WO2015018691A1

WO2015018691A1 - Oil mist separator

Info

Publication number: WO2015018691A1
Application number: PCT/EP2014/066230
Authority: WO
Inventors: Dimitri An; Niklas Kull; Yakup ÖZKAYA; Stefan Ruppel
Original assignee: Mahle International Gmbh
Priority date: 2013-08-07
Filing date: 2014-07-29
Publication date: 2015-02-12
Also published as: DE102013215611A1

Abstract

The invention relates to an oil mist separator (10, 11) comprising an inlet opening (12) for introducing an aerosol into the oil mist separator (10, 11), said aerosol containing a gaseous dispersion medium, in particular blowby, and oil dispersed in the dispersion medium, comprising a particle collecting container (13) for collecting the dispersed oil, comprising an outlet (14) for conducting the collected oil out of the oil mist separator (10, 11), and comprising a discharge opening (15) for discharging the dispersion medium out of the oil mist separator (10, 11), a flow path being formed between the inlet opening (12) and the discharge opening (15). The degree of separation is improved if the oil mist separator (10, 11) comprises a device for increasing a differential pressure between the introduced aerosol and the discharged dispersion medium, the differential pressure being increased by connecting the flow path to an additional pressure source. The invention further relates to a cylinder head cover (17) and an internal combustion engine (18) with such an oil mist separator (10, 11).

Description

Oil Mist Separators

The invention relates to an oil mist separator according to the preamble of claim 1. The invention further relates to a corresponding internal combustion engine.

The gas which strikes the engine room during compression in an internal combustion engine or piston compressor on the piston rings from the working space is known to the person skilled in the art as blow-by or blow-by. With optimum sealing according to the prior art, the blowby fraction amounts to about 0.5% to 2% of the total gas volume.

In the case of the internal combustion engine brings the Blowby next to a slight reduction in compression, the problem that during the combustion cycle hot and often contaminated with pollutants contaminated gas can get into the crankcase. For this purpose, conventional internal combustion engines include a venting of the crankcase, which typically opens into a so-called airbox or an air filter box. From there, the escaped gas can be sucked in the next working cycle of the internal combustion engine again to avoid unnecessary pollution of the environment by exhaust gas.

In addition to the pollutants typical of combustion gases, engine oil particles are also entrained in the venting of the crankcase. The introduction of blow-by gas into the intake tract thus threatens a heavy contamination of the throttle flap, turbocharger (ATL), valves and other components of the intake tract. In particular, ATL and intercooler can suffer in this way performance degradation and interference. Another unexpected The desired side effect of the blowby can be seen in the entrainment of unburned fuel residues, which cause a possible dilution of the engine oil, in particular during a cold start.

To reduce the adverse effects described so-called oil separators or oil mist are known in the exhaust gas purification technology to clean the blown off from the crankcase Blowby fine oil drops and other entrained aerosols and to avoid in this way contamination of engine components and malfunctions. Generic oil mist separators are designed, for example, as impact precipitators or, in the case of increased power requirements, as centrifugal separators. For example, EP 2021592 B1 discloses a vent for a crankcase, which in particular comprises a generic oil mist separator designed as a baffle separator.

A problem with these conventional oil mist separators lies in their limited degree of separation. In accordance with the terminology of process engineering, the effectiveness of the separation process used is referred to in the present context as the degree of separation or degree of separation. As a yardstick may serve the ratio of deposited by the Olnebelabscheider to the occurred in the Olnebelabscheider liquid amount or concentration.

The object of the invention is to provide an oil mist separator which, taking into account suitable framework conditions with respect to its size and complexity, has an improved separation efficiency. This object is achieved by a Olnebelabscheider with the features of claim 1.

The invention is therefore based on the idea of increasing the differential pressure between the aerosol of blow-by and oil particles introduced into the oil mist separator on the one hand and the dispersion medium remaining after the precipitation on the other hand. In this way, while largely dispensing with active components such as electrostatic precipitators or disk separators, the volume flow in the region of the inlet can be increased, so that when it flows through an oil separation unit arranged in the oil mist separator, the dispersed oil droplets absorb a larger amount of kinetic energy. Thus acts on the individual oil particles an increased inertial force, which leads to the adhesion of an increased number of particles on the particle collecting container and thus to an overall improved degree of separation at the Ölabscheide- unit. To increase the differential pressure, a flow path extending between the inlet opening and the outlet opening is connected to an additional pressure source. This pressure source is formed as a negative pressure source, with respect to the Ölabscheideeinheit downstream connection. In an upstream connection, the pressure source is designed as a pressure source. By connecting to the additional pressure source, the oil separator can have a higher flow resistance than pressure difference produced by the internal combustion engine.

