FR2933626A1 - Gas separating device for case of internal combustion engine of road vehicle e.g. car, has liquid e.g. oil, draining channel arranged at side of treated gas downstream zone for flow of liquid passed through medium - Google Patents

Abstract

The device (10) has a rotor mounted rotatively around an axis (A) and integrating a separation element (100) with a coalescer medium. A stator has a liquid e.g. oil, draining channel (24) and a periphery wall around the rotor, where the stator has an outlet for evacuating treated gas. The element defines a non-treated gas upstream zone (Z1) and a treated gas downstream zone (Z2), where the zones are defined by an interior surface (12a) and an exterior surface (12b), respectively. The channel is arranged at a side of the zone (Z2) for flow of the liquid passed through the medium. An independent claim is also included for a method for separating a gas issued from a case of an internal combustion engine.

Description

1 Device with coalescer media rotor for separating oil from crankcase gases of an internal combustion engine

TECHNICAL FIELD OF THE INVENTION The present invention relates to devices for separating elements suspended in a gas coming from an internal combustion engine casing. The field of application of the invention relates in particular to the separation of oil from the crankcase gases in the combustion engines of road vehicles (eg automobiles, trucks, motorcycles), boats or industrial engines (for example a generator) . BACKGROUND OF THE INVENTION In a manner known per se, the casing is connected to the air intake of the internal combustion engine via a separating device in order to continuously evacuate the crankcase gases and to extract the same. oil in suspension. This is known as a crankcase recirculation circuit or blow-by gas by one skilled in the art.

Various means of separating the oil from the crankcase gases are employed in the prior art, of which four large families can be distinguished. A first family brings together the chicane systems. A network of baffles is formed of several plates arranged to accelerate and sharply deflect the flow of gas. This results in the impaction of the oil droplets on these plates and thus the deoiling of the gas. These systems are usually arranged in the cylinder head cover or in a box attached to the engine. These systems generate little loss of load. However, they are not very effective for the separation of very fine oil aerosols. A second family brings together the cyclone devices. The conical volume into which the gas enters

2 by a tangential inlet allows the acceleration and the rotation of the gas. This rotation causes the oil drops to impinge on the walls of the cyclone, while the gaseous phase is evacuated by the outlet provided in the center. These devices are mounted either in a specific box attached to the engine, or in the oil filter module or in the cylinder head cover. These systems are not very effective. They become more complex by the addition of progressive opening valves cyclonic cells with the flow of gas. A third family includes static coalescers. These systems include a fiber network for the capture of fine oil droplets. The oil droplets then gather together to form larger drops capable of sliding by gravity along the media. The coalescers are typically placed in a housing attached to the engine, in the oil filter module or in the cylinder head cover. They are effective but can become dirty and generate pressure drop.

A fourth family groups centrifugal separator systems. Such systems include a network of disks or cups rotating about an axis of rotation. The crankcase gases are rotated by the rotation of the system. This rotation causes the impaction of oil drops on the walls (disks or cups). The oil thus grouped is expelled radially outwards while the purified gases exit at the center of the separator system. These systems are driven by a specific electric motor or by the camshaft or crankshaft, or by a Pelton wheel using the engine oil pressure. They are separators that generate no or little loss of load. They are placed in a box attached to the engine or integrated into the cylinder block or distribution. Based on measurements on engines equipped with rotating 'cup' type systems, the

