INTEGRATED MOTOR-COMPRESSOR ASSEMBLY

Abstract

The integrated motor-compressor assembly (1) comprises: – a gas inlet (7), – a drive shaft (3), magnetic bearings (9, 10) supporting the drive shaft (3), – an electric motor (2) mounted on a drive shaft, – a first compression section (4) cantilevered at a first end of the drive shaft and configured to compress a gas flowing at the gas inlet of the integrated motor-compressor assembly, and – a second compression section (5) cantilevered at a second end of the drive shaft.The integrated motor-compressor assembly further comprises a cooling fan (12) cantilevered on the drive shaft (3) between a compression section of the first and second compression sections (4, 5) and the electric motor (2), the cooling fan being configured to circulate a portion of the gas taken from the gas inlet of the integrated motor-compressor assembly into a cooling loop (11) of the integrated motor-compressor assembly, the portion of the gas being a cooling gas. Figure for abstract: Figure 1.

Description

Title of the invention: INTEGRATED MOTOR-COMPRESSOR ASSEMBLY FIELD OF THE INVENTION

[0001] The present invention relates to an integrated motor-compressor assembly and in particular relates to a specific arrangement of a cooling fan. DESCRIPTION OF THE ASSOCIATED TECHNIQUE

[0002] An integrated motor-compressor assembly may include an electric motor mounted on a drive shaft to drive said shaft. The drive shaft is generally rotatably supported by two magnetic bearings arranged on either side of the electric motor.

[0003] A compression section may be arranged at each end of the drive shaft.

[0004] The electric motor and the magnetic bearings are subject to losses generated, for example, by eddy currents.

[0005] In order to cool the electric motor and the magnetic bearings, the integrated motor-compressor assembly comprises a cooling loop comprising a filtration device filtering a portion of a compressed gas by means of a first compression section, the portion of the compressed gas being the cooling gas flowing into the electric motor and the bearings.

[0006] When the pressure of the compressed gas is too high to supply the cooling loop, a control valve expands the compressed gas filtered by the filtration device to decrease the pressure of the compressed gas to a predetermined pressure.

[0007] However, in order to decrease the pressure of the cooling gas, the control valve dissipates part of the energy used to drive the first compression section to compress the gas such that the efficiency of the integrated motor-compressor assembly is degraded.

[0008] Furthermore, the control valve is a pressure regulating component that may be defective, decreasing the reliability of the integrated motor-compressor assembly.

[0009] It is necessary to avoid at least some of the previously mentioned disadvantages.

[0010] SUMMARY

[0011] According to one aspect, a novel integrated motor-compressor assembly is provided.

[0012] The integrated motor-compressor assembly comprises:

[0013] - a gas inlet,

[0014] - a drive shaft, - magnetic bearings supporting the drive shaft,

[0015] - an electric motor mounted on a drive shaft,

[0016] - a first cantilevered compression section at a first end of the drive shaft and configured to compress a gas flowing at the gas inlet of the integrated motor-compressor assembly, and

[0017] - a second cantilevered compression section at a second end of the drive shaft.

[0018] The integrated motor-compressor assembly further comprises a cooling fan arranged in a cantilevered manner and mounted on the drive shaft between a compression section of the first and second compression sections and the electric motor, the cooling fan being configured to circulate a portion of the gas taken from the gas inlet of the integrated motor-compressor assembly into a cooling loop of the integrated motor-compressor assembly, the portion of the gas taken being a cooling gas.

[0019] Preferably, the cooling fan is mounted between the first compression section and the electric motor, and is configured to compress the cooling gas to supply the compressed cooling gas to the cooling loop of the integrated motor-compressor assembly.

[0020] Advantageously, the integrated motor-compressor assembly comprises the cooling loop comprising a filtration device, the filtration device being connected to the cooling fan and the electric motor such that a first portion of the compressed cooling gas filtered by the filtration device flows through the electric motor to cool the electric motor.

[0021] Preferably, the filtration device is further connected to each magnetic bearing such that a second portion of the compressed cooling gas filtered by the filtration device flows through the magnetic bearings to cool the magnetic bearings.

[0022] Advantageously, the integrated motor-compressor assembly further comprises a sealed housing, the drive shaft, the electric motor, the first compression section, the second compression section, the cooling fan and the magnetic bearings being arranged in the sealed housing, the cooling loop further comprising an exhaust duct configured to discharge the first portion of the compressed cooling gas, heated by the electric motor, released inside the sealed housing and to discharge the second portion of the compressed cooling gas, heated by the magnetic bearings, released inside the sealed housing.

