Details of the apparatus used; Details of the refrigerant compression system used
    • F25J1/0257—Construction and layout of liquefaction equipments, e.g. valves, machines
    • F25J1/0275—Construction and layout of liquefaction equipments, e.g. valves, machines adapted for special use of the liquefaction unit, e.g. portable or transportable devices
    • F25J1/0276—Laboratory or other miniature devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
    • F25D19/00—Arrangement or mounting of refrigeration units with respect to devices or objects to be refrigerated, e.g. infrared detectors
    • F25D19/006—Thermal coupling structure or interface

Definitions

  • the invention relates to a cryogenic cooler, of the type comprising a probe provided with a cooled end by expansion of a gas; it particularly targets chillers operating in a closed circuit following the thermodynamic cycles of Stirling, Gifford, Vuileumeum, Brayton or Joule-Thomson.
  • coolers are used to cool a sample, in particular one or more infrared detectors, and to keep it at a very low temperature, for example of the order of 70 ° to 80 ° K (Kelvin degree). It is preferable to use a vacuum jacketed cryostat in which the sample is fixed, so that this sample and the cryostat form an independent unit with respect to the probe, which can be separated from the latter without having to redo the vacuum at each installation.
  • the sample being located in the double envelope of the cryostat, it is necessary in this type of device to ensure a thermal connection between the cooled end of the probe and the interior envelope of the cryostat on which the sample is fixed.
  • the inner envelope of the cryostat is formed by a cylindrical wall closed by a circular bottom below which the sample is fixed, and all the solutions used consisted in making a thermal connection between the cooled end of the probe and the bottom inner envelope circular; however, none of these solutions is entirely satisfactory, each having specific faults which are summarized below.
  • a first solution (US patent 4194119) consists in placing a metal spring between the cooled end of the probe and the bottom of the envelope; however, the thermal transmission obtained is very poor due to the small thermal conduction section and the reduced surface contacts between the spring and the two elements which it connects.
  • Another solution consists in stuffing the space between the cooled end of the probe and the bottom of the envelope by means of metal flakes, metal sponges or equivalent material. This solution is impractical and the placement of the material is a delicate operation; in addition, each time the probe is dismantled (relative to the cryostat), these elements must be carefully cleaned, the material ensuring the thermal connection being changed each time.
  • Another solution consists in placing between the cooled end of the probe and the bottom of the envelope a soft metal pellet, which is crushed between these two elements; however, this type of device is unable to allow significant longitudinal expansions of the probe and can only operate in a narrow temperature range; in addition, the parts forming the probe and the internal envelope of the cryostat must be machined with very small tolerances so that the assembly can be carried out correctly.
  • the longitudinal vibrations of the probe are directly transmitted to the envelope of the cryostat and therefore to the sample, which constitutes a very serious defect in the case where the sample is formed by infrared detectors.
  • the crushed soft metal pellet causes the formation of incrustations in the probe and the envelope, and the cleaning of these elements is difficult to carry out with each disassembly, the soft metal pellet being generally to be changed.
  • Another solution consists in fixing the probe in the cryostat by means of a spring device which maintains the end of the probe directly in support against the bottom of the internal envelope (with possibly presence of a grease or 'a varnish).
  • This solution has the disadvantage of leading to greater mechanical complexity; moreover, it does not eliminate the defect of the previous solution, relating to the transmission of longitudinal vibrations from the probe to the sample.
  • the present invention proposes to provide a solution to the problem of thermal bonding of cryogenic coolers, which is free from the defects of traditional solutions and gives complete satisfaction.
  • An object of the invention is in particular to provide a cryogenic cooler benefiting from a good quality thermal bond between the cooled end of the probe and the envelope of the cryostat on which the sample is fixed.
  • Another object of the invention is to provide a cryogenic cooler, the probe of which can be easily mounted in the cryostat or disassembled relative thereto, without having to change any element or to carry out any cleaning.
  • Another essential objective of the invention is to avoid any transmission of longitudinal vibrations between the probe and the sample.
  • Another objective is to allow operation of the cooler over a wide temperature range.
  • Another objective is to provide a cryogenic cooler which achieves the preceding objectives, while being simple in structure and allowing wide manufacturing tolerances for the probe and the cryostat.
  • the term “longitudinal” designates the direction extending along the probe or the cryostat, parallel to the axis of these elements, and the term “radial” designates a perpendicular direction going from the axis from the probe to the periphery or vice versa.
  • said part preferably comprises a plurality of longitudinal slots distributed over its periphery with the exception of its heel.
  • the invention provides a thermal connection between the cooled end of the probe and the cylindrical wall of the cryostat, the connection piece or pieces being in abutment against this cylindrical wall and fixed on the probe.
  • the contact of the thermal connection part (s) with the cryostat and the probe made by a plurality of contact surfaces or by an extended contact surface, while the conduction section extending along a cylinder may be of dimension important, so that the invention makes it possible to achieve excellent thermal performance and to obtain a very small temperature difference between the cooled end of the probe and the sample.
  • the probe and the thermal connection piece or pieces attached to it are free longitudinally since these pieces simply come to bear against the cylindrical wall of the cryostat: the probe is therefore free to deform longitudinally, which allows operation cooler in a wide temperature range; in addition, the manufacturing tolerances are very wide, both in the longitudinal and radial directions (since the support of the thermal connection part (s) is produced by the radial elasticity of the latter without contact with the internal bottom of the cryostat) ; moreover, the longitudinal vibrations of the probe are not transmitted to the sample due in particular to this absence of contact between the probe and the bottom of the internal envelope of the cryostat.
  • the cryogenic cooler shown schematically by way of example in FIG. 1 comprises two separate assemblies 1 and 2 connected by a connecting tube 3.
  • the assembly 1 can be a motor-compressor group or a motor-oscillator group, suitable for generating a flow of gas under pressure or a pressure oscillation in the tube 3.
  • the assembly 2 comprises a probe shown diagrammatically at 4 (per se well known), comprising a cooled end 5 in which an expansion of the cold producing gas takes place.
  • This probe is fixed by conventional fixing means (not shown) on a cryostat 6 formed by an external envelope 7 and an internal envelope 8 between which a high vacuum is produced.
  • the internal envelope 8 is constituted by a cylindrical wall 8a and by a circular bottom 8b; the cooled end 5 of the probe is housed in the casing 8 in the vicinity of the bottom 8b.
  • a sample to be cooled for example one or more infrared detectors 9, is bonded under the bottom 8b between the two envelopes of the cryostat.
  • thermal connection piece 10 which has been shown in perspective on an expanded scale in FIG. 2, is fixed to the cooled end 5 of the probe.
  • This part made of metal which is a good conductor of heat such as copper, brass, aluminum, etc. comprises a fixing heel 11 which makes it possible to fix it on the cooled end 5 and support tabs such as 12 separated by slots longitudinal such as 13, which have radial elasticity.
  • the support heel 11 is adapted to be fixed on the end 5 of the probe with an extended surface contact.
  • the heel 11 has the shape of a flat disc applied and glued against the flat bottom 5a.
  • Each support tongue 12 has a support surface in the form of a cylinder portion and is radially projecting relative to the heel 11 so as to come to bear against the cylindrical wall 8a of the casing 8, without contact with the background 8b.
  • the part 10 thus achieves a thermal connection with the internal envelope 8 by a plurality of contacts distributed around its periphery. If necessary, the quality of these contacts can be increased by covering the contact surfaces of the tabs with a viscous product (good conductive grease, etc.).
  • the thermal connection piece 10 slides by the effect of its radial elasticity along the cylindrical wall 8a of the cryostat without any difficulty in positioning.
  • Fig. 3 shows a variant of connecting piece 14 in which the heel 15 has the same diameter as the circular flat bottom of the probe and is bonded over the entire surface of the latter to increase the surface contact between these elements.
  • the tongues 16 radially project in abutment against the cylindrical wall thanks to an external excess thickness which they present.
  • Fig. 4 shows another variant in which the cooled end of the probe comprises a head 5b of reduced diameter; the connecting piece 17 has a perforated heel 18 which is adapted to engage around this head.
  • the head is smooth and the heel 18 is glued around it.
  • the head 5c is full and threaded around its periphery, and the heel 19 of the connecting piece is tapped and screwed onto this head.