3 results for efficiency, however, were disappointing. The systems of the first two families have a reduced efficiency and are not particularly suitable for very fine oil aerosols generated when the engine is operating at maximum power. It is possible to expect at best 20% efficiency with these systems. The family of coalescers achieves better results for efficiency (60 to 75% at maximum power and 80 to 90% at idle) but their pressure drop, in the soaked state of oil, is already high at low flow rate. gas. This can be a problem at low speed and low load, while the gas flow can already be high and the vacuum at the air intake is low. The latter is not sufficient to compensate for the pressure drop of the coalescer and it is possible that the crankcase pressure is positive. This disadvantage limits the use, manufacturers preferring to be content with low efficiency (less than 20%) by not giving in on the problem of positive crankcase pressure. It is known from US 3708957 published in 1973, a coalescing cartridge rotatably mounted in a cylindrical cavity in communication with the motor housing. The media of the cartridge has an outer surface on which oil drops form by coalescence. The rotation of the cartridge produces a centrifugal effect sufficient to radially project the drops of oil outward to be collected and returned to the engine casing. The purified gases emerge axially from the cartridge and are then conveyed to the air intake. It is also known from document ITTO20020358 to use an oleophobic treated media on its outer face (so as to slide the oil particles onto the fibers thus treated) and mounted rotating on the

4 crankshaft. The gases from the casing enter through the periphery of the cartridge and emerge purified towards the air intake. The centrifugal effect makes it possible to expel the drops of oil formed on the oleophobic outer layer.

As a result, the media is not soaked with oil and the pressure loss of the media remains low. In addition, the efficiency of the system increases with the speed of rotation. For this type of separator, it should be understood that the media serves to coalesce the oil droplets. That is to say, allows to group small droplets in larger drops or liquid that can then be separated by mechanical means (impaction, gravity, centrifugal force). In this case, here, the means for separating the liquid phase and the gas is the centrifugal force. However, the media remains a porous material, a portion of the coalesced oil is 'pushed' by the flow of gas to the downstream side of the media and therefore the central axis.

At the end of the rotating shaft, the oil is re-expelled into the gas stream. In particular, the risk of oil entrainment to the air intake is higher when the gas flow is high and the system is driven with a low rotational speed. In the example of a drive by a camshaft, the speed is half the speed of the motor rotation speed. For the operating point at the maximum torque (usually at a speed of 2000 rpm), the system rotation speed is relatively low (1000 rpm) while the gas flow rate is maximum. In this case, the entrainment by the flow takes precedence over the centrifugal effect and the coalesced oil is evacuated mainly by the outlet. In the absence of drainage downstream of the separator, the oil is then re-entrained to the inlet and the separation will be useless. Furthermore, the rotation of this type of system tends to push the gas to the periphery and thus to create an overpressure at the housing. This is in addition to the pressure drop of the media. As a result, the pressure drop across the rotating element is greater than the pressure drop of a new static coalescer. In general, it has always been considered natural to separate the aerosols by expelling on the one hand the oil towards the outside of the media and by directing the deoiled gases towards the inside of the media. GENERAL DESCRIPTION OF THE INVENTION The purpose of the present invention is to overcome one or more of the aforementioned drawbacks by proposing a de-oiling device for the gases coming from a crankcase, which presents a better compromise between the pressure drop on the one hand and the effectiveness of separation on the other hand. For this purpose, the invention relates to a device for cleaning a gas coming from an internal combustion engine casing, comprising on the one hand a rotor rotatably mounted about an axis and integrating a separating element with a coalescer media of liquid, and secondly a stator including a drainage line of a liquid such as oil and at least one peripheral wall around the rotor, the stator having an outlet for evacuation of treated gases, the separating element delimiting an upstream zone of untreated gases communicating with the crankcase and a downstream zone of treated gases communicating with the outlet, the coalescer medium extending around an interior volume traversed by the axis of rotation of the rotor, characterized in that the upstream zone is delimited by an inner surface of the proximal media relative to the axis, while the downstream zone is delimited