[0023] Preferably, the cooling fan is configured to draw in the cooling gas.

[0024] Advantageously, the integrated motor-compressor assembly further comprises the cooling loop comprising a filtration device connected to the gas inlet and to the electric motor such that a first portion of the cooling gas filtered by the filtration device flows through the electric motor to cool the electric motor, the cooling gas heated by the electric motor being drawn in by the cooling fan.

[0025] Preferably, the cooling fan comprises a gas outlet configured to distribute the cooling gas drawn in by the cooling fan, the integrated motor-compressor assembly further comprises:

[0026] - a sealed casing, the drive shaft, the electric motor, the first compression section, the second compression section and the cooling fan being arranged in the sealed housing,

[0027] - a suction device configured to suck gas escaping therein from the sealed casing from the compression section of the first and second compression sections furthest from the cooling fan and for injecting the suctioned gas into a gas inlet of the first or second compression section,

[0028] - a gas diffuser configured to receive a second portion of the gas from filtered cooling and diffuse the second part of the filtered cooling gas into the sealed casing,

[0029] - the gas diffuser being arranged between the electric motor and the section of compression among the first and second compression sections furthest from the cooling fan and the suction device being arranged between the compression section among the first and second compression sections furthest from the cooling fan and the gas diffuser, and

[0030] - a buffer gas system connected to the gas outlet of the fan of cooling and arranged between the gas diffuser and the suction device, and configured to diffuse a portion of the cooling gas sucked in by the cooling fan.

[0031] Advantageously, the filtration device is further connected to each magnetic bearing so that a third portion of the filtered cooling gas flows through the magnetic bearings to cool the magnetic bearings, the cooling gas heated by the magnetic bearings being drawn in by the cooling fan.

[0032] Preferably, the filtration device is arranged outside the sealed housing. Brief description of the drawings

[0033] Other advantages and characteristics of the invention will appear on examining the detailed description of the embodiments, this being in no way restrictive, and the appended drawings in which:

[0034] [Fig.l] schematically illustrates a first embodiment of an integrated motor-compressor assembly according to the invention;

[0035] [Fig.2] schematically illustrates a second embodiment of the integrated motor-compressor assembly according to the invention;

[0036] [Fig.3] schematically illustrates a third embodiment of the assembly integrated motor-compressor according to the invention; and

[0037] [Fig.4] schematically illustrates a fourth embodiment of the integrated motor-compressor assembly according to the invention. DETAILED DESCRIPTION

[0038] Reference is made to [Fig.l] which schematically represents a first embodiment of an integrated motor-compressor assembly 1.

[0039] The integrated motor-compressor assembly 1 comprises an electric motor 2 mounted on a drive shaft 3, two compression sections 4, 5 and a sealed casing 6.

[0040] The electric motor 2 and the two compression sections 4, 5 are arranged in the sealed casing 6.

[0041] A first compression section 4 is cantilevered at a first end of the drive shaft 3 and the second compression section 5 is cantilevered at the second end of the drive shaft 3.

[0042] Each compression section 4, 5 comprises a gas inlet 4a, 5a and a gas outlet 4b, 5b.

[0043] As shown, the gas inlet 4a, 5a of each compression section 4, 5 may be an axial gas inlet.

[0044] The gas inlet 4a of the first compression section 4 is connected to a gas inlet 7 of the integrated motor-compressor assembly 1, the gas inlet 5a of the second compression section 5 is connected to the gas outlet 4b of the first compression section 4 and the gas outlet 5b of the second compression section 5 is connected to the gas outlet 8 of the integrated motor-compressor assembly 1.

[0045] Each compression section 4, 5 may comprise a compression wheel 4c, 5c.

[0046] Each compression section 4, 5 comprises sealing devices 4d, 5d to prevent gas from escaping into the sealed casing 6 from said compression section 4, 5.

[0047] The first compression section 4 is intended to be driven by the electric motor 2 to compress a gas flowing into the gas inlet 7 of the integrated motor-compressor assembly 1 and to distribute the compressed gas to the gas inlet 5a of the second compression section 5.

[0048] The second compression section 5 is intended to be driven by the electric motor 2 to further compress the gas delivered by the first compression section 4 and to deliver the compressed gas which has been further compressed by the second compression section 5 to the gas outlet 8 of the integrated motor-compressor assembly 1.

[0049] The drive shaft 3 is supported by two bearings 9, 10 in the sealed casing 6.