Typically, the differential pressures in crankcase vents are about 20 hPa. This value is set in particular by pressure control valves. By using the additional pressure source, differential pressures of up to 80hPa can be generated. The additionally available differential pressure, which can thus be up to 60 hPa, is available to the oil mist separator for an improved separation result. An oil mist separator adapted in the manner described can preferably be designed as a baffle separator having a suitable number of nozzles in fluid communication with the inlet opening. Such an embodiment has the advantage of low structural complexity and size, since by means of an easy to implement deflection of the dispersion medium, the inertia force of the oil particles can be used to effect their settling on a suitably arranged baffle plate of the particle catcher.

In the present scenario, the differential pressure can be advantageously increased by an embodiment of the baffle having two, three or four nozzles. In this case, the gas volume flowing through the nozzles is distributed over a reduced overall cross-sectional area of the nozzles, which in turn leads to an increased volume flow with the described positive effects. A comparable result can be achieved by reducing the cross-sectional area of individual or all nozzles, as an alternative or in addition to the aforementioned measure with regard to the number of nozzles. An area between 6.3 mm ² and 12.6 mm ² proves to be particularly advantageous in this context.

With regard to the relative positioning of the nozzles of such an impact separator, an annular arrangement is recommended, so that the nozzles can wet the largest possible area of the impact plate. The expansion of this area allows the settling oil drops to gradually reduce their flow rate within the particulate collection vessel such that the proportion of entrained particulate matter in the direction of the exit orifice is minimized, again benefiting the overall device separation efficiency. In order to maximize the area of the baffle plate which can be used for the outflow of the separated oil, a circular design also serves the same. In this embodiment, a suitable opening can be provided near the center of the circular shape, which allows a controlled flow of the separated oil in the direction of the drain.

One of the described embodiment of the impact separator corresponding effect can be achieved in the case of a centrifugal separator by the appropriate choice of the area ratio between inlet cylinder, cone, dip tube and particle collecting container - the expert speaks in this scenario of a bunker.

For further optimization may serve an embodiment of the Ölnebelabscheiders, which includes an externally driven turbomachine in addition to the components mentioned. This component makes it possible to cover the increased energy requirement of the oil mist separator in view of the increased differential pressure by supplying additional kinetic energy to the dispersion medium. In this way, with regard to the differential pressure, work areas of the oil mist separator can be opened up, which can not be readily realized by means of the kinetic energy inherent in the aerosol introduced.

With regard to the turbomachine is to think of a configuration as a vacuum, in particular as a jet pump. Due to the considerable versatility of movable components, this embodiment proves to be particularly simple, robust and potentially maintenance and wear. Given the simple geometry and low mechanical stress, the proposed variant also allows the use of thermally and chemically resistant ger Spezialwerkstoffe, as they are familiar to the expert in the field of pumping technology. As an alternative to generating a sufficient volume flow at comparatively low power consumption, the turbomachine can be realized in the form of a fan.

A controlled outflow of the collected oil droplets also favors a design of the oil mist separator in the form of a filtering separator with a filter fleece, whose serving as a support filter bed for the discharge of separated oil is optimized. Depending on the filter used and its particle filter class, this arrangement makes it possible to achieve a constantly high, defined degree of separation of the oil mist separator. When used for venting an internal combustion engine, a filtering separator also has the advantage, in the case of a specific design, of a performance which is largely independent of the operating state of the engine and uniform over the entire service life of the filter.

In addition, in combination with an internal combustion engine, a design simplification and compact construction can be achieved by integrally forming the oil mist separator with a cylinder head cover of the engine. If the crankcase is connected by means of a vent line to the inlet opening of the oil mist separator, the result is an efficient venting of the crankcase with a small space requirement.

In an advantageous embodiment, the turbomachine, in particular the fan, is integtiert in the cylinder head cover. For this purpose, a bearing may be provided in the cylinder head cover into which the turbomachine is inserted and fixed with a cover. Other important features and advantages of the invention will become apparent from the dependent claims, from the drawings and from the associated figure description with reference to the drawings.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

Preferred embodiments of the invention are illustrated in the drawings and will be described in more detail in the following description, wherein like reference numerals refer to the same or similar or functionally identical components.