Description

L'invention concerne un refroidisseur cryogénique, du type comprenant une sonde pourvue d'une extrémité refoidie par détente d'un gaz; elle vise particulièrement les refroidisseurs fonctionnant en circuit fermé suivant les cycles thermodynamiques de Stirling, de Gifford, de Vuil- leumier, de Brayton ou de Joule-Thomson.The invention relates to a cryogenic cooler, of the type comprising a probe provided with a cooled end by expansion of a gas; it particularly targets chillers operating in a closed circuit following the thermodynamic cycles of Stirling, Gifford, Vuileumeum, Brayton or Joule-Thomson.

Ces refroidisseurs sont maintenant bien connus et sont constitués de deux parties:

  • - un groupe moto-compresseur ou un moto- oscillateur »chaud« ayant pour fonction de générer un débit de gaz sous pression ou une oscillation de pression,
  • - une sonde de forme cylindrique, ayant une extrémité dans laquelle est réalisée une détente de gaz engendrant une production de froid, cette extrémité dite froide ou refroidie étant disposée dans un cryostat appelé à assurer une isolation thermique de celle-ci.
These coolers are now well known and consist of two parts:
  • - a motor-compressor unit or a "hot" motor-oscillator whose function is to generate a flow of gas under pressure or a pressure oscillation,
  • - A cylindrical probe, having one end in which is produced a gas expansion generating a cold production, this end called cold or cooled being disposed in a cryostat called to provide thermal insulation thereof.

