Compressor device, and cooling device having a compressor device

Abstract

The present invention relates to a compressor device (2) comprising a cylinder (4), a piston (6) which is situated within the cylinder (4) and delimits a transfer space (16) filled with a transfer fluid and which can be periodically reciprocatingly moved by means of a drive device (26), a compressor element (8), in particular (metal) bellows, which is arranged within the transfer space (16) and which delimits a working space / compression space (20) filled with a working gas, and comprising a connector (10) via which the working space (20) can be connected to a working gas line (36) to a Gifford-McMahon cooler or a pulse tube cooler (38), wherein the compressor element (8) and the working gas contained therein are periodically compressed indirectly by way of the transfer fluid that is displaced by the piston (6).

Description

[0001] Compressor device and cooling device with compressor device

[0002] Description

[0003] Technical area

[0004] The present disclosure relates to a compressor device and a refrigerator device comprising the compressor device and a Gifford-McMahon refrigerator or a pulse tube refrigerator.

[0005] Pulse tube coolers or Gifford-McMahon coolers are widely used to cool magnetic resonance imaging scanners, cryogenic pumps, quantum computers, quantum communication systems, and the like. Gas compressors, particularly helium compressors, are used in combination with rotary or rotary valves. A helium compressor is connected to a rotary valve via a high-pressure line and a low-pressure line. On the output side, the rotary valve is connected via a gas line to a cooling device in the form of a Gifford-McMahon cooler or a pulse tube cooler. The rotary valve alternately connects the high- and low-pressure sides of the gas compressor to the pulse tube cooler or Gifford-McMahon cooler. The rate at which the compressed helium is introduced into and removed from the cooling device is in the range of 1-2 Hz. A disadvantage of such cooling or compressor systems is that the motor-driven rotary valve incurs losses of approximately50% of the compressor's input power.

[0006] Cooling devices with pulse tube coolers or Gifford-McMahon coolers are known from DE 101 37 552 C1.

[0007] DE 633 104 A discloses a compressor device with a compressor unit in which a working medium is periodically compressed and expanded again by a reciprocating compressor element in the form of a piston. The drive device comprises a pressure cylinder with a reciprocating piston. The drive device is mechanically coupled to the compressor element. Both the drive device and the compressor element are constructed with individual pressure cylinders in which a compressor piston or piston is mounted. The drive device and the compressor element are mechanically connected, with the feedthroughs from the pressure cylinders being sealed. This design requires a relatively large amount of space for the apparatus, since the pressure cylinders are arranged in series.In addition, the design requires the use of two pistons and two bushings, which are structurally complex and prone to leakage failure.

[0008] The object of the present invention is to eliminate or at least reduce the disadvantages of the prior art. Specifically, the object of the present invention is to provide a compressor device and a cooling system that minimizes losses and installation space.

[0009] This object is achieved by a compressor device according to claim 1 and by the cooling device according to the independent claim.

[0010] Specifically, the problem is solved by a compressor device with a cylinder, a piston arranged inside the cylinder, which delimits a transfer chamber filled with a transfer fluid and can be moved back and forth periodically by means of a drive device, a compressor element arranged inside the transfer chamber, preferably a bellows, in particular a metal bellows, which delimits a working chamber (compression chamber) filled with a working gas, and a connection via which the working chamber can be connected to a working gas line (pressure line) to a Gifford-McMahon cooler or a pulse tube cooler, in particular a two-stage 4K (four Kelvin) cooler, wherein the compressor element and the working gas contained therein are periodically compressed indirectly via the transfer fluid displaced by the piston.

[0011] In other words, the compressor device includes the cylinder with a cylinder bore formed on the inner side of the cylinder and the piston running in the cylinder with a piston skirt formed in the circumferential direction of the piston. The piston skirt slides sealingly against the cylinder bore of the cylinder. Preferably, at least one annular seal / piston ring is formed between the piston skirt and the cylinder bore. The piston further includes a piston roof, which faces the transfer chamber filled with the transfer fluid and delimits it. The piston is provided and designed to execute a periodic linear movement in a direction of a cylinder center fiber (cylinder center axis), which extends in a cylinder longitudinal direction. The compressor element, which includes at least one, preferably accordion-shaped, wall, is formed in the transfer chamber.In other words, the compressor element is preferably designed as a bellows. The compressor element surrounds the working chamber filled with the working gas. In other words, the compressor element separates the working chamber from the transfer chamber. The working chamber is formed with the connection, which connects the working chamber to the working gas line, either permanently or detachably. The connection is preferably formed on a side of the compressor element facing away from the piston. The working gas line is provided and designed to connect the working chamber to the Gifford-McMahon cooler or the pulse tube cooler or any other suitable cooler. The working chamber is variable in volume due to the preferably accordion-shaped wall.Due to the linear movement of the piston, a force is exerted / transferred to the compressor element by means of the transmission fluid and the working gas contained in the working chamber is periodically compressed / compressed and expanded.