Show, in each case schematically,

Figure 1 is a partial view of a cylinder head cover with a Olnebelabscheider invention and

FIG. 2 is a sectional view of the cylinder head cover according to FIG

FIG. 1

The oil mist separator illustrated in FIG. 1 is composed of a coarse separator 10 and a fine separator 1 1 in fluid communication therewith, which are formed on a cylinder head cover 17. This cylinder head cover 17 forms the outer cover of a cylinder head, which limits the combustion space (not shown) of the designed as a reciprocating engine internal combustion engine 18 in the direction of movement of its oscillating piston. Any other components of the cylinder head, depending on the type and Model of the internal combustion engine 18, for example, inlet and outlet ports and valve control for the gas exchange operations, oil passages for the lubrication of the valve train, coolant passages, spark plugs, injectors or nozzles and glow plugs may include, are not shown for reasons of simplicity.

In the present scenario, the oil mist separator 10, 1 1 forms part of the ventilation system of a crankcase for the storage of the crankshaft of the internal combustion engine 18 which is fluidly connected via a substantially gas-tight vent line with an opening 12 provided on the coarse separator 10. About this vent line to the oil mist 10, 1 1 Blowby fed, which entrains dispersed as a dispersion medium engine oil droplets, which are generated by rotating components in the crankcase, from the crankcase. The described dispersion thus has the chemical properties of an aerosol whose engine oil concentration depends strongly on the medium pressure, the mutual pairing of cylinder, piston ring and bushing and the connection point of the vent line to the crankcase of the internal combustion engine 18.

The oil mist separator 10, 1 1 is designed as a inertial or impact separator. As such, the oil mist separator 10, 1 1 by means of a manifold or a baffle plate, the aerosol such that its phases are pressed according to their respective inertia different degrees to the outside of the manifold or the surface of the baffle plate. Regardless of the specific motor vehicle technical meaning of the term in the sense of an intake or exhaust manifold is to be considered in this context as a manifold any pipe section, which causes a change in direction of the aerosol by its curved shape. The higher density of the engine oil particles compared to acting as a dispersing Blowby causes a separation of the engine oil, which can be derived via a coarse separator 10 and fine separator 1 1 adjacent Partikelauffangbe- container 13 and associated with the latter sequence 14 separated from the blowby from the crankcase ventilation system. From there, the engine oil can be fed via a return, not shown again an oil pan screwed to the crankcase of the engine running as a four-stroke engine 18, where it may once again serve to lubricate moving machine elements.

In its state largely cleaned of engine oil, the blowby can be supplied via an outlet opening 15 provided for this purpose and an optional expansion valve approximately to an intake line of an exhaust gas turbocharger (ATL) of the internal combustion engine 18, thereby avoiding the emission of finer pollutant particles remaining. In order to increase the differential pressure of the introduced aerosol compared to the derived blowby according to the invention, is in the flow direction of the blowbys between the fine 11 and the outlet opening 15, a foreign-driven turbomachine 16 embedded in the piping system of the cylinder head cover 17, ie a fluid energy machine in which the energy transfer the blowby takes place within the line system primarily by a flow according to the laws of fluid dynamics by means of kinetic energy.

It is understood that the relative arrangement of the fine separator 1 1, the coarse separator 12 and the turbomachine 16 can be modified in other embodiments, without departing from the scope of the invention. Thus, the turbomachine 16 may follow directly in the flow direction of the aerosol to the inlet opening 12 or between coarse separator 10 and fine separator 1 1 may be provided. An integral training of coarse the 10 and fine 1 1 is not contrary to the idea of the invention.

The cross-sectional view according to FIG. 2 shows the turbomachine 16 installed in the cylinder head cover 17 of FIG. 1 in detail. In the present case, this has the shape of a fan, which is protected by a solid shell in the form of a plastic housing 20. A lower part of the plastic housing 20 is formed integrally with the cylinder head cover 17, while a cover 22 welded or mounted on the cylinder head cover 17 allows the possibility of exchanging or maintaining the turbomachine 16 as needed. The turbomachine 16 provided with an optional control electronics can be attached to the middle part of the plastic housing 20 for this purpose by means of a fastening element 21 - in the present embodiment as part of a screw connection. A corresponding bore in the region of a bearing 25 of the turbomachine 16 allows the production of a positive releasable connection in the context of manufacturing or maintenance.