Ces refroidisseurs servent à refroidir un échantillon, notamment un ou plusieurs détecteurs infra-rouges, et à maintenir celui-ci à très basse température, par exemple de l'ordre de 70° à 80° K (degré Kelvin). On utilise de préférence un cryostat à double enveloppe sous-vide dans lequel est fixé l'échantillon, de façon que cet échantillon et le cryostat forment un ensemble indépendant par rapport à la sonde, qui puisse être séparé de celle-ci sans avoir à refraire le vide à chaque mise en place.These coolers are used to cool a sample, in particular one or more infrared detectors, and to keep it at a very low temperature, for example of the order of 70 ° to 80 ° K (Kelvin degree). It is preferable to use a vacuum jacketed cryostat in which the sample is fixed, so that this sample and the cryostat form an independent unit with respect to the probe, which can be separated from the latter without having to redo the vacuum at each installation.

L'invention s'applique à ce type de refroidisseurs dont les avantages sont bien connus de l'homme du métier.The invention applies to this type of cooler, the advantages of which are well known to those skilled in the art.

L'échantillon étant situé dans la double enveloppe du cryostat, il est nécessaire dans ce type de dispositif d'assurer une liaison thermique entre l'extrémité refroidie de la sonde et l'enveloppe intérieure du cryostat sur laquelle est fixé l'échantillon.The sample being located in the double envelope of the cryostat, it is necessary in this type of device to ensure a thermal connection between the cooled end of the probe and the interior envelope of the cryostat on which the sample is fixed.

Plusieurs solutions sont connues et utilisées depuis de nombreuses années pour assurer cette liaison thermique. L'enveloppe intérieure du cryostat est formée par une paroi cylindrique fermée par un fond circulaire au-dessous duquel est fixé l'échantillon, et toutes les solutions utilisées ont consisté à réaliser une liaison thermique entre l'extrémité refroidie de la sonde et le fond circulaire de l'enveloppe interne; toutefois, aucune de ces solutions n'est entièrement satisfaisante, chacune possédant des défauts qui lui sont spécifiques et qui sont résumés ci-après.Several solutions have been known and used for many years to provide this thermal bond. The inner envelope of the cryostat is formed by a cylindrical wall closed by a circular bottom below which the sample is fixed, and all the solutions used consisted in making a thermal connection between the cooled end of the probe and the bottom inner envelope circular; however, none of these solutions is entirely satisfactory, each having specific faults which are summarized below.

Une première solution (brevet US 4194119) consiste à disposer un ressort métallique entre l'extrémité refroidie de la sonde et le fond de l'enveloppe; toutefois, la transmission thermique obtenue est très médiocre en raison de la faible section de conduction thermique et des contacts de surface réduite entre le ressort et les deux éléments qu'il relie.A first solution (US patent 4194119) consists in placing a metal spring between the cooled end of the probe and the bottom of the envelope; however, the thermal transmission obtained is very poor due to the small thermal conduction section and the reduced surface contacts between the spring and the two elements which it connects.

Une autre solution consiste à bourrer l'espace compris entre l'extrémité refroidie de la sonde et le fond de l'enveloppe au moyen de paillettes métalliques, éponges métalliques ou matériau équivalent. Cette solution est peu pratique et la mise en place du matériau est une opération délicate; de plus, à chaque démontage de la sonde (par rapport au cryostat), ces éléments doivent être soigneusement nettoyés, le matériau assurant la liaison thermique étant à changer chaque fois.Another solution consists in stuffing the space between the cooled end of the probe and the bottom of the envelope by means of metal flakes, metal sponges or equivalent material. This solution is impractical and the placement of the material is a delicate operation; in addition, each time the probe is dismantled (relative to the cryostat), these elements must be carefully cleaned, the material ensuring the thermal connection being changed each time.

Une autre solution consiste à disposer entre l'extrémité refroidie de la sonde et le fond de l'enveloppe une pastille de métal mou, qui est écrasée entre ces deux éléments; toutefois, ce type de dispositif est inapte à autoriser des dilatations longitudinales notables de la sonde et ne peut fonctionner que dans une plage étroite de température; en outre, les pièces formant la sonde et l'enveloppe interne de cryostat doivent être usinées avec de très faibles tolérances pour que le montage puisse s'effectuer correctement. De plus, les vibrations longitudinales de la sonde sont directement transmises à l'enveloppe du cryostat et donc à l'échantillon, ce qui constitue un très grave défaut dans le cas où l'échantillon est formé par des détecteurs infra-rouges. Par ailleurs, la pastille de métal mou écrasé entraine la formation d'incrustations dans la sonde et l'enveloppe, et le nettoyage de ces éléments est difficile à réaliser à chaque démontage, la pastille de métal mou étant généralement à changer.Another solution consists in placing between the cooled end of the probe and the bottom of the envelope a soft metal pellet, which is crushed between these two elements; however, this type of device is unable to allow significant longitudinal expansions of the probe and can only operate in a narrow temperature range; in addition, the parts forming the probe and the internal envelope of the cryostat must be machined with very small tolerances so that the assembly can be carried out correctly. In addition, the longitudinal vibrations of the probe are directly transmitted to the envelope of the cryostat and therefore to the sample, which constitutes a very serious defect in the case where the sample is formed by infrared detectors. Furthermore, the crushed soft metal pellet causes the formation of incrustations in the probe and the envelope, and the cleaning of these elements is difficult to carry out with each disassembly, the soft metal pellet being generally to be changed.