[0012] The essence of the invention is therefore to periodically compress and expand the working gas contained in the compressor element of the compressor device by moving the piston indirectly by means of the transfer fluid.

[0013] Furthermore, the core of the invention is that a pressure generation location (force generation location) and a compression location are formed in a cylinder.

[0014] Another core of the invention is that the piston and the compressor element are mechanically decoupled. In other words, the piston and the compressor element are arranged in the cylinder in such a way that they never touch each other. Furthermore, the force acting on the piston or the force to be transmitted by the piston is transmitted exclusively hydraulically to the compressor element. A mechanical connection between the piston and the compressor element for force transmission is dispensed with in the present invention.

[0015] By designing the compressor device in this way, a rotary valve can be omitted, thus reducing losses and significantly increasing the efficiency of the compressor device. Furthermore, such a compressor device can be designed more compactly, as a single-cylinder compressor device is possible. A further advantage of such a compressor device is that the reliability of the compressor device can be increased by reducing the number of components.

[0016] By designing the working chamber in the compressor element, particularly by designing the compressor element as a metal bellows, water, transmission fluid, oil, or other foreign substances can be prevented from penetrating / diffusing into the working gas and contaminating / polluting it. Contamination of the working gas with the foreign substance could cause the working gas to freeze and seals to be damaged. In particular, the design of the compressor element as a metal bellows has the advantage over, for example, a rubber compressor element in that the working gas cannot escape from the compressor element or through the compressor element into the transfer chamber.

[0017] In a first aspect, a volume of a space / fluid space enclosed by the piston, the compressor element and the cylinder may be constant.

[0018] In other words, a region of the transfer chamber outside the compressor element / working chamber may be completely filled with the transfer fluid, wherein the transfer fluid may be a substantially incompressible fluid.

[0019] This ensures that the force exerted by the piston on the transmission fluid can be transmitted to the bellows evenly and without local force peaks. This ensures that the compressor element is compressed and expanded exclusively in the intended manner, which significantly extends the service life of the compressor element and counteracts premature failure. Furthermore, completely filling the transmission chamber with the transmission fluid prevents the transmission fluid from foaming or foaming during operation.

[0020] Furthermore, the transmission chamber and the working chamber can be formed completely and without protrusion in the cylinder.

[0021] In a further aspect, a pressure of the working medium in the working chamber may correspond to a pressure of the transmission fluid in the transmission chamber at any time.

[0022] In other words, the pressure in the compressor element corresponds at any given time to the pressure surrounding the compressor element. In other words, the working fluid in the working chamber and the transfer fluid in the transfer chamber are in pressure equilibrium.

[0023] In this way, it can be ensured that the compressor element itself does not experience or absorb large loads / forces and that the compressor element can be designed with thin walls, which further reduces losses during compression of the compressor element.

[0024] In another aspect, the pressure of the working medium and the pressure of the transmission fluid can be greater than the ambient pressure of the environment surrounding the compressor device. In other words, the compressor device is preloaded so that, in every position of the piston in the cylinder, the working medium and the transmission medium are at an overpressure relative to the environment.

[0025] In another aspect, a piston maximum stroke may be greater than a compressor element maximum stroke.

[0026] In other words, an amplitude that the piston performs during the periodic back and forth movement in a piston movement direction can be greater than a maximum change in a compressor element extension of the compressor element in the piston movement direction.

[0027] By reducing the maximum stroke of the compressor element, mechanical stress on the compressor element, particularly in kinks / folds of the compressor element, can be kept to a minimum, which extends the service life of the compressor element and reduces the risk of failure.

[0028] In another aspect, the piston can be periodically reciprocated by a connecting rod. Using the connecting rod to move the piston, a conventional electric motor can be used as the drive device. Alternatively, the piston can be reciprocated by a threaded rod or the like.

