Device for separating oil from gas in the crankcase of an internal combustion engine

Disclosed is a device for purifying gas from a crankcase of an internal combustion engine, which includes: a transfer wall having a wall portion with a least one narrow accelerated-distribution opening; one gas-flow deflection wall placed behind the transfer wall and defining an impingement and guide surface; an auxiliary opening separate from the narrow opening, made in the transfer wall; and a bypass valve movable to meet a return member and provided to close the auxiliary opening via closure element for moving closer to the surface, the return member extending in the impingement chamber and having a portion that pushes behind the auxiliary opening in the event of overpressure upstream of the transfer wall.

FIELD OF THE INVENTION

The present invention relates to devices for separating particles in suspension in a gas originating from a crankcase of an internal combustion engine. The scope of the invention relates in particular to the separation of oil from crankcase gases in combustion engines for road vehicles (for example cars, trucks, motorcycle) or boats and in industrial combustion engines (engine-generator for example).

BACKGROUND OF THE INVENTION

In known manner, the crankcase is connected to the air intake of the internal combustion engine via a separation device in order to continuously evacuate the crankcase gases and extract the suspended oil. This is what is known to the skilled person as the crankcase gas or blowby gas recycling system. Various means for separating oil from crankcase gases are used in the prior art, among which are cyclones, baffles, or similar systems with multiple changes of direction, centrifugal separators, static colaescers and dynamic coalescers. There are also impingement separator systems. In this latter family, the systems comprise a set of calibrated holes or similar acceleration openings facing an impingement (or collision) plate. The crankcase gases are accelerated when passing through the holes. The oil droplets are thus accelerated and flung against the impingement plate.

In impingement separator systems which have an impingement plate, the oil droplets flung at high speed agglomerate on the surface of the plate to form a film of oil. The speed is then reduced by an enlarged flow area and the oil film drips towards the discharge system. An alternative is to attach a coalescing or similar nonwoven felt on the impingement plate to cause coalescence of the finer oil droplets before they hit the plate. This has the effect of significantly increasing effectiveness in separating the oil mist. Impingement separators offer a better compromise between efficiency/pressure loss than cyclone separators. However, the pressure loss in these systems may be high in cases of increased gas flow rate.

Some systems also include a valve allowing a greater flow rate, sensitive to pressure, in order to partially bypass the acceleration openings made in a transfer wall (wall preceding the impingement plate). The flow rate of crankcase gases is typically higher at the end of a separators service life (for example double or triple the nominal flow for a new engine).

Solutions that allow increasing the flow rate are therefore of interest in order to limit the pressure loss at the transfer wall. For example, FIGS. 2a-2c of U.S. Pat. No. 7,799,109 show a transfer wall placed facing an impingement plate and provided with a plurality of openings for accelerating the flow of blow-by gas. A valve of flexible material is provided which is deformed to define an auxiliary opening of large cross section when a pressure threshold (overpressure) is reached upstream of the transfer wall.

This type of solution has limitations, however, notably because of the temperature sensitivity of the flexible material and because, even at low flow rates, the valves may have a slightly open state (the closure being progressive). Poor separation performance may then be observed, especially during transition phases. In addition, a closure portion of flexible material can often wear out quickly (risk of wear).

There is therefore a need for an efficient separation of oil from crankcase gases by impingement (the ultimate purpose being to improve engine durability), while taking into account flow rate variations over time.

Known from document US2013/0032115 A1 is the use of non-hermetic valves which have openings formed in the movable element (partial closure element). Regardless of the position of the valve, the gases circulate in a region behind the valve where a coil spring is placed. This type of valve has stability problems in an environment that is generally subject to vibration. In some embodiments (see FIGS. 8 and 9 of US2013/0032115 A1) it is arranged to guide the closure element in order to stabilize the valve. In this case, it is necessary to provide a complex seating of at least two parts and there is more friction between the valve and the transfer wall, which subjects this system to premature wear or makes it less effective.

OBJECTS OF THE INVENTION

The present invention aims to overcome one or more of the above disadvantages by providing a device for removing the oil from gases originating from a crankcase, which remains simple in design and is simple to integrate while offering a good compromise between pressure loss and separation efficiency.

