Compressor device and cooling device equipped with a compressor device

Abstract

The present invention relates to a compressor device (2), which comprises a cylinder (4), a transmission space (16) located in the cylinder (4) and filled with a transmission fluid, defining a piston (6) that can be periodically reciprocated by a drive device (26), a compressor element (8) disposed in the transmission space (16) and defining an operating space / compression space (20) filled with an operating gas, in particular a (metal) bellows, and a connector (10) capable of connecting the operating space (20) and an operating gas pipeline (36) to a Gifford-McMahon cooler or a pulse tube cooler (38), wherein the compressor element (8) and the operating gas contained therein are indirectly and periodically compressed by the transmission fluid displaced by the piston (6).

Description

Technical Field

[0001] The present disclosure relates to a compressor device and a cooling device including the compressor device and a Gifford-McMahon cooler or a pulse tube cooler.

Background Art

[0002] A pulse tube cooler or a Gifford-McMahon cooler is widely used to cool a magnetic resonance imaging device, a cryopump, a quantum computer, a quantum communication system, and the like. A gas compressor, particularly a helium compressor, is used in combination with a rotary valve or a spin valve. The helium compressor is connected to the rotary valve via a high-pressure pipeline and a low-pressure pipeline. On the output side, the rotary valve is connected to a cooling device in the form of a Gifford-McMahon cooler or a pulse tube cooler via a gas pipeline. The high-pressure side or the low-pressure side of the gas compressor is alternately connected to the pulse tube cooler or the Gifford-McMahon cooler via the rotary valve. The compressed helium is supplied to the cooling device, and the speed at which it is displaced again is in the range of 1 to 2 Hz. A disadvantage of such a cooling system or compressor system is that about 50% of the input power of the compressor is lost due to the motor-driven rotary valve.

[0003] A cooling device including a pulse tube cooler or a Gifford-McMahon cooler is known from German Patent No. 10137552 C1.

[0004] German Patent No. DE633104A discloses a compressor device comprising a compressor that periodically compresses and re-expands a working medium by a piston-shaped reciprocating compressor element. The drive unit includes a pressure cylinder with a reciprocating piston. The drive unit is mechanically coupled to the compressor element. Both the drive unit and the compressor element consist of a compressor piston or separate pressure cylinders to which a compression piston is attached. The drive unit and the compressor element are mechanically connected, and the feedthrough from the pressure cylinder is sealed. This configuration means that the device requires a relatively large amount of space because the pressure cylinders are arranged in series. Also, this configuration requires the use of two pistons and two feedthroughs, and these pistons and feedthroughs are structurally complex and prone to airtightness failures. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] German Patent No. 10137552C1 [Patent Document 2] German Patent No. DE633104A [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The present invention aims to eliminate or at least mitigate the drawbacks of the prior art. Specifically, the present invention aims to provide a compressor device and a cooling system that minimize losses and installation space. [Means for solving the problem]

[0007] This objective is achieved by the compressor device described in claim 1 and the cooling device described in the independent claim.

[0008] Specifically, this objective is achieved by a compressor device, which includes a cylinder, a piston located within the cylinder and positioned to define a transmission space (Uebertragungsraum) filled with a transmission fluid (Uebertragungsfluid), and which is periodically movable back and forth by a drive device, a compressor element located within the transmission space and positioned to define an operating space (Arbeitsraum) (compression space) filled with working gas, preferably a bellows, particularly a metal bellows, and a connector capable of connecting the operating space to an operating gas pipeline (pressure pipeline) to a Gifford-McMahon cooler or pulse tube cooler (particularly a two-stage 4K (4 Kelvin) cooler), wherein the compressor element and the working gas contained therein are indirectly and periodically compressed / consolidated by the transmission fluid displaced by the piston.