[0029] In a further aspect, the compressor element can be guided in a stroke direction.

[0030] In other words, the compressor device can include at least one guide element designed to guide the compressor element during compression and expansion and to prevent the compressor element from buckling or collapsing in an uncontrolled manner. The guide element can be designed, for example, in a rod-shaped or sleeve-shaped configuration. Preferably, more than one guide element can be formed in the compressor device.

[0031] In a further aspect, a closed displacer (pot element) can be formed in the working space.

[0032] In other words, the displacement element can be formed on an inner side of the compressor element facing the working chamber, preferably on a front side of the compressor element near the piston. The displacement element can be a gas-tight, particularly cylindrical element, which can be rigidly connected to the compressor element.

[0033] By means of such a displacement element in the working chamber, the gas volume of the working chamber can be reduced. This makes it possible for the working chamber in the compressed state to have a (dead / residual) volume of almost zero, which reduces the deflection of the compressor element and thus the load on the compressor element.

[0034] In a further aspect, a maximum longitudinal extent of the compressor element in the stroke direction in the expanded state may be more than twice as large as a minimum longitudinal extent in the stroke direction of the compressor element in the compressed state.

[0035] In a further aspect, the transfer chamber and / or the working chamber can be connected to at least one compensation tank, optionally via a valve, in order to pre-load the compressor device and to compensate for any volume changes, in particular during start-up or commissioning of the compressor device.

[0036] In another aspect, the compression of the compressor element is reversible. This means that the compressor element changes its geometry during operation exclusively within a predefined range and then returns to its original geometry.

[0037] In a further aspect, a wall thickness of the compressor element can be constant. Preferably, the wall thickness of the compressor element can be less than 0.2 mm.

[0038] In a further aspect, the compressor element can be formed from a plurality of membrane pairs. Preferably, the compressor element can be formed from at least 30 membrane pairs. Particularly preferably, the compressor element can be formed from at least 40 membrane pairs.

[0039] By designing the compressor element with a large number of membrane pairs, it can be ensured that each of the membrane pairs experiences only a small deflection during the stroke movement of the compressor element, which significantly reduces mechanical stress on the compressor element.

[0040] In a further aspect, the transfer chamber can be configured with a multi-stage geometry, in particular a two-stage geometry. In other words, the transfer chamber can have a diameter jump, wherein a first diameter in a region of the piston can preferably be smaller than a second diameter in a region of the compressor element. In this way, the force to be applied by the piston to displace the transfer fluid can be adapted to the drive force or drive torque of the drive device.

[0041] In a further aspect, the drive device can be configured with and / or connected to a control device that controls the compression and expansion of the working medium in the working chamber via the periodic longitudinal movement of the piston, in particular via a rotational speed of the drive device. In a further aspect, a displacement volume displaced by the piston during the movement of the piston can correspond to a change in the working chamber volume, thereby significantly simplifying control of the compressor device.

[0042] In a further aspect, a filter may be connected downstream of the compressor device.

[0043] In another aspect, the working medium can be helium.

[0044] It is advantageous if the piston's motion profile is not linear or sinusoidal, but follows a step function in which the working gas is rapidly compressed, the pressure is maintained, and then the working gas is quickly released again. This motion profile can be achieved by appropriately variable control of the drive device.

[0045] Alternatively, the drive device can be controlled uniformly, and the step-function-like movement of the piston can be achieved by means of a corresponding transmission element, such as a cam. In other words, a linear movement of the drive device can be translated into a nearly step-function-like movement of the piston by a cam-shaped transmission element. In yet other words, the transmission element can be asymmetrical to a rotational axis of the transmission element.

[0046] In a further aspect, the one drive device can drive more than one compressor device. In such a configuration, the cylinders can preferably be arranged in a boxer formation. In other words, for example, two cylinders can be formed diametrically opposite the drive device, wherein the cylinders can be constructed identically. Each of the cylinders can be formed with a piston and a compressor element. In a further aspect, the transmission fluid can (also) be used as a lubricant for the drive device. In other words, the transmission fluid can be formed as a lubricant on a side of the piston facing away from the transmission chamber. In particular, the transmission fluid can lubricate an engine-connecting rod pairing and a connecting rod-piston pairing.By designing the transmission fluid as a lubricant, possible leakages of the transmission fluid via the piston towards the drive device can be prevented from having a negative effect on the drive device.

