Technical Field

[01] The present invention relates to a compressor device, for compressing or pressurizing a fluid, typically a gaseous fluid such as air or another gas, such as carbon dioxide, nitrogen, argon, helium or hydrogen. It is however not excluded from the invention that the compressor device is used for compressing or pressurizing a denser fluid, such as water vapor or the like.

[02] Furthermore, compressor devices of the invention comprise a fluid duct for guiding the fluid through the compressor device from a fluid duct inlet to a fluid duct outlet .

[03] The compressor device is typically a positive displacement type of compressor device, for example a tooth compressor, a twin lobes compressor or a rotary compressor such as a rotary screw compressor and so on. However, it is not excluded from the invention that the compressor device is still another kind of compressor device.

[04] The invention furthermore relates to compressor devices of a type which are designed to operate in certain nominal operational conditions. Typically, the nominal flow rate of a compressor device in accordance with the invention is in the range between 40 and 140 1/s. Additionally or as an alternative, a compressor device in accordance with the invention has a rotor or rotating element (for example a male or female screw rotor) which operates at a nominal rotor speed which is in the range between 3000 and 9000 rpm. Nevertheless, it is not excluded from the invention to design other types of compressor devices with nominal operational ranges which do not fall within to the afore-mentioned ranges. It is also not excluded from the invention that a compressor device which is designed for a certain nominal operational flow rate or nominal operational speed, operates at other flow rates or other operational speeds .

[05] The invention also relates to a compressor assembly which comprises one or more compressor stages and wherein at least one of the compressor stages is formed by a compressor device in accordance with the invention.

[06] Compressor devices in accordance with the invention are typically connected in series for forming a compressor assembly in accordance with the invention, but other configurations are not excluded from the invention.

[07] Typically, uncompressed ambient air is taken in at a fluid duct inlet of such a compressor assembly of the invention, which is transformed through the different compression stages in the compressor assembly into compressed air which is supplied at a fluid duct outlet of the compressor assembly for use by a user of compressed or pressurized air (or pressurized fluid in a more general case) .

[08] More specifically, the invention relates to such a kind of compressor assemblies which comprise means for cooling, which are preferably at least partly air-cooling means. To that end, a compressor assembly to which the invention is related comprises for example a device for forcing an airflow in an air channel through the housing from an air channel inlet to an air channel outlet.

[09] Furthermore, a compressor assembly in accordance with the invention typically comprises one or more heat-exchangers positioned in the air channel for transferring heat from the heat-exchanger to air forced through the air channel by means of the device for forcing an airflow. These heat-exchangers are typically intended for cooling the pressurized fluid and for transferring heat which is accumulated in the compressed or pressurized fluid during compression to the ambient air flowing through the concerned heat-exchanger ( s ) .

[10] Hot compressed or pressurized fluid is not suitable for being supplied to a consumer of compressed or pressurized fluid, not only because of its high temperature, but for example also because too much humidity would be accumulated in it as well .

[11] Often, a heat-exchanger is provided after each compression stage in the compression assembly for cooling the fluid before presenting it to the next compression stage or to a consumer of compressed or pressurized fluid.

[12] Recently a lot of effort is put in reducing the consumption of fossil fuels and in transforming to more environment friendly energy sources. The current high prices of fossil fuels are a great stimulant for a change in the behavior. Another aspect of this transformation is that there is a tendency towards reduction of energy consumption. [13] Al so, in the context of industrial production and manufacturing there is a strong need for reducing the cost related to energy consumption. In the context of this invention, which is the domain of compressor technology, energy consumption is a big issue, and a lot of effort is put in increasing the energy efficiency of the concerned compressor devices and compressor assemblies.

[14] Furthermore, it is a known phenomenon that in rotary types of compressor devices vibrations and pressure pulsations in the compressed fluid occur which depend on the rotational speed of the compressor rotors. These vibrations and pressure pulsations produce noise and can cause damage to the compressor devices and compressor assemblies itself as well as to elements surrounding these compressor devices and compressor assemblies .

[15] Another problem often encountered which is related to these vibrations and pressure pulsations, is that the compressed or pressurized fluid is not evacuated in an optimal way or that uncompressed fluid is not supplied in an efficient way to the compression chamber of the concerned compressor device .

Summary of the invention

[16] It is an aim of the invention to overcome one or more of the afore-mentioned problems and/or possibly still other problems .