Une autre solution consiste à fixer la sonde dans le cryostat par l'intermédiaire d'un dispositif à ressort qui maintient l'extrémité de la sonde directement en appui contre le fond de l'enveloppe interne (avec éventuellement présence d'une graisse ou d'un vernis). Cette solution présente l'inconvénient de conduire à une complexité mécanique plus grande; de plus, elle ne supprime pas le défaut de la solution précédente, relatif à la transmission des vibrations longitudinales de la sonde à l'échantillon.Another solution consists in fixing the probe in the cryostat by means of a spring device which maintains the end of the probe directly in support against the bottom of the internal envelope (with possibly presence of a grease or 'a varnish). This solution has the disadvantage of leading to greater mechanical complexity; moreover, it does not eliminate the defect of the previous solution, relating to the transmission of longitudinal vibrations from the probe to the sample.

On connait également (brevet US 3 306 075) un système de liaison thermique à ressorts interposé entre la paroi latérale cylindrique de la sonde et la paroi latérale cylindrique de l'enveloppe intérieure du cryostat. Ce système connu est d'une construction complexe et encombrante; de plus il est inutilisable avec des cryostats où la sonde est ajustée dans ledit cryostat avec un jeu périphérique relativement faible.Also known (US Pat. No. 3,306,075) is a thermal spring connection system interposed between the cylindrical side wall of the probe and the cylindrical side wall of the inner envelope of the cryostat. This known system is of a complex and bulky construction; moreover it cannot be used with cryostats where the probe is adjusted in said cryostat with a relatively small peripheral clearance.

Enfin, il est connu (brevet US 3807188) un système de liaison thermique comportant une chambre dont la paroi externe présente une souplesse dans le sens longitudinal et qui est remplie d'un liquide tel que du mercure. Ce système connu est très complexe et oblige à prévoir une enveloppe interne de cryostat ayant un fond de forme spéciale.Finally, it is known (US Pat. No. 3,807,188) a thermal bonding system comprising a chamber whose external wall has flexibility in the longitudinal direction and which is filled with a liquid such as mercury. This known system is very complex and requires the provision of an internal cryostat envelope having a bottom of special shape.

La présente invention se propose de fournir une solution au problème de liaison thermique des refroidisseurs cryogéniques, qui soit exempte des défauts des solutions tradition- ne!les et donne entière satisfaction.The present invention proposes to provide a solution to the problem of thermal bonding of cryogenic coolers, which is free from the defects of traditional solutions and gives complete satisfaction.

Un objectif de l'invention est en particulier de fournir un refroidisseur cryogénique bénéficiant d'une liaison thermique de bonne qualité entre l'extrémité refroidie de la sonde et l'enveloppe du cryostat sur laquelle est fixé l'échantillon.An object of the invention is in particular to provide a cryogenic cooler benefiting from a good quality thermal bond between the cooled end of the probe and the envelope of the cryostat on which the sample is fixed.

Un autre objectif de l'invention est de fournir un refroidisseur cryogénique, dont la sonde puisse être aisément montée dans le cryostat ou démontée par rapport à celui-ci, sans avoir à changer un quelconque élément ou à effectuer un quelconque nettoyage.Another object of the invention is to provide a cryogenic cooler, the probe of which can be easily mounted in the cryostat or disassembled relative thereto, without having to change any element or to carry out any cleaning.

Un autre objectif essentiel de l'invention est d'éviter toute transmission de vibrations longitudinales entre la sonde et l'échantillon.Another essential objective of the invention is to avoid any transmission of longitudinal vibrations between the probe and the sample.

Un autre objectif est de permettre un fonctionnement du refroidisseur dans une large plage de température.Another objective is to allow operation of the cooler over a wide temperature range.

Un autre objectif est de fournir un refroidisseur cryogénique qui atteigne les objectifs précédents, tout en étant de structure simple et en autorisant de larges tolérances de fabrication pour la sonde et le cryostat.Another objective is to provide a cryogenic cooler which achieves the preceding objectives, while being simple in structure and allowing wide manufacturing tolerances for the probe and the cryostat.

Dans la description qui suit, le terme »longitudinal« désigne la direction s'étendant le long de la sonde ou du cryostat, parallèlement à l'axe de ces éléments, et le terme »radial« désigne une direction perpendiculaire allant de l'axe de la sonde vers la périphérie ou inversement.In the description which follows, the term "longitudinal" designates the direction extending along the probe or the cryostat, parallel to the axis of these elements, and the term "radial" designates a perpendicular direction going from the axis from the probe to the periphery or vice versa.

