DE102022115715A1 - Compressor device and cooling device with compressor device - Google Patents

Abstract

The present invention relates to a compressor device (2), with a cylinder (4), a piston (6) arranged within the cylinder (4), which delimits a transfer space (16) filled with a transfer fluid and periodically by means of a drive device (26). and is movable, a compressor element (8) arranged within the transfer space (16), in particular a (metal) bellows, which delimits a working space/compression space (20) filled with a working gas, and a connection (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), the compressor element (8) and the working gas contained therein being periodically compressed indirectly via the transfer fluid displaced by the piston (6).

Description

Technical area

The present disclosure relates to a compressor device and a cooling device with the compressor device and a Gifford-McMahon cooler or a pulse tube cooler.

Pulse tube coolers or Gifford-McMahon coolers are widely used to cool magnetic resonance tomographs, cryo pumps, quantum computers, quantum communication systems and the like. Gas and especially 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 high and 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 rate at which the compressed helium is introduced into the cooling device and released again is in the range of 1-2 Hz. The disadvantage of such cooling or compressor systems is that the motor-driven rotary valve causes losses of approximately 50% of the compressor's input power caused.

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

The DE 633 104 A discloses a compressor device with a compressor device 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 includes a pressure cylinder with a piston that moves back and forth. 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 or compressor piston is mounted. The drive device and compressor element are mechanically connected, with the feedthroughs from the pressure cylinders being sealed. This structure requires a relatively large amount of space for the apparatus because the printing 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 failure in terms of leaks.

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

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

Specifically, the object is achieved by a compressor device with a cylinder, a piston arranged within the cylinder, which delimits a transfer space filled with a transfer fluid and can be periodically moved back and forth by means of a drive device, a compressor element arranged within the transfer space, preferably bellows, in particular metal bellows , which delimits a working space (compression space) filled with a working gas, and a connection via which the working space 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 is, wherein the compressor element and the working gas contained therein are periodically compressed/compressed indirectly via the transfer fluid displaced by the piston.

In other words, the compressor device includes the cylinder with a cylinder bore formed on the inside 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 on 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 and delimits the transfer space filled with the transfer fluid. The piston is provided and designed to carry out 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 is formed in the transmission space and contains at least one, preferably accordion-shaped, wall. In other words, the compressor element is preferably designed as a bellows. The compressor element surrounds the working space filled with the working gas. In other words, the compressor element separates the working space from the transmission space. The working space is designed with the connection, which connects the working space to the working gas line in a fixed or detachable manner. The connection is preferably formed on a side of the compressor element facing away from the piston. The working gas line is intended and designed for the working room with the Gifford-McMahon cooler or the pulse tube cooler or any other suitable cooler. The volume of the work space is variable due to the preferably accordion-shaped wall. Due to the linear movement of the piston, a force is exerted/transmitted to the compressor element by means of the transmission fluid and the working gas contained in the working space is periodically compressed/compressed and expanded.

The core 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.

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

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 power transmission is dispensed with in the present invention.

By designing the compressor device in this way, a rotary valve can be dispensed with, thereby reducing losses and thus significantly increasing the efficiency of the compressor device. In addition, such a compressor device can be designed to be more compact, since a single-cylinder structure of the 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 assemblies.

By designing the working space in the compressor element, in particular by designing the compressor element as a metal bellows, it can further be prevented that water, transmission fluid, oil or another foreign substance penetrates/diffuses into the working gas and contaminates/contaminates it. Contamination of the working gas with the foreign substance could cause the working gas to freeze and damage seals. In particular, the design of the compressor element as a metal bellows has the advantage over, for example, a design of the compressor element made of rubber that the working gas cannot escape from the compressor element or through the compressor element into the transmission space.

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

In other words, a region of the transfer space outside the compressor element/the working space can be completely filled with the transfer fluid, wherein the transfer fluid can be a substantially incompressible fluid.

In this way it can be ensured that the force exerted by the piston on the transmission fluid can be transmitted to the bellows uniformly and without local force peaks. This ensures that the compressor element is only compressed and expanded in the intended manner, which significantly extends the service life of the compressor element and counteracts premature failures of the compressor element. Furthermore, by completely filling the transfer space with the transfer fluid, it can be prevented that the transfer fluid foams during operation or that foam formation occurs.

Furthermore, the transmission space and the working space can be formed completely and without any protrusion in the cylinder.

In a further aspect, a pressure of the working medium in the working space at any time may correspond to a pressure of the transfer fluid in the transfer space.

In other words, the pressure in the compressor element at any time corresponds to the pressure surrounding the compressor element. In yet other words, the working medium in the working space and the transfer fluid in the transfer space are in a pressure equilibrium.

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

In another aspect, the pressure of the working medium and the pressure of the transfer fluid may be greater than an ambient pressure an environment surrounding the compressor device.

In other words, the compressor device is preloaded so that in every position of the piston in the cylinder there is an excess pressure of the working medium and the transmission medium relative to the environment.

In a further aspect, a piston maximum stroke may be greater than a compressor element maximum stroke.

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.