[17] In particular, the main goal of the invention is to increase the overall energy efficiency of compressor devices and compressor assemblies. [18] To this end, the present invention first of all relates to a compressor device comprising a compressor element for compressing a fluid, comprising a fluid duct for guiding the fluid through the compressor element from a fluid duct inlet to a fluid duct outlet, wherein an adapter of acoustic impedance is provided at the fluid duct outlet comprising an adapter inlet duct and an adapter outlet duct which are interconnected by means of an adapter intermediate duct part which encloses at least one expansion chamber, wherein an internal cross-sectional area of the adapter inlet duct forms a minimum opening with a certain minimum equivalent internal diameter and wherein an internal cross-sectional area of the adapter intermediate duct part forms a maximum opening with a certain maximum equivalent internal diameter and wherein the maximum equivalent internal diameter of the adapter intermediate duct part is substantially larger than the minimum equivalent internal diameter of the adapter inlet duct.

[19] A great advantage of such a compressor device in accordance with the invention is that it is provided at its fluid duct outlet with an adapter for modifying the acoustic impedance of the complete configuration, so that the flow of compressed or pressurized fluid at the adapter outlet duct is smoother than without such an adapter of acoustic impedance.

[20] In particular, the adapter of acoustic impedance has at least one expansion chamber, which serves as a kind of intermediate buffer between the fluid duct outlet and the adapter outlet for smoothing or leveling pressure fluctuations, pulsations or imbalances of the compressed fluid discharged from the compressor element. [21] In that way, a more energy efficient compressor device is obtained and the evacuation of compressed fluid from the compressor element is stimulated.

[22] Typically, the compression of fluid in the compressor element results in a forward or downstream (in the fluid stream) pressure pulsation wave in the compressed fluid.

[23] In a preferred embodiment of a compressor device in accordance with the invention the adapter of acoustic impedance modifies the acoustic impedance in such a way that the compressed or partly compressed fluid which is present in the compressor element is influenced and this in such a way that a reflection pressure pulsation wave coming from the adapter of acoustic impedance in a backward or upstream direction, compensates at least partly the forward or downstream pressure pulsation wave, so that the pressure of the compressed fluid downstream of the adapter has an overall less pulsating character .

[24] Such an embodiment of a compressor device in accordance with the invention is very advantageous, since the adapter of acoustic impedance influences the fluid pressure of the fluid that is being compressed or is already compressed in the compressor chamber itself, i.e. , in a location upstream (in the fluid stream) of the adapter of acoustic impedance.

[25] This is very different from what is known in the prior art as a so-called "silencer" or "pulsation filter". Indeed, silencers and pulsation filters are devices in which a transformation takes place from something that is coming in into something else that is going out. The thing going out is generally less than what is coming in. [26] In the context of the invention the incoming "thing" is a flow of pressurized or compressed fluid having a certain pressure which changes dynamically in time. In a silencer or filter this incoming flow of pressurized or compressed fluid is transformed into an outgoing flow of pressurized or compressed fluid having another dynamic behavior. So, the concerned transformation takes place downstream of the actual compressor element.

[27] Generally, in such a silencer or filter certain disturbing frequencies or certain harmful pulsations in the pressure fluctuation of the concerned outgoing flow of pressurized or compressed fluid are filtered away or their intensity is decreased. In that way typically noise or detrimental vibrations are eliminated. A disadvantage however is that during the transformation in such silencers or filters a lot of energy is lost and that the energy efficiency of the compressor device is therefore decreased.

[28] Instead, an afore-mentioned embodiment of a compressor device in accordance with the invention is provided with an adapter of acoustic impedance which influences the pressure status of the fluid to be compressed or which is already partly or entirely compressed in the compressor chamber of the compressor element itself, upstream of the adapter. In that way energy accumulated in the compressed fluid present in the adapter of acoustic impedance is transferred to the fluid present in the compressor element. No or almost no energy is lost, while the conditions for evacuating compressed fluid from the compressor element are improved, the overall intensity of fluid pressure pulsations are decreased and a smoother flow of compressed fluid through the compressor element is obtained. In short, the energy efficiency of such a compressor device in accordance with the invention is higher and the supply of compressed fluid less harmful for other parts of the equipment.

[29] In a preferred embodiment of a compressor device in accordance with the invention the length of the adapter inlet duct between the compressor element and the adapter intermediate duct part is smaller than four times the minimum equivalent internal diameter of the adapter inlet duct.

[30] Such an embodiment of a compressor device in accordance with the invention is very advantageous, since the adapter of acoustic impedance is positioned at a rather short distance from the compressor element itself, so that it certainly fulfils its role as an adapter which influences the course of the fluid pressure in the compressor element itself.