To this end, the invention relates to a device for purifying gas from a crankcase of an internal combustion engine, intended to be interposed between a blow-by gas inlet and a purified gas outlet, comprising a separation section for separating oil from the gas flow, this separation section comprising:a transfer wall which comprises a stationary wall portion having at least one accelerated distribution opening, preferably a plurality of accelerated distribution openings, allowing the gas flowing in the inlet to pass through the transfer wall;a gas-flow deflection wall positioned in an area of passage for at least one gas flow having passed through said at least one accelerated distribution opening;an auxiliary opening separate from the accelerated distribution opening or openings made in the transfer wall;
the device comprising a valve biased by a return member towards a closed position so as to close the auxiliary opening, the valve comprising a movable closure element, the return member being configured to allow all or part of the closure element to approach an oil guiding surface of the deflection wall in case of overpressure at the inlet side, preferably such that the closure element is in a position away from the transfer wall.

With this arrangement, the auxiliary opening (wider than the narrow openings for the accelerated distribution) defines a passage bypassing the accelerated distribution opening or openings in case of overpressure at the inlet side. The return member allows reliable and repeatable closure of the low-flow auxiliary opening. In addition, the closure element and oil guiding surface (impingement and guiding surface) positioned close together define a bypass that lengthens the travel distance by very little or not at all in comparison to the gas flow through the accelerated distribution openings. A more compact device can thus be obtained. The guiding surface of the deflection wall typically extends to a lower edge and uses gravity to guide the oil to an oil drainage line.

The return member is preferably arranged in an area behind the auxiliary opening, on the deflection wall side. The return member comprises one or more connection portions connected to one among the deflection wall and the stationary wall portion, the return member further comprising at least one end integral to the closure element. The return function may be obtained by an elastic return structure, a structure of magnetic repulsion between two complementary members, or by another functionally similar structure. Preferably, the return member extends between two connection points: one with the closure element which closes off the auxiliary opening from the rear, and the other with the deflection wall. With this arrangement, it is possible to obtain a particularly stable valve (despite an environment subjected to many vibrations) and thus improves the closure of the auxiliary opening.

According to one feature, the closure element has a larger cross-section than the flow area defined by the auxiliary opening, in order to hermetically seal the auxiliary opening in a state where it bears against a valve seat, the valve seat preferably being defined by an annular region bordering the auxiliary opening. It is understood that the closure element can be defined by an unpierced element.

According to one feature, the transfer wall is adapted for directing towards the deflection wall, in a single general direction of flow, the blow-by gas arriving through the inlet (direction defined at least in the no-overpressure configuration). The deflection wall extends crosswise to this single general direction of flow of loaded gas. In this case, the transfer wall (which is typically in the form of a non-annular plate) can be simple in design and mounted simultaneously with the deflection wall in a line of a cylinder head cover. It is understood that the respective openings made through the transfer wall thus define directions of flow with a same general orientation towards the guiding surface of the deflection wall, which is not the case for example with a cylindrical wall having openings allowing a centrifugal flow of gas in different directions.

According to one feature, the device comprises the inlet and the closure element extends parallel to the stationary wall portion and has an annular edge, the valve preferably comprising a rod which extends perpendicularly to the stationary wall portion, opposite the inlet, from an inner face of the closure element. It is understood that the closure element bears on the periphery of the auxiliary opening which defines a valve seat. The valve may advantageously be guided by the rod. More generally, it is understood that the valve is a check valve and is movable by a thrust directed towards the deflection wall.

As indicated by the term “stationary”, it is understood that the wall with the passages is neither movable nor deformable, so that the accelerated distribution opening(s) have a (calibrated) size and shape that are predetermined independently of the variations in pressure or temperature conditions in the cylinder head cover area or similar area for integration of the device.

In a preferred embodiment, the separation section comprises at least one baffle extending at the periphery of the closure element so as to direct towards the deflection wall, in the position of the closure element that is distanced from the seat, all or part of the flow of loaded gas passing between a boundary edge of the auxiliary opening and the annular edge. This arrangement allows the separation of oil from flows bypassing the narrow openings, by impingement on the deflection wall.