[0009] In other words, the compressor device includes a cylinder with an internal cylinder track and a piston that runs inside the cylinder and has a circumferential piston skirt. The piston skirt slides in a sealed manner on the cylinder track of the cylinder. Preferably, at least one annular seal / piston ring is provided between the piston skirt and the cylinder track. The piston faces a transmission space filled with a transmission fluid and also includes a piston roof that defines the transmission space. The piston is provided and configured to perform periodic linear motion in the direction of a central cylinder fiber (cylinder central axis) extending longitudinally in the cylinder. The compressor element is provided within the transmission space and includes at least one wall, preferably an accordion-shaped wall. In other words, the compressor element is preferably provided as a bellows. The compressor element surrounds the working space filled with working gas. In other words, the compressor element separates the working space from the transmission space. A connector is provided in the working space, which securely or detachably connects the working space to a working gas pipeline. The connector is preferably located on the side of the compressor element away from the piston. The working gas pipeline is provided and configured to connect the working space to a Gifford-McMahon cooler, pulse tube cooler, or any other suitable cooler. The working space has a variable volume due to its preferred accordion-shaped walls. The linear motion of the piston exerts / transmits force to the compressor element via the transmission fluid, and the working gas contained in the working space is periodically compressed / consolidated and expanded.

[0010] Therefore, the core of the present invention is to indirectly and periodically compress and expand the working gas contained in the compressor element of the compressor device via a transmission fluid by the displacement of the piston.

[0011] Furthermore, the core of this invention is that a pressure generation area (force generation area) and a compression area are configured within the cylinder.

[0012] Another core aspect of the present invention is that the piston and compressor elements are mechanically separated.

[0013] In other words, the piston and compressor elements are arranged within the cylinder so that they never come into contact with each other. Furthermore, the force acting on the piston or the force transmitted by the piston is transmitted to the compressor elements solely by hydraulic pressure. This invention eliminates the mechanical connection between the piston and the compressor elements for power transmission.

[0014] By configuring the compressor in this way, the rotary valve can be eliminated, thereby reducing losses and significantly improving the efficiency of the compressor. Furthermore, because a single-cylinder configuration is possible, such a compressor can be made more compact. A further advantage of this type of compressor is that its reliability can be improved by reducing the number of assemblies.

[0015] The configuration of the working space within the compressor element, particularly the configuration of the compressor element as a metal bellows, can also prevent water, transmission fluid, oil, or any other foreign matter from entering / diffusing into the working gas and causing contamination / impurities to the working gas. If the working gas is contaminated with foreign matter, it can freeze and damage the seal. In particular, the configuration of the compressor element as a metal bellows has the advantage, for example, that the working gas does not leak from the compressor element or leak through the compressor element into the transmission space, compared to the configuration of the compressor element made of rubber.

[0016] In the first embodiment, the volume of the space / fluid space enclosed by the piston, compressor element and cylinder may be constant.

[0017] In other words, the area of ​​the transmission space outside the compressor element / working space may be completely filled with a transmission fluid, and the transmission fluid may be substantially incompressible.

[0018] This ensures that the force exerted by the piston on the transmission fluid is uniformly transmitted to the bellows without local force peaks. As a result, the compressor element is only intentionally compressed and expanded, thus ensuring a significant extension of the service life of the compressor element and preventing premature failure of the compressor element. Furthermore, by completely filling the transmission space with the transmission fluid, it is possible to prevent the transmission fluid from foaming or forming bubbles during operation.

[0019] Furthermore, the transmission space and the working space may be completely configured within the cylinder without protruding.

[0020] In a further aspect, the pressure of the working medium in the working space may correspond to the pressure of the transmission fluid in the transmission space at any given time.

[0021] In other words, the pressure within the compressor element always corresponds to the pressure surrounding the compressor element. Stated more precisely, the working medium in the working space and the transmission fluid in the transmission space are in pressure equilibrium.

[0022] In this way, it is ensured that the compressor element itself does not receive or absorb large loads / forces, and by constructing the compressor element with a thin wall, it is further ensured that the losses during compression of the compressor element are reduced.

[0023] In a further aspect, the pressure of the working medium and the pressure of the transmission fluid may be greater than the ambient pressure of the environment surrounding the compressor device.

[0024] In other words, the compressor device is pre-stressed (vorgespannt) such that an overpressure of the working medium and the transmission medium occurs compared to the environment at every position of the piston within the cylinder.

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

[0026] In other words, the amplitude with which the piston performs a periodic reciprocating motion in the piston movement direction may be greater than the maximum change in the expansion of the compressor element in the piston movement direction of the compressor element.