Le refroidisseur cryogénique visé par cette invention est du type comprenant une sonde pourvue d'une extrémité refroidie par détente de gaz et fermée par un fond, un cryostat à double enveloppe sous vide dont l'enveloppe intérieure formée par une paroi cylindrique fermée par un fond est adaptée pour contenir l'extrémité refroidie de la sonde, un échantillon à refroidir, notamment un ou des détecteurs infra-rouges, fixés dans la double enveloppe du cryostat sur le fond de l'enveloppe intérieure et une pièce de liaision thermique bonne conductrice de chaleur positionnée dans l'espace libre compris entre ledit fond de la sonde et le fond de l'enveloppe intérieure du cryostat. Selon la présente invention, la pièce de liaison thermique de ce refroidisseur cryogénique:

  • a) est d'un seul tenant,
  • b) possède un talon de fixation central par lequel elle est fixée sur le fond fermant l'extrémité de la sonde,
  • c) présente une forme générale de révolution autour de l'axe longitudinal de la sonde adaptée pour lui conférer une élasticité radiale propre,
  • d) est pourvue de surfaces périphériques venant en appui sous l'effet de ladite élasticité, contre la paroi cylindrique de l'enveloppe interne, sur le pourtour de l'espace libre précité compris entre le fond de la sonde et le fond de l'enveloppe intérieure du cryostat.
The cryogenic cooler targeted by this invention is of the type comprising a probe provided with an end cooled by gas expansion and closed by a bottom, a vacuum jacketed cryostat whose inner jacket formed by a cylindrical wall closed by a bottom is adapted to contain the cooled end of the probe, a sample to be cooled, in particular one or more infrared detectors, fixed in the double jacket of the cryostat on the bottom of the inner jacket and a good conductive thermal bonding piece of heat positioned in the free space between said bottom of the probe and the bottom of the inner envelope of the cryostat. According to the present invention, the thermal connection part of this cryogenic cooler:
  • a) is in one piece,
  • b) has a central fixing heel by which it is fixed to the bottom closing the end of the probe,
  • c) has a general shape of revolution around the longitudinal axis of the probe adapted to give it its own radial elasticity,
  • d) is provided with peripheral surfaces bearing under the effect of said elasticity, against the cylindrical wall of the internal envelope, on the periphery of the aforementioned free space between the bottom of the probe and the bottom of the inner envelope of the cryostat.

Pour conférer l'élasticité radiale propre ladite pièce comporte de préférence une pluralité de fentes longitudinales réparties sur son pourtour à l'exception de son talon.To impart its own radial elasticity, said part preferably comprises a plurality of longitudinal slots distributed over its periphery with the exception of its heel.

Ainsi, l'invention réalise une liaison thermique entre l'extrémité refroidie de la sonde et la paroi cylindrique du cryostat, la ou les pièces de liaison étant en appui contre cette paroi cylindrique et fixée sur la sonde. Le contact de la ou des pièces de liaison thermique avec le cryostat et la sonde d'effectue par une pluralité de surfaces de contact ou par une surface de contact étendue, cependant que la section de conduction s'étendant selon un cylindre peut être de dimension importante, de sorte que l'invention permet d'at- teindre d'excellentes performances thermiques et d'obtenir un écart de température de valeur très faible entre l'extrémité refroidie de la sonde et l'échantillon.Thus, the invention provides a thermal connection between the cooled end of the probe and the cylindrical wall of the cryostat, the connection piece or pieces being in abutment against this cylindrical wall and fixed on the probe. The contact of the thermal connection part (s) with the cryostat and the probe made by a plurality of contact surfaces or by an extended contact surface, while the conduction section extending along a cylinder may be of dimension important, so that the invention makes it possible to achieve excellent thermal performance and to obtain a very small temperature difference between the cooled end of the probe and the sample.

De plus, la sonde et la ou les pièces de liaison thermique fixées sur celle-ci sont libres longitudinalement puisque ces pièces viennent simplement en appui contre la paroi cylindrique du cryostat: la sonde est donc libre de se déformer longitudinalement, ce qui autorise un fonctionnement du refroidisseur dans une large gamme de température; en outre, les tolérances de fabrication sont très larges, tant dans le sens longitudinal que radial (puisque l'appui de la ou des pièces de liaison thermique est produit par l'élasticité radiale de ces dernières sans contact avec le fond interne du cryostat); par ailleurs, les vibrations longitudinales de la sonde ne sont pas transmises à l'échantillon en raison notamment de cette absence de contact entre la sonde et le fond de l'enveloppe interne du cryostat.In addition, the probe and the thermal connection piece or pieces attached to it are free longitudinally since these pieces simply come to bear against the cylindrical wall of the cryostat: the probe is therefore free to deform longitudinally, which allows operation cooler in a wide temperature range; in addition, the manufacturing tolerances are very wide, both in the longitudinal and radial directions (since the support of the thermal connection part (s) is produced by the radial elasticity of the latter without contact with the internal bottom of the cryostat) ; moreover, the longitudinal vibrations of the probe are not transmitted to the sample due in particular to this absence of contact between the probe and the bottom of the internal envelope of the cryostat.

