EP2877748B1 - Compressor device, and cooling device equipped therewith and refrigeration machine equipped therewith - Google Patents

Description

The invention relates to a compressor device and a cooling device equipped therewith or a refrigeration machine equipped therewith.

For cooling of magnetic resonance tomographs, cryopumps, etc., pulse tube coolers or Gifford-McMahon coolers are used. Gas and especially helium compressors are used in combination with rotary or rotary valves, as they are used in Fig. 6 is shown. A helium compressor 100 is connected to a rotary valve 106 via a high pressure line 102 and a low pressure line 104. On the output side, the rotary valve 106 is connected via a gas line 108 to a cooling device 110 in the form of a Gifford-McMahon cooler or a pulse tube cooler. In this case, via the rotary valve 106 alternately the high and low pressure side of the gas compressor 100 is connected to the pulse tube cooler or the Gifford-McMahon cooler. The rate at which compressed helium is introduced and re-exported to the cooling device 100 is in the range of 1 Hz. A disadvantage of such cooling or compressor systems is that the motorized rotary valve 106 causes losses of up to 50% of the input power of the compressor.

There are also known acoustic compressors or high-frequency compressors in which one or more pistons are caused by a magnetic field in linear resonant vibrations. These resonant frequencies are in the range of a few 10 Hz and are therefore not suitable for use with pulse tube coolers and Gifford-McMahon coolers to produce very low temperatures in the lower than 10 K range.

From the CH 457147 B For example, a membrane compressor or pump is known, which has a working space that is divided into a gas volume and a liquid volume by an elastic, gas and liquid-tight membrane. By means of a Liquid pump, liquid is periodically pressed into the liquid volume of the working space, whereby the elastic membrane expands in the direction of gas volume and this compresses - compressor function - or pushes out of the gas volume - pump function. A disadvantage is the fact that the gas-liquid-tight and pressure-resistant sealing of the elastic membrane in the working space is comparatively expensive. Especially in the field of sealing, the membrane is heavily loaded, so that either very expensive materials must be used or a shorter life has to be accepted.

The US 5,181,383 shows a cooling device in which compressed helium gas is expanded in a pressure transmission tube with a piston and a bellows. The compression of the helium gas takes place in the compressor, which is not described in detail. However, in an intermediate step during the expansion of the compressed in the compressor helium gas in the pressure transfer tube compression of enclosed in the bellows helium residue gas with closed valves - step a), 3a , However, this compression obviously only serves to adapt the gas pressure in the pressure transfer tube to the pressure of the compressed helium gas, so that in subsequent step b), Fig. 3b the controlled expansion of the helium gas can take place. There is gas on both sides of the bellows.

From the D2, US 1,780,336 a pumping device is known in which via a drive medium (gaseous or liquid) to be pumped fluid (also gaseous or liquid) is promoted. A compressor device is not disclosed.

From the US 2006/0110259 A1 For example, a linear compressor is known in which a compressor piston driven by a linear motor compresses a gas. In one embodiment, a piston is displaced by a liquid pressed into a bellows, thereby changing the dead volume and the resonance frequency of the compressor. The bellows is not used to compress a gas.

Out US 2010/0178184 A1 in turn, no compressor device, but only a pump device is known in which the drive side of a drive gas from a bellows structure is included. The fluid to be pumped (gas or liquid) is outside the bellows. Further pumping devices are off WO2011 / 018244A1 . US4483665A . US3524714A such as DE2801671A1 known.

From the DE10344698B4 For example, a heat pump and a refrigerator with a compressor device are known. The compressor device comprises a compressor chamber in which a balloon is arranged. The balloon is periodically pressurized with liquid so that the gas surrounding the balloon is periodically compressed and relaxed again. The disadvantage here is that the balloon envelope can scrape or rub in certain operating conditions on the hard and possibly edged inner surface of the compressor chamber. As a result, due to the pressure conditions hole or cracking in the balloon envelope occur.

From the SU440534A1 is a cryogenic cooling device with a compressor device with gas-filled bellows known, which are surrounded by a periodically pumped liquid.

Starting from the SU440534A1 or the DE10344698B4 It is therefore an object of the invention to provide a compressor device, are compensated in the volume reduction of the working gas due to low temperatures. It is another object of the invention to provide a cooling device and a refrigerating machine with such a compressor device.