In various embodiments of the device for purifying crankcase gases according to the invention, at least one of the following arrangements may possibly be used:The baffle is integrally formed with the stationary wall portion and preferably has a plurality of projections which protrude parallel to a central axis of the auxiliary opening.The projections are configured in two sets, so as to define first baffles radially closest to the annular edge and second baffles radially furthest from the annular edge, said first and second baffles being arranged so as to alternate.The return member is an elastic return member, located entirely between the transfer wall and the deflection wall or extending to an end positioned further rearward than the oil guiding surface (a mounting on the rear side, in the impingement chamber, allows repeatability in obtaining the same closure configuration and provides very good valve stability despite the engine vibrations; in options with translation of the closure element, it is advantageous for stability to form a housing in a sufficiently long guide channel, which preferably extends further back than the impingement area).The separation section further comprises at least one outlet section on the deflection wall side, which opens into an oil discharge channel, the outlet section being defined by an end edge of the deflection wall which extends between two opposite and distanced ends of the deflection wall.The gas-flow deflection wall is in the form of an impingement plate which extends parallel to the stationary wall portion, an inner space being defined between the transfer wall and the deflection wall.The valve is guided in translation in a housing receiving one end of the return member, the housing being secured to or formed by the impingement plate.The deflection wall comprises a smooth or ribbed plate, preferably covered with coalescing media on the inner space side.The deflection wall is covered with nonwoven media on the inner space side.A plurality of accelerated distribution openings are provided in the stationary wall portion, the auxiliary opening being oval, oblong, or circular and defining a maximum diameter D2, the following relation being satisfied:
D2/D1>4.5
where D1represents a maximum diameter of one of the accelerated distribution openings.The closure element bears against an inner annular face of the transfer wall (this face thus facing the deflection wall and extending at a first distance from the deflection wall), the stationary wall portion being arranged at the end of a projection which protrudes toward the deflection wall from the inner annular face, such that the accelerated distribution opening extends at a second distance, less than the first distance, from the deflection wall.The transfer wall also comprises an auxiliary accelerated distribution channel, preferably parallel to a central axis of the auxiliary opening, which extends through the transfer wall between a first end defining an access opening and a second deformable end facing the deflection wall, the second deformable end being adapted to define a flow area that increases in size due to deformation of the second end when the alas flow rate increases in the inlet (with this type of distribution, one can combine two different methods of gradually increasing the flow rate, in the same transfer wall which is typically flat).At least one among the transfer wall and the deflection wall comprises attachment members distributed around the auxiliary opening and extending parallel to a central axis of the auxiliary opening, in order to maintain a predetermined spacing between the transfer wall and the deflection wall, at least one of the attachment members traversing a layer defined by a fibrous material, preferably a nonwoven material.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

In the various figures, identical references indicate identical or similar elements.

Referring toFIG. 2, the separation device1serves to separate liquid (and possibly solid) components from gases originating from the crankcase of an internal combustion engine and which come directly from the crankcase. An inlet2for oil-loaded gas can extend to an outer face3aof a transfer wall3that is part of the separation device1. The separation device1is typically part of an engine sub-assembly with a connection back to the air intake. A purified gas discharge line4is formed in this sub-assembly, here at a level at least as high as the transfer wall3. The line4is preferably directly connected to the connection which rejoins the air intake. At a level that is typically lower than the transfer wall3, downstream of the transfer wall3, a channel5for discharging the separated oil6is provided.

By way of non-limiting example, the separation device1may be located in a line CC of a cylinder head cover, in a motor vehicle. The separation device1has, between the inlet2and the line4, a separation section8for extracting oil from the gas flow F supplied by the inlet2.

As can be clearly seen inFIGS. 1, 5, and 9, the separation section8comprises:the transfer wall3which here defines a first end8aof the separation section8, the outer face3adefining an area Z1upstream of the separation;a gas-flow deflection wall10, which here defines a second end8bof the separation section8, an outer face10b(opposite to the transfer wall3) and/or an outer edge10cof the deflection wall10defining an area Z2downstream of the separation.