L'invention ayant été exposée dans sa forme générale, d'autres caractéristiques et avantages se dégageront de la description qui suit en référence des dessins annexés, lesquels en présentent à titre d'exemples non limitatifs des modes de réalisation; sur ces dessins qui font partie intégrante de la description:

  • la fig. 1 est une vue d'ensemble d'un refroidisseur cryogénique conforme à l'invention, les moyens connus de ce refroidisseur ayant simplement été schématisés sur cette figure,
  • la fig. 2 est une vue en perspective de détail de la pièce de liaison thermique équipant ledit refroidisseur,
  • les fig. 3, 4 et 5 sont des vues partielles, illustrant d'autres modes de réalisation de l'invention.
The invention having been explained in its general form, other characteristics and advantages will emerge from the description which follows with reference to the appended drawings, which present non-limiting examples of embodiments thereof; on these drawings which form an integral part of the description:
  • fig. 1 is an overall view of a cryogenic cooler according to the invention, the known means of this cooler having simply been shown diagrammatically in this figure,
  • fig. 2 is a perspective view of a detail of the thermal connection piece equipping said cooler,
  • fig. 3, 4 and 5 are partial views illustrating other embodiments of the invention.

Le refroidisseur cryogénique représenté schématiquement à titre d'exemple à la fig. 1 comprend deux ensembles séparés 1 et 2 reliés par un tube de liaison 3. L'ensemble 1 peut être un groupe moto-compresseur ou un groupe moto- oscillateur, adapté pour générer un débit de gaz sous pression ou une oscillation de pression dans le tube 3.The cryogenic cooler shown schematically by way of example in FIG. 1 comprises two separate assemblies 1 and 2 connected by a connecting tube 3. The assembly 1 can be a motor-compressor group or a motor-oscillator group, suitable for generating a flow of gas under pressure or a pressure oscillation in the tube 3.

L'ensemble 2 comprend une sonde schématisée en 4 (en soi bien connue), comportant une extrémité refroidie 5 dans laquelle s'effectue une détente de gaz productrice de froid. Cette sonde est fixée par des moyens de fixation classiques (non représentés) sur un cryostat 6 formé par une enveloppe externe 7 et une enveloppe interne 8 entre lesquelles est réalisé un vide poussé.The assembly 2 comprises a probe shown diagrammatically at 4 (per se well known), comprising a cooled end 5 in which an expansion of the cold producing gas takes place. This probe is fixed by conventional fixing means (not shown) on a cryostat 6 formed by an external envelope 7 and an internal envelope 8 between which a high vacuum is produced.

L'enveloppe interne 8 est constituée par une paroi cylindrique 8a et par un fond circulaire 8b; l'extrémité refroidie 5 de la sonde est logée dans l'enveloppe 8 au voisinage du fond 8b. Un échantillon à refroidir par exemple un ou plusieurs détecteurs infra-rouges 9, est collé sous le fond 8b entre les deux enveloppes du cryostat.The internal envelope 8 is constituted by a cylindrical wall 8a and by a circular bottom 8b; the cooled end 5 of the probe is housed in the casing 8 in the vicinity of the bottom 8b. A sample to be cooled, for example one or more infrared detectors 9, is bonded under the bottom 8b between the two envelopes of the cryostat.

Les divers organes décrits jusqu'à présent sont classiques et ne seront pas davantage détaillés.The various organs described so far are conventional and will not be further detailed.

Selon l'invention une pièce de liaison thermique 10 qui a été représentée en perspective à échelle dilatée à la fig. 2, est fixée sur l'extrémité refroidie 5 de la sonde.According to the invention a thermal connection piece 10 which has been shown in perspective on an expanded scale in FIG. 2, is fixed to the cooled end 5 of the probe.

Cette pièce réalisée en métal bon conducteur de la chaleur tel que cuivre, laiton, aluminium ... comprend un talon de fixation 11 qui permet de la fixer sur l'extrémité refroidie 5 et des languettes d'appui telles que 12 séparées par des fentes longitudinales telles que 13, qui présentent une élasticité radiale.This part made of metal which is a good conductor of heat such as copper, brass, aluminum, etc. comprises a fixing heel 11 which makes it possible to fix it on the cooled end 5 and support tabs such as 12 separated by slots longitudinal such as 13, which have radial elasticity.