A lower compressor element maximum stroke can ensure that mechanical stress on the compressor element, especially in bends/folds of the compressor element, is kept low, which extends the service life of the compressor element and reduces the risk of failure.

In a further aspect, the piston can be periodically movable back and forth by a connecting rod. By using the connecting rod to move the piston, a conventional electric motor can be used as the driving means. Alternatively, the piston can be movable back and forth by a threaded rod or the like.

In a further aspect, the compressor element can be guided in a lifting direction.

In other words, the compressor device can include at least one guide element, which is 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, for example, be rod-shaped or sleeve-shaped.

More than one guide element can preferably be formed in the compressor device.

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

In other words, the displacer element can be formed on an inside of the compressor element facing the working space, preferably on an end face of the compressor element close to the piston. The displacement element can be a gas-tight, in particular cylindrical, element which can be designed to be firmly connected to the compressor element.

The (gas) volume of the working space can be reduced by such a displacement element in the working space. This can ensure that the working space in the compressed state has a (dead/residual) volume of approximately zero, which reduces the deflection of the compressor element and thus the load on the compressor element.

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.

In a further aspect, the transfer space and/or the working space can be connected to at least one expansion tank, optionally via a valve, in order to bias the compressor device and to compensate for any changes in volume, in particular when starting up or starting up the compressor device.

In a further aspect, the compression of the compressor element is reversible. This means that the compressor element changes its geometry during operation only within a predefined framework and then regains an initial geometry.

In a further aspect, a wall thickness of the compressor element can be constant. The wall thickness of the compressor element can preferably be less than 0.2 mm.

In a further aspect, the compressor element can be formed from a plurality of membrane pairs. The compressor element can preferably be formed from at least 30 pairs of membranes. Particularly preferably, the compressor element can be formed from at least 40 pairs of membranes.

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.

In a further aspect, the transmission space can be designed with a multi-stage geometry, in particular a two-stage geometry. In other words, the transmission space can have a jump in diameter, 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 transmission fluid can be adapted to the driving force or the driving torque of the drive device.

In a further aspect, the drive device can be designed with a control device and/or connected to the control device, which controls the compression/compression and relaxation of the working medium in the working space via the periodic longitudinal movement of the piston, in particular via a 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 volume of the working space, whereby control of the compressor device is considerably simplified.

In a further aspect, a filter can be connected downstream of the compressor device.

In a further aspect, the working medium can be helium.

It is advantageous if the movement profile of the piston is not a linear or sinusoidal profile, but follows a step function in which the working gas is compressed quickly, the pressure is maintained and then the working gas is quickly expanded again. This movement profile can be achieved by a corresponding variable control of the drive device.

Alternatively, the drive device can be controlled uniformly and the jump function-shaped 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 an almost jump function-shaped movement of the piston by a cam-shaped transmission element. In yet other words, the transmission element can be asymmetrical to an axis of rotation of the transmission element.

In a further aspect, the one drive device can drive more than one compressor device. With such a design, the cylinders can preferably be arranged in a boxer formation. In other words, for example, two cylinders can be designed diametrically opposite the drive device, whereby the cylinders can be constructed identically. Each of the cylinders may be formed with a piston and a compressor element.

In a further aspect, the transmission fluid may (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 space. In particular, the transmission fluid can lubricate an engine-connecting rod pairing and a connecting rod-piston pairing. By designing the transfer fluid as a lubricant, possible leaks of the transfer fluid via the piston in the direction of the drive device can be prevented from having a negative effect on the drive device.

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

Furthermore, the object is solved 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.

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.

In this way it is possible to do without a rotary valve and to produce a pressure curve directly with the compressor device. The Gifford-McMahon cooler or pulse tube cooler may be directly connected to the compressor device. Extremely clean helium gas (6N = 99.9999% helium) is required to operate the Gifford-McMahon cooler or the pulse tube cooler.

In one aspect, the compressor device and the Gifford-McMahon cooler or the pulse tube cooler may be connected via a high pressure port.

In a further aspect, the cooling device or the compressor device can operate at 16 bar be biased. A working range of the compressor device can be between 8 bar and 24 bar.

Furthermore, a compressor refrigerator may be formed with a compressor device according to one of the above aspects, an evaporator and a condenser.

Short description of the characters

• 1 is a schematic representation of a compressor device according to the invention in a general embodiment;
• 2 is a schematic representation of the compressor device according to the invention in a specific embodiment;
• 3 is a schematic representation of a structure of a cooling device according to the invention in a first embodiment;
• 4 is a schematic representation of a structure of the cooling device according to the invention in a second embodiment;
• 5 is a schematic representation of a compressor device according to the invention in a first alternative embodiment;
• 6 is a schematic representation of a compressor device according to the invention in a second alternative embodiment;
• 7 is a schematic representation of a compressor device according to the invention in a third alternative embodiment; and
• 8th is a schematic representation of a compressor device according to the invention in a fourth alternative embodiment;

Description of the exemplary embodiments

Embodiments of the present disclosure are described below based on the associated figures.