The solution of these objects is achieved by the features of claims 1, 11 and 14, respectively.

Due to the fact that the gas volume in the balloon and the volume of liquid on the outside, the balloon envelope is always protected by a liquid film on the hard inside (usually metal) from damage when due to irregular operating conditions rubs the balloon envelope on the hard inside of the compressor room. Since the working fluid is usually hydraulic oil (claim 8), the protective effect is additionally improved by the lubricating oil effect.

Instead of a balloon, a tubular bellows can be used as a membrane. A bellows has the advantage that due to the construction and the arrangement of the folds, the volume increase or volume reduction takes place "directed" along the longitudinal direction of the bellows. Frictional contact of the bellows with the hard inside of the compressor chamber is thus almost impossible. Thus, when using a bellows as a compressor diaphragm, the gas volume can also be provided in the interior of the bellows. This "directionality" of the volume change can be improved by positive guidance of the bellows along a rod with longitudinal bearings. The bellows usually consists of a stainless steel alloy and, with the exception of hydrogen, is extremely gastight for all relevant working gases.

The fact that the gas volume is connected to a gas reservoir, volume reductions of the working gas in a downstream consumer, z. As a cooler to be compensated due to low temperatures.

According to the advantageous embodiment of the invention according to claim 2, a working fluid reservoir is provided. This makes it possible conventional liquid pumps, eg. b. Gear pumps - claim 7 - to use. The working fluid reservoir ensures that the correct amount of working fluid in the correct pressure range is always available for the pumping device.

The compressor device according to the present invention may be formed as a non-gas-conveying compressor or as a gas-conveying compressor - claim 3 -. In the case of non-gas-generating compressor only pressure oscillations, z. B. for a so driven cryocooler - claim 11 - provided. As a gas-conveying compressor, compressed working gas is supplied via a first working gas connection, which is designed as a high pressure port, a downstream device. Working gas at a lower pressure is returned via a second working gas connection, which is designed as a low-pressure connection, in the compressor device-claim 13.

According to the preferred embodiment of the invention according to claim 4, the working gas reservoir is connected via a differential pressure regulator with the gas volume of the compressor device. This ensures that the working gas is already precompressed available. The working gas in the gas reservoir is located approximately at the level of the low pressure of the compressor device. If the pressure of the working gas in the compressor device drops below the pressure in the gas reservoir during the expansion phase, working gas flows via the differential pressure regulator from the gas reservoir into the gas volume of the compressor device.

By connecting the gas reservoir with the gas volume in the compressor chamber via a pressure relief valve according to claim 5 working gas can flow into the working gas reservoir, if the pressure of the working gas in the gas volume is too high. This safety measure prevents damage to the compressor units due to overpressure.

The pumping device preferably comprises an electric drive, claim 6, since such a can be easily controlled.

Particularly suitable is a gear pump as a pumping device - claim 7. Gear pumps are characterized by a long service life, low maintenance and low dead volume and are suitable for high pressure applications up to 300 bar.

As a working fluid preferably hydraulic oil according to DIN 51524 is used, which is additionally dehydrated or anhydrous. The hydraulic oil is in a closed system of pumping device, working fluid equalizing device and fluid volume in the compressor chamber, so that during operation no water from the environment can be absorbed by the hydraulic oil. Alternatively, water can be used as a working fluid, especially when extremely impermeable membrane materials, eg. B. bellows made of stainless steel, are applied. Water as a working fluid is also advantageous, since in the event of defects, water that has penetrated into a downstream cryocooler can be removed more easily than has penetrated into a downstream cooler Hydraulic oil. Also, water is suitable as a working medium in explosion-protected applications, since water is non-flammable and non-explosive. In addition, water is non-toxic and therefore environmentally friendly - claim 8.

For cryogenic applications, depending on the temperature range, helium or nitrogen is preferably used as the working gas.

The balloon-shaped membrane or the tubular bellows must be impermeable and resistant both for the particular working gas used and for the working fluid. Since a material can not always meet these different requirements, these membranes are preferably multi-layered of different materials - claim 10. Thus, the membrane can be adjusted both in terms of working fluid and with respect to the working gas.

The compressor device according to the invention provides compressed working gas in the frequency range necessary for the Gifford-McMahon cooler and pulse tube cooler - claims 11 to 13.