[0027] To minimize the mechanical stress on the compressor element, especially on the twist / fold of the compressor element, the maximum stroke of the compressor element may be reduced, thereby extending the service life of the compressor element and reducing the risk of failure.

[0028] In a further aspect, the piston may be periodically movable back and forth by a connecting rod. By using a connecting rod to move the piston, a conventional electric motor may be used as the drive device. Alternatively, the piston may be movable back and forth by a threaded rod or the like.

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

[0030] In other words, the compressor device may include at least one guiding element, which is provided and configured to guide the compressor element during compression and expansion and to prevent the compressor element from buckling or collapsing uncontrollably. The guiding element may be configured, for example, in the form of a rod or a sleeve. Preferably, two or more guiding elements may be configured within the compressor device.

[0031] In a further aspect, a closed displacer (dome element) may be configured within the working space.

[0032] In other words, the displacer element may be configured on the inner side facing the working space of the compressor element, preferably on the end face close to the piston of the compressor element. The displacer element may be an airtight, especially cylindrical, closed element and may be configured to be firmly connected to the compressor element.

[0033] Such displacer elements within the working space can reduce the (gas) volume of the working space. This results in the working space having a near-zero (dead / residual) volume when compressed, reducing the displacement and load on the compressor elements.

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

[0035] In a further embodiment, the transmission space and / or working space may optionally be connected via a valve to at least one compensation tank to pre-pressurize the compressor unit and to compensate for any volume changes, particularly during startup or commissioning of the compressor unit.

[0036] In a further embodiment, the compression of the compressor element is reversible. That is, the compressor element changes shape only within a predetermined range during operation and then returns to its original shape.

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

[0038] In a further embodiment, the compressor element may be composed of a plurality of membrane pairs. Preferably, the compressor element may be composed of at least 30 membrane pairs. Particularly preferably, the compressor element may be composed of at least 40 membrane pairs.

[0039] By configuring the compressor element with many membrane pairs, each membrane pair will be slightly deflected during the stroke movement of the compressor element, thereby ensuring a significant reduction in the mechanical load on the compressor element.

[0040] In a further embodiment, the transmission space may be configured in a multi-stage shape, particularly a two-stage shape. In other words, the diameter of the transmission space may change abruptly, and the first diameter in the piston region may preferably be smaller than the second diameter in the compressor element region. Thus, the force exerted by the piston to displace the transmission fluid may be matched to the driving force or driving torque of the drive unit.

[0041] In a further embodiment, the drive unit may consist of a control device and / or be connected to a control device which controls the compression / consolidation and expansion of the working medium in the working space via the periodic longitudinal (forward and backward) movement of the piston, in particular via the rotational speed of the drive unit.

[0042] In a further embodiment, the amount of displacement displaced by the piston during its movement may correspond to a change in the volume of the working space, thereby greatly simplifying the control of the compressor device.

[0043] In a further embodiment, a filter may be connected downstream of the compressor device.

[0044] In a further embodiment, the working medium may be helium.

[0045] It is advantageous if the piston's travel profile follows a step function rather than a linear or sinusoidal profile, where the working gas is rapidly compressed, the pressure is maintained, and then the working gas rapidly re-expands. This travel profile may be achieved by a corresponding variable drive of the drive unit.

[0046] Alternatively, the drive mechanism may be driven uniformly, and the step function movement of the piston may be realized via a corresponding transmission element, such as a cam. In other words, the linear motion of the drive mechanism may be converted into approximately step function motion of the piston by a cam-shaped transmission element. In other words, the transmission element may be asymmetric with respect to its axis of rotation.

[0047] In a further embodiment, one drive unit may drive two or more compressor units. Preferably, in such a configuration, the cylinders may be arranged in a boxer structure. In other words, for example, the two cylinders may be configured opposite each other in the drive unit, and the cylinders may have the same structure. Each cylinder may consist of a piston and a compressor element.

[0048] In a further embodiment, the transmission fluid may also be used as a lubricant for the drive unit. In other words, on the side away from the piston's transmission space, the transmission fluid may be configured as a lubricant. In particular, the transmission fluid may lubricate the motor-to-connecting rod pair and the connecting rod-to-piston pair. By configuring the transmission fluid as a lubricant, it is possible to prevent any leakage of the transmission fluid from the piston toward the drive unit from adversely affecting the drive unit.

