EP0803687A1 - Cryostat for cryogenic refrigerator and refrigerators comprising such a cryostat - Google Patents

Cryostat for cryogenic refrigerator and refrigerators comprising such a cryostat Download PDF

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Publication number
EP0803687A1
EP0803687A1 EP97400898A EP97400898A EP0803687A1 EP 0803687 A1 EP0803687 A1 EP 0803687A1 EP 97400898 A EP97400898 A EP 97400898A EP 97400898 A EP97400898 A EP 97400898A EP 0803687 A1 EP0803687 A1 EP 0803687A1
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EP
European Patent Office
Prior art keywords
cryostat
gas
cooler
regenerator
piston
Prior art date
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Granted
Application number
EP97400898A
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German (de)
French (fr)
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EP0803687B1 (en
Inventor
Patrick Curlier
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Thales Cryogenie SA
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Cryotechnologies 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
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
    • F25B9/14—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the cycle used, e.g. Stirling cycle
    • F25B9/145—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the cycle used, e.g. Stirling cycle pulse-tube cycle
    • 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
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
    • F25B9/14—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the cycle used, e.g. Stirling cycle
    • 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
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2309/00—Gas cycle refrigeration machines
    • F25B2309/003—Gas cycle refrigeration machines characterised by construction or composition of the regenerator
    • 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
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2309/00—Gas cycle refrigeration machines
    • F25B2309/14—Compression machines, plants or systems characterised by the cycle used 
    • F25B2309/1406—Pulse-tube cycles with pulse tube in co-axial or concentric geometrical arrangements
    • 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
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2309/00—Gas cycle refrigeration machines
    • F25B2309/14—Compression machines, plants or systems characterised by the cycle used 
    • F25B2309/1407—Pulse-tube cycles with pulse tube having in-line geometrical arrangements
    • 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
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2309/00—Gas cycle refrigeration machines
    • F25B2309/14—Compression machines, plants or systems characterised by the cycle used 
    • F25B2309/1421—Pulse-tube cycles characterised by details not otherwise provided for
    • 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
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2309/00—Gas cycle refrigeration machines
    • F25B2309/14—Compression machines, plants or systems characterised by the cycle used 
    • F25B2309/1424—Pulse tubes with basic schematic including an orifice and a reservoir
    • F25B2309/14241—Pulse tubes with basic schematic including an orifice reservoir multiple inlet pulse tube

Definitions

  • the present invention relates to the design and production of cryogenic coolers which use a working gas following a thermodynamic cycle in a closed circuit between a compression chamber and an expansion chamber, passing through a so-called regenerative thermal accumulator, which provides a recovery exchange between compressed hot gas and expanded cold gas.
  • coolers conventionally comprise a pressure oscillator controlled to vary the volume of the compression chamber, and a cold finger terminating in the expansion chamber, in thermal contact with an element to be cooled, placed at the bottom of a thermal insulation envelope.
  • the element to be cooled is commonly an electronic component which must be kept in operation at temperatures between 60 ° K and 200 ° K, in particular in order to improve the signal to noise ratio.
  • cryogenic coolers of the type in question meet with increasing success every day, mainly when they are designed to be manufactured at low cost under shapes integrating the pressure oscillator with the cold finger in the same mechanical assembly, no longer needing external pipes to close the working gas circuit.
  • the present invention is mainly intended to provide users with a cryostat which is not limited to an envelope insulator capable of receiving the cold finger of the cooler, but which incorporates part of its essential organs, in a form allowing their interchangeable adaptation to different configurations.
  • a cryostat for cryogenic cooler produced according to the invention easily adapts, in accordance with its interchangeable nature, both to a configuration with pulsed gas tube and to a Stirling cycle configuration, and that the control of the pressure oscillator goes through a rotary crankshaft or linear type drive, depending on the expressions used by those skilled in the art, as they are included in particular in the article already cited.
  • the invention also makes it possible to bring appreciable improvements to the construction of the coolers incorporating such a cryostat and to their control mode.
  • the resulting advantages relate in particular to the combination of the cryostat with a pressure oscillator in an embodiment relating to a configuration with a pulsed gas tube.
  • the features proposed for the various components of the cryostats according to the invention have the advantage of lending themselves particularly well to the respective operating modes of the two types of coolers and of improving their own performance.
  • This is the case in particular of the provisions recommended for the regenerator, which is responsible for absorbing and releasing heat, alternately, relative to the gas which passes through it.
  • This is also the case for an exchanger advantageously provided in a cold zone, at the level of the expansion chamber, to promote heat transfer to the component to be cooled, as well as for an exchanger located in a hot zone and under pressure which is specially useful in pulsed gas type coolers, to promote heat loss to the outside.
  • the invention more specifically relates to a cryostat for a cryogenic cooler implementing a closed working gas circuit between a compression chamber located in an associated pressure oscillator casing and an expansion chamber located at the bottom of the cryostat.
  • a thermal regenerator interposed on the working gas circuit.
  • This regenerator is in annular arrangement around an axial volume extending between a cold exchanger which is in thermal contact with the component to be cooled and makes the regenerator communicate with said axial volume at the bottom of the cryostat.
  • the cryostat also includes a gas distribution ring in said regenerator, at the head of the cryostat, from a conduit drilled through the base for connection to the compression chamber.
  • the distribution ring is formed by a central piece which is mounted through said base axially at its center. Said central part is removably mounted in said base, in particular by tight screwing.
  • At least one channel for the passage of gas under controlled flow between a gas buffer tank formed inside the casing of the pressure oscillator, and the internal axial volume of the cryostat which operates in a gas tube. It is also advantageous to add one or more other channels with controlled flow allowing a withdrawal of hot gas directly at the compression outlet, at the level of the distribution ring towards the regenerator.
  • the internal volume is at on the contrary occupied by the displacement piston, which is preferably full, made of a material of low thermal conductivity, and which leaves free to the gas only the volume of the expansion chamber at the bottom of the cryostat.
  • the central part is made integral with a central tube limiting said axial volume.
  • This tube is then advantageously of the same internal diameter as the axial bore of the model intended for a connection of the cryostat to a Stirling cycle cooler. It can therefore constitute either the tube containing the pulsed gas in the first model, or the guide tube of the displacer piston of the cooler in the second case.
  • a hot exchanger positioned in the internal volume at the head of the cryostat. Its role is in the evacuation of calories which takes place by heat loss to the outside through the base and the casing of the compressor part of the cooler, made for this purpose from thermally conductive material. It is especially useful in the variant of a pulsed gas tube cooler, taking into account the heat to be evacuated at the outlet of the gas tube, which is added to the heat stored by the gas in return from the regenerator.
  • the invention provides, according to a secondary characteristic, which can be applied advantageously with the others in any operating combination, to use a structure with geometry of revolution, alternating around the axis of the cryostat, in a daisy arrangement, massive zones made of a material which is a good thermal conductor and empty zones open to the passage of gas. As a result, these areas are located in particular on horseback, on both sides, relative to a centering shoulder of the end of the central tube.
  • a cooler according to the invention constructed to operate on the principle of the pulsed gas tube, it is advantageous to provide the buffer volume of gas supplying the gas piston inside a compression piston, which at this indeed, on the side opposite to the compression chamber, is directly open in a jacket for guiding said piston which is connected to the appropriate central part of the cryostat.
  • control means comprising a crankshaft actuating a movement transmission mechanism by movable ball bearing in a groove formed transversely outside said piston.
  • the annular arrangement of the regenerator lends itself particularly well to manufacture from a sheet wound on itself.
  • the invention makes it possible to significantly improve the efficiency of the desired heat exchanges, compared with the stacks of grids or conventional balls, by using for this a sheet of suitable material, which has been previously machined, in particular by photolithographic process, so as to form separate longitudinal bands with smooth surface and transverse bars in excess thickness punctually joining the successive bands.
  • the different bands follow one another along the length of the regenerator. They form annular layers of smooth surface intersected by the intervals between bands and the bars inserted between the layers help to distribute the flow in all directions at each level of cross section.
  • the cryostat of FIG. 1 is used in combination with a pressure oscillator either to constitute a cryogenic cooler of the pulsed gas type in accordance with FIG. 6, or alternatively to constitute a cooler of the Stirling cycle type in accordance with FIG. 5.
  • a pressure oscillator either to constitute a cryogenic cooler of the pulsed gas type in accordance with FIG. 6, or alternatively to constitute a cooler of the Stirling cycle type in accordance with FIG. 5.
  • the cooler thus formed is of compact construction, the cryostat and the pressure oscillator being integrated in the same mechanical assembly.
  • cryostat according to the invention is not limited, as in the known embodiments, to a thermal insulation envelope intended to receive a cold finger previously formed in all its functional organs necessary for the implementation of the thermodynamic cycle of the working gas.
  • the passive functional members which are not subjected to displacements during operation, are provided permanently in the cryostat, the latter being constructed so as to be able to be connected, alternatively at the option of the user, to the casing a pressure oscillator belonging either to a specific cooler for implementing a Stirling cycle, or to a cooler of the pulsed gas tube type.
  • a thermal insulation envelope 1 mounted integral with a base 4 serving for its mechanical and pneumatic connection with the pressure oscillator part of the cooler.
  • concentric tubulars namely a central tube 3 and an internal wall 2 of the casing 1, which delimit between them an annular space occupied by a thermal regenerator 5.
  • the regenerator 5 is thus constructed in annular arrangement around an axial volume 6 , limited on its periphery by the central tube 3 among the two previous ferrules.
  • the other ferrule which externally limits the thermal regenerator, is therefore here directly constituted by the internal wall 2 of the thermal insulation envelope 1.
  • This is in fact, in itself conventional, of the type to double sided. Between its two walls, it is either filled with an inert gas with a low condensation point, or subjected to a high vacuum, for which it is provided with a charging port 25.
  • regenerator 5 with its own envelopes, including an external envelope which is then distinct from the internal wall 2 of the thermal insulation envelope and / or an internal envelope which is then added against the central tube 3.
  • this exchanger 8 which in operation constitutes the cold exchanger of the cooler.
  • this exchanger is designed and arranged so as to promote the transfer of the cooling power resulting from the expansion of the working gas to a component to be cooled 21, while ensuring pneumatic communication allowing the passage of the working gas between the bottom of the axial volume 6 and the annular space occupied by the regenerator 5.
  • the intermediate shell of the cryostat of the invention constituted by the wall 2, is closed at its lower end, at the bottom of the cryostat, by a transverse plate 22 against which the cold exchanger 8 is affixed. On its face opposite this exchanger component 21 is assembled, generally by simple bonding.
  • FIG. 1 therefore shows an electrical distribution ring 23, the conductive parts of which pass through watertight crossings through the external wall of the thermal insulation envelope 1, as well as the conductive wires 24 which connect them then to component 21.
  • the envelope 1 as a whole has the function of limiting the heat losses by radiation or convection at the level of the organs involved in the thermodynamic cycle of the complete cooler in the cold zone thereof.
  • a quality of stainless steel corresponding to an alloy with low thermal conductivity adapted to be compatible with the working gas used, which is preferably helium in the case of the regenerator. with metallic foil rolled up as described below.
  • the outer wall of the casing 1 is also made of stainless steel, or possibly of an appropriate quality of glass, for economic reasons.
  • the base 4 is, on the contrary, in the hot zone of the cooler in operation, where there is also a dynamic pressure of the working gas, subjected to periodic pressure pulses, printed by the mobile elements of the cooler when the cryostat is connected to the casing 50 of an associated pressure oscillator.
  • the base 4 In this hot zone, it is necessary to evacuate the calories of the gas returning from the expansion, after the recovery carried out in the regenerator 5. For this, it is planned to make the base 4 in a material of good conductivity thermal, generally of stainless steel, in a form favoring the losses towards the outside.
  • the base 4 there is a circular flange 16, pierced with holes for the passage of the screws 48 ensuring the attachment to the casing 50 of the cooler, which is connected to bear on the upper face of the flange 16, opposite to the thermal envelope 1.
  • the sealed connection of these two elements (cryostat and pressure oscillator) to the outside is provided by a seal 19, housed in an annular groove on the upper face of the flange 16.
  • the base 4 delivers passage, in the axis of the system, to a central part 10, screwed in a sealed manner in the ring 17, which is internally threaded.
  • a hexagonal groove 41 formed in its upper flat face, is used for its manipulation during assembly.
  • this central part of the cryostat is designed in two different models which, by their external geometry, their dimensioning, and their functional design, are interchangeable in the same cryostat construction.
  • the two models are illustrated in FIG. 1 and in FIG. 2, depending on whether the cryostat 30 is mounted to be coupled with the housings 50 or 60 of one or the other of the two pressure oscillators in the two cooler variants. shown in Figures 6 and 5 respectively.
  • this central part therefore in particular that bearing the reference 10 in FIG. 1, here consists of a single part with the internal tube 3 of the cryostat.
  • this ring forms a distribution ring 71, for the annular distribution of the gas at the head of the regenerator 5. Consequently, this ring is placed above the latter (in the vertical arrangement shown, cryostat under the casing 50), and more precisely at the center of the base 4 in its main part formed by the collar 16.
  • the distribution ring 71 has a circular groove 45, hollowed out in its lower face, which abuts on the regenerator 5. This groove communicates through orifices 46 with an annular chamber 43, extended upwards at 42, which is formed externally in the part of the central part 10 located at the level of the collar 16, between this part and the face opposite the base 4.
  • the central part 10 is shown in FIG. 1 in the model suitable for a TGP type cooler illustrated in FIG. 6.
  • the second model of central part of the cryostat, intended for a Stirling cycle cooler, is shown in the schematic representation in exploded arrangement of FIG. 2.
  • the central part 20 is identical to the previous one externally, but internally, it simply comprises an axial bore 72, formed all along it, with the same diameter as the tube 3, the central volume of which it extends.
  • a channel 11 opens which is drilled axially in the central part 10 to its upper face, where it ends in a calibrated orifice 13 imposing a controlled gas flow.
  • Another pneumatic connection involving one or more channels, is provided through the part 10, with the annular chamber 43 of the gas distribution ring towards the regenerator 5.
  • a calibrated orifice 14 has thus appeared on a channel 12 opening into the axial channel 11.
  • the calibrated orifices of the channels 11-12 function, in a conventional manner in themselves, like valves introducing pneumatic impedances.
  • the main channel 11 thus equipped in operation provides the useful phase shift between the pressure wave generated by the pressure oscillator and the resulting flow variations in the tube containing the pulsed gas.
  • the secondary impedance (channel 12) makes it possible to provide a fraction of the periodic supply flow rate of the tube by withdrawing it directly from the compression outlet, by diverting the circulation passing through the regenerator and the tube. This reduces the thermal load on the regenerator and contributes to improving the efficiency of the cooler, in the case of a pulsed gas cycle.
  • FIG. 1 finally shows an exchanger 9, located in the hot zone in the central volume, at the level of the distribution ring 71.
  • This hot exchanger can optionally be produced in a similar manner to that which will be described below for the cold exchanger, the main thing is that, in this variant embodiment of the cryostat of the invention, it completes the evacuation of the excess calories from the thermodynamic cycle by completing, from the zone hot of the pulsed gas tube, the heat losses to the outside taking place through the base 4, and incidentally from the associated pressure oscillator casing.
  • the thermal regenerator 5 is advantageously constituted, as it appears in FIGS. 1 and 3, so as to fully play its role of thermal accumulator for the recovery taking place, so in itself conventional, between the working gas passing from the compression phase to the expansion phase and the working gas passing from the expansion phase to the compression phase.
  • such a regenerator is in the form of a continuous sheet which is wound in a series of turns around the central tube 3 which limits the internal volume 6 of the regenerator, so as to fill, as completely as is possible in industrial practice, the annular space comprised between this tube 3, which forms its inner shell ferrule, and its associated outer shell ferrule, constituted by the inner wall 2 of the insulating jacket 1.
  • machining processes by photolithography which are known in themselves, are particularly advantageous in this sense, insofar as they represent particularly simple technological means to implement for a limited cost price, when it comes to lead to the configuration illustrated by the detail in FIG. 3.
  • the sheet which is thus wound in contiguous consecutive turns forms a succession of distinct longitudinal bands 27, which are oriented perpendicular to the axis of the cryostat and which are separated from each other by intervals 28.
  • Bars 26 are formed in excess thickness of the strips and across them in a perpendicular direction. They are regularly distributed over the entire length and height of the sheet and staggered, each uniting two successive bands over the gap between them.
  • a regenerator thus constructed, one can cite as an example the case of a sheet 100 to 200 microns thick, hollowed out at mid-thickness by each face, for a regenerator of 2 to 3 millimeters of radial thickness.
  • the strips and the intervals between them can, for example, be of the same width, of the order of 50 to 100 microns.
  • the transverse length of the bars 26 may correspond, here again by way of example, to 1.5 times the repetition pitch of the longitudinal strips 27, with a width approximately half less and a distance between two successive bars offset, equivalent to approximately three times the width of each.
  • the invention thus makes it possible to take advantage of a relationship between the local convective exchange and the losses of longitudinal loads which, in the case of plates parallel to the axis of the cold finger, would be greater than the value which can be obtained by the usual stacks of grids or balls, however, in this practical embodiment, it allows a better distribution of the gas flow between the parallel layers of smooth surfaces.
  • the presence of the barriers 26, which remain small compared to the length and the thickness of the regenerator, also makes it possible to introduce a periodic interruption of the longitudinal flow between the layers of successive strips from one end to the other of the regenerator, and thereby stabilize the overall gas flow. Simultaneously, as these bars adjoin two adjacent layers of strips, we obtain thanks to them a reduction of the losses of thermal energy by conduction in the longitudinal direction. Simultaneously, this ensures a reduction in losses of thermal energy by conduction in the longitudinal direction.
  • regenerator 5 makes it possible, in a particularly advantageous manner in the context of the present invention, to obtain a ratio between the local convective exchange and the very advantageous longitudinal pressure drop, while improving the distribution of the flow rate. gas between the parallel layers oriented longitudinally, until thermal recovery performance at least equivalent, if not greater than that which is known to be obtained in known embodiments by regenerators with stacked transverse grids or with balls.
  • Another characteristic common to the two variants of coolers described here, by way of example, relates to the production of the cold exchanger 8 installed at the bottom of the thermal insulation envelope 1 of the cryostat according to the invention, such as it is more particularly illustrated in FIG. 4.
  • This cold exchanger is produced, in accordance with what emerges from FIGS. 1, 2 and 4, in a so-called daisy shape. It consists of a structure with a geometry of revolution, which is made of a highly conductive material such as copper or aluminum.
  • This structure alternates in a star around a central core 31, empty zones 32 hollowed out through its longitudinal thickness and massive zones 33 ensuring thermal conduction. Both extend radially astride the shoulder 34, on either side of the end of the central tube 3. They therefore allow the gas to circulate freely between the central volume 6 of the cryostat (or at least the expansion chamber remaining at the bottom of the cryostat in the case of a cooler according to FIG. 5 applying a Stirling cycle), bypassing the lower end of the central tube 3 received in the shoulder 34.
  • Such a miniature exchanger for example 5 mm in diameter and 3 mm thick, can be easily manufactured by electrochemical machining of a cylindrical bar, which is then cut into sections.
  • the core 31 can be additionally pierced with an empty passage in its center, and it is not necessary to leave a peripheral crown of material, continuously contiguous with the central tube 3.
  • the massive zones form lobes of material exchanger, again in a configuration straddling the diameter of the tube 3, in which the empty zones between the lobes ensure the passage of gas between the regenerator and either the expansion chamber of a Stirling cycle cooler, the bottom of the gas piston of a pulsed gas tube cooler.
  • FIG. 5 illustrates the combination of the cryostat of the preceding figures, using the central part 20 of FIG. 2, with a pressure oscillator responding to the configuration of a Stirling cycle cooler, in which the control is with a rotary engine.
  • a conventional drive system is schematically represented by a crankshaft 51 whose eccentric is linked to two connecting rods 53, 54, arranged at 90 degrees from one another.
  • the connecting rod 53 is articulated on the end of the displacing piston 55, while the connecting rod 54 is articulated on the compression piston 56 which limits the compression chamber 57.
  • the compressed gas is conveyed by conduits 58, 59 to the channel 39 of the cryostat supplying the distribution chamber 71 of the cryostat, and from there the regenerator 5.
  • the displacer piston 55 is axially movable in the internal volume 6 of the cryostat 30. It occupies almost all of this volume, leaving space at the bottom of the tube 3 which constitutes its guide, only to the thickness of the expansion chamber, considerably enlarged in the figure in relation to practical reality.
  • FIG. 6 uses a pressure oscillator designed for a TGP type cooler, the housing 50 of which is connected to the cryostat around the central part 10 of the model of FIG. 1.
  • control mode is of the rotary type.
  • the engine shaft is perpendicular to the axis of the system and, by an off-center crankshaft 66, it drives in a oscillating movement, a single piston 74.
  • the piston 74 is movable, vertically in the figure, in the axis of the cryostat, in a jacket formed inside the casing 50.
  • the internal cage 68 of a ball bearing On the offset axis 66 is mounted the internal cage 68 of a ball bearing, the external cage 67 of which is trapped in a rectilinear groove 75 hollowed out laterally in the peripheral surface of the piston 74, perpendicular to its axis and to the plane of the figure. This arrangement ensures the reciprocating movement of the piston while immobilizing it in rotation.
  • the compression chamber 63 is formed between the upper end face of the piston and the casing 60. It is connected, as in the previous case, by a bore 62 and a conduit 61 to the channel 39 opening into the distribution chamber of the cryostat .
  • the opposite side of the piston is hollow. There is thus formed, on the side opposite to the compression chamber, a reservoir 65, of large volume relative to the volume of gas in circulation. The pressure prevailing in this tank therefore remains practically constant in operation.
  • the same arrangement can advantageously be applied, leaving the buffer tank directly open on the free surface of the central part 10 at the head of the cryostat, inside the compression piston, in the case of a TGP type cooler whose control is ensured by a linear motor rather than a rotary motor.
  • FIG 7 we have shown a particularly advantageous embodiment for the bottom of the cryostat.
  • the exploded representation used for clarity, schematically shows the regenerator 5 between the tube 3 of pulsed gas and the tubular wall 2, which leaves room for the cold exchanger 8 against the plate 22.
  • the exchanger 8 here consists of lobes 77 of solid material in radiating arrangement around a central core 34. Between these lobes 77 are located the gas passages 78 which make the lower end of the regenerator communicate with the axial volume of the tube 3.
  • the laminate for tranquilizing the gas flow which has already been discussed, is represented by a stack of perforated grids 81 mounted in cross section of the tube 3 at this lower end. These grids can be retained by lugs of the tube 3, as shown, or simply wedged between the end of the tube and the exchanger 8 in its central part limited by a shoulder 79 for centering the tube 3. In all cases, the gas passing between the exchanger lobes is found to have to pass through the stack of grids.
  • This circulation is indicated by arrows in FIG. 8, which relates to another particularly advantageous embodiment in particular in that it facilitates a tranquilization of the gas flow as close as possible to the cold plate 22.
  • the cold exchanger is produced therein.
  • two parts 83 and 84 nested concentrically one inside the other; Each has its own lobes of heat exchange material alternating with empty areas free for gas circulation.
  • the exchanger is therefore pierced with channels dividing into two rings, one under the regenerator 5, the other at the end of the tube 3.
  • the internal part 83 of the exchanger is more shorter than the external part 84 which surrounds it and so that the end of the tube 3 is centered in the part 84 abutting on the part 83.
  • a stack of grids 82 constitutes the laminate for tranquilizing the gas flow. These grids are interposed directly against the cold plate 22 between the latter and the two parts 83 and 84 of the exchanger. If necessary, they could be blocked in the exchanger at the periphery, providing for this purpose a shoulder in the part 84 forming the annular ring of this exchanger.