6 by an outer surface of the media distal to the axis, and in that the drainage pipe is disposed on the side of the downstream zone, periphery of the rotor, to allow the flow of liquid having passed through the media. Thanks to these provisions, the centrifugal effect and the pressure related to the flow add up so that the drainage takes place only in one direction: in this case from upstream to downstream. This allows the system to evacuate the oil contained in the media more quickly. The oil expelled from the media is collected on a fixed wall and then evacuated by a drain located in the lower part. The fact that this wall is fixed and that the gas velocity is lower at the periphery of the rotor part than in the center, make the risks of retraining are greatly minimized. On the other hand, by reversing the direction of gas flow, the overpressure related to the rotation of the system now becomes a vacuum to partially compensate for the pressure drop due to the flow of gas through the media. In the prior art, the faster the system rotates, the greater the loss of load becomes important. With the present provisions, the higher the speed of rotation increases and the pressure loss decreases. As the oil is coalesced by the media, this oil comes out of the media in the form of sufficiently large drops, which therefore more particularly under the effect of the centrifugal force and will be systematically pressed against the peripheral wall of the stator, without being able to driven with the outgoing gas flow. The stator may comprise an enclosure defining a cavity for the rotor and enveloping the separating element. This enclosure has, at a low point, a collection vessel for a liquid. The drainage pipe is for example positioned substantially at a bottom of this tank, so as to allow evacuation and

7 optimal oil recovery. According to another feature, the enclosure comprises a wall and a cover defining a cavity for housing an end of the rotor, the rotor being driven from outside the cavity and passing through an orifice of the wall centered on the axis of rotation, said wall being devoid of passage openings for gases around the orifice and said cover being devoid of radial passage openings for gases at the periphery of the rotor.

Thus, the oil-gas interactions are minimized at the periphery of the rotor, an area in which the oil drops are propelled outwards by the centrifugal force. According to another feature, the collection tank comprises a valve for purging the collected liquid through the drainage pipe. Advantageously, the oil can be purged during the stopping of the engine, when the hydrostatic pressure generated by the level of the oil collected overrides the negative pressure difference between upstream and downstream.

According to another feature, the separating element comprises two plastic flanges between which is affixed by an adhesive, the media, at least one of the two flanges being snapped into a hollow tube aligned with the axis of the rotor. The separating element can thus constitute a removable and replaceable cartridge. According to another feature, the output of the stator comprises a pipe substantially parallel to the axis of rotation of the rotor. Thus, the purified gas can flow in a return passage to the axis of rotation of the rotor and the gas arriving in the outlet pipe is thus protected from oil projections directed towards the peripheral wall of the stator. For example, the outlet pipe may have an outlet or inlet passage vis-à-vis a flange of the separating element. The purified gas that comes out around the media can be guided along this

8 flange, centripetally, to join the output line to more axial position. According to another feature, the rotor comprises blades integral with a rotation shaft about the axis and / or a flange of the separation element. With these blades and the associated additional suction effect, the pressure drop is significantly reduced, especially at low rotational speed and high gas flow rates. According to another feature, the rotor is rotated by a programmable rotational speed electric motor. With this type of drive, the speed can be set at a constant speed. It is thus allowed to move at high speed whatever the engine speed (eg 4000 rpm). From experience, it is known that beyond 2000 rpm, the oil is better removed from the media and the efficiency increases with the speed of rotation of the rotor element. Furthermore, the subject of the invention is also a process for purifying a gas coming from an internal combustion engine casing, comprising the steps of: rotating around an axis of an element of separation including liquid coalescer media, the media having an input surface interfacing with untreated gases from the motor housing and a different size exit surface through which the treated gases emerge from the media; - circulation of gas in the media during rotation; and recovering a liquid such as oil at a distance from the axis of rotation, the method being characterized in that the direction of the step of circulating the gas in the media is a sense of relative to the axis of rotation. BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the invention will become apparent from the following description of several embodiments, given by way of non-limiting examples, with reference to the accompanying drawings, in which: FIG. 1 is a diagrammatic view of vertical section of the separation device according to a first embodiment according to the invention; - Figure 2 is a schematic vertical sectional view of a second embodiment of the device according to the invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION In the various figures, identical references indicate identical or similar elements. With reference to FIGS. 1 and 2, the separation device 10 makes it possible to separate the liquid (and possibly solid) parts from the gases coming from the internal combustion engine casing and which are directly coming from the casing. The separation device 10 is typically part of a motor subassembly with a connecting line joining the air intake. As can be seen in each of FIGS. 1 and 2, the separating device 10 is disposed at the end of a shaft 11 which is directly or indirectly rotated (pinion) by any drive member. rotation of the timing case, such as crankshaft, camshaft or chain tensioner. The rotational drive can also be obtained by one of the members related to the distribution, such as a pulley, the high-pressure diesel pump, the alternator, the air conditioning compressor, the water pump. The drive can still be performed by an electric motor (not shown) independent of the motor to