[31] In another preferred embodiment of a compressor device in accordance with the invention the maximum equivalent internal diameter of the adapter intermediate duct part is larger than twice the minimum equivalent internal diameter of the adapter inlet duct.

[32] A great advantage of such an embodiment of a compressor device in accordance with the invention is that the expansion chamber formed in the adapter of acoustic impedance is large enough to have the required capacity for creating a reflection pressure pulsation wave that can compensate important pressure pulsations in the compressor element itself.

[33] In still another preferred embodiment of a compressor device in accordance with the invention an internal cross- sectional area or opening of the adapter intermediate duct part forms an opening with an equivalent internal diameter which is at least twice the minimum equivalent internal diameter of the adapter inlet duct and the ratio defined by the distance between this internal cross-sectional area or opening of the adapter intermediate duct part and the far end of the adapter inlet duct divided by the double of the minimum equivalent internal diameter of the adapter inlet duct is less than 1.

[34] A great advantage of such an embodiment of a compressor device in accordance with the invention is that the internal size of the adapter intermediate duct part for forming an expansion chamber increases rapidly over a relatively short distance from the location where the adapter intermediate duct part connects to the adapter inlet duct. In that way the expansion chamber can provide an influence on the course of the fluid pressure which is sufficiently high to be effective.

[35] The invention also relates to a compressor assembly for compressing a fluid, comprising a housing, a fluid duct for guiding the fluid through the compressor assembly from a fluid duct inlet to a fluid duct outlet, one or more compressor stages in the fluid duct, wherein at least one of the compressor stages is formed by a compressor device in accordance with the invention which comprises a concerned adapter for acoustic impedance and wherein downstream (in the fluid stream) of each compressor stage a cooler for cooling compressed fluid is provided in the fluid duct.

[36] An advantage of such a compressor assembly in accordance with the invention is that cooled, pressurized or compressed fluid can be provided at a low specific energy requirement (SER) , i.e. , in an energy efficient way. [37] In a preferred embodiment of a compressor assembly in accordance with the invention the compressor assembly comprises a low-pressure stage and a high pressure stage, wherein downstream of the low-pressure stage an air-cooled intercooler is provided in the fluid duct and wherein downstream of the high-pressure stage an air-cooled aftercooler is provided in the fluid duct, wherein the low-pressure stage comprises a compressor element and adapter of acoustic impedance according to the invention as described before and/ or the high-pressure stage comprises a compressor element and an adapter of acoustic impedance according to the invention as described before.

[38] It is not excluded from the invention to apply an acoustic adapter as described at an inlet side of the compressor element, as an alternative or additionally. In that way the filling of the compression chamber can be improved, and so-called acoustic super-filling can be applied.

Brief Description of the Drawings

[39] The invention will further be illustrated with references to the drawings, wherein:

- figure 1 is a schematic drawing of a possible embodiment of a compressor assembly in accordance with the invention;

- figure 2 is a schematic cross-sectional illustration of a part of a compressor device with an adapter of acoustic impedance in accordance with the invention; and,

- figures 3 to 8 are illustrations similar to figure 1 of alternative embodiments of a compressor device with an adapter of acoustic impedance in accordance with the invention;

- figure 9 represents a perspective view of a part of a compressor device in accordance with the invention wherein in an adapter outlet duct a flexible coupling is provided;

- figure 10 is a cross-sectional view through the part of the compressor device represented in figure 9;

- figure 11 is a partial perspective view of a combination of an adapter of acoustic impedance which is connected to a heat exchanger or cooler and to a compressor element of a compressor device of the invention, not shown in the figure; and,

- figures 12 to 16 are perspective views similar to the perspective view of figure 11 for other embodiments of compressor elements of a compressor device in accordance with the invention.

Detailed Description of Embodiment (s)

[40] Figure 1 illustrates a compressor assembly 100 in accordance with the invention comprising some compressor devices 1 in accordance with the invention for compressing a fluid 2, which is in this case air 2 drawn from the surroundings. The compressor assembly 100 comprises a housing 3 wherein a fluid duct 4 is provided for guiding the fluid 2 through the compressor assembly 100 from a compressor assembly fluid duct inlet 5 to a compressor assembly fluid duct outlet 6. [41] Furthermore, the compressor assembly 1 comprises one or more compressor stages, in this case two compressor stages 7 and 8, which are included in the fluid duct 4 and form a part of the fluid duct 4. At least one of the compressor stages 7 and 8 is formed by a compressor device 1 in accordance with the invention. In the example of figure 1 both stages 7 and 8 are formed by such a compressor device 1 in accordance with the invention.