The transfer wall3comprises a stationary wall portion12having at least one accelerated distribution opening14a, and preferably several accelerated distribution openings14a,14b,14c,14d, allowing the gas flowing in the inlet2to traverse the transfer wall3. An acceleration effect is achieved due to the small flow area of these openings14a,14b,14c,14din comparison to the flow area of the outer face3aof the transfer wall3. The general direction of flow on the outlet side of the openings14a,14b,14c,14dmay be substantially the same, as illustrated by arrow25inFIG. 1(single direction of orientation in the absence of overpressure).

With reference toFIGS. 1 and 6-7, the transfer wall3allows orienting, in a single general direction of flow, the loaded gas arriving through the inlet2. In this example, the stationary wall portion12is placed at the end16aof a projection16which protrudes toward the deflection wall from the inner annular face. The stationary wall portion12is placed at the end16aso as to define a face which is substantially flat and close to the deflection wall10. It is understood that the deflection wall10extends crosswise relative to the single general direction of flow of the loaded gas. In this non-limiting option, the deflection wall10extends perpendicularly to a longitudinal axis A defined by the projection16and possibly parallel to the stationary wall portion12.

More generally, the deflection wall10is placed in an area of passage for at least one gas flow having passed through one or more accelerated distribution openings14b,14c,14dformed in the transfer wall. Impingement on the deflection wall10enables the separation of oil droplets6, which then flow due to gravity to the discharge channel5. The deflection wall10is for example in the form of an impingement plate (possibly resulting from an assembly of multiple plates), which extends parallel to the stationary wall portion12.

At least one outlet section is provided on the lower side of the deflection wall10to avoid any lasting retention of oil within the inner space V along the oil guiding surface20. The output section of the separation section8leads to the channel5, as can be clearly seen inFIG. 2. The output section may be defined by the edge10cextending between two opposite and distanced ends17a,17b(seeFIG. 4) of the deflection wall10. The edge10cmay be longer than the opposite upper edge10d(seeFIG. 4in particular), so that the output section is a section that is typically wider in comparison to the distribution area of the accelerated distribution openings14a,14b,14c,14d. This slows down the flow at the outlet section and reduces turbulence (minimizing the risk of entraining oil droplets6to the gas discharge line4).

Within the inner space V defined between the transfer wall3and the deflection wall10, the loaded gas passing through openings14b,14c,14dis directed onto an oil guiding surface20of the deflection wall10, here in a substantially horizontal direction. This inner space V therefore corresponds to an impingement chamber, with no intermediate partition between the transfer wall3and the deflection wall10. The surface20extends downward here, preferably vertically, to a lower edge defined by the outer edge10c. This surface20allows the oil to be guided by gravity. Media allowing the oil droplets to enlarge by coalescence or any other suitable porous media may be part of the deflection wall10, defining the guide surface20. It is understood that the deflection wall10may thus include nonwoven media21on the inner space V side. In some embodiment options, the deflection wall10comprises a smooth or ribbed plate, preferably covered with nonwoven coalescing media21on the inner space V side. Of course, options without media in the deflection wall10may also be suitable.

Referring toFIG. 2, the separation section8forms a boundary between the upstream area Z1of untreated gas F in communication with the engine crankcase, and the downstream area Z2of treated gas GP in communication with the outlet via the line4. The untreated gas F loaded with oil mist entering the separation device1via the inlet2hits the deflection wall10, with impingement for the liquid phase, and exits from the lower side of the separation section8, here by traversing the nonwoven media21or similar media. Inside the media21, it is understood that the oil droplets6in contact with the fibers of the media21join together to form larger drops which are then pushed by the gas flow and gravity towards the lower area with the channel5. Media21provided with such fibers thus perform a coalescence function for the oil.

The treated gas GP is guided to a passage, here defined by the line4, which diverges from the path of the oil droplets6in order to protect against oil splashes on a lower face located directly above the lower edge10c.

When the separation section8is integrally secured to a cylinder head cover9of an internal combustion engine, the transfer wall3can be mounted in the head cover9so as to form a fluidtight barrier which prevents the return, into the inlet2, of gas redirected due to impingement against the deflection wall10. In particular, the peripheral edge of the assembly or single piece forming the transfer wall3can be fixed to a first assembly interface I1which forms a first frame without leaving a bypass. A peripheral annular groove G can thus be defined to engage with the first interface I1.