If the compressor device is designed as a conveying compressor device, it can be used as a drive for a conventional refrigerating machine.

The remaining subclaims relate to further advantageous embodiments of the invention. Further details, features and advantages of the invention will become apparent from the following description of various embodiments.

• Fig. 1 eine schematische Darstellung einer ersten beispielhaften Ausführungsform zur Erläuterung der Erfindung als fördernde Kompressorvorrichtung,
• Fig. 2 eine schematische Darstellung einer zweiten beispielhaften Ausführungsform zur Erläuterung der Erfindung als fördernde Kompressorvorrichtung,
• Fig. 3 eine schematische Darstellung einer dritten beispielhaften Ausführungsform zur Erläuterung der Erfindung als nicht-fördernde Kompressorvorrichtung,
• Fig. 4 eine schematische Darstellung einer ersten Ausführungsform der Erfindung als nicht-fördernde Kompressorvorrichtung,
• Fig. 5 eine schematische Darstellung einer zweiten Ausführungsform der Erfindung als fördernde Kompressorvorrichtung, und
• Fig. 6 eine schematische Darstellung einer Heliumkompressoreinrichtung mit Drehventil und einer Kühleinrichtung gemäß dem Stand der Technik.

It shows:

• Fig. 1 1 is a schematic representation of a first exemplary embodiment for explaining the invention as a conveying compressor device,
• Fig. 2 FIG. 2 a schematic illustration of a second exemplary embodiment for explaining the invention as a conveying compressor device, FIG.
• Fig. 3 1 is a schematic representation of a third exemplary embodiment for explaining the invention as a non-conveying compressor device,
• Fig. 4 a schematic representation of a first embodiment of the invention as a non-promotional compressor device,
• Fig. 5 a schematic representation of a second embodiment of the invention as a conveying compressor device, and
• Fig. 6 a schematic representation of a helium compressor device with rotary valve and a cooling device according to the prior art.

In the explanation of the various embodiments, the same or corresponding components are given the same reference numerals.

Fig. 1 shows a first exemplary embodiment for explaining the compressor device according to the invention, which is designed as a gas or working gas-promoting compressor device. The compressor device comprises a compressor device 2, which has a gas-tight closed compressor chamber 4. In the compressor chamber 4, a balloon or a balloon-shaped membrane 6 is arranged. The balloon 6 divides the compressor chamber 4 into a gas volume 8 for a working gas 10 and a liquid volume 12 for a working fluid 14. The gas volume 8 is the interior of the balloon 6 and the fluid volume 12 is the area of the compressor chamber 4 outside the balloon 6 Fluid volume 12 outside of the balloon 6 is connected to a first working fluid line 18 which leads out of the compressor chamber 4. The balloon 6 includes a first balloon port 19 connected to the high pressure gas outlet 20 and a second balloon port 21 connected to the low pressure gas outlet 22. The first working fluid line 18 opens into a pumping device 24, which via a second working fluid line 26th is connected to a working fluid equalization device 28 in the form of a working fluid reservoir.

By the pumping device 24 working fluid 14 is periodically pressed into the liquid volume 12 via the first working fluid line 18 and let out again. By pumping the working fluid 14 in the liquid volume 12, the working gas 10 is compressed in the balloon 6. By discharging working fluid 14 in the working fluid reservoir 28, the working gas 10 expands in the balloon 6 and thereby relaxes. By the periodic pressing of working fluid 14 into the fluid volume 12, the working gas 10 is periodically compressed in the gas volume 8 in the balloon 6 and relaxed again. The compressed working gas 10 is the high-pressure gas outlet 20 a downstream consumer, z. B. a cryocooler - not shown - supplied. Via the low-pressure gas inlet 22, the working gas 10 is returned to the gas volume 8 in the balloon 6 at a lower pressure, so that the circuit is closed.

The working fluid compensation device 28 ensures that sufficient working fluid 14 is always present and can be pumped into the fluid volume 12 in the compressor chamber 4 in order to compress the working gas 10 in the gas volume 8 in the balloon 6. In the expansion phase of the compressor device, the working gas 10 expands the balloon 6 and working fluid 14 is forced into the working fluid equalizing device 28 via the first working fluid line 18, the pumping device 24 and the second working fluid line 26.