10 internal combustion or by a hydraulic motor linked to the oil pressure. The separating element 100 has a static type separation capability, thus operating even in the absence of rotation or similar movement. This separating member 100 consists of a media cartridge having an ability to coalesce oil particles. It is mounted on the shaft 11 detachably or as an integral part of this shaft 11. The axis of rotation A defined by the shaft 11 is typically a horizontal axis but may have any other orientation. The media 12 has a symmetry of revolution with respect to the axis of rotation A. This medium 12 comprises in particular at least one input surface 12a, through which the untreated gases G arrive in the upstream zone Z1, and at least an outlet surface 12b, through which the purified gases GP emerge. The media 12 extends between these two surfaces, with a thickness and a composition adapted to the desired efficiency and the tolerable pressure drop. The media 12 is of the coalescer type with, for example, an arrangement of folds of pleated straight, curved, chevron or rolled type. In the downstream zone Z2, the purified gases GP flow sinuously to the outlet S which communicates with the air intake. The inlet section or surface 12a corresponds to the inner cylindrical surface of the media 12 coalescer, that is to say the proximal surface relative to the axis A. This input surface 12a is less extensive than the exit surface 12b distal, these two surfaces (12a, 12b) being preferably cylindrical. It will be understood that the untreated gases G will follow inside the media 12 a path that moves away from the axis A and thus undergo the effect of the centrifugal force inside this medium 12 when the element separator 100 is rotated.

As shown in FIGS. 1 and 2, the separating element 100 comprises two flanges (13, 14) between which the media 12 is fixed. The flanges (13, 14) may have the same diameter which corresponds to the apparent diameter. d2 of the separating element 100. In no way limiting, the preferred form of the media 12 is annular. Other forms, in particular forms that are partially annular and / or symmetrical with respect to the axis of rotation A can also be used. The shape must have in all cases at least one proximal inlet surface 12a and at least one distal outlet surface 12b. With reference to FIG. 1, the separation device 10 may have a generally cylindrical shape centered on the axis A. A cylindrical cavity is defined inside this device 10 and communication channels are provided to allow circulation of the untreated gases G from the crankcase to the coalescer media 12, via a central recess 15 in the shaft 11. This recess 15 forms the part of the upstream zone Z1 in which the crankcase gases G are brought into contact with the input surface 12a of the media 12. The circulation through the rotating separating member 100 can therefore be from the inside to the outside.

To pass a fluid from the upstream zone Z1 which communicates with the crankcase to the downstream zone Z2 v, it is necessary to pass through the media 12 of the separating element 100. In the example of FIGS. 1 and 2 a dynamic seal 16 in contact with the shaft 11 forms an interface between the stator part and the rotor part, making it possible to separate the upstream zone Z1 from the downstream zone Z2 of the device 10. The dynamic seal 16, fixed for example in a throat of the wall P of the stator part, thus ensures a rotating seal between the stator part and the rotor part. The rotor part comprises the element of

10 and the shaft 11, while the stator comprises the enclosure or cover C which surrounds the separating element 100. The cover C can optionally be detached from the wall P through which the shaft 11 passes. .