For the deflection wall10, it can be defined by an impingement plate having more than half its circumference continuously fixed in a sealed manner to a second assembly interface I2. The remaining portion of the edge corresponds in particular to the outer edge10cand extends to a distance from a bottom allowing the flow of oil droplets6,6′ where the channel inlet5may be formed.

Referring toFIGS. 3 and 4, one can see that the separation section8can be the result of assembling three elements, here parallel (which then each extend perpendicularly to the single orientation defined by the opening or openings14a,14b,14c,14d);the transfer wall3, which may be rigid and obtained by molding a plastic or composite material;a support S such as an impingement plate, of rigid plastic and/or optionally another rigid and lightweight material (for example aluminum), defining a non-deformable rear layer of the deflection wall10in the assembled configuration of the separation section8;an optional component such as a fibrous nonwoven media21, formed as a plate or other shape matching the shape of the support S.

At least one among the transfer wall3and the deflection wall10comprises attachment members31,32distributed around the auxiliary opening24and extending parallel to a central axis X of the auxiliary opening24, in order to maintain a predetermined spacing between the transfer wall3and the deflection wall10. In the example illustrated, at least one of the attachment members31,32is defined by a male member31extending from the inner face of the transfer wall3and passing through the layer defined by the optional element. Preferably, the nonwoven media21which constitutes the optional element has one or more predefined orifices33allowing the passage of male members31without damage to the nonwoven media21or similar material.

The support S has cavities32configured to guide and lock the male members31. Retaining lugs31aare for example formed on the free end side of these male members31, to lock the assembled position of transfer wall3and deflection wall10. When nonwoven media21is used, the male members31may have an axial shoulder31bwhich abuts against the surface of the nonwoven media21opposite to the support S. This holds the nonwoven media21in place against the support5, with no need for bonding. Assembly is simple, particularly because the transfer wall3is a molded plastic part that incorporates the male members31and can be attached quickly by snap-fitting onto the support S.

An auxiliary opening24provided in the transfer wall3and an exemplary associated valve15responsive to overpressure on the upstream side will now be described with reference toFIGS. 1 to 3 and 5-6.

The auxiliary opening24, separate from the accelerated distribution opening or openings14a,14b,14c,14d, is formed in the transfer wall3and has a wider cross-section than any of openings14a,14b,14c,14d. Without it being limiting, this cross-section may be oval, oblong, or circular, and a maximum diameter D2may be defined by the auxiliary opening24, as is clearly visible inFIG. 3. The valve15has a closure element30having a cross-section greater than the cross-section defined by the auxiliary opening24, preferably with an outer shape similar to its annular edge30a. The seat of the valve15is here defined by an inner annular face28(seeFIG. 1) of the transfer wall3. Although the opening24here is closed by a closure element30implemented as one piece, a comparable closure element30can also be obtained by assembling multiple parts.

The closure element30, which extends into the inner space V, is supported on a continuous annular seat area of this inner annular face28. It is understood that this seat area may be further away from the deflection wall10than the end16aof the projection16. The closure element30is movable and a return member36, which here has a fixed end37mounted to be integral with the deflection wall10, biases the valve15to a closed position where the closure element30closes the auxiliary opening24(complete closure in practice, in the absence of overpressure at the upstream area Z1side). As is clearly visible inFIG. 1, the closure element30may optionally extend parallel to the transfer wall3. The return member36is preferably placed entirely rearward relative to the auxiliary opening24.

In the example illustrated, while a guide track26can be defined parallel to the longitudinal axis A in the hollow portion of the projection16, to allow the openings14a,14b,14c,14dto be closer to the deflection wall10, auxiliary opening24may be defined at substantially the same level as the base16bof the projection16. Auxiliary opening24may be placed centrally in the transfer wall3, at a greater radial distance from the groove G or similar periphery than any longitudinal axis of the passage of the openings14a,14b,14c,14d.

It is understood here that there is longitudinal guidance for the loaded gas (gas-liquid mixture) on the upstream side of the transfer wall3for flows through openings14a,14b,14c,14d, which are smaller, while there is (preferably) no longitudinal guidance before the passage through the auxiliary opening24.