[42] Such a compressor device 1 of the invention is special in that it comprises a compressor element 9 and it has an adapter of acoustic impedance 10 which is preferably connected to the outlet side 11 of the compressor element 1. However, it is not excluded from the invention to provide an adapter of acoustic impedance 10 which is mounted at an inlet 12 of such a compressor element 9.

[43] Downstream (in the fluid stream) of each compressor stage 7 and 8 a cooler, respectively a cooler 14 and a cooler 15, for cooling compressed fluid 13 is provided in the fluid duct 4.

[44] In the example of figure 1, the compressor stage 7 is a low-pressure stage, and the compressor stage 8 is a high- pressure stage, which are mounted in series with respect to one another. Downstream of the low-pressure stage 7 an aircooled intercooler 14 is provided in the fluid duct 4 and downstream of the high-pressure stage 8 an air-cooled aftercooler 15 is provided in the fluid duct 4.

[45] The coolers 14 and 15 are air-cooled coolers which are provided in an air channel 16 provided in the housing 3 of the compressor device 1. The air channel 16 is separated from a compartment 17 in the housing 3 wherein the compressor devices 1 are provided, by means of an intermediate wall 18.

[46] Ambient air 19 is drawn from the environment 20 by means of a fan 21 which forces the air 19 through the air channel 16 from an air channel inlet 22 to an air channel outlet 23. During flow through the air channel 16 heat is transferred from the coolers 14 and 15 to the air 19.

[47] Figure 2 illustrates schematically a part of a compressor device 1 for compressing a fluid 2 in accordance with the invention. The compressor element 9 of the compressor device 1 is schematically represented as a square and the size is completely not representative.

[48] The compressor element 9 comprises a compressor element fluid duct 24 for guiding the fluid 2 through the compressor element 9 from a compressor element fluid duct inlet 25 to a compressor element fluid duct outlet 26. According to the invention an adapter of acoustic impedance 10 is provided at the fluid duct outlet 26 of the compressor element 9.

[49] This adapter of acoustic impedance 10 comprises an adapter inlet duct 27 and an adapter outlet duct 28, part of which is only represented in figure 2. This adapter inlet duct 27 and adapter outlet duct 28 are interconnected by means of an adapter intermediate duct part 29 which encloses at least one expansion chamber 30.

[50] In this case, the adapter inlet duct 27 and the adapter outlet duct 28 are both rectilinear, but this is according to the invention not necessarily the case. The adapter inlet duct 27 extends in a direction YY' and the adapter outlet duct 28 extends in a direction ZZ' . These directions YY' and ZZ' can be colinear, but preferably they are parallel to one another at a certain offset distance 0 from one another, but even that is not necessarily the case.

[51] An internal cross-sectional area 31 of the adapter inlet duct 27 in a plane which is perpendicular to the direction YY' in which it extends between the compressor element 9 and the adapter intermediate duct part 29 forms a minimum opening 31 with a certain minimum equivalent internal diameter B. In this case the adapter inlet duct 27 has an internal cross-sectional area 31 or opening 31 perpendicular to said direction YY' which is invariable over its length, but this is not necessarily the case .

[52] The adapter intermediate duct part 29 extends in a direction AA' between the adapter inlet duct 27 and the adapter outlet duct 28. This direction AA' can be colinear with both directions YY' and ZZ' or one of the directions YY' and ZZ' in which the adapter inlet duct 27 and the adapter outlet duct 28 extend, but this is also not necessarily the case.

[53] Furthermore, an internal cross-sectional area 32 of the adapter intermediate duct part 29 forms a maximum opening 32 with a certain maximum equivalent internal diameter C. This internal cross-sectional area 32 or opening 32is typically defined in a plane perpendicular to the direction AA' in which the adapter intermediate duct part 29 extends between the adapter inlet duct 27 and the adapter outlet duct 28, or which is perpendicular to the afore-mentioned directions YY' and/or ZZ' in which the adapter inlet duct 27 and/or the adapter outlet duct 28 extend(s) . [54] According to the invention the maximum equivalent internal diameter C of the adapter intermediate duct part 29 is substantially larger than the minimum equivalent internal diameter B of the adapter inlet duct 27 (C »> B) . In that way it is ensured that the expansion chamber 30 is large compared to the minimum opening 31 of the adapter inlet duct 27.