This cover C has at a low point an oil collection zone expelled downstream of the separation element 100. As can be seen in FIGS. 1 and 2, the casing gases G loaded with aerosols oil enter the separation device 10 via one or more openings 20 for communication with the internal recess 15 of the shaft 11. The wall P is also devoid of radially offset gas passage holes G. The gases G must therefore enter axially into the cavity, via the axial orifice of the wall P allowing insertion of the shaft 11 into the cavity of the device 10. The casing gases G emerge from the shaft 11 via means passageways 21 which open on the input surface 12a of the media 12. These passageways 21 are formed radially and are located between the two flanges (13, 14). At the outlet of this medium 12, emerge treated gases GP, as well as drops of HG oil whose size is large enough to withstand the centrifugal force associated with the rotation of the rotor part about the axis A. Fibers media 12 allow the coalescence of the oil microdroplets arriving on the upstream side Z1 by interception, sedimentation, inertial impact or Brownian diffusion on the fibers, so that the oil particles must regroup to form larger drops HG which they can be pushed by the gas flow combined with the centrifugal force to the outer surface 12b of the coalescer media. The media 12 provided with such fibers thus has a function of coalescing the oil. Thanks to the centrifugal effect, drops of HG oil of large mass are expelled radially towards the

13 The peripheral wall 22 of the lid C. The treated gases GP are guided towards a passage which diverges with respect to the path of the oil drops HG. At the distal exit surface 12b (outer perimeter), the section of the coalescer media 12 is large, so that the treated gases GP are slowed down and can therefore more easily flow without turbulence in the downstream zone Z2. Guiding of the treated gases GP is permitted thanks to the presence of guiding walls 22, 23 of the cover C. The treated gases GP which circulate inside the cavity delimited by the cover C and the wall P thus follow a path towards the outlet S, while the oil drops HG flow essentially by gravity along the peripheral wall 22 of the cover C. It is understood that the heavy phase formed by the oil drops HG effectively separates from the light phase formed by the GP treated gases and that there is no oil re-entrainment to the outlet S. The oil drops HG simply evacuate by gravity to the drainage pipe 24. The film of oil is not rotated, the peripheral wall 22 being fixed. The return to the sump of the drained oil can be done in two ways. Either the oil descends via a flexible pipe or any drainage pipe 24 opening below the oil level, as shown in FIG. 2. Either the oil is stored in a tank forming a buffer tank which empties when it is stopped. via a valve 27, as shown in FIG. 1. The valve 27 is, for example, elastically deformable so as to allow the collected liquid to be drained through a drainage pipe 24. In a preferred embodiment, during operation of the engine, the difference in pressure maintains the resilient member of the valve 27 against a bearing surface of the manifold tank 26. When stopping the engine, the pressures are balanced and, under the weight of the oil contained in the

14 tank 26, the elastic member moves away from the bearing surface, which allows the oil to flow to the engine oil sump. In the embodiment of Figure 1, the valve 27 is described in a non-exhaustive manner as elastic / with an elastically deformable component. Without restriction of the invention, the valve 27 may be elastic (leaf spring or mushroom elastomer) but also mechanical (for example a ball or pad that is plate to the drain port by suction effect).

The device 10 will now be specifically described in connection with Figure 1. One of the flanges, called the first flange 13, has a central portion which closes an end of the hollow shaft 11 and a peripheral portion which supports the media 12 coalescer. The second flange 14 is drilled in the center to allow the passage of the shaft 11, an O-ring 28 can be inserted between the flange 14 and the shaft 11. In the embodiment of Figure 1, the cover C in a restricted angular sector, for example less than 90 °, an additional volume corresponding to the collection tank 26. The positioning of the lid C is such that the tank 26 forms a bottom of the cavity in which is placed the separating element 100. The output S in communication with the air intake is produced by an outlet cannula 30 substantially horizontal and aligned with the shaft 11. The outlet of this outlet cannula 30 is vis-à-vis the first flange 13 of the separating element 100. More generally the outlet cannula 30 which emerges the treated gas GP may be placed axially or as close as possible to the central axis A of the device 10, in order to protect against project oil ions at the periphery of the rotor part. The embodiment of FIG. 2 differs from that of FIG. 1 in particular by the position of the