Le talon d'appui 11 est adapté pour se fixer sur l'extrémité 5 de la sonde avec un contact surfacique étendu. En l'exemple de la fig. 1 où la sonde 4 possède une extrémité refroidie 5 fermée par un fond plat circulaire 5a, le talon 11 présente la forme d'un disque plat appliqué et collé contre le fond plat 5a.The support heel 11 is adapted to be fixed on the end 5 of the probe with an extended surface contact. In the example of fig. 1 where the probe 4 has a cooled end 5 closed by a circular flat bottom 5a, the heel 11 has the shape of a flat disc applied and glued against the flat bottom 5a.

Chaque languette d'appui 12 possède une surface d'appui en forme de portion de cylindre et se trouve radialement en saillie par rapport au talon 11 de façon à venir en appui contre la paroi cylindrique 8a de l'enveloppe 8, sans contact avec le fond 8b. La pièce 10 réalise ainsi une liaison thermique avec l'enveloppe interne 8 par une pluralité de contacts répartis sur son pourtour. On peut, le cas échéant, augmenter la qualité de ces contacts en recouvrant les surfaces de contact des languettes au moyen d'un produit visqueux (graisse bonne conductrice...).Each support tongue 12 has a support surface in the form of a cylinder portion and is radially projecting relative to the heel 11 so as to come to bear against the cylindrical wall 8a of the casing 8, without contact with the background 8b. The part 10 thus achieves a thermal connection with the internal envelope 8 by a plurality of contacts distributed around its periphery. If necessary, the quality of these contacts can be increased by covering the contact surfaces of the tabs with a viscous product (good conductive grease, etc.).

Lors du montage ou du démontage de la sonde, la pièce de liaison thermique 10 glisse par l'effet de son élasticité radiale le long de la paroi cylindrique 8a du cryostat sand aucune difficulté de mise en place.During assembly or disassembly of the probe, the thermal connection piece 10 slides by the effect of its radial elasticity along the cylindrical wall 8a of the cryostat without any difficulty in positioning.

La fig. 3 montre une variante de pièce de liaison 14 dans laquelle le talon 15 présente le même diamètre que le fond plat circulaire de la sonde et est collé sur toute la surface de celui-ci pour augmenter le contact surfacique entre ces éléments. Dans cette variante, les languettes 16 viennent radialement en saillie en appui contre la paroi cylindrique grâce à une surépaisseur externe qu'elles présentent.Fig. 3 shows a variant of connecting piece 14 in which the heel 15 has the same diameter as the circular flat bottom of the probe and is bonded over the entire surface of the latter to increase the surface contact between these elements. In this variant, the tongues 16 radially project in abutment against the cylindrical wall thanks to an external excess thickness which they present.

La fig. 4 montre une autre variante dans laquelle l'extrémité refroidie de la sonde comporte une tête 5b de diamètre réduit; la pièce de liaison 17 présente un talon ajouré 18 qui est adapté pour s'engager autour de cette tête. Dans cette variante, la tête est lisse et le talon 18 est collé autour de celle-ci.Fig. 4 shows another variant in which the cooled end of the probe comprises a head 5b of reduced diameter; the connecting piece 17 has a perforated heel 18 which is adapted to engage around this head. In this variant, the head is smooth and the heel 18 is glued around it.

Dans la variante représentée à la fig. 5, la tête 5c est pleine et filetée sur son pourtour, et le talon 19 de la pièce de liaison est taraudé et vissé sur cette tête.In the variant shown in FIG. 5, the head 5c is full and threaded around its periphery, and the heel 19 of the connecting piece is tapped and screwed onto this head.

L'invention permet d'écarter tous les inconvénients des solutions traditionnelles et confère à la liaison thermique du refroidisseur tous les avantages souhaitables:

  • - excellentes performances thermiques,
  • - faculté de fonctionnement dans une large plage de température,
  • - absence de transmission des vibrations longitudinales de la sonde,
  • - absence de résidu lors des démontage et, donc, pas d'opération de nettoyage à exécuter,
  • - simplicité et larges tolérances de fabrication.
The invention eliminates all the drawbacks of traditional solutions and gives the thermal connection of the cooler all the desirable advantages:
  • - excellent thermal performance,
  • - ability to operate over a wide temperature range,
  • - absence of transmission of the longitudinal vibrations of the probe,
  • - absence of residue during disassembly and, therefore, no cleaning operation to be performed,
  • - simplicity and wide manufacturing tolerances.