Fig. 2 shows a second exemplary embodiment for explaining the invention, which differs from the first exemplary embodiment Fig. 1 only differs in that a gear pump 30 is used as a pumping device, which is driven by an electric motor 32. This type of pumping device has proved to be particularly advantageous, since they are characterized by a long service life, low maintenance and low dead volume. Due to their construction, they are suitable for high pressure applications up to 300 bar.

Fig. 3 shows a third exemplary embodiment for explaining the invention, which differs from the first exemplary embodiment Fig. 1 only differs in that the compressor device is designed as a non-promotional compressor device. The balloon 6 comprised a balloon opening 40 connected to a working gas port 42. This opens into the gas volume 8 in the working gas port 40. About this working gas port 40, the periodic pressure change generated in the gas volume 8 is not shown - transferred to the downstream cooler.

Fig. 4 shows a first embodiment of the invention, which differs from the third exemplary embodiment Fig. 3 distinguished by a working gas balancing device. The working gas balancing device comprises a working gas reservoir 50, which is connected via a first gas line 52, a differential pressure regulator 54 and a common gas line 55 with the gas volume 8 in the balloon 6. The working gas reservoir 50 is also connected via a second gas line 56, a pressure relief valve 58 and the common gas line 55 to the gas volume 8 in the balloon 6. The common gas line 55 opens into the balloon opening 40. The working gas connection 42 branches off from the common gas line 55 and ends in a cooling device 60.

Working gas 10 flows into the gas volume 8 in the balloon 6 via the first gas line 52, the differential pressure regulator 54 and the common gas line 55 when the pressure of the working gas 10 in the gas volume 8 drops below the pressure in the working gas reservoir 50 due to low temperatures. By the working gas reservoir 50 thus "working gas losses", which can occur in a downstream cooler, are compensated. In this case, the working gas 10 to be supplied is already pre-compressed by the differential pressure regulator 54 for further compression in the gas volume 8 in the balloon 6. Working gas 10 can flow into the working gas reservoir 50 via the second gas line 56, the pressure relief valve 58 and the common gas line 55 if the pressure of the working gas 10 in the gas volume 8 becomes too high.

Fig. 5 shows a second embodiment of the invention, which differs from the first embodiment Fig. 4 only differs in that instead of a balloon, a tubular bellows 80 is used, which surrounds the gas volume 8. The bellows 80 has the advantage over the balloon 6 that the increase in volume and the reduction in volume are in each case directed along the longitudinal extent of the tubular bellows 80. The bellows 80 is made of a stainless steel alloy and is extremely gas-tight with the exception of hydrogen for all relevant working gases. Thus, the tubular bellows 80 does not bend at maximum volume against the longitudinal extent, the bellows is usually by a arranged in the longitudinal direction of the Faltebalgs stable rod with longitudinal bearings - not shown - out. In this way, it is reliably prevented that the bellows 80 can be damaged by frictional contact with the inner surface of the compressor chamber 4.

Since the volume change is very controlled in the bellows 80, there is no risk that the bellows scrapes on the inner wall of the compressor chamber 4 and thereby could be damaged. Consequently, when using the bellows 80, the gas volume 8 and the liquid volume 12 can be reversed.

As in the second exemplary embodiment of Fig. 2 can also according to the embodiments Fig. 3 . 4 and 5 a gear pump driven by an electric motor may be used as the pumping means 24.

Hydraulic oils according to DIN 51524 are suitable as working fluids. These H, HL, HLP and HVLP oils are oils which are well tolerated with common sealants such as NBR (acrylonitrile-butadiene rubber) etc. NBR, however, is not sufficiently helium-tight. HF oils are often incompatible with commonly used sealing materials (http://de.wikipedia.org/wiki/List_of_Plastic_materials). For helium-tight balloons is synthetic rubber such. For example, chlorobutyl. When using helium as working gas 10, it is therefore advantageous if the balloon-shaped membrane 6 consists of several layers, for. B. from a working fluid 14 in the form of hydraulic oil facing layer of NBR and from a helium as working gas 10 facing layer of chlorobutyl.

Alternatively, water can be used as a working fluid, especially when extremely impermeable membrane materials, eg. B. bellows made of stainless steel, are used. Water as a working fluid is also advantageous because in the event of defects, water that has penetrated into a downstream cryocooler can be removed more easily than hydraulic oil that has entered a downstream cooler. Also, water is suitable as a working medium in explosion-protected applications, since water is non-flammable and non-explosive. In addition, water is non-toxic and therefore environmentally friendly.