Abstract

At the warm zone, a mounting plate (4), screwed (48) and sealed (19) to the pulsed gas compressor (50), has an integral projecting cylinder (2) with a cold-zone base (22). Against this the cooled item typically an opto-electronic component (21) is held, e.g. by adhesive. An insulating jacket (1), evacuated or gas-filled, encloses the finger (2,22). A ducted (11, 12) block (10) screws into a neck (17), on the plate, fitting into the compressor reservoir chamber. Its integral sleeve (3), with warm and cold-zone heat exchangers (9,8), enters the skirt (2), the annular space between containing a rolled mesh regenerator (5), percolated by gas ducted (61, 39, 42, 43, 46, 45) from the compressor's compression chamber. Fingers for Stirling cycle coolers are similar, but the inner sleeve (3), extending up through the block (10), accommodates the reciprocating displacer piston.

Description

La présente invention concerne la conception et la réalisation des refroidisseurs cryogéniques qui mettent en oeuvre un gaz de travail suivant un cycle thermodynamique en circuit fermé entre une chambre de compression et une chambre de détente, en passant par un accumulateur thermique dit régénérateur, qui assure un échange de récupération entre gaz chaud comprimé et gaz froid détendu.The present invention relates to the design and production of cryogenic coolers which use a working gas following a thermodynamic cycle in a closed circuit between a compression chamber and an expansion chamber, passing through a so-called regenerative thermal accumulator, which provides a recovery exchange between compressed hot gas and expanded cold gas.

Ces refroidisseurs comportent, de manière classique, un oscillateur de pression piloté pour faire varier le volume de la chambre de compression, et un doigt froid se terminant par la chambre de détente, en contact thermique avec un élément à refroidir, placé au fond d'une enveloppe d'isolation thermique. L'élément à refroidir est couramment un composant électronique qu'il s'agit de maintenir en fonctionnement à des températures comprises entre 60 °K et 200 °K, afin notamment d'améliorer le rapport signal sur bruit.These coolers conventionally comprise a pressure oscillator controlled to vary the volume of the compression chamber, and a cold finger terminating in the expansion chamber, in thermal contact with an element to be cooled, placed at the bottom of a thermal insulation envelope. The element to be cooled is commonly an electronic component which must be kept in operation at temperatures between 60 ° K and 200 ° K, in particular in order to improve the signal to noise ratio.

Dans un tel contexte, qui implique bien des domaines de l'industrie où il est utilisé des composants électroniques ou optoélectroniques, les refroidisseurs cryogéniques du type en question rencontrent un succès chaque jour grandissant, principalement quand ils sont conçus pour être fabriqués à faible coût sous des formes intégrant l'oscillateur de pression avec le doigt froid dans un même ensemble mécanique n'ayant plus besoin de conduites externes pour fermer le circuit de gaz de travail.In such a context, which involves many areas of the industry where electronic or optoelectronic components are used, cryogenic coolers of the type in question meet with increasing success every day, mainly when they are designed to be manufactured at low cost under shapes integrating the pressure oscillator with the cold finger in the same mechanical assembly, no longer needing external pipes to close the working gas circuit.