[0049] In a further embodiment, the compressor device may be configured to operate in a frequency range of 0.1 to 10 Hz, particularly in a frequency range of 0.5 to 5 Hz.

[0050] The above objectives are further addressed by a cooling system comprising the compressor device described in one of the above embodiments and a Gifford-McMahon cooler or a pulse tube cooler.

[0051] In other words, the cooling system includes a compressor system as described in one of the above embodiments and a Gifford-McMahon cooler or pulse tube cooler connected via a connector. Optionally, a heat exchanger for cooling the working gas may be configured between the cooling system and the Gifford-McMahon cooler or pulse tube cooler, and the cooling system may be configured directly with the Gifford-McMahon cooler or pulse tube cooler.

[0052] In this way, the rotary valve can be omitted, and the pressure curve can be directly generated in the compressor unit. The Gifford-McMahon condenser or pulse tube condenser may be directly connected to the compressor unit. Extremely clean helium gas (6N = 99.9999% helium) is required to operate the Gifford-McMahon condenser or pulse tube condenser.

[0053] In one embodiment, the compressor and the Gifford-McMahon cooler or pulse tube cooler may be connected via a high-pressure connection.

[0054] In a further embodiment, the cooling device or compressor device may be pre-pressurized to 16 bar. The operating range of the compressor device may be 8 bar to 24 bar.

[0055] Furthermore, the compressor refrigerator may consist of the compressor device described in one of the above embodiments, an evaporator, and a condenser. [Brief explanation of the drawing]

[0056] [Figure 1] This is a schematic diagram of a compressor device according to the present invention in a general embodiment. [Figure 2] This is a schematic diagram of a compressor device according to the present invention in a specific embodiment. [Figure 3] This is a schematic diagram of the structure of the cooling device according to the present invention in the first embodiment. [Figure 4] This is a schematic diagram of the structure of the cooling device according to the present invention in the second embodiment. [Figure 5] This is a schematic diagram of a compressor device according to the present invention in a first alternative embodiment. [Figure 6] This is a schematic diagram of a compressor device according to the present invention in a second alternative embodiment. [Figure 7] This is a schematic diagram of the compressor device according to the present invention in a third alternative embodiment. [Figure 8] This is a schematic diagram of the compressor device according to the present invention in a fourth alternative embodiment. [Modes for carrying out the invention]

[0057] The following describes an embodiment of the configuration of this disclosure based on the relevant drawings.

[0058] Figure 1 shows a compressor device 2 according to the present invention, which includes an airtight cylinder 4, a piston 6 disposed within the cylinder 4, a compressor element in the form of a (metal) bellows 8, and a connector 10, wherein the compressor device 2 is configured to be coupled to or form part of a cooling device. The cylinder 4 includes a (cylinder) running surface 12 configured inside the cylinder 4. The piston 6 includes a piston skirt 14 configured on the outer circumferential surface of the piston 6, and the running surface 12 of the cylinder 4 and the piston skirt 14 of the piston 6 are adapted so that the piston 6 can move linearly and sealedly within the cylinder 4 along the cylinder central axis ZM. The piston 6 and cylinder 4 define a transmission space 16. The transmission space 16 is filled with a transmission fluid. The bellows 8 is disposed within the transmission space 16 and surrounded by the (incompressible) transmission fluid. Specifically, the transmission fluid is contained within a fluid space 18 sealed / surrounded between the cylinder 4, the piston 6, and the bellows 8. The volume of the fluid space 18 is substantially constant, but the shape of the fluid space 18 can change.

[0059] The bellows 8 encompasses / limits the working space 20. The working space 20 is filled with a working gas, preferably helium. In the embodiment shown in Figure 1, the bellows 8 is configured as a bellows with accordion-shaped walls 22. The bellows 8 hermetically and liquidally separates the transmission space 16 and the working space 20 from each other. The connector 10 is located on the side of the working space 20 away from the piston 6. The connector 10 is provided and configured to connect the compressor unit 2 to a cold head / cooler 38 (see Figure 3), such as a Gifford-McMahon cooler or a pulse tube cooler.