In the non-promotional embodiments according to the Figures 3 . 4 and 5 No valve is provided in the working gas connection 42 leading out of the gas volume 8. However, a valve can be provided here in order to build up a higher pressure difference in the expansion phase of the compressor device 2. Ie. Although the gas volume 8 in the compressor chamber 4 already increases in the expansion phase, the valve in the working gas connection 42 is still closed. Only when a certain pressure difference has built up, this valve is opened. In this way, the backflow of the working gas 10 can be accelerated via the working gas connection 42 into the compressor device 2.

LIST OF REFERENCE NUMBERS

2

compressor means

4

compressor room

6

balloon

8th

gas volume

10

working gas

12

liquid volume

14

working fluid

18

first working fluid line

19

first balloon opening

20

Hochdruckgasauslass

21

second balloon opening

22

Low pressure gas inlet

24

pumping device

26

second working fluid line

28

Working fluid balancing device

30

gear pump

32

electric motor

40

balloon opening

42

Working gas connection

50

Working gas reservoir

52

first gas line

54

Differential pressure regulator

55

common gas line

56

second gas line

58

Pressure relief valve

60

cooling device

80

bellow

100

Helium compressor

102

High-pressure line

104

Low-pressure line

106

rotary valve

108

gas pipe

110

cooler

Claims (14)

1. A compressor device, with a compressor apparatus (2) that comprises a compressor chamber (4) with a defined volume and in which an elastic, gas-tight and liquid-tight membrane (6) divides the compressor chamber (4) into a gas volume (8) with a working gas (10) and the liquid volume (12) with a working liquid (14),
   a working gas connection (20, 22; 40) that empties into the gas volume (8), and a pump device (24) that periodically pumps the working liquid (14) into the liquid volume (12) and as a result periodically compresses the working gas (10) in the gas volume (8), wherein the membrane is constructed as a balloon (6) or as a bellows, and wherein the balloon (6) or the bellows surrounds the gas volume (8),
   characterized in that the gas volume (8) in the compressor chamber (4) is connected via a third working gas connection (52) to a working gas reservoir (50).
2. The compressor device of claim 1, characterized in that the pump device (24) is connected to a working liquid reservoir (28).
3. The compressor device of one of the preceding claims, characterized in that a second working gas connection (22) empties into the gas volume (8), and that the first working gas connection (20) is constructed as a high-pressure outlet, and the second working gas connection (22) is constructed as a low-pressure inlet.
4. The compressor device of claim 3, characterized in that the working gas reservoir (50) is connected via a differential pressure regulator (54) to the gas volume (8) in the compressor chamber (4).
5. The compressor device of claim 3 or 4, characterized in that the working gas reservoir (50) is connected via an over pressure valve (58) to the gas volume (8) in the compressor chamber (4).
6. The compressor device of one of the preceding claims, characterized in that the pump device (24) comprises an electric drive (32).
7. The compressor device of one of the preceding claims, characterized in that the pump device (24) comprises a geared pump (30).
8. The compressor device of one of the preceding claims, characterized in that the working liquid (14) is a hydraulic oil or water.
9. The compressor device of one of the preceding claims, characterized in that the working gas (10) is helium or nitrogen.
10. The compressor device of one of the preceding claims, characterized in that the balloon-shaped membrane or bellows is formed from several layers.
11. Cooling device with a compressor device of one of the preceding claims and a Gifford-McMahon cooling device or a pulsed tube cooling device, wherein the compressor apparatus (2) is coupled to the Gifford-McMahon cooling device or the pulsed tube cooling device.
12. The cooling device of claim 11, characterized in that the compressor apparatus (2) has a high-pressure connection (20), and that the Gifford-McMahon cooling device or the pulsed tube cooling device is connected to the high-pressure connection (20) of the compressor device (2).
13. The cooling device of claim 12, characterized in that the compressor apparatus (2) comprises a low-pressure connection (22) and that the Gifford-McMahon cooling device or the pulsed tube cooling device is connected to the low-pressure connection (22) of the compressor apparatus (2).
14. A compressor refrigeration machine, in particular for traditional refrigerators, comprising a compressor device of one of the preceding claims 1 to 10, an evaporator, and a condenser.

Images