[55] In a preferred embodiment of a compressor device 1 of the invention the maximum equivalent internal diameter C of the adapter intermediate duct part 29 is larger than twice the minimum equivalent internal diameter B of the adapter inlet duct 27.

[56] Another aspect of the invention is that the adapter intermediate duct part 29 is preferably positioned relatively near to the outlet 11 or 26 of the compressor element 9. In particular, it is preferred according to the invention that the length L of the adapter inlet duct 27 between the compressor element 9 and the adapter intermediate duct part 29 is smaller than four times the minimum equivalent internal diameter B of the adapter inlet duct 27. This measure must ensure that the expansion chamber 30 can have a sufficiently important influence on the fluid present in the compressor chamber of the compressor element 9 upstream of the adapter of acoustic impedance 10.

[57] An internal cross-sectional area 33 of the adapter intermediate duct part 29 forms an opening 33 with an equivalent internal diameter D which is at least twice the minimum equivalent internal diameter B of the adapter inlet duct 28 (D > 2xB) . This internal cross-sectional area 33 or opening 33 is again typically defined in a plane perpendicular to the direction AA' in which the adapter intermediate duct part 29 extends between the adapter inlet duct 27 and the adapter outlet duct 28, or which is perpendicular to the aforementioned directions YY' and/or ZZ' in which the adapter inlet duct 27 and/or the adapter outlet duct 28 extend (s) .

[58] Still another preferred aspect of the invention prescribes that the ratio R defined by the distance E between this internal cross-sectional area 33 of the adapter intermediate duct part 29 and the far end 34 of the adapter inlet duct 27 divided by the double of the minimum equivalent internal diameter 2 x B of the adapter inlet duct 27 is less than 1.

1 > R = E / (2 x B)

[59] This means that the expansion chamber 30 of the adapter intermediate duct part 29 is rapidly increasing in size in a direction away from the far end 34 of the adapter inlet duct 27, which ensures its effectivity.

[60] The adapter intermediate duct part 29 encloses in the embodiment of figure 2 a single expansion chamber 30 which is essentially of spherical shape formed by a sphere with diameter C.

[61] In the example of figure 2 the internal cross-sectional area of the adapter intermediate duct part 29 increases monotonically from the adapter inlet duct 27 towards the maximum internal cross-sectional area 32 of the adapter intermediate duct part 29. The internal cross-sectional area of the adapter intermediate duct part 29 also decreases monotonically from the maximum internal cross-sectional area 32 of the adapter intermediate duct part 29 towards the adapter outlet duct 28. This is however according to the invention not necessarily the case.

[62] Figure 3 illustrates a compressor device 1 according to the invention wherein the adapter intermediate duct part 29 encloses more than one expansion chamber, i.e. , in this example two expansion chambers 35 and 36.

[63] Both expansion chambers 35 and 36 have, in the case of figure 3, each a hemispherical shape. The shape is more or less obtained by two halves of a spherical expansion chamber 32, as illustrated in figure 1, which are spaced from one another by means of an intermediate spacer duct 37. In the case of figure 3 intermediate spacer duct 37 extends in the prolongment of the adapter inlet duct 27 and the adapter outlet duct 28 and all these afore-mentioned ducts 27, 28 and 37 have the same internal diameter B.

[64] In the embodiment of figure 3, the adapter intermediate duct part 29 comprises a pair of expansion chambers 35 and 36 which are symmetrically with respect to a plane FF' which is perpendicular to the direction YY' in which the adapter inlet duct 27 extends and/or to a direction ZZ' in which the adapter outlet duct 28 extends and/or to a direction AA' in which the intermediate spacer duct 37 extends.

[65] Figure 4 illustrates an embodiment of a compressor device 1 in accordance with the invention which is similar to the one in figure 2 and it has an adapter intermediate duct part 29 which encloses a single expansion chamber 30 which is again essentially of spherical shape. [66] However, this time the essentially spherical expansion chamber 30 is somewhat modified in shape. The connection 38 between the adapter outlet duct 28 and the spherical expansion chamber 30 is brought somewhat inwards into the spherical expansion chamber 30 and the outer wall 39 of the spherical expansion chamber 30 is connected to the adapter outlet duct 28 by means of an intermediate wall part 40, which has preferably a cylindrical wall part 41 concentric with the adapter outlet duct 28 and/or one or more flat shaped wall parts 42.

[67] Figure 5 illustrates still another embodiment of a compressor device 1 in accordance with the invention which is similar to the embodiment illustrated in figure 3 in that it comprises again a pair of expansion chambers 35 and 36 of essentially semispherical shape which spaced from one another by means of an intermediate spacer duct 37.