Mais, par ailleurs, la variété de leurs applications industrielles a entraîné le développement de différentes configurations technologiques de refroidisseurs en fonction du cycle de travail le mieux adapté aux circonstances. On les trouvera décrites dans leur principe dans un article de Damien Feger intitulé "Refroidissement des détecteurs optoélectroniques" paru dans "Techniques de l'Ingénieur, traité Electronique" pages E4070-1 à 11.But, moreover, the variety of their industrial applications has led to the development of different technological configurations of chillers according to the work cycle best suited to the circumstances. They will be found described in principle in an article by Damien Feger entitled "Cooling of optoelectronic detectors" published in "Engineering techniques, Electronic treaty" pages E4070-1 to 11.

Cet article fait déjà état des particularités spécifiques à chaque configuration et des critères présidant au choix de l'une ou l'autre. En relation avec la présente invention, il convient de souligner en particulier que, d'une manière générale, les refroidisseurs du type à tube à gaz pulsé (TGP) pêchent par un rendement inférieur à celui des configurations à cycle de Stirling, alors que quand la notion de rendement perd de son importance, les refroidisseurs à tube à gaz pulsé prennent le pas sur les refroidisseurs à cycle de Stirling. Ne serait-ce que pour des questions de coût, ils ont l'avantage d'impliquer un nombre de pièces plus limité et une exigence moindre dans la réalisation des étanchéités. De ce dernier point de vue, on rappellera que les refroidisseurs à cycle de Stirling comportent un piston dit "déplaceur" qui est monté à coulissement dans le doigt froid terminé par la chambre de détente, d'où le besoin d'une étanchéité au gaz de type dynamique.This article already describes the specific features of each configuration and the criteria for choosing one or the other. In connection with the present invention, it should be emphasized in particular that, in general, the pulsed gas tube type (TGP) type coolers fish by a lower efficiency than that of the Stirling cycle configurations, whereas when the concept of efficiency loses its importance, pulsed gas tube coolers take precedence over Stirling cycle coolers. If only for cost reasons, they have the advantage of involving a more limited number of parts and a lower requirement in the production of seals. From this last point of view, it will be recalled that the Stirling cycle coolers include a piston called "displacer" which is slidably mounted in the cold finger terminated by the expansion chamber, hence the need for gas tightness dynamic type.

Dans le but de diminuer encore le coût et d'apporter une meilleure souplesse d'utilisation des refroidisseurs dans toutes sortes d'applications, la présente invention se propose principalement de mettre à la disposition des utilisateurs un cryostat qui ne se limite pas à une enveloppe isolante apte à recevoir le doigt froid du refroidisseur, mais qui incorpore une partie de ses organes essentiels, sous une forme permettant leur adaptation interchangeable à différentes configurations.In order to further reduce the cost and provide better flexibility in the use of coolers in all kinds of applications, the present invention is mainly intended to provide users with a cryostat which is not limited to an envelope insulator capable of receiving the cold finger of the cooler, but which incorporates part of its essential organs, in a form allowing their interchangeable adaptation to different configurations.

Plus précisément, un cryostat pour refroidisseur cryogénique réalisé suivant l'invention s'adapte aisément, conformément à son caractère interchangeable, tant à une configuration à tube à gaz pulsé qu'à une configuration à cycle de Stirling, et que le pilotage de l'oscillateur de pression passe par un entraînement de type rotatif à vilebrequin ou de type linéaire, suivant les expressions utilisées par l'homme de l'art, telles qu'elles sont reprises notamment dans l'article déjà cité.More precisely, a cryostat for cryogenic cooler produced according to the invention easily adapts, in accordance with its interchangeable nature, both to a configuration with pulsed gas tube and to a Stirling cycle configuration, and that the control of the pressure oscillator goes through a rotary crankshaft or linear type drive, depending on the expressions used by those skilled in the art, as they are included in particular in the article already cited.

Par ses différentes caractéristiques telles qu'elles seront décrites et revendiquées ci-après, l'invention permet aussi d'apporter des améliorations sensibles à la construction des refroidisseurs intégrant un tel cryostat et à leur mode de pilotage. Les avantages qui en résultent concernent en particulier la combinaison du cryostat avec un oscillateur de pression dans un mode réalisation relevant d'une configuration à tube à gaz pulsé.By its various characteristics as will be described and claimed below, the invention also makes it possible to bring appreciable improvements to the construction of the coolers incorporating such a cryostat and to their control mode. The resulting advantages relate in particular to the combination of the cryostat with a pressure oscillator in an embodiment relating to a configuration with a pulsed gas tube.

En outre, les particularités proposées pour les différents éléments constitutifs des cryostats selon l'invention présentent l'avantage de se prêter particulièrement bien aux modes de fonctionnement respectifs des deux types de refroidisseurs et d'améliorer leurs performances propres. Tel est le cas notamment des dispositions préconisées pour le régénérateur, qui a la charge d'absorber et libérer de la chaleur, alternativement, par rapport au gaz qui le traverse. Tel est le cas également d'un échangeur avantageusement prévu en zone froide, au niveau de la chambre de détente, pour favoriser le transfert thermique vers le composant à refroidir, ainsi que pour un échangeur se situant en zone chaude et sous pression qui est spécialement utile dans les refroidisseurs du type à gaz pulsé, pour favoriser une déperdition thermique vers l'extérieur.In addition, the features proposed for the various components of the cryostats according to the invention have the advantage of lending themselves particularly well to the respective operating modes of the two types of coolers and of improving their own performance. This is the case in particular of the provisions recommended for the regenerator, which is responsible for absorbing and releasing heat, alternately, relative to the gas which passes through it. This is also the case for an exchanger advantageously provided in a cold zone, at the level of the expansion chamber, to promote heat transfer to the component to be cooled, as well as for an exchanger located in a hot zone and under pressure which is specially useful in pulsed gas type coolers, to promote heat loss to the outside.

Ainsi, l'invention a plus précisément pour objet un cryostat pour refroidisseur cryogénique mettant en oeuvre un circuit fermé de gaz de travail entre une chambre de compression située dans un carter d'oscillateur de pression associé et une chambre de détente située en fond du cryostat, en situation d'échange thermique avec un composant à refroidir, comportant à l'intérieur d'une enveloppe d'isolation thermique, solidaire d'une embase de montage sur ledit carter, un régénérateur thermique interposé sur le circuit du gaz de travail. Ce régénérateur est en disposition annulaire autour d'un volume axial s'étendant entre un échangeur froid qui est en contact thermique avec le composant à refroidir et fait communiquer le régénérateur avec ledit volume axial en fond du cryostat. Le cryostat comporte aussi une couronne de distribution de gaz dans ledit régénérateur, en tête du cryostat, à partir d'un conduit percé à travers l'embase pour connexion à la chambre de compression. La couronne de distribution est formée par une pièce centrale se montant à travers ladite embase axialement en son centre. Ladite pièce centrale est montée de manière amovible dans ladite embase, notamment par vissage étanche. Ceci la rend facilement interchangeable entre un premier modèle pour fonctionnement du volume axial en piston gazeux dans un refroidisseur du type à tube à gaz pulsé, et un second modèle, présentant un alésage axial propre à être traversé par un piston déplaceur de refroidisseur à cycle de Stirling, introduit à coulissement étanche dans le même volume axial. Ainsi, on peut utiliser un même cryostat, construit suivant l'invention, sans rien changer d'autre à son dimensionnement ou à sa fabrication, pour l'intégrer avec un oscillateur de pression adapté de manière à constituer un refroidisseur répondant à l'une ou l'autre de ces configurations majeures.Thus, the invention more specifically relates to a cryostat for a cryogenic cooler implementing a closed working gas circuit between a compression chamber located in an associated pressure oscillator casing and an expansion chamber located at the bottom of the cryostat. , in a heat exchange situation with a component to be cooled, comprising inside a thermal insulation envelope, integral with a mounting base on said casing, a thermal regenerator interposed on the working gas circuit. This regenerator is in annular arrangement around an axial volume extending between a cold exchanger which is in thermal contact with the component to be cooled and makes the regenerator communicate with said axial volume at the bottom of the cryostat. The cryostat also includes a gas distribution ring in said regenerator, at the head of the cryostat, from a conduit drilled through the base for connection to the compression chamber. The distribution ring is formed by a central piece which is mounted through said base axially at its center. Said central part is removably mounted in said base, in particular by tight screwing. This makes it easily interchangeable between a first model for operating the axial volume by gas piston in a cooler of the pulsed gas tube type, and a second model, having an axial bore suitable for being traversed by a displacement piston of the cycle cooler. Stirling, introduced with sliding sliding in the same axial volume. Thus, one can use the same cryostat, constructed according to the invention, without changing anything else in its design or in its manufacture, to integrate it with a pressure oscillator adapted so as to constitute a cooler corresponding to one either of these major configurations.

Dans la pièce centrale suivant le modèle destiné à un refroidisseur fonctionnant suivant le principe du cycle à gaz pulsé, il est avantageusement ménagé au moins un canal de passage du gaz sous débit contrôlé entre un réservoir tampon de gaz formé à l'intérieur du carter de l'oscillateur de pression, et le volume axial interne au cryostat qui fonctionne en tube à gaz. Il est d'ailleurs avantageux d'y ajouter un ou plusieurs autres canaux à débit contrôlé permettant un prélèvement de gaz chaud directement en sortie de compression, au niveau de la couronne de distribution vers le régénérateur.In the central part according to the model intended for a cooler operating according to the principle of the pulsed gas cycle, there is advantageously provided at least one channel for the passage of gas under controlled flow between a gas buffer tank formed inside the casing of the pressure oscillator, and the internal axial volume of the cryostat which operates in a gas tube. It is also advantageous to add one or more other channels with controlled flow allowing a withdrawal of hot gas directly at the compression outlet, at the level of the distribution ring towards the regenerator.

Dans le cas alternatif d'un refroidisseur mettant en oeuvre un cycle de Stirling, le volume interne se trouve au contraire occupé par le piston déplaceur, qui est préférentiellement plein, réalisé en un matériau de faible conductivité thermique, et qui ne laisse libre au gaz que le volume de la chambre de détente au fond du cryostat.In the alternative case of a chiller implementing a Stirling cycle, the internal volume is at on the contrary occupied by the displacement piston, which is preferably full, made of a material of low thermal conductivity, and which leaves free to the gas only the volume of the expansion chamber at the bottom of the cryostat.

De préférence, la pièce centrale, avec sa couronne de distribution, est réalisée solidaire d'un tube central limitant ledit volume axial. Ce tube est alors avantageusement de même diamètre interne que l'alésage axial du modèle destiné à un raccordement du cryostat sur un refroidisseur à cycle de Stirling. Il peut donc constituer soit le tube contenant le gaz pulsé dans le premier modèle, soit le tube guide du piston déplaceur du refroidisseur dans le second cas.Preferably, the central part, with its distribution crown, is made integral with a central tube limiting said axial volume. This tube is then advantageously of the same internal diameter as the axial bore of the model intended for a connection of the cryostat to a Stirling cycle cooler. It can therefore constitute either the tube containing the pulsed gas in the first model, or the guide tube of the displacer piston of the cooler in the second case.

Suivant une autre caractéristique de l'invention, il est associé au cryostat un échangeur chaud, se positionnant dans le volume interne en tête du cryostat. Son rôle se situe dans l'évacuation des calories qui s'effectue par déperdition thermique vers l'extérieur à travers l'embase et le carter de la partie compresseur du refroidisseur, réalisés à cette fin en matériau thermiquement conducteur. Il est spécialement utile dans la variante de refroidisseur à tube à gaz pulsé, compte tenu de la chaleur à évacuer en sortie du tube à gaz, qui se rajoute à la chaleur emmagasinée par le gaz en retour du régénérateur.According to another characteristic of the invention, there is associated with the cryostat a hot exchanger, positioned in the internal volume at the head of the cryostat. Its role is in the evacuation of calories which takes place by heat loss to the outside through the base and the casing of the compressor part of the cooler, made for this purpose from thermally conductive material. It is especially useful in the variant of a pulsed gas tube cooler, taking into account the heat to be evacuated at the outlet of the gas tube, which is added to the heat stored by the gas in return from the regenerator.

En ce qui concerne du moins l'échangeur froid, mais le cas échéant également l'échangeur chaud, l'invention prévoit, suivant une caractéristique secondaire, que l'on peut appliquer avantageusement avec les autres en toute combinaison opérante, d'utiliser une structure à géométrie de révolution, faisant alterner autour de l'axe du cryostat, dans une disposition de marguerite, des zones massives en matériau bon conducteur thermique et des zones vides ouvertes au passage du gaz. En conséquence, ces zones se situent notamment à cheval, de part et d'autre, par rapport à un épaulement de centrage de l'extrémité du tube central.With regard to at least the cold exchanger, but where appropriate also the hot exchanger, the invention provides, according to a secondary characteristic, which can be applied advantageously with the others in any operating combination, to use a structure with geometry of revolution, alternating around the axis of the cryostat, in a daisy arrangement, massive zones made of a material which is a good thermal conductor and empty zones open to the passage of gas. As a result, these areas are located in particular on horseback, on both sides, relative to a centering shoulder of the end of the central tube.