[0060] Figure 2 shows a compressor device 2 in one embodiment in which the piston 6 can move linearly along the cylinder central axis ZM by a connecting rod 24.

[0061] The functional principle of the compressor device 2 according to the present invention will be explained below with reference to Figure 2. The driving of the piston by the connecting rod 24 is illustrative. Naturally, other types of driving of the piston 6 that are suitable for periodically moving the piston 6 back and forth along the cylinder central axis ZM are considered equivalent.

[0062] A drive unit in the form of an electric motor 26, driven by a corresponding control device (not shown), rotates a disk 28, which is eccentrically mounted on a connecting rod 24 at a first bearing point 30. The connecting rod 24 is also attached to / fixed to a piston 6 at a second bearing point 32. The connecting rod 24 converts the rotational / circular motion of the disk 28 into linear motion of the piston 6 along the cylinder axis ZM. In other words, the force generated by the electric motor 26 is transmitted to the piston 6 via the disk 28 and the connecting rod 24.

[0063] When the piston 6 moves toward the bellows 8 along the cylinder central axis ZM, the force is transmitted to the transmission fluid in the fluid space 18. The transmission fluid surrounding the bellows 8 transmits the force to the bellows 8, compressing the working gas contained within it. Since the transmission fluid is a nearly incompressible fluid, the force applied by the electric motor 26 (excluding friction losses) is substantially converted into compression of the working gas contained within the bellows 8 and the working space 20. In other words, the working gas in the working space 20 is periodically compressed by the force of the electric motor 26. The operating region of the bellows 8 is between a first length L1 in the compressed state and a second length L2 in the relaxed state. The (maximum) change ΔL of the length of the bellows 8 corresponding to the difference between the first length L1 and the second length L2 is much smaller than the first length L1 or the second length L2.

[0064] Figure 3 shows a cooling device 34 according to the present invention, equipped with a compressor device 2 in the first embodiment. The working space 20 of the compressor device 2 is connected to a pressure pipeline 36 via a connector 10. The pressure pipeline 36 hermetically connects the compressor device 2 to a cold head 38 configured as a Gifford-McMahon cooler or a pulse tube cooler. To operate such a cold head 38, the compressor device 2 periodically compresses and expands a specific working gas volume within a predetermined frequency range.

[0065] Figure 4 shows a cooling device 34 according to the present invention, equipped with a compressor device 2 in a second embodiment. The cooling device 34 of the second embodiment substantially corresponds to the cooling device 34 of the first embodiment. In the second embodiment, the heat exchanger 40 is configured between the connector 10 of the compressor device 2 and the cold head 38, and is provided to cool the working gas in particular after compression.

[0066] The following describes alternative embodiments of the compressor device 2 with reference to Figures 5 to 8. Elements corresponding to the general embodiment described in Figure 1 will not be described again.

[0067] A first alternative embodiment of the compressor device 2 shown in Figure 5 includes a dome element 42 within the bellows 8. The dome element 42 is located on the end face of the bellows 8 facing the piston 6 within the working space 20. The dome element 42 reduces the gas volume / internal volume of the working space 20. The dome element 42 is airtightly sealed to the working space 20.

[0068] Figure 6 shows a second alternative embodiment of the compressor device 2 equipped with axial or rod-shaped guide elements 44. The rod-shaped guide elements 44 are configured in the transmission space 16 on the end face of the bellows 8 facing the piston 6. The rod-shaped guide elements 44 extend from the bellows 8 toward the piston 6 and are attached to the piston 6. The rod-shaped guide elements 44 are linearly guided or attached to the piston 6. Preferably, the rod-shaped guide elements 44 are guided or attached to a bushing in the piston 6. Optionally, two or more rod-shaped guide elements 44 are configured on the bellows 8. The rod-shaped guide elements 44 prevent the bellows 8 from tilting relative to the piston 6.

[0069] Figure 7 shows a third alternative embodiment of the compressor device 2 equipped with a flat guide element 46. The flat guide element 46 is configured within the transmission space 16 on the end face of the bellows 8 facing the piston 6. The flat guide element 46 extends radially outward toward the travel surface 12 and guides the bellows 8 toward the travel surface 12. The borehole 48 is configured within the flat guide element 46 to ensure that the transmission fluid flows through the transmission space without obstruction. The flat guide element 46 prevents the bellows 8 from tilting relative to the cylinder 4.