[0047] In a further aspect, the compressor device can be designed for an operating frequency range between 0.1 and 10 Hz and in particular for an operating frequency range between 0.5 and 5 Hz.

[0048] Furthermore, the object is achieved by a cooling device with a compressor device according to one of the above aspects and a Gifford-McMahon cooler or a pulse tube cooler.

[0049] In other words, the cooling device includes a compressor device according to one of the above aspects and the Gifford-McMahon cooler or the pulse tube cooler connected via the connection. Optionally, a heat exchanger for cooling the working gas can be formed between the cooling device and the Gifford-McMahon cooler or the pulse tube cooler, or a cooling device can be formed directly on the Gifford-McMahon cooler or the pulse tube cooler.

[0050] This makes it possible to dispense with a rotary valve and establish a pressure curve directly with the compressor device. The Gifford-McMahon cooler or pulse tube cooler can be connected directly to the compressor device. Extremely clean helium gas (6N = 99.9999% helium) is required for operation of the Gifford-McMahon cooler or pulse tube cooler.

[0051] In one aspect, the compressor device and the Gifford-McMahon cooler or the pulse tube cooler can be connected via a high-pressure connection. In another aspect, the cooler device or the compressor device can be pre-pressurized at 16 bar. The operating range of the compressor device can be between 8 bar and 24 bar.

[0052] Furthermore, a compressor refrigeration machine can be formed with a compressor device according to one of the above aspects, an evaporator and a condenser.

[0053] Short description of the characters

[0054] Fig. 1 is a schematic representation of a compressor device according to the invention in a general embodiment;

[0055] Fig. 2 is a schematic representation of the compressor device according to the invention in a specific embodiment;

[0056] Fig. 3 is a schematic diagram of a structure of a cooling device according to the invention in a first embodiment;

[0057] Fig. 4 is a schematic diagram of a structure of the cooling device according to the invention in a second embodiment;

[0058] Fig. 5 is a schematic representation of a compressor device according to the invention in a first alternative embodiment;

[0059] Fig. 6 is a schematic representation of a compressor device according to the invention in a second alternative embodiment;

[0060] Fig. 7 is a schematic representation of an inventive

[0061] Compressor device in a third alternative embodiment; and Fig. 8 is a schematic representation of a compressor device according to the invention in a fourth alternative embodiment;

[0062] Description of the embodiments

[0063] Hereinafter, embodiments of the present disclosure will be described based on the accompanying figures.

[0064] Fig. 1 shows a compressor device 2 according to the invention with a gas-tight cylinder 4, a piston 6 arranged in the cylinder 4, a compressor element in the form of a (metal) bellows 8 and a connection 10, wherein the compressor device 2 is provided and designed to be coupled to a cooling device or to form part of the cooling device. The cylinder 4 includes a (cylinder) running surface 12 formed on an inner side of the cylinder 4. The piston 6 includes a piston skirt 14 formed on an outer peripheral surface of the piston 6, wherein the running surface 12 of the cylinder 4 and the piston skirt 14 of the piston 6 are coordinated with one another such that the piston 6 is movable in a sealing manner in the cylinder 4 linearly along a cylinder center axis ZM. The piston 6 and the cylinder 4 delimit a transfer chamber 16. The transfer chamber 16 is filled with a transfer fluid.The bellows 8 is arranged in the transmission chamber 16 and surrounded by the (incompressible) transmission fluid. Specifically, the transmission fluid is formed in a fluid chamber 18 enclosed between the cylinder 4, the piston 6, and the bellows 8. The volume of the fluid chamber 18 is essentially constant, although the geometry of the fluid chamber 18 can vary.

[0065] The bellows 8 contains / delimits a working chamber 20. The working chamber 20 is filled with a working gas, preferably helium. In the embodiment shown here, the bellows 8 is designed as a bellows with an accordion-shaped wall 22. The bellows 8 separates the transfer chamber 16 and the working chamber 20 from one another in a gas-tight and fluid-tight manner. The connection 10 is formed on a side of the working chamber 20 facing away from the piston 6. The connection 10 is provided and designed to connect the compressor device 2 to a cold head / cooler 38 (see Fig. 3), for example, a Gifford-McMahon cooler or a pulse tube cooler.