15 passages for supplying oil-cooled crankcase gases G in the vicinity of the medium 12. In the example of FIG. 2, the crankcase gases G enter the upstream zone Z1 via an axial outlet of the recess internal 15 of the rotation shaft 11. A pipe 41 of the stator portion of the separation device 10 may comprise a cylindrical element 42 coaxial with the shaft 11 and serve to bring the casing gases G inside the internal digging 15. A rotary seal is provided via the dynamic seal 16 between the cylindrical member 42 and an end 43 of the shaft 11. This seal 16 and at least a portion of the cylindrical member 42 can separate the arrival passage of gas G in the upstream zone Z1 of the discharge passage of the downstream zone Z2. In contrast to the output S, an additional dynamic seal J is provided between an axial rotary drive member and the wall P of the stator portion. This wall P is typically perpendicular to the axis A of rotation. The axial rotational drive member may be a shaft portion removably attached to a shaft 110 of a drive system. One or more screws 51 may be used for this attachment. The separating element 100 can in this case be removably removed from the cavity of the separating device 10.

This can be opened by removing the lid C. The pipes 42, 44 and the peripheral wall 22 are an integral part of this cover C. An O-ring 52 ensures, for example, the sealing of the fastener between this cover C and the wall P, in addition to the dynamic seal J which encloses the shaft 110 of the drive system. Due to the axial position of the cylindrical element 42 of the supply line 41, the exhaust duct 44 can be circumscribed in an area close to the axis A (at short distance d1) and which does not extend not radially beyond the outlet of the medium 12. The downstream zone

Z2 then comprises a first volume at the periphery of the media 12 in which oil is projected towards the peripheral wall 22 and a second volume axially offset relative to the first volume and which corresponds to a narrowing section of the downstream zone Z2 . Inside this second volume, the purified gas GP can join the conduit 44 for evacuation, for example formed of a bent exit cannula, without being contaminated by splashing oil drops HG.

The oil is recovered at the bottom of the peripheral wall 22, where the drainage pipe 24 is provided. The separation element 100 may have a cylindrical shape as in FIG. 1 and be enclosed in a cylindrical cavity delimited by the peripheral wall. 22.

Moreover, as can be seen in FIG. 2, blades 50 can be formed on the shaft 11 and / or on a flange of the separation element 100. Such aerodynamic elements to create a suction effect can be placed, depending on the orientation of the blades 50 and the direction of rotation of the shaft 11, either near the outlet S, or opposite to the outlet S. The suction thus created allows a decrease the pressure drop of the separation member 100 at low rotational speed and high gas flow rates. The blades 50, optional, may be formed integrally with the second flange 14, for example by molding. It is thus possible to provide a separating element 100 of removable type with or without blades 50. The rotor part of the device 10 may comprise a drive connection with a programmable speed electric motor. The speed of rotation is thus adjustable according to the relevant parameters. If the drive system is connected to the crankshaft, it is understood that the speed of rotation can be that of the engine speed (maximum: 5000 rpm for a diesel engine, 7000 rpm for a gasoline engine, 10000 rpm for a

17 motorcycle engine). If the system is linked to a camshaft, then the rotational speed corresponds to half that of the engine speed (therefore low at idle: about 400 rpm and at most typically 2500 rpm).

When the drive system is driven by a Pelton wheel, the rotational speed is a function of the oil pressure and thus the engine speed. Such a drive connection can be adapted for the systems mounted in the oil filter module since the oil is available at the pressure at the pump outlet. When another rotating member is used, the speed of rotation is generally a function of tooth or pulley ratio but is always proportional to the engine speed. The efficiency of the process for purifying the casing gases G according to the invention is less affected by a decrease in the speed of rotation than the efficiency of the separation mode, so that the choice of the drive system is wider. . One of the advantages of the dynamic coalescer according to the invention is to allow a very efficient separation of the crankcase gases by reducing the pressure losses associated with the presence of oil relative to a static coalescer. In addition, this efficiency can be obtained with a coalescer media of conventional type, without oleophobic treatment, for example, and without depending on a speed threshold of rotation of the drive shaft. Moreover, with an electric motor, it is allowed to modulate the rotational speed in particular according to the engine speed, the crankcase pressure (for example by having a pressure sensor), a fuel economy strategy. energy (rotation only 5 minutes every 1000 km) and other relevant parameters as required. Another advantage of a device according to the invention is that it can be placed outside the timing case, so that it is no longer subjected to