Such a configuration, with more space in the inner space V between auxiliary opening24and the deflection wall10(in comparison to the space at the accelerated distribution openings14a,14b,14c,14d), enables the placement of one or more baffles40,41,42at the periphery of the closure element30. Here, a side wall portion of the projection16defines all or part of a first baffle40, which optionally may continuously surround the closure element30, with a little spacing.

It is understood that the deflection wall10, here provided with nonwoven media21, may extend in a planar manner both facing the accelerated distribution opening(s)14a,14b,14and facing the auxiliary opening24. The return member36is typically surrounded by the first baffle40and the possible additional baffles, which allows directing and recentering the flow admitted through the auxiliary opening24toward the deflection wall10as illustrated by the arrows F2inFIG. 5, limiting the radial component of this flow. After impingement, a downward flow of gas relieved of particles is directed towards the exit.

By comparingFIG. 1andFIG. 5, one will understand that opening the valve15corresponds to a bypass function. Indeed, in case of overpressure in the flow F of untreated gas supplied through the inlet2, the spring or similar element which here defines the return member36is compressed with respect to its default position shown inFIG. 1, thereby defining a larger flow area for the untreated gas F. In other words, the auxiliary opening24defines a bypass around the accelerated distribution opening(s)14a,14b,14c,14din case of overpressure at the inlet2side. For example, a spring with constant K greater than 0.06 N/mm may be used. A rest length of approximately 20 mm may be suitable in this non-limiting case, in order to gain compactness.

More generally, the return member36is configured to allow all or part of the closure element30to move closer to the guiding surface20in case of overpressure at the inlet2side, preferably so that the closure element30occupies a position away from the transfer wall3. The fixed end37here bears against a shoulder or similar abutment100formed in a housing110defined by a recess or a through passage in the support S or similar rigid rear layer of the deflection wall10.

The return member36here biases the closure element30towards the closed position. The return member36here is a spring extending parallel to the central axis X, from the fixed end37to a movable end38which the closure element30or a slidingly integral projection bears against. The spring surrounds a rod300that extends from the closure element30(planar here) to the free end305, as is clearly visible inFIGS. 1 and 5. The free end305slides rearward through the housing110when the closure element30moves away from the auxiliary opening24. In case of overpressure of the untreated gas F, it is understood that the pressurized flow can push the movable end38(which is mounted to be integral with the closure element30) rearward. The closure element30is actuated and thus moves in a manner comparable to a pushbutton, in the same direction as the orientation of the gas in a configuration without overpressure.

The housing110is defined by a tubular face which guides the valve15as it slides. More generally, it is understood that the valve15is guided in translation in a housing110receiving preferably a fixed end37of the return member36. The housing110may be formed in a part integrally attached to the support S which here is formed by the impingement plate.

As can be seen inFIG. 1, the length L1of this housing110is much greater than the minimum thickness e of the deflection wall10, thereby stabilizing the valve15. The guidance parallel to the central axis X allows maintaining the orientation of the valve15despite engine vibrations. In one non-limiting embodiment, the length L1exceeds a fifth, and preferably a quarter, of the distance L4measured longitudinally between auxiliary opening24and the mouth of the housing110connecting to the inner space V. Preferably, length L1can be less than or equal to distance L4and/or the sum L1+L4can be less than 80 or 110 mm, preferably less than or equal to 30 or 40 mm, which in practice provides very good compactness for the separation device1. In the example represented here, the sum L1+L4is about 20 mm.

Referring toFIG. 6, one will also note that the diameter D2of the auxiliary opening4is typically at least equal to one third of the largest dimension of the transfer wall3, optionally without this diameter D2exceeding a threshold of 100 mm, and preferably a threshold of 60 mm. The auxiliary opening24can be closed by a surface area of the closure element that is greater than or equal to 120 mm2. These parameters can of course change, particularly depending on the space available in the impingement chamber. However, it is preferable that the characteristic dimension of the auxiliary opening24remains much larger than the size (here, diameter D1) of the openings14a,14b,14c,14d, which define a flow area for example that is less than or equal to 10 or 20 mm2.

If one also considers that D1represents the maximum diameter of one of the accelerated distribution openings14a,14b,14c,14d, the following relation can typically be satisfied:
D2/D1>4.5

The closure element30, which may be planar, here extends parallel to the stationary wall portion12in which are provided the one or more accelerated distribution openings14a,14b,14c,14d. When the valve15has a rod300received in a housing110of fixed guiding orientation, the rod300may extend perpendicularly to the stationary wall portion12.