[0066] Fig. 2 shows the compressor device 2 in an embodiment, wherein the piston 6 is linearly movable along the cylinder center axis ZM by means of a connecting rod 24.

[0067] The following describes the operation of the compressor device 2 according to the invention with reference to Fig. 2. The drive of the piston 6 via the connecting rod 24 is exemplary. Of course, other types of drive of the piston 6, which are suitable for periodically moving the piston 6 back and forth along the cylinder center axis ZM, are to be considered equivalent.

[0068] A drive device in the form of an electric motor 26, controlled by a corresponding control device (not shown), rotates a disk 28, on which the connecting rod 24 is eccentrically mounted at a first bearing point 30. The connecting rod 24 is further mounted / fixed to the piston 6 at a second bearing point 32. Via the connecting rod 24, a rotary / circular movement of the disk 28 is converted into a linear movement of the piston 6 along the cylinder center axis ZM. In other words, a force generated by the electric motor 26 is transmitted to the piston 6 via the disk 28 and the connecting rod 24.

[0069] When the piston 6 moves along the cylinder center axis ZM in a direction toward the bellows 8, the force is transferred to the transmission fluid in the fluid chamber 18. The transmission fluid surrounding the bellows 8 transfers the force to the bellows 8 and compresses the working gas contained in the bellows 8. Since the transmission fluid is an approximately incompressible fluid, the force applied by the electric motor 26 (minus any friction losses) is essentially completely converted into a compression of the bellows 8 and the working gas located in the working chamber 20. In other words, the force of the electric motor 26 periodically compresses the working gas in the working chamber 20. A working range of the bellows 8 lies between a first length L1 in the compressed state and a second length L2 in the relaxed state.A (maximum) change in length AL of the bellows 8, which corresponds to a difference between the first length L1 and the second length L2, is much smaller than the first length L1 or the second length L2.

[0070] Fig. 3 shows a cooling device 34 according to the invention with the compressor device 2 in a first embodiment. The working chamber 20 of the compressor device 2 is connected to a pressure line 36 via the connection 10. The pressure line 36 connects the compressor device 2 in a gas-tight manner to a cold head 38 designed as a Gifford-McMahon cooler or pulse tube cooler. To operate such a cold head 38, a specific working gas volume is periodically compressed and expanded by the compressor device 2 within a predetermined frequency range.

[0071] Fig. 4 shows the cooling device 34 according to the invention with the compressor device 2 in a second embodiment. The cooling device 34 of the second embodiment essentially corresponds to the cooling device 34 of the first embodiment. In the second embodiment, a heat exchanger 40 is formed between the connection 10 of the compressor device 2 and the cold head 38. This heat exchanger is provided and designed to cool the working gas, particularly after compression.

[0072] Alternative embodiments of the compressor device 2 are explained below with reference to Figures 5 to 8. A repeated description of elements corresponding to the general embodiment described in Figure 1 will be omitted below.

[0073] The first alternative embodiment of the compressor device 2 shown in Fig. 5 includes a pot element 42 in the bellows 8. The pot element 42 is formed on an end face of the bellows 8 facing the piston 6 in the working chamber 20. The pot element 42 reduces a gas volume / internal volume of the working chamber 20. The pot element 42 is sealed gas-tight with respect to the working chamber 20. Fig. 6 shows a second alternative embodiment of the compressor device 2 with a wave- or rod-shaped guide element 44. The rod-shaped guide element 44 is formed on the end face of the bellows 8 facing the piston 6 in the transfer chamber 16. The rod-shaped guide element 44 extends away from the bellows 8 towards the piston 6 and is mounted in the piston 6. The rod-shaped guide element 44 is linearly guided or mounted in the piston 6. Preferably, the rod-shaped guide element 44 is guided or mounted in a bushing in the piston 6.Optionally, more than one rod-shaped guide element 44 is formed on the bellows 8. The rod-shaped guide element 44 prevents the bellows 8 from tilting relative to the piston 6.

[0074] Fig. 7 shows a third alternative embodiment of the compressor device 2 with a flat guide element 46. The flat guide element 46 is formed on the end face of the bellows 8 facing the piston 6 in the transfer chamber 16. The flat guide element 46 extends radially outward toward the running surface 12 and guides the bellows 8 relative to the running surface 12. Bores 48 are formed in the flat guide element 46, which ensure unhindered flow of the transfer fluid in the transfer chamber. The flat guide element 46 prevents the bellows 8 from tilting relative to the cylinder 4.