Il est souvent avantageux de combiner un tel échangeur froid avec un feuilleté de grilles perforées ayant pour effet d'assurer une tranquillisation du flux gazeux au passage de l'échangeur.It is often advantageous to combine such a cold exchanger with a laminate of perforated grids having the effect of ensuring a tranquilization of the gas flow when the exchanger passes.

Soulignons encore que dans un refroidisseur suivant l'invention construit pour fonctionner suivant le principe du tube à gaz pulsé, il est avantageux de ménager le volume tampon de gaz alimentant le piston gazeux à l'intérieur d'un piston de compression, qui à cet effet, du côté opposé à la chambre de compression, est directement ouvert dans une chemise de guidage dudit piston qui vient se raccorder sur la pièce centrale appropriée du cryostat.It should also be emphasized that in a cooler according to the invention constructed to operate on the principle of the pulsed gas tube, it is advantageous to provide the buffer volume of gas supplying the gas piston inside a compression piston, which at this indeed, on the side opposite to the compression chamber, is directly open in a jacket for guiding said piston which is connected to the appropriate central part of the cryostat.

Pour l'entraînement du piston dans un tel refroidisseur, piston unique de préférence, il est en général souhaitable d'avoir recours à des moyens de pilotage à moteur linéaire, dans la mesure où le coût en est plus faible que pour un pilotage rotatif.For driving the piston in such a cooler, preferably a single piston, it is generally desirable to have recourse to control means with a linear motor, insofar as the cost is lower than for rotary control.

Dans certaines applications, une configuration du type à moteur rotatif peut cependant se révéler utile. La solution préférée passe alors par des moyens de pilotage comportant un vilebrequin actionnant un mécanisme de transmission de mouvement par roulement à billes mobile dans une gorge ménagée transversalement à l'extérieur dudit piston.In certain applications, a configuration of the rotary motor type may however prove useful. The preferred solution then passes through control means comprising a crankshaft actuating a movement transmission mechanism by movable ball bearing in a groove formed transversely outside said piston.

Quelle que soit la forme de réalisation choisie pour le refroidisseur suivant l'invention, la disposition annulaire du régénérateur se prête particulièrement bien à une fabrication à partir d'une feuille enroulée sur elle-même. En outre, l'invention permet d'améliorer sensiblement l'efficacité des échanges thermiques recherchés, par rapport aux empilements de grilles ou de billes classiques, en utilisant pour cela une feuille en matériau convenable, qui a été au préalable usinée, notamment par procédé photolithographique, de sorte à former des bandes longitudinales distinctes à surface lisse et des barrettes transversales en surépaisseur réunissant ponctuellement les bandes successives.Whatever the embodiment chosen for the cooler according to the invention, the annular arrangement of the regenerator lends itself particularly well to manufacture from a sheet wound on itself. In addition, the invention makes it possible to significantly improve the efficiency of the desired heat exchanges, compared with the stacks of grids or conventional balls, by using for this a sheet of suitable material, which has been previously machined, in particular by photolithographic process, so as to form separate longitudinal bands with smooth surface and transverse bars in excess thickness punctually joining the successive bands.

Préférentiellement, les différentes bandes se succèdent sur la longueur du régénérateur. Elles forment des couches annulaires de surface lisse entrecoupées par les intervalles entre bandes et les barrettes intercalées entre les couches contribuent à répartir le flux dans toutes les directions à chaque niveau de section transversale.Preferably, the different bands follow one another along the length of the regenerator. They form annular layers of smooth surface intersected by the intervals between bands and the bars inserted between the layers help to distribute the flow in all directions at each level of cross section.

L'invention sera maintenant plus complètement décrite dans le cadre de caractéristiques préférées répondant au mieux aux propos de l'invention par leurs avantages, en faisant référence aux figures des dessins annexés qui les illustrent et dans lesquelles :

  • La figure 1 représente en coupe longitudinale un cryostat suivant l'invention, vu dans ses spécificités plus particulièrement destinées à un accouplement avec un oscillateur de pression de sorte à constituer un refroidisseur cryogénique appliquant un cycle à tube à gaz pulsé ;
  • La figure 2 montre les organes principaux du même cryostat, dans une vue éclatée, en s'intéressant au contraire à sa constitution pour accouplement avec l'oscillateur de pression d'un refroidisseur de type à cycle de Stirling ;
  • La figure 3 schématise une forme de réalisation préférée du régénérateur thermique, valable dans l'un et l'autre cas ;
  • La figure 4 montre une coupe transversale du cryostat au niveau de l'échangeur thermique disposé en zone froide du circuit de gaz de travail, dans la chambre de détente ;
  • La figure 5 illustre le montage du cryostat de l'invention, avec sa pièce de distribution interchangeable suivant la figure 2, dans un cas d'application pratique où il sert à constituer un refroidisseur cryogénique à cycle de Stirling suivant l'invention, qui est ici du type à pilotage rotatif ;
  • La figure 6 illustre, quant à elle, un autre mode de réalisation de l'invention, fournissant au total un refroidisseur à cycle TGP (tube à gaz pulsé), et elle montre en plus comment se concrétise préférentiellement, conformément à l'invention, un pilotage rotatif dans cette configuration de refroidisseur cryogénique.
  • La figure 7 illustre en vue éclatée une conception particulière de l'échangeur froid associé à un feuilleté de grilles de tranquilisation de gaz.
  • La figure 8 représente, dans une coupe schématique partielle, une variante de l'échangeur froid faisant appel à une réalisation en deux parties concentriques.
The invention will now be more fully described in the context of preferred characteristics which best meet the aims of the invention by their advantages, with reference to the figures of the appended drawings which illustrate them and in which:
  • FIG. 1 represents in longitudinal section a cryostat according to the invention, seen in its specificities more particularly intended for coupling with a pressure oscillator so as to constitute a cryogenic cooler applying a cycle with pulsed gas tube;
  • Figure 2 shows the main organs of the same cryostat, in an exploded view, looking instead to its constitution for coupling with the pressure oscillator of a Stirling cycle type cooler;
  • Figure 3 shows schematically a preferred embodiment of the thermal regenerator, valid in both cases;
  • Figure 4 shows a cross section of the cryostat at the heat exchanger located in the area cold working gas circuit, in the expansion chamber;
  • FIG. 5 illustrates the assembly of the cryostat of the invention, with its interchangeable distribution part according to FIG. 2, in a case of practical application where it serves to constitute a cryogenic cooler with a Stirling cycle according to the invention, which is here of the rotary pilot type;
  • FIG. 6 illustrates, for its part, another embodiment of the invention, providing a total cooler with a TGP cycle (pulsed gas tube), and it also shows how preferentially takes shape, in accordance with the invention, rotary control in this cryogenic cooler configuration.
  • FIG. 7 illustrates in exploded view a particular design of the cold exchanger associated with a laminate of gas stilling grids.
  • Figure 8 shows, in a partial schematic section, a variant of the cold exchanger using an embodiment in two concentric parts.

Conformément à l'invention, le cryostat de la figure 1 est utilisé en combinaison avec un oscillateur de pression soit pour constituer un refroidisseur cryogénique de type à gaz pulsé conformément à la figure 6, soit alternativement pour constituer un refroidisseur de type à cycle de Stirling conformément à la figure 5. Dans tous les cas, le refroidisseur ainsi constitué est de construction compacte, le cryostat et l'oscillateur de pression étant intégrés en un même ensemble mécanique.In accordance with the invention, the cryostat of FIG. 1 is used in combination with a pressure oscillator either to constitute a cryogenic cooler of the pulsed gas type in accordance with FIG. 6, or alternatively to constitute a cooler of the Stirling cycle type in accordance with FIG. 5. In all cases, the cooler thus formed is of compact construction, the cryostat and the pressure oscillator being integrated in the same mechanical assembly.

Dès la figure 1, on peut observer que le cryostat suivant l'invention ne se limite pas, comme dans les réalisations connues, à une enveloppe d'isolation thermique destinée à recevoir un doigt froid préalablement constitué en tous ses organes fonctionnels nécessaires à la mise en oeuvre du cycle thermodynamique du gaz de travail. Au contraire, les organes fonctionnels passifs, qui ne sont pas soumis à des déplacements en cours de fonctionnement, sont prévus à demeure dans le cryostat, ce dernier étant construit de sorte à pouvoir se raccorder, alternativement au choix de l'utilisateur, au carter d'un oscillateur de pression relevant soit d'un refroidisseur spécifique pour mise en oeuvre d'un cycle de Stirling, soit d'un refroidisseur du type à tube à gaz pulsé.From FIG. 1, it can be observed that the cryostat according to the invention is not limited, as in the known embodiments, to a thermal insulation envelope intended to receive a cold finger previously formed in all its functional organs necessary for the implementation of the thermodynamic cycle of the working gas. On the contrary, the passive functional members, which are not subjected to displacements during operation, are provided permanently in the cryostat, the latter being constructed so as to be able to be connected, alternatively at the option of the user, to the casing a pressure oscillator belonging either to a specific cooler for implementing a Stirling cycle, or to a cooler of the pulsed gas tube type.

C'est ainsi que dans le cryostat, on trouve, à l'intérieur d'une enveloppe d'isolation thermique 1 montée solidaire d'une embase 4 servant à son raccordement mécanique et pneumatique avec la partie oscillateur de pression du refroidisseur, deux viroles tubulaires concentriques, à savoir un tube central 3 et une paroi interne 2 de l'enveloppe 1, qui délimitent entre elles un espace annulaire occupé par un régénérateur thermique 5. Le régénérateur 5 est ainsi construit en disposition annulaire autour d'un volume axial 6, limité sur son pourtour par le tube central 3 parmi les deux viroles précédentes.Thus in the cryostat, there are two ferrules inside a thermal insulation envelope 1 mounted integral with a base 4 serving for its mechanical and pneumatic connection with the pressure oscillator part of the cooler. concentric tubulars, namely a central tube 3 and an internal wall 2 of the casing 1, which delimit between them an annular space occupied by a thermal regenerator 5. The regenerator 5 is thus constructed in annular arrangement around an axial volume 6 , limited on its periphery by the central tube 3 among the two previous ferrules.

En pratique l'autre virole, qui limite extérieurement le régénérateur thermique, est donc ici directement constituée par la paroi interne 2 de l'enveloppe d'isolation thermique 1. Celle-ci est en effet, de manière en soi classique, du type à double paroi. Entre ses deux parois, elle est soit remplie d'un gaz d'inertage à faible point de condensation, soit soumise à un vide poussé, ce pour quoi elle est munie d'un port de chargement 25.In practice, the other ferrule, which externally limits the thermal regenerator, is therefore here directly constituted by the internal wall 2 of the thermal insulation envelope 1. This is in fact, in itself conventional, of the type to double sided. Between its two walls, it is either filled with an inert gas with a low condensation point, or subjected to a high vacuum, for which it is provided with a charging port 25.

Dans d'autres réalisations toutefois, mais de manière généralement moins avantageuse, on préférera construire le régénérateur 5 avec ses propres enveloppes, dont une enveloppe externe qui est alors distincte de la paroi interne 2 de l'enveloppe d'isolation thermique et/ou une enveloppe interne qui est alors ajoutée contre le tube central 3.In other embodiments, however, but generally less advantageously, it will be preferred to construct the regenerator 5 with its own envelopes, including an external envelope which is then distinct from the internal wall 2 of the thermal insulation envelope and / or an internal envelope which is then added against the central tube 3.

En fond du cryostat, au-delà du régénérateur et de son enveloppe interne constituée par le tube 3, il est disposé un échangeur 8, qui constitue en fonctionnement l'échangeur froid du refroidisseur. Pour cela, cet échangeur est conçu et disposé de sorte à favoriser le transfert de la puissance frigorifique résultant de la détente du gaz de travail vers un composant à refroidir 21, tout en assurant une communication pneumatique permettant le passage du gaz de travail entre le fond du volume axial 6 et l'espace annulaire occupé par le régénérateur 5.At the bottom of the cryostat, beyond the regenerator and its internal envelope formed by the tube 3, there is an exchanger 8, which in operation constitutes the cold exchanger of the cooler. For this, this exchanger is designed and arranged so as to promote the transfer of the cooling power resulting from the expansion of the working gas to a component to be cooled 21, while ensuring pneumatic communication allowing the passage of the working gas between the bottom of the axial volume 6 and the annular space occupied by the regenerator 5.

La virole intermédiaire du cryostat de l'invention, constituée par la paroi 2, est fermée en son extrémité inférieure, au fond du cryostat, par une plaque transversale 22 contre laquelle est apposé l'échangeur froid 8. Sur sa face opposée à cet échangeur vient se monter le composant 21, généralement par simple collage.The intermediate shell of the cryostat of the invention, constituted by the wall 2, is closed at its lower end, at the bottom of the cryostat, by a transverse plate 22 against which the cold exchanger 8 is affixed. On its face opposite this exchanger component 21 is assembled, generally by simple bonding.

Quand l'élément à refroidir est constitué, comme illustré, par un composant électronique 21, par exemple un détecteur optoélectronique, il est nécessaire de pourvoir à sa liaison avec un circuit électrique véhiculant les signaux qu'il reçoit ou qu'il émet. On a donc fait apparaître sur la figure 1, une couronne de distribution électrique 23, dont les parties conductrices passent par des traversées étanches à travers la paroi externe de l'enveloppe d'isolation thermique 1, ainsi que des fils conducteurs 24 qui les relient ensuite au composant 21.When the element to be cooled consists, as illustrated, of an electronic component 21, for example an optoelectronic detector, it is necessary to provide for its connection with an electric circuit carrying the signals which it receives or which it emits. FIG. 1 therefore shows an electrical distribution ring 23, the conductive parts of which pass through watertight crossings through the external wall of the thermal insulation envelope 1, as well as the conductive wires 24 which connect them then to component 21.