Although the example illustrated inFIG. 1shows an axis of the rod300which is close to or coincides with the central axis X of the auxiliary opening24, an offset assembly can also fulfill the same return function, holding the closure element in its default position pressed against the inner annular face28. Thus, the rod300can also extend opposite the inlet2, not from a central portion of the inner face of the closure element30but from an area near the edge.

Furthermore, the biasing effect may alternately be obtained by an elastic blade and/or by magnetic coupling (possibility of having forces of attraction or repulsion in a longitudinal or radial direction). In an option with magnetic attraction by forces in a radial direction, one can use at least one first magnetic member integrated in the movable annular edge30aand at least one second fixed magnetic member integral to the transfer wall3and biasing the closure element30towards the closed position. In an option with magnetic repulsion in a longitudinal direction, it is sufficient to place two poles of the same nature facing one another. The rod300(without spring) and the associated housing110may possibly be preserved for the last two options, where appropriate with an abutment or shoulder100restricting the backward stroke of the valve15, which ensures good mechanical stability.

Referring toFIG. 6, one can see that a single baffle40of annular shape can define an impingement surface for part of the flow F of untreated gas entering the inner space V by the auxiliary opening24due to overpressure. In this case, the baffle40and the stationary wall portion12can be integral (formed as one part typically of plastic or aluminum).

In the variant embodiment ofFIG. 7, the baffle40is only defined by the projection16and thus only extends facing a portion of the closure element30, which represents between one third and one fifth of the full circumference of the closure element30. Optionally, there is provided a plurality of baffles41,42, defined by projections protruding parallel to the central axis X of the auxiliary opening24, which coincides in this non-limiting example with the axis of the rod300. More generally, a configuration with alternating baffles41,42around the circumference of the closure element30, with a difference in proximity between the sets of baffles, presents a significant advantage in limiting pressure losses while maintaining the effect of redirecting the gas flow toward the deflection wall10.

All or part of the projections can be configured into two sets, with first projections defining baffles40,41,41′ radially closer to the annular edge30a, and second projections defining baffles42radially further away from the annular edge30a. Here, baffles40,41and baffles42alternate along a circumferential region of the auxiliary opening24.

More generally, it is understood that the separation section8comprises at least one baffle40,41,41′,42extending along the periphery of the closure element30in order to limit diverging directions of flow and to direct towards the deflection wall10all or part of the loaded gas flow passing between a boundary edge24aof the auxiliary opening24and the annular edge30a.

Arrows F1, F2ofFIG. 5schematically illustrate the directions taken by the loaded gas when the closure element30is in the position away from the transfer wall3(under the effect of overpressure which pushes the closure element against one or more return members36). Oil droplets6′ are collected from some of the gases passing through the auxiliary opening24without requiring impingement against the deflection wall10. Such oil droplets6′ result from impingement with the baffle or baffles40,41,41′,42.

In addition, the guiding function of the baffles40,41,41′,42can also help direct the flow of loaded gas (partially relieved of oil by impingement against the baffles40,41,41′,42) in the same general direction as is obtained through the accelerated distribution opening or openings14a,14b,14c,14d, as shown by the arrows F2. The impingement against the deflection wall10, here preferably against the plate of nonwoven media21, allows separating the oil droplets6which fall vertically while being guided by the guiding surface20. A double impingement effect can thus be obtained without requiring an intermediate partition with other distribution openings.

As illustrated inFIG. 2, the inner space V communicates with the discharge channel5for the separated oil6, at a lower end of the separation section8. Although the accelerated distribution openings14a,14b,14c,14dhere are represented in a position opposite the lower end of the separation section8, preferably above a central axis of the auxiliary opening24, it is understood that the openings14a,14b,14c,14dmay be positioned otherwise while maintaining the same type of valve15.

An alternative embodiment of the valve15′ will now be described with reference toFIGS. 8 and 9.