[0070] Figure 8 shows a fourth alternative embodiment of the compressor device 2 in which the cylinder 4 is configured in two stages. The cylinder 4 includes a first cylinder section 50 in which a bellows 8 is configured and a second cylinder section 52 in which a piston 6 is configured. The first diameter of the first cylinder section 50 is larger than the second diameter of the second cylinder section 52. In other words, the pressure ratio is achieved within the cylinder 4 by the first cylinder section 50 and the second cylinder section 52.

[0071] Naturally, if technically possible, the features of all the embodiments described may be combined as necessary within the scope of the claims.

[0072] For example, the compressor 2 may have a dome element 42 configured in the working space 20, and the bellows 8 may further have a rod-shaped guide element 44 and / or a flat guide element 46.

[0073] Furthermore, the compression device 2 is thought to be composed of a cylinder 4 having a first cylinder section 50 and a second cylinder section 52, and a dome element 42.

[0074] Furthermore, the compressor device may be configured to include a cylinder 4 having a first cylinder section 50 and a second cylinder section 52, a dome element 42, and a rod-shaped guide element 44 and / or a flat guide element 46. [Explanation of Symbols]

[0075] 2. Compressor device 4 cylinders 6 pistons 8 Bellows 10 connectors 12 (Cylinder) Running surface 14 Piston skirt 16 Communication space 18 Fluid Space 20 working space 22 Wall 24 connecting rods 26 Electric motor 28 discs 30 First bearing point 32 Second bearing point 34 Cooling device 36 Pressure pipeline 38 Coldhead 40 Heat exchanger 42 Dome element / displacer element 44 Rod-shaped guide elements 46 Flat guidance elements 48 boreholes 50 First Cylinder Section 52 Second Cylinder Section ZM Cylinder Center Axis L1 First length L2 Second length Change in length ΔL

Claims

1. Cylinder and A piston is positioned within the cylinder, defining a transmission space filled with a transmission fluid, and is capable of periodically moving back and forth by a drive device. A compressor element is placed within the transmission space and surrounds the working space filled with working gas, A connector capable of connecting the aforementioned working space to the working gas pipeline to the Gifford-McMahon cooler or pulse tube cooler. The compressor element and the working gas contained therein are indirectly and periodically compressed by the transmission fluid displaced by the piston. A compressor device comprising a rod-shaped guide element configured on the end face of the compressor element facing the piston within the transmission space, the rod-shaped guide element extending from the compressor element toward the piston and being linearly guided or attached to the piston.

2. The compressor device according to claim 1, wherein the volume of the space enclosed by the piston, the compressor element, and the cylinder is constant.

3. The compressor device according to claim 1, wherein the transmission space and the operating space are entirely located within the cylinder.

4. The compressor device according to claim 1, wherein the pressure of the working gas in the working space corresponds to the pressure of the transmission fluid in the transmission space at any given time.

5. The compressor device according to claim 4, wherein the pressure of the working gas and the pressure of the transmission fluid are greater than the ambient pressure of the environment surrounding the compressor device.

6. The compressor device according to claim 1, wherein the maximum piston stroke is greater than the maximum compressor element stroke.

7. The compressor device according to claim 1, wherein the piston is periodically movable back and forth by a connecting rod.

8. The compressor device according to claim 1, wherein a closed displacer element is configured within the operating space.

9. The compressor device according to claim 1, wherein the compressor element is pre-pressurized to 16 bar, and the operating range of the compressor device is 8 bar to 24 bar.

10. The compressor device according to claim 1, wherein the thickness of the wall of the compressor element is less than 0.2 mm, and the compressor element is composed of at least 30 membrane pairs.

11. The compressor device according to claim 1, wherein the transmission space and / or the operating space is optionally connected to at least one compensation tank via a valve.

12. The compressor device according to claim 1, wherein the compressor device has an operating frequency range of 0.1 Hz to 10 Hz.

13. The compressor device according to claim 1, wherein the compressor element is a metal bellows.

14. A cooling device comprising the compressor device described in claim 1 and a Gifford-McMahon cooler or a pulse tube cooler.

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