L'enveloppe 1 dans son ensemble a pour fonction de limiter les pertes thermiques par radiation ou convection au niveau des organes intervenant dans le cycle thermodynamique du refroidisseur complet dans la zone froide de celui-ci.The envelope 1 as a whole has the function of limiting the heat losses by radiation or convection at the level of the organs involved in the thermodynamic cycle of the complete cooler in the cold zone thereof.

Ainsi qu'il apparaît sur la figure 1, sa paroi externe est soudée en sous-face de l'embase 4, tandis que sa paroi interne 2 est monolithique avec celle-ci. L'une et l'autre peuvent être réalisées en acier inoxydable.As it appears in FIG. 1, its external wall is welded on the underside of the base 4, while its internal wall 2 is monolithic therewith. Both can be made of stainless steel.

Cependant, on peut aussi choisir, pour la paroi interne 2, une qualité d'acier inoxydable correspondant à un alliage à faible conductivité thermique, adaptée pour être compatible avec le gaz de travail utilisé, lequel est préférentiellement l'hélium dans le cas du régénérateur à feuille métallique enroulée comme décrit plus loin.However, one can also choose, for the internal wall 2, a quality of stainless steel corresponding to an alloy with low thermal conductivity, adapted to be compatible with the working gas used, which is preferably helium in the case of the regenerator. with metallic foil rolled up as described below.

La paroi extérieure de l'enveloppe 1 est réalisée également en acier inoxydable, ou éventuellement en une qualité appropriée de verre, pour des raisons d'ordre économique.The outer wall of the casing 1 is also made of stainless steel, or possibly of an appropriate quality of glass, for economic reasons.

Suivant le matériau choisi, il peut donc être nécessaire d'avoir recours à des jonctions verre/métal pour assurer l'étanchéité des soudures et des traversées électriques, ce qui toutefois posera d'autant moins de problèmes à l'homme de l'art que ce besoin se situe en des endroits sous pression statique.Depending on the material chosen, it may therefore be necessary to have recourse to glass / metal junctions to ensure the sealing of the welds and of the electrical bushings, which however will pose all the less problems for those skilled in the art. that this need is located in places under static pressure.

En tête du cryostat, à l'extrémité supérieure de l'enveloppe thermiquement isolante 1 et du régénérateur 5, l'embase 4 se trouve au contraire en zone chaude du refroidisseur en fonctionnement, là où règne aussi une pression dynamique du gaz de travail, soumise à des pulsations de pression périodiques, imprimées par les éléments mobiles du refroidisseur lorsque le cryostat est raccordé au carter 50 d'un oscillateur de pression associé.At the head of the cryostat, at the upper end of the thermally insulating envelope 1 and of the regenerator 5, the base 4 is, on the contrary, in the hot zone of the cooler in operation, where there is also a dynamic pressure of the working gas, subjected to periodic pressure pulses, printed by the mobile elements of the cooler when the cryostat is connected to the casing 50 of an associated pressure oscillator.

Dans cette zone chaude, il convient d'évacuer les calories du gaz revenant de la détente, après la récupération effectuée dans le régénérateur 5. Pour cela, il est prévu de réaliser l'embase 4 en un matériau de bonne conductivité thermique, généralement de l'acier inoxydable, sous une forme favorisant les déperditions vers l'extérieur.In this hot zone, it is necessary to evacuate the calories of the gas returning from the expansion, after the recovery carried out in the regenerator 5. For this, it is planned to make the base 4 in a material of good conductivity thermal, generally of stainless steel, in a form favoring the losses towards the outside.

Dans l'embase 4 on distingue une collerette circulaire 16, percée de trous pour le passage des vis 48 assurant la fixation sur le carter 50 du refroidisseur, qui vient se raccorder en appui sur la face supérieure de la collerette 16, opposée à l'enveloppe thermique 1. On distingue aussi une bague 17, faisant partie de l'embase 4, qui assure le centrage des deux éléments l'un dans l'autre. Le raccordement étanche de ces deux éléments (cryostat et oscillateur de pression) vis-à-vis de l'extérieur est assuré par un joint 19, logé dans une gorge annulaire de la face supérieure de la collerette 16.In the base 4 there is a circular flange 16, pierced with holes for the passage of the screws 48 ensuring the attachment to the casing 50 of the cooler, which is connected to bear on the upper face of the flange 16, opposite to the thermal envelope 1. There is also a ring 17, forming part of the base 4, which ensures the centering of the two elements one inside the other. The sealed connection of these two elements (cryostat and pressure oscillator) to the outside is provided by a seal 19, housed in an annular groove on the upper face of the flange 16.

L'embase 4 livre passage, dans l'axe du système, à une pièce centrale 10, vissée de manière étanche dans la bague 17, laquelle est filetée intérieurement. Une gorge hexagonale 41, ménagée dans sa face plane supérieure, sert à sa manipulation lors du montage.The base 4 delivers passage, in the axis of the system, to a central part 10, screwed in a sealed manner in the ring 17, which is internally threaded. A hexagonal groove 41, formed in its upper flat face, is used for its manipulation during assembly.

Comme on l'a déjà expliqué, cette pièce centrale du cryostat est conçue sous deux modèles différents qui, par leur géométrie extérieure, leur dimensionnement, et leur conception fonctionnelle, sont interchangeables dans une même construction de cryostat. Les deux modèles sont illustrés par la figure 1 et par la figure 2, suivant que le cryostat 30 est monté pour être accouplé avec les carters 50 ou 60 de l'un ou l'autre des deux oscillateurs de pression dans les deux variantes de refroidisseur montrées sur les figures 6 et 5 respectivement.As already explained, this central part of the cryostat is designed in two different models which, by their external geometry, their dimensioning, and their functional design, are interchangeable in the same cryostat construction. The two models are illustrated in FIG. 1 and in FIG. 2, depending on whether the cryostat 30 is mounted to be coupled with the housings 50 or 60 of one or the other of the two pressure oscillators in the two cooler variants. shown in Figures 6 and 5 respectively.

Dans tous les cas, cette pièce centrale, donc en particulier celle portant la référence 10 sur la figure 1, est ici constituée d'une seule pièce avec le tube interne 3 du cryostat.In all cases, this central part, therefore in particular that bearing the reference 10 in FIG. 1, here consists of a single part with the internal tube 3 of the cryostat.

D'autre part, elle forme une couronne de distribution 71, pour la répartition annulaire du gaz en tête du régénérateur 5. En conséquence, cette couronne se place au-dessus de celui-ci (dans la disposition verticale représentée, cryostat sous le carter 50), et plus précisément au centre de l'embase 4 en sa partie principale formée par la collerette 16.On the other hand, it forms a distribution ring 71, for the annular distribution of the gas at the head of the regenerator 5. Consequently, this ring is placed above the latter (in the vertical arrangement shown, cryostat under the casing 50), and more precisely at the center of the base 4 in its main part formed by the collar 16.

Dans le mode de réalisation illustré, la couronne de distribution 71 présente une gorge circulaire 45, creusée dans sa face inférieure, qui vient en butée sur le régénérateur 5. Cette gorge communique par des orifices 46 avec une chambre annulaire 43, prolongée vers le haut en 42, qui est ménagée extérieurement dans la partie de la pièce centrale 10 se trouvant au niveau de la collerette 16, entre cette pièce et la face en vis-à-vis de l'embase 4.In the illustrated embodiment, the distribution ring 71 has a circular groove 45, hollowed out in its lower face, which abuts on the regenerator 5. This groove communicates through orifices 46 with an annular chamber 43, extended upwards at 42, which is formed externally in the part of the central part 10 located at the level of the collar 16, between this part and the face opposite the base 4.

C'est là que débouche un canal 39, percé à travers cette collerette de l'embase 4 jusqu'à communiquer, une fois le montage du refroidisseur terminé, avec un conduit 61 par lequel s'effectue la liaison pneumatique avec la chambre de compression située dans l'oscillateur de pression.This is where a channel 39 opens, pierced through this collar of the base 4 until it communicates, once the assembly of the cooler is finished, with a conduit 61 through which the pneumatic connection is made to the compression chamber. located in the pressure oscillator.

Pour le reste, la pièce centrale 10 est représentée sur la figure 1 dans le modèle convenant pour un refroidisseur type TGP illustré par la figure 6.For the rest, the central part 10 is shown in FIG. 1 in the model suitable for a TGP type cooler illustrated in FIG. 6.

Le second modèle de pièce centrale du cryostat, destiné lui à un refroidisseur à cycle Stirling, est montré sur la représentation schématique en disposition éclatée de la figure 2. Dans ce cas, le pièce centrale 20 est identique à la précédente extérieurement, mais intérieurement, elle comporte simplement un alésage axial 72, ménagé tout du long à travers elle, au même diamètre que le tube 3 dont elle prolonge le volume central.The second model of central part of the cryostat, intended for a Stirling cycle cooler, is shown in the schematic representation in exploded arrangement of FIG. 2. In this case, the central part 20 is identical to the previous one externally, but internally, it simply comprises an axial bore 72, formed all along it, with the same diameter as the tube 3, the central volume of which it extends.

En revenant à la figure 1, on observe la constitution des moyens d'alimentation du piston gazeux occupant le volume interne 6 du cryostat. A l'entrée de celui-ci débouche un canal 11, qui est percé axialement dans la pièce centrale 10 jusqu'à sa face supérieure, où il se termine par un orifice calibré 13 imposant un débit gazeux contrôlé.Returning to FIG. 1, the constitution of the means for supplying the gas piston occupying the internal volume 6 of the cryostat is observed. At the entrance to the latter, a channel 11 opens which is drilled axially in the central part 10 to its upper face, where it ends in a calibrated orifice 13 imposing a controlled gas flow.

Une autre liaison pneumatique, impliquant un ou plusieurs canaux, est assurée à travers la pièce 10, avec la chambre annulaire 43 de la couronne de distribution de gaz vers le régénérateur 5. On a ainsi fait apparaître un orifice calibré 14, sur un canal 12 débouchant dans le canal axial 11.Another pneumatic connection, involving one or more channels, is provided through the part 10, with the annular chamber 43 of the gas distribution ring towards the regenerator 5. A calibrated orifice 14 has thus appeared on a channel 12 opening into the axial channel 11.

Les orifices calibrés des canaux 11-12 fonctionnent, de manière en soi classique, comme des vannes introduisant des impédances pneumatiques. Le canal principal 11 ainsi équipé procure en fonctionnement le déphasage utile entre l'onde de pression générée par l'oscillateur de pression et les variations de débit en résultant dans le tube contenant le gaz pulsé. L'impédance secondaire (canal 12) permet d'apporter une fraction du débit d'alimentation périodique du tube en la prélevant directement en sortie de compression, par dérivation de la circulation passant à travers le régénérateur et le tube. Ceci diminue la charge thermique sur le régénérateur et contribue à améliorer l'efficacité du refroidisseur, dans le cas d'un cycle à gaz pulsé.The calibrated orifices of the channels 11-12 function, in a conventional manner in themselves, like valves introducing pneumatic impedances. The main channel 11 thus equipped in operation provides the useful phase shift between the pressure wave generated by the pressure oscillator and the resulting flow variations in the tube containing the pulsed gas. The secondary impedance (channel 12) makes it possible to provide a fraction of the periodic supply flow rate of the tube by withdrawing it directly from the compression outlet, by diverting the circulation passing through the regenerator and the tube. This reduces the thermal load on the regenerator and contributes to improving the efficiency of the cooler, in the case of a pulsed gas cycle.

La figure 1 montre enfin un échangeur 9, situé en zone chaude dans le volume central, au niveau de la couronne de distribution 71. Cet échangeur chaud peut éventuellement être réalisé de manière analogue à ce qui sera décrit plus loin pour l'échangeur froid, l'essentiel étant que, dans cette variante de réalisation du cryostat de l'invention, il vienne parfaire l'évacuation des calories excédentaires du cycle thermodynamique en complétant, à partir de la zone chaude du tube de gaz pulsé, les déperditions thermiques vers l'extérieur ayant lieu par le biais de l'embase 4, et accessoirement du carter d'oscillateur de pression associé.FIG. 1 finally shows an exchanger 9, located in the hot zone in the central volume, at the level of the distribution ring 71. This hot exchanger can optionally be produced in a similar manner to that which will be described below for the cold exchanger, the main thing is that, in this variant embodiment of the cryostat of the invention, it completes the evacuation of the excess calories from the thermodynamic cycle by completing, from the zone hot of the pulsed gas tube, the heat losses to the outside taking place through the base 4, and incidentally from the associated pressure oscillator casing.

Pour l'un et l'autre des deux types de refroidisseurs, le régénérateur thermique 5 est avantageusement constitué, comme il apparaît des figures 1 et 3, de manière à jouer pleinement son rôle d'accumulateur thermique pour la récupération ayant lieu, de manière en soi classique, entre le gaz de travail passant de la phase de compression à la phase de détente et le gaz de travail passant de la phase de détente à la phase de compression.For either of the two types of coolers, the thermal regenerator 5 is advantageously constituted, as it appears in FIGS. 1 and 3, so as to fully play its role of thermal accumulator for the recovery taking place, so in itself conventional, between the working gas passing from the compression phase to the expansion phase and the working gas passing from the expansion phase to the compression phase.