[0050] Each bearing 9, 10 comprises a radial bearing and an axial bearing.

[0051] The first and second compression sections 4, 5 are cantilevered.

[0052] The bearings 9, 10 may comprise gas bearings or, preferably, magnetic bearings.

[0053] It is assumed hereinafter that the bearings 9, 10 are magnetic bearings, each bearing 9, 10 comprises a radial magnetic bearing and / or an axial magnetic bearing.

[0054] A first bearing 9 is arranged between the first compression section 4 and the electric motor 2, and the second bearing 10 is arranged between the second compression section 5 and the electric motor 2.

[0055] The integrated motor-compressor assembly 1 further comprises a cooling loop 11 and a cooling fan 12.

[0056] The cooling fan 12 is cantilevered on the drive shaft 3 between the first compression section 4 and the electric motor 2.

[0057] This integrated motor-compressor assembly 1 makes it possible to produce an integrated double-overhang motor-compressor assembly combined with a fan 12 instead of a control valve known in the prior art which generates a significant pressure drop and flow rate drop in the assembly.

[0058] The cooling fan 12 driven by the drive shaft 3 is intended to circulate a portion of the gas taken from the gas inlet 7 of the integrated motor-compressor assembly 1 in the cooling loop 11.

[0059] The part of the gas taken from the gas inlet 7 of the integrated motor-compressor assembly 1 is called cooling gas.

[0060] The cooling fan 12 comprises a gas inlet 12a connected to the gas inlet 7 of the integrated motor-compressor assembly 1, a gas outlet 12b, a compression wheel 12c and sealing devices 12d for preventing the gas compressed by the cooling fan 12 from escaping into the sealed casing 6.

[0061] The cooling loop 11 comprises a filtration device 13 comprising an inlet 13a connected to the gas outlet 12b of the cooling fan 12, and an outlet 13b connected to the electric motor 2 and / or to the magnetic bearings 9, 10.

[0062] The sealing devices 4d, 5d may comprise labyrinths and may further comprise intermediate connecting lines (not shown) connected to the gas inlet 7 and the outlet 13b of the filtration device 13. The arrangement of the labyrinths and the various connecting lines is made so that unfiltered gas cannot enter a bearing or compressor elements, such as the magnetic bearings 9, 10 and the electric motor 2.

[0063] Each intermediate connecting line may, for example, comprise a pipe.

[0064] The sealing device 12d may comprise labyrinths and may further comprise an intermediate connection to the outlet 13b.

[0065] The sealing devices 4d, 5d and 12d prevent unfiltered gas from flowing into the magnetic bearings 9, 10 and the electric motor 2.

[0066] The integrated motor-compressor assembly 1 further comprises an exhaust duct 14 connecting the interior of the sealed casing 6 to the gas inlet 7 of the integrated motor-compressor assembly 1.

[0067] When the electric motor 2 drives the drive shaft 3, the cooling fan 12 compresses the cooling gas to supply the compressed cooling gas to the cooling loop 11 and the filtering device 13 filters the compressed cooling gas. The compressed cooling gas flows into the electric motor 2 and / or the magnetic bearings 9, 10.

[0068] A first portion of the compressed cooling gas filtered by the filtration device 13 flows through the electric motor 2 to cool the electric motor 2 and a second portion of the compressed cooling gas filtered by the filtration device 13 flows through the magnetic bearings 9, 10 to cool the magnetic bearings 9, 10.

[0069] The first part of the compressed cooling gas heated by the electric motor 2 and the second part of the compressed cooling gas heated by the magnetic bearings 9, 10 are released inside the sealed casing 6.

[0070] The heated cooling gas released into the sealed casing 6 is discharged through the gas inlet 7 of the integrated motor-compressor assembly 1 via the exhaust duct 14.

[0071] The cooling fan 12 is designed so that the pressure at the gas outlet 12b is equal to a predetermined pressure determined according to the flow of cooling gas circulating in the electric motor 2 and / or the magnetic bearings 9, 10, and depending on the pressure drop in the cooling loop 11.

[0072] As shown, the filtration device 13 can be arranged outside the sealed casing 6.

[0073] Alternatively, the filtration device 13 can be arranged inside the sealed casing 6.

[0074] The unfiltered gas flowing into the gas inlet 7 may contain particles that may damage components inside the sealed casing 6, for example, that may damage the magnetic bearings 9, 10 and / or the electric motor 2.

[0075] The particles may be a corrosion product of a process pipe, rust, water droplets transferred by a process stream or any solid particle present in the treated gas flowing into the gas inlet 7.