The accelerated distribution opening or openings14acan be implemented as in the embodiments previously described, with or without closeness to the deflection wall10. The closure element30of the valve15here is kept in the closure position by one or more elastic return members36a,36b, so as to hermetically seal the auxiliary opening24. Each elastic return member36a,36bis formed of plastic with shape memory and here is integrally connected to the transfer wall3, on the annular face28at a location adjacent to the auxiliary opening24.

To improve stability, it is preferred to use a pair of spiral elastic return members36a,36bwhich are arranged symmetrically on opposite sides of the auxiliary opening24. The closure element30defines a non-deformable plate, and the elastic return members36a,36bare stretched toward the deflection wall10, as can be clearly seen inFIG. 9, when the pressure of the flow F of untreated gas increases. A fixed rod (not shown) secured to the deflection wall10may optionally form an abutment to define a maximum away distance of the closure element30. The surface S1, S2defined by each of the elastic return members36a,36bis deformed in a spiral at a predetermined angle. This guides the loaded gas in a spiral on two opposite sides of the closure element30. An elastic return member36bmay extend from the lower side in order to play a redirection role which prevents the downward gas flows from flowing directly beyond the edge10c, and/or a lower baffle member40may lie immediately adjacent to the auxiliary opening24in order play a redirection role as well.

The arrows F2′ indicate that the directions taken by the gas correspond to paths after impingement on the deflection wall10, here with droplets6coming in contact with the nonwoven media21or similar fibrous material. A configuration with at least one baffle40, preferably similar to the example illustrated inFIGS. 1 and 5, also enables obtaining droplets6′ by radial impingement on the baffle or baffles40. A compact, stable configuration is thus obtained, enabling at least partial separation when bypassing the accelerated distribution openings14avia the auxiliary opening24. Here also, the one or more return members36a,36b, which extend further into the inner space V relative to the auxiliary opening24, allow all or part of the closure element30to move closer to the impingement surface, typically planar, defined by the deflection wall10.

Of course, the valve15′ may also lie at the same level as openings14a,14b,14c,14dand is not necessarily of reduced size relative to the closure element30shown inFIGS. 1 and 5. The embodiment with one or more baffles40is preferred, to prevent some of the gas from following a path without deflection by the surface20between the auxiliary opening24and the area with the channel5(seeFIG. 2) which extends below the separation section8.

In another embodiment (not shown) adapted for the case where multiple auxiliary bypass openings can be used, the transfer wall3comprises valve15and also at least one among valve15′ and a channel having a flow area which varies according to the pressure in the upstream area Z1. The channel of variable flow area is defined by an additional accelerated distribution channel, which preferably extends parallel to a central axis X of the auxiliary opening24(optionally in the stationary wall portion12). The channel of variable flow area extends through the transfer wall3between a first end defining an access opening and a second deformable end (for example duckbill) which faces the deflection wall10. The second deformable end allows defining a flow area which increases, due to deformation of the second end, when the flow rate F of the untreated gas increases in the inlet2.

Regardless of the exact configuration of the closure system of the auxiliary opening24, one will appreciate that the arrangement of the transfer wall3with an auxiliary opening24located farther away from the impingement surface than the accelerated distribution openings14a,14b,14c,14dallows incorporating auxiliary deflection surfaces, here formed by the baffle or baffles40,41,42, which are advantageous for redirecting gas flows around a closure element30extending parallel to the deflection wall10and thus forming an obstacle (no possible short path of impingement in the impingement chamber without additional deflection in an area adjacent to the annular edge30a). It is preferred to form the baffles40,41,42by projections protruding parallel to the general direction of flow permitted by the openings14a,14b,14c,14dand to the central axis X. These projections protrude at least from a nominal surface level where the auxiliary opening24opens into the inner space V.

One advantage of the invention is good adaptation to a wide range of flow rates for the untreated gas F without complicating the separation section8, and enabling the separation of oil even in the bypass configuration that uses the auxiliary opening24of large flow area.

Another advantage of a separation device1according to the invention is that it can be placed in confined areas, typically in a cylinder head cover (having the advantage of being generally removable and detachable), for example in a constriction area or similar location outside the engine cover, so it is not subject to gushes or splattered oil. This results in fewer pressure peaks and better oil removal.

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. Thus, by way of example, the terms used to designate constituent elements of the separation section8may, as appropriate, correspond to one well-defined part or to an assembly of multiple parts.