18 splashes and massive oil arrivals. This results in fewer peaks of pressure loss and better evacuation of the oil. It should be obvious to those skilled in the art that the present invention allows embodiments in many other specific forms without departing from the scope of the invention as claimed.

Claims (9)

REVENDICATIONS1. Device (10) for cleaning a gas coming from an internal combustion engine casing, comprising on the one hand a rotor (11, 100) rotatably mounted about an axis (A) and incorporating a separating element (100) with a coalescer media (12), and secondly a stator including a drain line (24) of a liquid such as oil and at least one peripheral wall (22) around the rotor (11). , 100), the stator having an outlet (S) for discharging treated gases, the separating element (100) delimiting an upstream zone (Z1) of untreated gases (G) communicating with the crankcase and a zone downstream (Z2) treated gas (GP) communicating with the outlet (S), the media (12) extending around an interior volume through the axis (A) of rotation of the rotor, characterized in that the upstream zone (Z1) is delimited by an inner surface (12a) of the media proximal to the axis (A), while the downstream zone (Z2) is delimited by an outer surface e (12b) of the distal media with respect to the axis (A), and in that the drain line (24) is arranged on the downstream zone (Z2) side, at the periphery of the rotor (11, 100), to allow liquid to flow through the media (12). 2. Device according to claim 1, wherein the stator comprises an enclosure (C, P) enveloping the separating element (100) and having at a low point a tank (26) for collecting a liquid, the drainage pipe (24) being positioned substantially at a bottom of the tank (26). 3. Device according to claim 2, wherein the enclosure comprises a wall (P) and a cover (C) defining a cavity for housing an end of the rotor, the rotor being driven from outside the cavity and passing through an orifice. of the wall (P) centered on the axis (A) of rotation, said wall (P) being devoid of passage openings for gases around the orifice and said cover (C) being devoid of openings radial passage for gases on the periphery of the rotor. 4. Device according to one of claims 2 and 3, wherein the tank (26) comprises a collector valve (27) for purging the collected liquid through the drainage pipe (24). 5. Device according to one of claims 1 to 4, wherein the separating element (100) comprises two flanges (13, 14) between which is fixed the media (12), at least one of the two flanges being snapped into a tube hollow aligned with the axis (A) of the rotor. 6. Device according to one of claims 1 to 5, wherein the output of the stator comprises a pipe (44) substantially parallel to the axis of rotation of the rotor. 7. Device according to one of claims 1 to 6, wherein the rotor comprises blades (50) integral with a shaft (11) for rotation about the axis (A) and / or a flange (13, 14 ) of the separating element (100). 8. Device according to one of claims 1 to 7, wherein the rotor is rotated by a programmable rotational speed electric motor. 9. A method of cleaning a gas from an internal combustion engine casing, comprising the steps of: - rotating about an axis (A) of a separating element (100) including a media (12) coalescer, the media having an inlet surface (12a) interfacing with untreated gases (G) from the engine housing and an exit surface (12b) of different size, through which the treated gases (GP ) emerge from the media (12); - Circulation of gas in the media (12) during rotation; and recovering a liquid such as oil at a distance 21 from the axis of rotation (A); characterized in that the direction of the step of circulating the gas in the coalescer media (12) is a direction away from the axis of rotation (A) and is chosen such that the entrance surface (12a) of the media is smaller than said output surface (12b).