[0076] The filtration device 13 is designed to remove these components from the gas flowing into the gas inlet 7 of the integrated motor-compressor assembly 1.

[0077] The cooling fan 12 may be arranged in proximity to the first compression section 4 so that gas that may escape from the first compression section 4 through the sealing devices 4d of the first compression section 4 flows into the cooling fan 12 to prevent unfiltered gas from flowing into the sealed housing 6.

[0078] [Fig.2] schematically represents a second embodiment of the integrated motor-compressor assembly 1.

[0079] The same references designate the same elements as those previously referenced in the first embodiment of the integrated motor-compressor assembly 1 shown in [Fig.l].

[0080] The integrated motor-compressor assembly 1 comprises the electric motor 2, the drive shaft 3, the first and second compression sections 4, 5, the sealed casing 6, the gas inlet 7, the gas outlet 8 and the magnetic bearings 9, 10 arranged as described above in the first embodiment of the integrated motor-compressor assembly 1.

[0081] The integrated motor-compressor assembly 1 further comprises the cantilevered cooling fan 12 and the filtration device 13.

[0082] As explained below, in the second embodiment, the cooling fan 12 is intended to suck in cooling gas.

[0083] The gas inlet 12a of the cooling fan 12 is arranged in the sealed casing 6 to suck gas into the sealed casing 6 and the gas outlet 12b of the cooling fan 12 is connected to the gas inlet 7 of the integrated motor-compressor assembly 1.

[0084] The cooling fan 12 is mounted on the drive shaft 3 between the first compression section 4 and the electric motor 2.

[0085] The integrated motor-compressor assembly 1 comprises a cooling loop 15 comprising the filtration device 13.

[0086] The inlet 13a of the filtration device 13 is connected to the gas inlet 7 of the integrated motor-compressor assembly 1 and the outlet 13b of the filtration device 13 is connected to the electric motor 2 and to the magnetic bearings 9, 10.

[0087] When the electric motor 2 drives the drive shaft 3, the cooling fan 12 creates a vacuum inside the sealed housing 6 so that a portion of the gas taken from the gas inlet 7 of the integrated motor-compressor assembly 1 (cooling gas) is sucked through the filtering device 13 to be filtered. The filtered cooling gas can then be divided into a first portion, a second portion and a third portion. The first portion of the filtered cooling gas is sucked through the electric motor 2 and the second portion of the filtered cooling gas is sucked through the magnetic bearings 9, 10.

[0088] The first part of the compressed cooling gas heated by the electric motor 2 and the second part of the compressed cooling gas heated by the magnetic bearings 9, 10 released inside the sealed casing 6 are sucked in by the cooling fan 12 and pushed by the cooling fan 12 into the gas inlet 7 of the integrated motor-compressor assembly 1.

[0089] When a vacuum is created inside the sealed casing 6, to prevent unfiltered gas in the first compression section 4 from escaping inside the sealed casing 6, the cooling fan 12 may be adjacent to the first compression section 4. The integrated motor-compressor assembly 1 may comprise a gas diffuser 16 between the electric motor 2 and the second compression section 5, and a suction device 17 arranged between the second compression section 5 and the gas diffuser 16 to prevent unfiltered gas in the second compression section 5 from escaping inside the sealed casing 6.

[0090] The gas diffuser 16 receives the third part of the filtered cooling gas and diffuses the third part of the filtered cooling gas into the sealed casing 6, the third part of the filtered cooling gas forming a gas barrier.

[0091] The suction device 17 sucks the gas escaping inside the sealed casing 6 from the compression section among the first and second compression sections 4, 5 which is arranged furthest from the cooling fan 12 and injects the sucked gas into the gas inlet of the integrated motor-compressor assembly 1.

[0092] The integrated motor-compressor assembly 1 further comprises a buffer gas system 18 connected to the gas outlet 12b of the cooling fan 12 and arranged between the gas diffuser 16 and the suction device 17.

[0093] The buffer gas system 18 receives a portion of the cooling gas drawn in by the cooling fan 12 and diffuses said portion of the cooling gas to create a buffer zone with slight overpressure preventing unfiltered gas escaping from the suction device 17 from flowing into the gas diffuser 16 and flowing into the sealed casing 6.

[0094] In this embodiment, the suction device 17 sucks the gas escaping from the second compression section 5 inside the sealed casing 6 and injects the sucked gas into the gas inlet 5a of the second compression section 5.