[68] The intermediate spacer duct 37 extends in the example of figure 5 in a direction perpendicular to a direction YY' in which the adapter inlet duct 27 and/or to a direction ZZ' in which the adapter outlet duct 28 extend (s) and/or a direction AA' in which the adapter intermediate part 29 extends between the adapter inlet duct 27 and the adapter outlet duct 28.

[69] The expansion chambers 35 and 36 are this time also orientated in another way and are positioned symmetrically around the adapter inlet duct 27 and/or the adapter outlet duct 28.

[70] The embodiment of a compressor device 1 in accordance with the invention illustrated in figure 6 is similar to the embodiment of figure 2 wherein the adapter intermediate duct part 29 comprises a single expansion chamber 30 of essentially spherical shape.

[71] In the example of figure 6, the adapter inlet duct 27 and/or the adapter outlet duct 28 extend (s) entirely through the adapter intermediate duct part 29 for interconnecting the adapter inlet duct 27 and the adapter outlet duct 28 by means of an internal duct part 43. The internal duct part 43 of the adapter inlet duct 27 and/or the adapter outlet duct 28 which extends into the adapter intermediate duct part 29 is perforated, so that the compressed fluid 13 can expand into the entire expansion chamber 30. Perforations 44 are provided over the entire length of the internal duct part 43.

[72] In another embodiment of a compressor device 1 according to the invention the adapter inlet duct 27 and the adapter outlet duct 28 can also extend only partly into the adapter intermediate duct part 29. This is for example the case in the embodiment which is represented in figure 12.

[73] The embodiment of a compressor device 1 in accordance with the invention represented in figure 7 is completely equivalent to the embodiment of figure 6. However, in the example of figure 7, a damping material 45 for attenuating gas pulsations, such as an acoustic foam, steel wool or the like is provided in the expansion chamber 30 of the adapter intermediate duct part 29.

[74] Figure 8 illustrates an embodiment of a compressor device 1 in accordance with the invention which is equivalent to the embodiment illustrated in figure 3 with two expansion chambers which are spaced from one another by means of an intermediate spacer duct 37 which extends in a direction AA' parallel to the directions YY' and ZZ' of the adapter inlet duct 27 and the adapter outlet duct 28.

[75] However, in figure 8, only one of the expansion chambers 35 has a semi-spherical shape, while the other expansion chamber 46 has a conical shape and is provided at the side which is the most far from the compressor element 9. The dimensions of conical shape decrease in a direction away from the compressor element 9.

[76] The expansion chamber 46 with conical shape is again filled with damping material 45, while the other expansion chamber 35 of semi-spherical shape is kept empty.

[77] The adapter outlet duct 28 is entirely incorporated in the expansion chamber 46 and does not extend to the outside of the adapter intermediate duct part 29.

[78] Figures 9 and 10 illustrate an embodiment of an adapter of acoustic impedance 10 of a compressor device lin accordance with the invention in which the adapter outlet duct 28 is provided with a flexible coupling 47 or a flexible spacer ring 47.

[79] As an alternative such a flexible coupling 47 or a flexible spacer ring 47 could as well be provided in the adapter inlet duct 27.

[80] In that case the adapter inlet duct 27 comprises three parts, i.e. , a first part and a second part connected by the concerned flexible coupling 47 or a flexible spacer ring 47. Obviously, the length L of the adapter inlet duct 27 should in this case be considered as being the total length of the adapter inlet duct 27 formed by tis three composing parts. [81] Figures 11 to 16 illustrate still other different configurations of a combination of an adapter of acoustic impedance 10 of a compressor device 1 in accordance with the invention and a cooler 14 or 15.

[82] In figure 11 the adapter intermediate duct part 29 comprises an expansion chamber with a mainly spherical shape as was the case in figure 2 for example, while in figures 12 and 14 the expansion chamber is more of a rectangular shape or box shape or cubical shape.

[83] In figure 13 the adapter intermediate duct part 29 comprises an expansion chamber which has an S-shaped crosssection, while in figures 15 and 16 the expansion chamber is enclosed in a more rounded shape or cylindrical shape. In still other bodies the expansions chamber could form a prismatic shape and even form another more irregular shape.

[84] The present invention is in no way limited to the embodiments of a compressor assembly 100 or a compressor device 1 as described before, but such a compressor assembly 1 or a compressor device 1 can be applied and be implemented in many different ways without departure from the scope of the invention .