Claims (8)

1. Cryogenic cooling device of the type comprising a probe (4) provided with an extremity (5) cooled by expansion of a gas and closed by a bottom (5a), a cryostat (6) with double envelope under vacuum, the inner envelope (8) of which formed by a cylindrical wall (8a) closed by a bottom (8b) is adapted to contain the cooled extremity (5) of the probe, a sample to be cooled (9), in particular one or more infrared detectors, fixed in the double envelope of the cryostat on the bottom (8b) of the inner envelope, and a thermal connecting piece (10) of good thermal conductivity located in the free space between said bottom (5a) of the probe and the bottom (8b) of the inner envelope (8) of the cryostat, the cryogenic cooling device being characterized in that the thermal connecting piece:
a) is in one piece,
b) comprises a central securing heel (11) by which it is fixed on the bottom (5a) closing the extremity of the probe,
c) has a general revolution form about the longitudinal axis of the probe adapted to impart to it a radial inherent elasticity,
d) is provided with peripheral surfaces coming to bear under the effect of the said elasticity against the cylindrical wall (8a) of the inner envelope on the periphery of the aforementioned free space between the bottom (5a) of the probe and the bottom (8b) of the inner envelope of the cryostat.
2. Cryogenic cooling device according to claim 1, characterized in that the thermal connecting piece comprises a plurality of longitudinal slots (13) distributed on its periphery with the exeption of its heel (11) in order to impart thereto the aforementioned radial elasticity.
3. Cryogenic cooling device according to one of claims 1 or 2 in which the probe (4) comprises a cooled end (5) closed by a circularly flat bottom (5a), characterized in that the thermal connecting piece (10, 14) is fixed on said flat bottom (5a) by its heel (11, 15) in the form of a flat disc applied against said flat bottom.
4. Cryogenic cooling device according to claim 3, characterized in that the heel (11, 15) having the form of a flat disc is adhered against the flat bottom (5a) of the cooled extremity (5) of the probe.
5. Cryogenic cooling device according to one of claims 1 or 2, characterized in that the probe (4) comprises a cooled extremity (5) whose bottom has the form of a head (5b, 5c) of reduced diameter, the thermal connecting piece having a recessed heel (18, 19) adapted to said head and engaged around the latter.
6. Cryogenic cooling device according to claim 5, characterized in that the head (5c) of the cooled extremity (5) is threaded, the heel (19) of the connecting piece being threaded and screwed thereon.
7. Cryogenic cooling device according to claim 5, characterized in that the heel (18) of the piece is adhered round the head (5b) of the cooled extremity (5).
8. Cryogenic cooling device according to any one of the preceding claims in which the thermal connecting piece is made from metal of good thermal conductivity.
EP19810200646 1981-02-26 1981-06-12 Cryogenic refrigerator with improved thermal-coupling device Expired EP0059272B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8104070 1981-02-26
FR8104070A FR2500581A1 (en) 1981-02-26 1981-02-26 CRYOGENIC COOLER WITH IMPROVED THERMAL CONNECTION

Publications (2)

Publication Number Publication Date
EP0059272A1 EP0059272A1 (en) 1982-09-08
EP0059272B1 true EP0059272B1 (en) 1984-08-29

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ID=9255745

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19810200646 Expired EP0059272B1 (en) 1981-02-26 1981-06-12 Cryogenic refrigerator with improved thermal-coupling device

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EP (1) EP0059272B1 (en)
DE (1) DE3165767D1 (en)
FR (1) FR2500581A1 (en)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4514204A (en) * 1983-03-21 1985-04-30 Air Products And Chemicals, Inc. Bakeable cryopump
FR2613046B1 (en) * 1987-03-23 1989-06-23 Abg Semca CRYOGENIC COOLER
FR2699263B1 (en) * 1992-12-15 1995-01-27 Cryotechnologies Chiller fitted with a cold finger fitted with a thermal coupler.
GB2297844A (en) * 1995-02-10 1996-08-14 Oxford Magnet Tech Flexible thermal connectors for a superconducting MRI magnet
US6070414A (en) * 1998-04-03 2000-06-06 Raytheon Company Cryogenic cooler with mechanically-flexible thermal interface
US6604366B1 (en) * 2002-09-19 2003-08-12 Raytheon Company Solid cryogen cooling system for focal plane arrays
CN102538551A (en) * 2012-01-20 2012-07-04 中国科学院上海技术物理研究所 Cylindrical flexible cold chain used for large cold quantity transmission of space refrigerating machine

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Publication number Priority date Publication date Assignee Title
US3435137A (en) * 1965-06-14 1969-03-25 Us Navy Infrared camera tube utilizing a superconductor material detector
US3306075A (en) * 1965-10-04 1967-02-28 Hughes Aircraft Co Thermal coupling structure for cryogenic refrigeration
FR1468862A (en) * 1965-10-21 1967-02-10 Air Liquide Miniature refrigerator; especially for quantum detector
US3693374A (en) * 1970-11-18 1972-09-26 Honeywell Inc Variable temperature cooling apparatus
US3807188A (en) * 1973-05-11 1974-04-30 Hughes Aircraft Co Thermal coupling device for cryogenic refrigeration
US4194119A (en) * 1977-11-30 1980-03-18 Ford Motor Company Self-adjusting cryogenic thermal interface assembly

Also Published As

Publication number Publication date
EP0059272A1 (en) 1982-09-08
FR2500581B1 (en) 1983-12-09
DE3165767D1 (en) 1984-10-04
FR2500581A1 (en) 1982-08-27

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