[0095] In this embodiment, the cooling fan 12 is designed so that the pressure at the outlet 13b of the filtration device 13 is equal to a predetermined pressure determined according to the flow of cooling gas circulating in the electric motor 2 and / or the bearings 9, 10, and according to the pressure drop in the cooling loop 15.

[0096] As shown, the filtration device 13 can be arranged outside the sealed casing 6.

[0097] Alternatively, the filtration device 13 can be arranged inside the sealed casing 6.

[0098] [Fig. 3] schematically represents a third embodiment of the integrated motor-compressor assembly 1.

[0099] The same references designate the same elements as those previously referenced in the first embodiment of the integrated motor-compressor assembly 1 shown in Figures 1 and 2.

[0100] The third embodiment of the integrated motor-compressor assembly 1 differs from the second embodiment of the integrated motor-compressor assembly 1 illustrated in [Fig.2] in that the integrated motor-compressor assembly 1 comprises a first pipe 19 connecting a first connection of the electric motor 2 to the gas inlet 12a of the cooling fan 12 and a second pipe 20 connecting a second connection of the electric motor 2 to the gas inlet 12a of the cooling fan 12.

[0101] The first connection of the electric motor 2 is located on a first side of the electric motor 2 and the second connection of the electric motor 2 is located on a side of the electric motor 2 opposite the first side of the electric motor 2.

[0102] The first part of the compressed cooling gas heated by the electric motor 2 is sucked in by the cooling fan 12 via the first and second pipes 19, 20 forming bilateral cooling.

[0103] The first and second pipes 19, 20 are located inside the sealed casing 6 as shown.

[0104] Alternatively, the first pipe 19 and / or the second pipe 20 may be located outside the sealed casing 6.

[0105] In another embodiment, the first pipe 19 can be replaced by a channel drilled in at least one wall of the sealed casing 6, the channel connecting the second connection of the electric motor 2 to the gas inlet 12a of the cooling fan 12.

[0106] A first end of a pipe 21 is connected to the gas inlet 12a of the cooling fan 12 and the second end of the pipe 21 opens into the sealed casing 6 so that the cooling fan 12 sucks the compressed cooling gas released inside the sealed casing 6.

[0107] [Fig.4] schematically represents a fourth embodiment of the integrated motor-compressor assembly 1.

[0108] The same references designate the same elements as those previously referenced in the first embodiment of the integrated motor-compressor assembly 1 shown in Figures 1 and 2.

[0109] The fourth embodiment of the integrated motor-compressor assembly 1 differs from the second embodiment of the integrated motor-compressor assembly 1 shown in [Fig. 2] in that the cooling fan 12 is cantilevered on the drive shaft 3 between the second compression section 5 and the electric motor 2, the gas diffuser 16 is arranged between the electric motor 2 and the first compression section 4, and the suction device 17 is arranged between the first compression section 4 and the gas diffuser 16 to prevent unfiltered gas in the first compression section 4 from escaping inside the sealed casing 6.

[0110] The buffer gas system 18 is connected to the gas outlet 12b of the cooling fan 12 and arranged between the gas diffuser 16 and the suction device 17.

[0111] The suction device 17 sucks the gas escaping from the first compression section 4 into the sealed casing 6 and injects the sucked gas into the gas inlet 5a of the second compression section 5.

[0112] In the embodiments of the integrated motor-compressor assembly 1, the cooling gas for cooling the electric motor 2 and / or the bearings 9, 10 is taken from the gas inlet of the integrated motor-compressor assembly 1 so that the cooling gas is not compressed by a compression section 4, 5 of the integrated motor-compressor assembly 1.

[0113] The cooling gas is set in motion in the cooling loop 15 by the rotation of the cooling fan 12 to cool components at inside the sealed casing 6, for example, the electric motor 2 and / or the bearings 9, 10.

[0114] The term "cantilevered" means that a component of the integrated motor-compressor assembly such as the cooling fan 12, the first compression section 4 or the second compression section 5 is not located between the first and second bearings 9, 10.

[0115] Said component is positioned cantilevered relative to the first and second bearings 9, 10.

[0116] Since the energy consumed by the cooling fan 12 to set the cooling gas in motion in the cooling loop 15 is lower than the energy consumed to compress the cooling gas in the first compression section 4, the energy consumed by the integrated motor-compressor assembly 1 is reduced compared to an integrated motor-compressor assembly 1 comprising a cooling loop having a control valve configured to expand the gas known in the prior art.

[0117] Furthermore, the reliability of the cooling fan is superior to the reliability of a regulated control valve expanding gas to a predetermined pressure known in the prior art so that the reliability of the integrated motor-compressor assembly 1 is improved.