Dans le mode de réalisation préférentiel de l'invention décrit ici et illustré par la figure 3, un tel régénérateur se présente sous la forme d'une feuille continue qui est enroulée en une série de spires autour du tube central 3 qui limite le volume interne 6 du régénérateur, de manière à remplir, aussi complètement qu'il est possible dans la pratique industrielle, l'espace annulaire compris entre ce tube 3, qui forme sa virole enveloppe interne, et sa virole enveloppe externe associée, constituée par la paroi interne 2 de l'enveloppe isolante 1.In the preferred embodiment of the invention described here and illustrated in Figure 3, such a regenerator is in the form of a continuous sheet which is wound in a series of turns around the central tube 3 which limits the internal volume 6 of the regenerator, so as to fill, as completely as is possible in industrial practice, the annular space comprised between this tube 3, which forms its inner shell ferrule, and its associated outer shell ferrule, constituted by the inner wall 2 of the insulating jacket 1.

Les procédés d'usinage par photolithographie, qui sont connus en eux-mêmes, sont particulièrement intéressants en ce sens, dans la mesure où ils représentent des moyens technologiques particulièrement simples à mettre en oeuvre pour un prix de revient limité, quand il s'agit de conduire à la configuration illustrée par le détail de la figure 3.The machining processes by photolithography, which are known in themselves, are particularly advantageous in this sense, insofar as they represent particularly simple technological means to implement for a limited cost price, when it comes to lead to the configuration illustrated by the detail in FIG. 3.

Suivant cette configuration, la feuille qui est ainsi enroulée en spires consécutives jointives, forme une succession de bandes longitudinales distinctes 27, qui s'orientent perpendiculairement à l'axe du cryostat et qui sont séparées les unes des autres par des intervalles 28. Des barrettes 26 sont formées en surépaisseur des bandes et en travers de celles-ci dans le sens perpendiculaire. Elles sont régulièrement réparties sur toute la longueur et la hauteur de la feuille et disposées en quinconce, chacune réunissant deux bandes successives par dessus l'intervalle qui les sépare.According to this configuration, the sheet which is thus wound in contiguous consecutive turns, forms a succession of distinct longitudinal bands 27, which are oriented perpendicular to the axis of the cryostat and which are separated from each other by intervals 28. Bars 26 are formed in excess thickness of the strips and across them in a perpendicular direction. They are regularly distributed over the entire length and height of the sheet and staggered, each uniting two successive bands over the gap between them.

On réalise de cette manière, à la fois des couches de surfaces lisses qui seront léchées par le gaz de travail suivant son sens global de circulation sous l'effet des différences de pression mais qui sont périodiquement interrompues par les intervalles 28, et des barrières orientées transversalement aux bandes et aux intervalles entre deux spires consécutives de la feuille. Ceci permet d'obtenir une bonne distribution du gaz entre les couches, équilibrée dans toutes les directions d'une section transversale du régénérateur, ainsi que d'éviter l'apparition d'instabilités préjudiciables à l'efficacité des échanges, tout en créant la perte de charge importante qui est nécessaire au déphasage dans le pilotage de certains refroidisseurs.In this way, layers of smooth surfaces are produced which will be licked by the working gas according to its overall direction of circulation under the effect of pressure differences but which are periodically interrupted by the intervals 28, and oriented barriers transversely to the strips and to the intervals between two consecutive turns of the sheet. This makes it possible to obtain a good distribution of the gas between the layers, balanced in all the directions of a cross section of the regenerator, as well as to avoid the appearance of instabilities detrimental to the efficiency of the exchanges, while creating the significant pressure drop which is necessary for the phase shift in the control of certain chillers.

En ce qui concerne le dimensionnement géométrique d'un régénérateur ainsi construit, on peut citer en exemple le cas d'une feuille de 100 à 200 microns d'épaisseur, creusée à mi-épaisseur par chaque face, pour un régénérateur de 2 à 3 millimètres d'épaisseur radiale. Les bandes et les intervalles entre elles peuvent, par exemple, être d'une même largeur, de l'ordre de 50 à 100 microns. La longueur transversale des barrettes 26 peut correspondre, ici encore à titre d'exemple, à 1,5 fois le pas de répétition des bandes longitudinales 27, avec une largeur environ moitié moindre et une distance entre deux barrettes successives décalées, équivalente à environ trois fois la largeur de chacune.With regard to the geometrical dimensioning of a regenerator thus constructed, one can cite as an example the case of a sheet 100 to 200 microns thick, hollowed out at mid-thickness by each face, for a regenerator of 2 to 3 millimeters of radial thickness. The strips and the intervals between them can, for example, be of the same width, of the order of 50 to 100 microns. The transverse length of the bars 26 may correspond, here again by way of example, to 1.5 times the repetition pitch of the longitudinal strips 27, with a width approximately half less and a distance between two successive bars offset, equivalent to approximately three times the width of each.

L'invention permet ainsi de tirer profit d'un rapport entre l'échange convectif local et les pertes de charges longitudinales qui, dans le cas de plaques parallèles à l'axe du doigt froid, serait supérieur à la valeur que l'on peut obtenir par les empilements usuels de grilles ou de billes, cependant que, sous cette forme de réalisation pratique, elle permet d'assurer une meilleure distribution du débit de gaz entre les couches parallèles de surfaces lisses.The invention thus makes it possible to take advantage of a relationship between the local convective exchange and the losses of longitudinal loads which, in the case of plates parallel to the axis of the cold finger, would be greater than the value which can be obtained by the usual stacks of grids or balls, however, in this practical embodiment, it allows a better distribution of the gas flow between the parallel layers of smooth surfaces.

De la sorte, on parvient à équilibrer le débit de gaz de travail circulant entre les couches annulaires à surface parallèle à l'axe du cryostat de l'invention, et le débit de gaz circulant transversalement, dans toutes les directions radiales du régénérateur aux différents niveaux entre bandes successives. En conséquence, on évite les différences qui existent dans les régénérateurs connus entre le débit radial et le débit axial, alors que l'on peut constater qu'une telle différence de répartition entraîne des transferts thermiques déséquilibrés qui dégradent les performances des régénérateurs.In this way, it is possible to balance the flow of working gas flowing between the annular layers with a surface parallel to the axis of the cryostat of the invention, and the flow of gas flowing transversely, in all the radial directions of the regenerator at the different levels between successive bands. Consequently, the differences which exist in known regenerators between the radial flow rate and the axial flow rate are avoided, while it can be seen that such a difference in distribution results in unbalanced heat transfers which degrade the performance of the regenerators.

La présence des barrières 26, qui restent de faibles dimensions en regard de la longueur et de l'épaisseur du régénérateur, permet en outre d'introduire une interruption périodique du flux longitudinal entre les couches de bandes successives d'un bout à l'autre du régénérateur, et par là de stabiliser le débit gazeux global. Simultanément, comme ces barrettes jouxtent deux couches adjacentes de bandes, on obtient grâce à elles une réduction des pertes d'énergie thermique par conduction dans le sens longitudinal. Simultanément, on assure ainsi une réduction des pertes d'énergie thermique par conduction dans le sens longitudinal.The presence of the barriers 26, which remain small compared to the length and the thickness of the regenerator, also makes it possible to introduce a periodic interruption of the longitudinal flow between the layers of successive strips from one end to the other of the regenerator, and thereby stabilize the overall gas flow. Simultaneously, as these bars adjoin two adjacent layers of strips, we obtain thanks to them a reduction of the losses of thermal energy by conduction in the longitudinal direction. Simultaneously, this ensures a reduction in losses of thermal energy by conduction in the longitudinal direction.

Par là même, on résout les problèmes qui, dans les refroidisseurs connus, sont liés aux variations de la viscosité du gaz de travail en fonction de la température locale, et qui causent des variations entraînant une instabilité intrinsèque du débit de gaz, et ainsi une faible efficacité du régénérateur.In this way, the problems which in known coolers are linked to variations in the viscosity of the working gas as a function of the local temperature and which cause variations leading to instability are resolved. intrinsic gas flow, and thus low efficiency of the regenerator.

Une telle réalisation du régénérateur 5 permet, d'une façon particulièrement avantageuse dans le cadre de la présente invention, d'obtenir un rapport entre l'échange convectif local et la perte de charge longitudinale très avantageux, tout en améliorant la distribution du débit de gaz entre les couches parallèles orientées longitudinalement, jusqu'à atteindre des performances de récupération thermique au moins équivalentes, si ce n'est supérieures à celles que l'on sait obtenir dans les réalisations connues par des régénérateurs à grilles transversales empilées ou à billes.Such an embodiment of the regenerator 5 makes it possible, in a particularly advantageous manner in the context of the present invention, to obtain a ratio between the local convective exchange and the very advantageous longitudinal pressure drop, while improving the distribution of the flow rate. gas between the parallel layers oriented longitudinally, until thermal recovery performance at least equivalent, if not greater than that which is known to be obtained in known embodiments by regenerators with stacked transverse grids or with balls.

Une autre caractéristique commune aux deux variantes de refroidisseurs décrites ici, à titre d'exemples, concerne la réalisation de l'échangeur froid 8 mis en place en fond de l'enveloppe d'isolation thermique 1 du cryostat suivant l'invention, telle qu'elle est illustrée plus particulièrement par la figure 4.Another characteristic common to the two variants of coolers described here, by way of example, relates to the production of the cold exchanger 8 installed at the bottom of the thermal insulation envelope 1 of the cryostat according to the invention, such as it is more particularly illustrated in FIG. 4.

On remarquera tout d'abord que, lors de la mise en place de la pièce centrale 10 ou 20 dans le cryostat, son centrage est assuré au niveau de la couronne de distribution 71, directement dans l'axe de l'embase 4 et sur la paroi interne 2 de l'enveloppe 1, jusqu'à pousser le régénérateur 5 en butée sur l'échangeur froid 8. Dans la mesure où elle porte avec elle le tube central 3, cette pièce centrale est également centrée, à l'extrémité de ce dernier, grâce à un épaulement 34 formé en face supérieure de l'échangeur 8.First of all, it will be noted that, when the central part 10 or 20 is placed in the cryostat, its centering is ensured at the level of the distribution ring 71, directly in the axis of the base 4 and on the internal wall 2 of the casing 1, until the regenerator 5 is pushed into abutment on the cold exchanger 8. Insofar as it carries with it the central tube 3, this central part is also centered, at the end of the latter, thanks to a shoulder 34 formed on the upper face of the exchanger 8.

Cet échangeur froid est réalisé, conformément à ce qui ressort des figures 1, 2 et 4, sous une forme dite en marguerite. Il est constitué par une structure à géométrie de révolution, qui est réalisée en un matériau fortement conducteur tel que du cuivre ou de l'aluminium.This cold exchanger is produced, in accordance with what emerges from FIGS. 1, 2 and 4, in a so-called daisy shape. It consists of a structure with a geometry of revolution, which is made of a highly conductive material such as copper or aluminum.

Cette structure fait alterner en étoile autour d'un noyau central 31, des zones vides 32 creusées à travers son épaisseur longitudinale et des zones massives 33 assurant la conduction thermique. Les unes et les autres s'étendent radialement à cheval par rapport à l'épaulement 34, de part et d'autre de l'extrémité du tube central 3. Elles laissent donc le gaz circuler librement entre le volume central 6 du cryostat (ou du moins la chambre de détente restant en fond du cryostat dans le cas d'un refroidisseur suivant la figure 5 appliquant un cycle de Stirling), en contournement de l'extrémité inférieure du tube central 3 reçue dans l'épaulement 34.This structure alternates in a star around a central core 31, empty zones 32 hollowed out through its longitudinal thickness and massive zones 33 ensuring thermal conduction. Both extend radially astride the shoulder 34, on either side of the end of the central tube 3. They therefore allow the gas to circulate freely between the central volume 6 of the cryostat (or at least the expansion chamber remaining at the bottom of the cryostat in the case of a cooler according to FIG. 5 applying a Stirling cycle), bypassing the lower end of the central tube 3 received in the shoulder 34.

Un tel échangeur miniature, sous par exemple 5 mm de diamètre et 3 mm d'épaisseur, peut être fabriqué aisément par usinage électrochimique d'un barreau cylindrique, qui est ensuite découpé en tronçons.Such a miniature exchanger, for example 5 mm in diameter and 3 mm thick, can be easily manufactured by electrochemical machining of a cylindrical bar, which is then cut into sections.

Il permet d'apporter une surface d'échange importante pour un encombrement réduit, et sans créer de pertes de charge perturbatrices, tout en assurant une tranquillisation bénéfique en fond du tube 3 dans le cas où il reçoit du gaz pulsé. Aux fins de mieux tranquilliser le flux gazeux des feuilletés de grilles perforés sont interposés entre le tube 3 et les lobes de l'échangeur. Ils n'ont pas été représentés sur la figure 3.It makes it possible to provide a large exchange surface for a reduced bulk, and without creating disturbing pressure losses, while ensuring a beneficial tranquilization at the bottom of the tube 3 in the case where it receives pulsed gas. In order to better tranquilize the gas flow, the laminated perforated grids are interposed between the tube 3 and the lobes of the exchanger. They have not been shown in Figure 3.