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, the compressor device 2 being 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 inside of the cylinder 4. The piston 6 includes a piston skirt 14 formed on an outer peripheral surface of the piston 6, the running surface 12 of the cylinder 4 and the piston skirt 14 of the piston 6 being on top of each other in this way are coordinated so that the piston 6 is sealingly movable in the cylinder 4 linearly along a cylinder central axis ZM. The piston 6 and the cylinder 4 delimit a transfer space 16. The transfer space 16 is filled with a transfer fluid. The bellows 8 is arranged in the transmission space 16 and surrounded by the (incompressible) transmission fluid. Specifically, the transfer fluid is formed in a fluid space 18 enclosed/enclosed between the cylinder 4, the piston 6 and the bellows 8. A volume of the fluid space 18 is essentially unchangeable, although a geometry of the fluid space 18 can change.

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

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.

The following is based on: 2 a mode of operation of the compressor device 2 according to the invention is described. 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 central axis ZM, are to be considered equivalent.

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 mounted eccentrically at a first bearing point 30. The connecting rod 24 is still mounted/fixed on the piston 6 at a second bearing point 32. Via the connecting rod 24, a rotary/circular movement of the disk 28 becomes a linear movement of the piston 6 along the cylinder central 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.

When the piston 6 moves along the cylinder center axis ZM in a direction towards the bellows 8, the force on the transmission fluid in the Transfer fluid space 18. The transmission fluid surrounding the bellows 8 transmits the force to the bellows 8 and compresses the working gas contained in the bellows 8. Since the transfer 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 space 20. In other words, the working gas in the working space 20 is periodically compressed by the force of the electric motor 26. 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 ΔL 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.

3 shows a cooling device 34 according to the invention with the compressor device 2 in a first embodiment. The working space 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 with a cold head 38 designed as a Gifford-McMahon cooler or pulse tube cooler. To operate such a lime head 38, a specific working gas volume is periodically compressed and expanded by the compressor device 2 in a predetermined frequency range.

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, which is provided and designed to cool down the working gas, in particular after compression.

The following is based on the 5 until 8th alternative embodiments of the compressor device 2 explained. For a renewed description of elements that are in 1 correspond to the general embodiment described, is omitted below.

In the 5 The first alternative embodiment of the compressor device 2 shown contains 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 space 20. The pot element 42 reduces a gas volume/internal volume of the working space 20. The pot element 42 is sealed gas-tight from the working space 20.

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 transmission space 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 guided or mounted linearly 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.

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 transmission space 16. The flat guide element 46 extends radially outwards towards 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 transmission fluid in the transmission space. The flat guide element 46 prevents the bellows 8 from tilting relative to the cylinder 4.

8th 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 transmission in the cylinder 4 is implemented by the first cylinder section 50 and the second cylinder section 52.

Of course, the features of all described embodiments can, if technically possible, be combined as desired within the claims.

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.

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

Furthermore, it is conceivable that the compressor device is designed 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.

Reference symbol list

2

Compressor device

4

cylinder

6

Pistons

8th

bellows

10

Connection

12

(Cylinder) running surface

14

Piston shirt

16

transmission room

18

Fluid space

20

working space

22

wall

24

connecting rod

26

Electric motor

28

disc

30

first storage location

32

second storage location

34

Cooling device

36

pressure line

38

Cold head

40

Heat exchanger

42

Pot element/displacer element

44

rod-shaped guide element

46

flat guide element

48

drilling

50

first cylinder section

52

second cylinder section

ZM

Cylinder center axis

L1

first length

L2

second length

ΔL

Change in length

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10137552 C1 [0003]
• DE 633104 A [0004]

Claims (10)

Compressor device (2), with a cylinder (4), a piston (6) arranged within the cylinder (4), which delimits a transfer space (16) filled with a transfer fluid and can be periodically moved back and forth by means of a drive device (26); a compressor element (8), in particular a (metal) bellows, arranged within the transmission space (16), which delimits a working space (20) filled with a working gas, and a connection (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 via the transfer fluid displaced by the piston (6). Compressor device (2). Claim 1 , wherein a volume of a (fluid) space (18) enclosed by the piston (6), the compressor element (8) and the cylinder (4) is constant. Compressor device (2) according to one of the Claims 1 or 2 , wherein the transmission space (16) and the working space (20) are formed completely in the cylinder (4). Compressor device (2) according to one of the Claims 1 until 3 , wherein a pressure of the working medium in the working space (20) corresponds to a pressure of the transfer fluid in the transfer space (16) at any time. Compressor device (2). Claim 4 , wherein the pressure of the working medium and the pressure of the transfer fluid are greater than an ambient pressure of an environment surrounding the compressor device (2). Compressor device (2) according to one of the Claims 1 until 5 , where a piston maximum stroke is greater than a compressor element maximum stroke (ΔL). Compressor device (2) according to one of the Claims 1 until 6 , whereby the piston (6) can be periodically moved back and forth by a connecting rod (24). Compressor device (2) according to one of the Claims 1 until 7 , wherein the compressor element (8) is guided in a lifting direction. Compressor device (2) according to one of the Claims 1 until 8th , wherein a closed displacement element (42) is formed in the working space (20). Cooling device (34) with a compressor device (2) according to one of Claims 1 until 9 and a Gifford-McMahon cooler or a pulse tube cooler (38).

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