Claims

Claims

1. An integrated motor-compressor assembly (1) comprising: - a gas inlet (7), - a drive shaft (3), - magnetic bearings (9, 10) supporting the drive shaft (3), - an electric motor (2) mounted on a drive shaft - a first compression section (4) cantilevered at a first end of the drive shaft and configured to compress a gas flowing at the gas inlet of the integrated motor-compressor assembly, and - a second compression section (5) cantilevered at a second end of the drive shaft, characterized in that the integrated motor-compressor assembly further comprises a cooling fan (12) arranged cantilevered and mounted on the drive shaft (3) between one of the first and second compression sections (4, 5) and the electric motor (2),the cooling fan being configured to circulate a portion of the gas taken from the gas inlet of the integrated motor-compressor assembly in a cooling loop (11, 15) of the integrated motor-compressor assembly, the portion of the gas taken being a cooling gas.,

2. An integrated motor-compressor assembly according to claim 1, wherein the cooling fan (12) is mounted between the first compression section (4) and the electric motor (2), the cooling fan (12) being configured to compress the cooling gas to supply the compressed cooling gas to the cooling loop (11) of the integrated motor-compressor assembly.

3. An integrated motor-compressor assembly according to claim 2, further comprising the cooling loop (11) having a filtration device (13), the filtration device being connected to the cooling fan (12) and the electric motor (2) such that a first portion of the compressed cooling gas filtered by the filtration device flows through the electric motor to cool the electric motor.

4. An integrated motor-compressor assembly according to claim 3, wherein the filtration device (13) is further connected to each magnetic bearing such that a second portion of the compressed cooling gas filtered by the filtration device flows through the magnetic bearings to cool the magnetic bearings.

5. An integrated motor-compressor assembly according to claim 4, further comprising a sealed housing (6), the drive shaft (3), the electric motor (2), the first compression section (4), the second compression section (5), the cooling fan (12) and the magnetic bearings (9, 10) being arranged in the sealed housing (6), the cooling loop (11) further comprising an exhaust duct (14) configured to discharge the first portion of the compressed cooling gas, heated by the electric motor (2), released inside the sealed housing and to discharge the second portion of the compressed cooling gas, heated by the magnetic bearings (9, 10), released inside the sealed housing.

6. An integrated motor-compressor assembly according to claim 1, wherein the cooling fan (12) is configured to draw in the cooling gas.

7. An integrated motor-compressor assembly according to claim 6, further comprising the cooling loop (15) comprising a filtration device (13) connected to the gas inlet (7) and to the electric motor (2) such that a first portion of the cooling gas filtered by the filtration device flows through the electric motor to cool the electric motor, the cooling gas heated by the electric motor being drawn in by the cooling fan.

8. An integrated motor-compressor assembly according to claim 7, wherein the cooling fan (12) comprises a gas outlet (12b) configured to distribute the cooling gas drawn by the cooling fan (12), the integrated motor-compressor assembly further comprising:

9. - a sealed housing (6), the drive shaft (3), the electric motor (2), the first compression section (4), the second compression section (5) and the cooling fan (12) being arranged in the sealed housing (6), - a suction device (17) configured to suck gas escaping inside the sealed casing (6) from the compression section among the first and second compression sections (4, 5) furthest from the cooling fan (12) and to inject the sucked gas into a gas inlet of the first or second compression section, - a gas diffuser (16) configured to receive a second portion of the filtered cooling gas and diffuse the second portion of the filtered cooling gas into the sealed casing (6), - the gas diffuser (16) being arranged between the electric motor (2) and the compression section among the first and second compression sections (4, 5) furthest from the cooling fan (12), and the suction device (17) being arranged between the compression section among the first and second compression sections (4, 5) furthest from the cooling fan (12) and the gas diffuser (16), and - a buffer gas system (18) connected to the gas outlet of the cooling fan and arranged between the gas diffuser and the suction device, and configured to diffuse a portion of the cooling gas sucked in by the cooling fan. An integrated motor-compressor assembly according to claim 8, wherein the filtration device (13) is further connected to each magnetic bearing such that a third portion of the filtered compressed cooling gas flows through the magnetic bearings to cool the magnetic bearings, the cooling gas heated by the magnetic bearings being drawn in by the cooling fan.

10. Integrated motor-compressor assembly according to any one of claims 5, 8 and 9, wherein the filtration device (13) is arranged outside the sealed casing.

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