Les mêmes avantages se retrouvent si les zones rayonnantes alternativement pleines et vides sont interverties. Le noyau 31 peut être en plus percé d'un passage vide en son centre, et il n'est pas nécessaire de laisser subsister une couronne périphérique de matériau, jointive en continu avec le tube central 3. Les zones massives forment des lobes de matériau échangeur, ici encore dans une configuration à cheval par rapport au diamètre du tube 3, dans laquelle les zones vides entre les lobes assurent le passage du gaz entre le régénérateur et soit la chambre de détente d'un refroidisseur à cycle Stirling, soit le fond du piston gazeux d'un refroidisseur à tube à gaz pulsé.The same advantages are found if the alternatingly full and empty radiating zones are inverted. The core 31 can be additionally pierced with an empty passage in its center, and it is not necessary to leave a peripheral crown of material, continuously contiguous with the central tube 3. The massive zones form lobes of material exchanger, again in a configuration straddling the diameter of the tube 3, in which the empty zones between the lobes ensure the passage of gas between the regenerator and either the expansion chamber of a Stirling cycle cooler, the bottom of the gas piston of a pulsed gas tube cooler.

La figure 5 illustre la combinaison du cryostat des figures précédentes, utilisant la pièce centrale 20 de la figure 2, avec un oscillateur de pression répondant à la configuration d'un refroidisseur à cycle Stirling, dans lequel le pilotage est à moteur rotatif.FIG. 5 illustrates the combination of the cryostat of the preceding figures, using the central part 20 of FIG. 2, with a pressure oscillator responding to the configuration of a Stirling cycle cooler, in which the control is with a rotary engine.

On a représenté schématiquement un système d'entraînement classique par un vilebrequin 51 dont l'excentrique est lié à deux bielles 53, 54, disposées à 90 degrés l'une de l'autre. A l'intérieur du carter 60, la bielle 53 est articulée sur l'extrémité du piston déplaceur 55, tandis que la bielle 54 est articulée sur le piston de compression 56 qui limite la chambre de compression 57. Le gaz comprimé est véhiculé par des conduits 58, 59 jusqu'au canal 39 du cryostat alimentant la chambre de distribution 71 du cryostat, et de là le régénérateur 5.A conventional drive system is schematically represented by a crankshaft 51 whose eccentric is linked to two connecting rods 53, 54, arranged at 90 degrees from one another. Inside the casing 60, the connecting rod 53 is articulated on the end of the displacing piston 55, while the connecting rod 54 is articulated on the compression piston 56 which limits the compression chamber 57. The compressed gas is conveyed by conduits 58, 59 to the channel 39 of the cryostat supplying the distribution chamber 71 of the cryostat, and from there the regenerator 5.

Le piston déplaceur 55 est mobile axialement dans le volume interne 6 du cryostat 30. Il occupe quasiment tout ce volume, en ne laissant place au fond du tube 3 qui constitue son guide, qu'à l'épaisseur de la chambre de détente, considérablement agrandie sur la figure par rapport à la réalité pratique.The displacer piston 55 is axially movable in the internal volume 6 of the cryostat 30. It occupies almost all of this volume, leaving space at the bottom of the tube 3 which constitutes its guide, only to the thickness of the expansion chamber, considerably enlarged in the figure in relation to practical reality.

Il passe donc par l'alésage axial 72 de la pièce centrale 20. Son coulissement dans celle-ci est assuré sous étanchéité au gaz par un revêtement adapté appliqué sur sa surface périphérique.It therefore passes through the axial bore 72 of the central part 20. Its sliding in the latter is ensured under gas tightness by a suitable coating applied to its peripheral surface.

La figure 6 utilise au contraire un oscillateur de pression conçu pour un refroidisseur type TGP dont le carter 50 est raccordé sur le cryostat autour de la pièce centrale 10 du modèle de la figure 1.FIG. 6, on the other hand, uses a pressure oscillator designed for a TGP type cooler, the housing 50 of which is connected to the cryostat around the central part 10 of the model of FIG. 1.

On voit donc sur cette figure 6 que l'échangeur chaud 9 est présent et que le volume interne 6 du cryostat est resté vide pour être occupé par le gaz pulsé et fonctionner comme un piston gazeux.It can therefore be seen in this FIG. 6 that the hot exchanger 9 is present and that the internal volume 6 of the cryostat has remained empty to be occupied by the pulsed gas and to function as a gas piston.

Dans le cas particulier illustré, le mode de pilotage est de type rotatif. L'arbre moteur est perpendiculaire à l'axe du système et, par un vilebrequin à axe décentré 66, il entraîne dans un mouvement oscillant, un piston unique 74.In the particular case illustrated, the control mode is of the rotary type. The engine shaft is perpendicular to the axis of the system and, by an off-center crankshaft 66, it drives in a oscillating movement, a single piston 74.

Le piston 74 est mobile, verticalement sur la figure, dans l'axe du cryostat, dans une chemise formée à l'intérieur du carter 50.The piston 74 is movable, vertically in the figure, in the axis of the cryostat, in a jacket formed inside the casing 50.

Sur l'axe décentré 66 est montée la cage interne 68 d'un roulement à billes, dont la cage externe 67 est emprisonnée dans une gorge rectiligne 75 creusée latéralement dans la surface périphérique du piston 74, perpendiculairement à son axe et au plan de la figure. Cette disposition permet d'assurer le mouvement alternatif du piston tout en l'immobilisant en rotation.On the offset axis 66 is mounted the internal cage 68 of a ball bearing, the external cage 67 of which is trapped in a rectilinear groove 75 hollowed out laterally in the peripheral surface of the piston 74, perpendicular to its axis and to the plane of the figure. This arrangement ensures the reciprocating movement of the piston while immobilizing it in rotation.

La chambre de compression 63 est ménagée entre la face d'extrémité supérieure du piston et le carter 60. Elle est reliée, comme dans le cas précédent, par un perçage 62 et un conduit 61 au canal 39 débouchant dans la chambre de distribution du cryostat.The compression chamber 63 is formed between the upper end face of the piston and the casing 60. It is connected, as in the previous case, by a bore 62 and a conduit 61 to the channel 39 opening into the distribution chamber of the cryostat .

La face opposée du piston est creuse. On ménage ainsi, du côté opposé à la chambre de compression, un réservoir 65, de volume important par rapport au volume de gaz en circulation. La pression régnant dans ce réservoir reste donc pratiquement constante en fonctionnement.The opposite side of the piston is hollow. There is thus formed, on the side opposite to the compression chamber, a reservoir 65, of large volume relative to the volume of gas in circulation. The pressure prevailing in this tank therefore remains practically constant in operation.

C'est ainsi que le piston 74 ménage là, à l'intérieur de sa chemise de guidage, un réservoir qui est directement ouvert sur la partie centrale du cryostat et qui remplit la fonction de volume tampon pour la vanne sous débit contrôlé constituée par l'orifice calibré 13 de la figure 1, à l'alimentation du piston gazeux occupant la volume central 6.This is how the piston 74 provides there, inside its guide jacket, a reservoir which is directly open on the central part of the cryostat and which fulfills the function of buffer volume for the valve under controlled flow constituted by the calibrated orifice 13 of FIG. 1, at the supply of the gas piston occupying the central volume 6.

Conformément à une variante de réalisation pratique restant dans le cadre de l'invention, on peut avantageusement appliquer la même disposition, ménageant le réservoir tampon, directement ouvert sur la surface libre de la pièce centrale 10 en tête du cryostat, à l'intérieur du piston de compression, dans le cas d'un refroidisseur de type TGP dont le pilotage est assuré par moteur linéaire plutôt que par moteur rotatif.In accordance with a practical variant remaining within the scope of the invention, the same arrangement can advantageously be applied, leaving the buffer tank directly open on the free surface of the central part 10 at the head of the cryostat, inside the compression piston, in the case of a TGP type cooler whose control is ensured by a linear motor rather than a rotary motor.

Sur la figure 7 on a fait apparaître une variante de réalisation particulièrement avantageuse pour le fond du cryostat. La représentation éclatée, utilisée pour plus de clarté, montre schématiquement le régénérateur 5 entre le tube 3 de gaz pulsé et la paroi tubulaire 2, qui laisse place à l'échangeur froid 8 contre la plaque 22.In Figure 7 we have shown a particularly advantageous embodiment for the bottom of the cryostat. The exploded representation, used for clarity, schematically shows the regenerator 5 between the tube 3 of pulsed gas and the tubular wall 2, which leaves room for the cold exchanger 8 against the plate 22.

L'échangeur 8 est ici constitué de lobes 77 de matériau massif en disposition rayonnante autour d'un noyau central 34. Entre ces lobes 77 se situent les passages de gaz 78 qui font communiquer l'extrémité inférieure du régénérateur avec le volume axial du tube 3.The exchanger 8 here consists of lobes 77 of solid material in radiating arrangement around a central core 34. Between these lobes 77 are located the gas passages 78 which make the lower end of the regenerator communicate with the axial volume of the tube 3.

Le feuilleté de tranquillisation du flux gazeux, dont il a déjà été question, est représenté constitué par un empilement de grilles perforées 81 monté en section transversale du tube 3 à cette extrémité inférieure. Ces grilles peuvent être retenues par des pattes du tube 3, comme représenté, ou simplement coincées entre le bout du tube et l'échangeur 8 dans sa partie centrale limitée par un épaulement 79 de centrage du tube 3. Dans tous les cas, le gaz passant entre les lobes de l'échangeur se trouve devoir traverser l'empilement de grilles.The laminate for tranquilizing the gas flow, which has already been discussed, is represented by a stack of perforated grids 81 mounted in cross section of the tube 3 at this lower end. These grids can be retained by lugs of the tube 3, as shown, or simply wedged between the end of the tube and the exchanger 8 in its central part limited by a shoulder 79 for centering the tube 3. In all cases, the gas passing between the exchanger lobes is found to have to pass through the stack of grids.

Cette circulation est matérialisée par des flèches sur la figure 8, qui concerne un autre mode de réalisation particulièrement avantageux dans la mesure notamment où il facilite une tranquillisation du flux gazeux au plus près de la plaque froide 22. L'échangeur froid y est réalisé en deux parties 83 et 84 emboîtées concentriquement l'une dans l'autre; Chacune présente ses propres lobes de matériau d'échange thermique alternant avec des zones vides libres à la circulation gazeuse. Autrement dit, fonctionnellement l'échangeur est donc percé de canaux se répartissant en deux couronnes, l'une sous le régénérateur 5, l'autre en bout du tube 3. On voit en plus que la pièce interne 83 de l'échangeur est plus courte que la pièce externe 84 qui l'entoure et que, de la sorte, le bout du tube 3 vient se centrer dans la pièce 84 en butée sur la pièce 83.This circulation is indicated by arrows in FIG. 8, which relates to another particularly advantageous embodiment in particular in that it facilitates a tranquilization of the gas flow as close as possible to the cold plate 22. The cold exchanger is produced therein. two parts 83 and 84 nested concentrically one inside the other; Each has its own lobes of heat exchange material alternating with empty areas free for gas circulation. In other words, functionally the exchanger is therefore pierced with channels dividing into two rings, one under the regenerator 5, the other at the end of the tube 3. It can also be seen that the internal part 83 of the exchanger is more shorter than the external part 84 which surrounds it and so that the end of the tube 3 is centered in the part 84 abutting on the part 83.

Un empilement de grilles 82 constitue le feuilleté de tranquillisation du flux gazeux. Ces grilles sont interposées directement contre la plaque froide 22 entre celle-ci et les deux pièces 83 et 84 de l'échangeur. En cas de besoin, elles pourraient être bloquées dans l'échangeur en périphérie, en ménageant à cet effet un épaulement dans la pièce 84 formant la couronne annulaire de cet échangeur.A stack of grids 82 constitutes the laminate for tranquilizing the gas flow. These grids are interposed directly against the cold plate 22 between the latter and the two parts 83 and 84 of the exchanger. If necessary, they could be blocked in the exchanger at the periphery, providing for this purpose a shoulder in the part 84 forming the annular ring of this exchanger.

On aura ainsi décrit en détail différentes variantes de réalisation des divers éléments constituant un cryostat suivant l'invention. Elles peuvent avantageusement se combiner sous toute forme opérante dans la réalisation d'un refroidisseur répondant aux caractéristiques de l'invention.We have thus described in detail different embodiments of the various elements constituting a cryostat according to the invention. They can advantageously be combined in any operating form in the production of a cooler meeting the characteristics of the invention.