[0075] Fig. 8 shows a fourth alternative embodiment of the compressor device 2, wherein the cylinder 4 is designed in two stages. The cylinder 4 includes a first cylinder section 50, in which the bellows 8 is formed, and a second cylinder section 52, in which the piston 6 is formed. A first diameter of the first cylinder section 50 is larger than a second diameter of the second cylinder section 52. In other words, a pressure boost in the cylinder 4 is implemented by the first cylinder section 50 and the second cylinder section 52.

[0076] Of course, all described embodiments can be combined in their features as desired within the claims, if technically possible.

[0077] For example, it is conceivable that the compression device 2 is formed with the pot element 42 in the working space 20 and the bellows 8 is additionally formed with the rod-shaped guide element 44 and / or the flat guide element 46.

[0078] It is also conceivable that the compression device 2 is formed with the cylinder 4, which has the first cylinder section 50 and the second cylinder section 52, and the pot element 42.

[0079] Furthermore, it is conceivable that the compressor device is formed with the cylinder 4, which has the first cylinder section 50 and the second cylinder section 52, the pot element 42 and the rod-shaped guide element 44 and / or the flat guide element 46.

[0080] List of reference symbols

[0081] 2 Compressor device

[0082] 4 cylinders

[0083] 6 pistons

[0084] 8 bellows

[0085] 10 Connection

[0086] 12 (cylinder) running surface

[0087] 14 Piston skirt

[0088] 16 Transmission room

[0089] 18 Fluid chamber

[0090] 20 workspace

[0091] 22 wall

[0092] 24 connecting rods

[0093] 26 electric motor

[0094] 28 slices

[0095] 30 first storage location

[0096] 32 second storage location

[0097] 34 Cooling device

[0098] 36 pressure line

[0099] 38 Cold Head

[0100] 40 heat exchangers

[0101] 42 Pot element / displacement element

[0102] 44 rod-shaped guide element

[0103] 46 flat guide element

[0104] 48 bore

[0105] 50 first cylinder section

[0106] 52 second cylinder section

[0107] ZM cylinder center axis

[0108] L1 first length

[0109] L2 second length

[0110] AL change in length

Claims

Claims 1. Compressor device (2), comprising a cylinder (4), a piston (6) arranged within the cylinder (4) which defines a transmission chamber (16) filled with a transmission fluid and which can be periodically moved back and forth by means of a drive device (26); a piston arranged within the transmission chamber (16) Compressor element (8), in particular a (metal) bellows, which delimits a working chamber (20) filled with a working gas, and a connection (10) via which the working chamber (20) is connected to a The working gas line (36) can be connected to a Gifford-McMahon cooler or a pulse tube cooler (38); wherein the compressor element (8) and the working gas contained therein are periodically compressed indirectly via the transmission fluid displaced by the piston (6).

2. Compressor device (2) according to claim 1, wherein the volume of a (fluid) space (18) enclosed by the piston (6), the compressor element (8) and the cylinder (4) is constant.

3. Compressor device (2) according to one of claims 1 or 2, wherein the transmission space (16) and the working space (20) are formed completely in the cylinder (4).

4. Compressor device (2) according to one of claims 1 to 3, wherein the pressure of the working medium in the working chamber (20) corresponds at any given time to the pressure of the transmission fluid in the transmission chamber (16).

5. Compressor device (2) according to claim 4, wherein the pressure of the working medium and the pressure of the transmission fluid are greater than the ambient pressure of an environment surrounding the compressor device (2).

6. Compressor device (2) according to any one of claims 1 to 5, wherein a piston maximum stroke is greater than a compressor element maximum stroke (AL).

7. Compressor device (2) according to one of claims 1 to 6, wherein the piston (6) is periodically movable back and forth by a connecting rod (24).

8. Compressor device (2) according to one of claims 1 to 7, wherein the compressor element (8) is guided in a stroke direction.

9. Compressor device (2) according to one of claims 1 to 8, wherein a closed displacement element (42) is formed in the working chamber (20).

10. Cooling device (34) comprising a compressor device (2) according to one of claims 1 to 9 and a Gifford-McMahon cooler or a pulse tube cooler (38).

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