Claims (15)

Cryostat pour refroidisseur cryogénique mettant en oeuvre un circuit fermé de gaz de travail entre une chambre de compression située dans un carter d'oscillateur de pression associé et une chambre de détente située en fond du cryostat, en situation d'échange thermique avec un composant à refroidir, comportant à l'intérieur d'une enveloppe d'isolation thermique (1), solidaire d'une embase (4) de montage sur ledit carter (50, 60), un régénérateur thermique (5) interposé sur le circuit du gaz de travail, caractérisé en ce que le régénérateur (5) est en disposition annulaire autour d'un volume axial (6) s'étendant entre un échangeur froid (8) qui est en contact thermique avec le composant à refroidir (21) et fait communiquer le régénérateur (5) avec ledit volume axial en fond du cryostat (30), et en ce qu'il comporte une couronne (71) de distribution de gaz dans ledit régénérateur (5), en tête du cryostat, à partir d'un conduit (39) percé à travers l'embase (4) pour connexion à la chambre de compression, ladite couronne de distribution (71) étant formée par une pièce centrale (10, 20) se montant de manière amovible et à travers ladite embase (4) axialement en son centre, et interchangeable entre un modèle convenant pour un refroidisseur de type à gaz pulsé dans lequel le volume axial (6) fonctionne en piston gazeux et un modèle convenant à un refroidisseur de type à cycle de Stirling.Cryostat for cryogenic cooler implementing a closed working gas circuit between a compression chamber located in an associated pressure oscillator casing and an expansion chamber located at the bottom of the cryostat, in a heat exchange situation with a component to cooling, comprising inside a thermal insulation envelope (1), integral with a base (4) for mounting on said casing (50, 60), a thermal regenerator (5) interposed on the gas circuit working, characterized in that the regenerator (5) is in an annular arrangement around an axial volume (6) extending between a cold exchanger (8) which is in thermal contact with the component to be cooled (21) and makes communicate the regenerator (5) with said axial volume at the bottom of the cryostat (30), and in that it comprises a ring (71) for distributing gas in said regenerator (5), at the head of the cryostat, from a conduit (39) drilled through the base (4) for connection to the compression chamber, said distribution ring (71) being formed by a central part (10, 20) being mounted removably and through said base (4) axially in its center, and interchangeable between a model suitable for a pulsed gas type cooler in which the axial volume (6) operates as a gas piston and a model suitable for a Stirling cycle type cooler. Cryostat suivant la revendication 1, caractérisé en ce que ladite pièce centrale, avec ladite couronne de distribution (71), est solidaire d'un tube (3) limitant ledit volume axial (6).Cryostat according to claim 1, characterized in that said central part, with said distribution ring (71), is integral with a tube (3) limiting said axial volume (6). Cryostat suivant l'une des revendications 1 ou 2, caractérisé en ce que ladite pièce centrale présente, dans le modèle convenant à un refroidisseur de type à cycle de Stirling, un alésage axial propre à être traversé par un piston déplaceur du refroidisseur, introduit à coulissement étanche dans ledit volume axial (6).Cryostat according to one of claims 1 or 2, characterized in that said central part has, in the model suitable for a Stirling cycle type cooler, an axial bore suitable for being traversed by a displacer piston of the cooler, introduced with sealed sliding in said axial volume (6). Cryostat suivant l'une quelconque des revendications 1 à 3, caractérisé en ce que ledit échangeur froid (8) présente une structure à géométrie de révolution, faisant alterner autour de l'axe du cryostat, des zones massives (33) en matériau bon conducteur thermique et des zones vides (32) ouvertes au passage du gaz.Cryostat according to any one of Claims 1 to 3, characterized in that the said cold exchanger (8) has a structure with geometry of revolution, causing massive zones (33) of good conductive material to alternate around the axis of the cryostat. thermal and empty zones (32) open to the passage of gas. Cryostat suivant la revendication 4, caractérisé en ce que lesdites zones vides (33) s'étendent de part et d'autre d'un épaulement (34) de centrage d'un tube central (3) limitant ledit volume axial.Cryostat according to claim 4, characterized in that said empty zones (33) extend on either side of a shoulder (34) for centering a central tube (3) limiting said axial volume. Cryostat suivant l'une quelconque des revendications 1 à 5, caractérisé en ce que ladite enveloppe d'isolation thermique (1) présente une paroi tubulaire interne (2) contiguë au régénérateur, fermée par une plaque (22) de réception du composant à refroidir, contre laquelle est apposé ledit échangeur froid (8).Cryostat according to any one of Claims 1 to 5, characterized in that the said thermal insulation envelope (1) has an internal tubular wall (2) contiguous to the regenerator, closed by a plate (22) for receiving the component to be cooled , against which is affixed said cold exchanger (8). Cryostat suivant l'une quelconque des revendications 1 à 6, caractérisé en ce que ledit régénérateur est constitué d'une feuille enroulée sur elle-même dans l'espace annulaire compris entre une paroi interne (2) de ladite enveloppe (1) et un tube central (3) limitant ledit volume axial, dans le prolongement de ladite couronne de distribution, ladite feuille étant usinée, notamment par procédé photo-lithographique, de sorte à former des bandes distinctes (27) à surfaces lisses parallèles à l'axe du cryostat et des barrettes transversales (26) en surépaisseur réunissant ponctuellement les bandes successives.Cryostat according to any one of Claims 1 to 6, characterized in that the said regenerator consists of a sheet wound on itself in the annular space comprised between an internal wall (2) of the said envelope (1) and a central tube (3) limiting said axial volume, in the extension of said distribution ring, said sheet being machined, in particular by photo-lithographic process, so as to form separate strips (27) with smooth surfaces parallel to the axis of the cryostat and transverse bars (26) in excess thickness punctually joining the successive bands. Cryostat suivant l'une quelconque des revendications 1 à 7, caractérisé en ce que ladite couronne de distribution présente une face inférieure de butée sur ledit régénérateur dans laquelle est creusée une gorge circulaire (45) communiquant par des orifices régulièrement répartis avec une chambre annulaire (42, 43) ménagée extérieurement autour de ladite pièce centrale au niveau de l'embase (4) du cryostat, en communication avec ledit canal (39).Cryostat according to any one of Claims 1 to 7, characterized in that the said distribution ring has a lower abutment face on the said regenerator in which a groove is hollowed out circular (45) communicating through regularly distributed orifices with an annular chamber (42, 43) formed externally around said central part at the base (4) of the cryostat, in communication with said channel (39). Cryostat suivant l'une quelconque des revendications 1 à 8, caractérisé par un feuilleté de grilles de tranquillisation du flux gazeux interposé au fond dudit volume axial contre l'échangeur froid.Cryostat according to any one of claims 1 to 8, characterized by a laminate of gaseous tranquilization grids interposed at the bottom of said axial volume against the cold exchanger. Refroidisseur à cycle de Stirling, caractérisé en ce qu'il comporte un cryostat suivant l'une quelconque des revendications 1 à 9, raccordé au carter (60) d'un oscillateur de pression comportant un piston déplaceur à pilotage synchronisé en déphasage avec un piston de compression et en ce que ledit piston déplaceur (55) est mobile axialement dans ledit volume interne (6) du cryostat (30) et passe à coulissement étanche dans un alésage axial (72) prévu à cet effet dans ladite pièce centrale (20) montée dans ladite embase du cryostat.Stirling cycle cooler, characterized in that it comprises a cryostat according to any one of Claims 1 to 9, connected to the casing (60) of a pressure oscillator comprising a displacing piston with piloting synchronized in phase shift with a piston compression and in that said displacing piston (55) is axially movable in said internal volume (6) of the cryostat (30) and passes in leaktight sliding in an axial bore (72) provided for this purpose in said central part (20) mounted in said base of the cryostat. Refroidisseur à tube à gaz pulsé, caractérisé en ce qu'il comporte un cryostat suivant l'une quelconque des revendications 1 à 9, raccordé au carter (50) d'un oscillateur de pression comportant des moyens de pilotage périodique d'un piston de compression du gaz faisant varier le volume de la chambre de compression et un réservoir tampon de gaz à pression constante, et en ce que ladite pièce centrale (10) montée dans l'embase (4) du cryostat comporte des moyens de liaison pneumatique à débit contrôlé avec ledit réservoir (65).Pulsed gas tube cooler, characterized in that it comprises a cryostat according to any one of claims 1 to 9, connected to the casing (50) of a pressure oscillator comprising means for periodically controlling a piston of compression of the gas varying the volume of the compression chamber and a buffer tank of gas at constant pressure, and in that said central part (10) mounted in the base (4) of the cryostat comprises pneumatic flow rate connection means controlled with said tank (65). Refroidisseur suivant la revendication 10, caractérisé en ce que ladite pièce centrale comporte, en plus d'un canal (11) de passage du gaz sous débit contrôlé entre ledit réservoir tampon de gaz à pression constante ménagé à l'intérieur du carter (50) de l'oscillateur de pression, et ledit volume axial (6) interne au cryostat, ce dernier se remplissant de gaz en fonctionnement pour constituer piston gazeux en déphasage par rapport à la compression périodique, au moins un autre canal (12) à débit contrôlé, débouchant dans une chambre annulaire (42, 43) formée par ladite pièce centrale (10) réalisée conformément à la revendication 8.Cooler according to Claim 10, characterized in that the said central part comprises, in addition to a channel (11) for the passage of gas under controlled flow between the said constant pressure gas buffer tank arranged inside the casing (50) of the pressure oscillator, and said axial volume (6) internal to the cryostat, the latter filling with gas in operation to constitute a gas piston out of phase with respect to the periodic compression, at least one other channel (12) with controlled flow, opening into an annular chamber (42, 43) formed by said central part (10) produced in accordance to claim 8. Refroidisseur suivant la revendication 10 ou 11, caractérisé en ce que ledit volume tampon de gaz est ménagé à l'intérieur d'un piston de compression commandé par lesdits moyens de pilotage, qui est à cet effet directement ouvert, dans une chemise de guidage dudit piston, sur ladite pièce centrale (10) du cryostat.Cooler according to claim 10 or 11, characterized in that said gas buffer volume is formed inside a compression piston controlled by said piloting means, which for this purpose is directly open, in a guide jacket of said piston, on said central part (10) of the cryostat. Refroidisseur suivant l'une quelconque des revendications 10 à 12, caractérisé en ce que, dans une configuration du type à moteur rotatif, lesdits moyens de pilotage comportent un vilebrequin actionnant un mécanisme de transmission de mouvement par roulement à billes mobile dans une gorge ménagée transversalement à l'extérieur dudit piston.Cooler according to any one of claims 10 to 12, characterized in that, in a configuration of the rotary engine type, said control means comprise a crankshaft actuating a movement transmission mechanism by movable ball bearing in a groove formed transversely outside of said piston. Cryostat suivant l'une quelconque des revendications 1 à 8, dans leurs combinaisons opérantes avec l'une quelconque des revendications 9 à 13, caractérisé en ce que ladite embase (4) forme une bague (17) de montage de ladite pièce centrale (10, 20), dans le prolongement dudit volume axial (6).Cryostat according to any one of Claims 1 to 8, in their operating combinations with any one of Claims 9 to 13, characterized in that the said base (4) forms a ring (17) for mounting the said central part (10 , 20), in the extension of said axial volume (6).
EP19970400898 1996-04-23 1997-04-22 Cryostat for cryogenic refrigerator and refrigerators comprising such a cryostat Expired - Lifetime EP0803687B1 (en)

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FR9605086A FR2747767B1 (en) 1996-04-23 1996-04-23 CRYOSTAT FOR CRYOGENIC COOLER AND COOLERS COMPRISING SUCH A CRYOSTAT
FR9605086 1996-04-23

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FR2821150A1 (en) * 2001-02-17 2002-08-23 Lg Electronics Inc Pulse tube refrigerator has cover partially inserted into hollow cylinder with central cylinder combined with pulse tube and regenerator
EP1251320A1 (en) * 1999-12-21 2002-10-23 Sharp Kabushiki Kaisha Stirling refrigerating machine
WO2012012785A1 (en) * 2010-07-22 2012-01-26 Flir Systems, Inc. Expander for stirling engines and cryogenic coolers
EP2767781A1 (en) * 2013-02-19 2014-08-20 The Hymatic Engineering Company Limited A Pulse Tube Refrigerator / Cryocooler Apparatus

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Cited By (12)

* Cited by examiner, † Cited by third party
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EP1251320A1 (en) * 1999-12-21 2002-10-23 Sharp Kabushiki Kaisha Stirling refrigerating machine
EP1251320A4 (en) * 1999-12-21 2004-03-24 Sharp Kk Stirling refrigerating machine
FR2815700A1 (en) * 2000-10-19 2002-04-26 Sagem Cryogenic closed cycle system, e.g. functioning in Stirling cycle, includes same guide ring which guides both regenerator tube and control rod, thus preventing misalignment
FR2821150A1 (en) * 2001-02-17 2002-08-23 Lg Electronics Inc Pulse tube refrigerator has cover partially inserted into hollow cylinder with central cylinder combined with pulse tube and regenerator
WO2012012785A1 (en) * 2010-07-22 2012-01-26 Flir Systems, Inc. Expander for stirling engines and cryogenic coolers
US8910486B2 (en) 2010-07-22 2014-12-16 Flir Systems, Inc. Expander for stirling engines and cryogenic coolers
EP2767781A1 (en) * 2013-02-19 2014-08-20 The Hymatic Engineering Company Limited A Pulse Tube Refrigerator / Cryocooler Apparatus
US20140230457A1 (en) * 2013-02-19 2014-08-21 The Hymatic Engineering Company Limited Pulse tube refrigerator/cryocooler apparatus
GB2524893A (en) * 2013-02-19 2015-10-07 Hymatic Eng Co Ltd A pulse tube refrigerator / cryocooler apparatus
US9909787B2 (en) * 2013-02-19 2018-03-06 The Hymatic Engineering Company Limited Pulse tube refrigerator/cryocooler apparatus
GB2510912B (en) * 2013-02-19 2018-09-26 The Hymatic Engineering Company Ltd A pulse tube refrigerator / cryocooler apparatus
GB2524893B (en) * 2013-02-19 2018-11-28 The Hymatic Engineering Company Ltd A gas flow distribution device for distributing gas to a regenerator of a pulse tube refrigerator cryocooler apparatus

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EP0803687B1 (en) 2002-06-26
DE69713547T2 (en) 2003-01-16
DE69713547D1 (en) 2002-08-01
FR2747767A1 (en) 1997-10-24
FR2747767B1 (en) 1998-08-28

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