The aforementioned bearing 25 of the turbomachine 16 in turn carries a fan wheel 24 acting, rotatable within the plastic housing 20 impeller, which sucks via a connected to the oil mist 10, 1 1 supply line 23 cleaned blowby from the direction of the fine separator 1 1. According to the design of an axial fan, the fan wheel 24 is substantially coaxially aligned with a bore 23 of the cylinder head cover 17 which connects the supply line 23 to the installation space of the turbomachine 16 and thus is oriented approximately parallel to the flow direction of the blowby.

To drive the fan 24 is a coupled thereto via a shaft electric drive motor 26, which in the form of an external rotor as an electric a commutated DC motor comprises a plurality of alternately radially aligned annularly arranged permanent magnets or a corresponding multi-pole magnetized ring. The person skilled in the art is also familiar with this type of electric motor as a brushless DC motor, BLDC motor, BL motor or EC motor. If the internal combustion engine 18 is used to drive a motor vehicle with an electrical vehicle electrical system, then the latter can be used in an advantageous manner for supplying energy to the electric motor 26.

Claims

claims

1 . Oil mist separator (10, 1 1) with

- An inlet opening (12) for introducing an aerosol into the oil mist separator (10, 1 1), which contains a gaseous dispersion medium, in particular Blowby, and an oil dispersed in the dispersion medium,

a particle collecting container (13) for collecting the dispersed oil,

- A process (14) for discharging the collected oil from the oil mist separator (10, 1 1) and

- An outlet opening (15) for discharging the dispersion medium from the oil mist separator (10, 1 1),

- wherein between the inlet opening (12) and the outlet opening (15) is formed a flow path,

characterized,

in that the oil mist separator (10, 11) comprises a device for increasing a differential pressure between the introduced aerosol and the discharged dispersion medium, wherein the increase of the differential pressure is realized by a connection of the flow path with an additional pressure source.

2. oil mist separator (10, 1 1) according to claim 1,

characterized,

in that the oil mist separator (10, 11) is an impingement separator and comprises nozzles in fluid communication with the inlet opening (12).

3. oil mist separator (10, 1 1) according to claim 2,

characterized,

that the nozzles have a number between 2 and 4.

4. oil mist separator (10, 1 1) according to claim 2 or 3,

characterized,

in that at least one of the nozzles has a cross-sectional area between 6.3 mm ² and 12.6 mm ² .

5. oil mist separator (10, 1 1) according to any one of claims 2 to 4,

characterized,

that the nozzles are arranged at least partially substantially annular.

6. oil mist separator (10, 1 1) according to any one of claims 2 to 5,

characterized,

in that the particle collecting container (13) comprises a substantially circular baffle plate with an approximately central opening which is in fluid communication with the outlet (14).

7. oil mist separator (10, 1 1) according to claim 1,

characterized,

that the oil mist separator (10, 1 1) is a centrifugal separator with an inlet cylinder, a cone and a dip tube, wherein the inlet cylinder, the cone, the dip tube and the particle collecting container (13) are dimensioned relative to each other so that they can increase the differential pressure.

8. Olnebelabscheider (10, 1 1) according to one of claims 1 to 7,

characterized,

in that the device for increasing the differential pressure comprises an externally driven turbomachine (16) for transmitting kinetic energy to the dispersion medium.

9. Olnebelabscheider (10, 1 1) according to claim 8,

characterized,

the turbomachine (16) is a vacuum pump, in particular a jet pump.

10. Olnebelabscheider (10, 1 1) according to claim 8,

characterized,

the turbomachine (16) is a fan.

1 1. Olnebelabscheider (10, 1 1) according to any one of claims 1 to 10,

characterized,

in that the particle collecting container (13) has at least one rib for retaining the collected oil.

12. Olnebelabscheider (10, 1 1) according to any one of claims 1 to 1 1,

characterized,

in that the oil mist separator (10, 11) comprises a filter bed for laying a filter fleece, the filter bed being such that it can guide the collected oil in the direction of the drain (14).

13. Cylinder head cover (17) with an oil mist separator (10, 1 1) according to one of claims 1 to 12,

characterized,

the oil mist separator (10, 11) is molded integrally on the cylinder head cover (17) at least in regions.

14. Internal combustion engine (18), in particular reciprocating engine, with a crankshaft, a crankcase for supporting the crankshaft, a vent line for venting the crankcase and a Ölnebelabscheider (10, 1 1) according to one of claims 1 to 12, whose inlet opening (12) the vent line is connected.

15. internal combustion engine (18) according to claim 14,

characterized,

in that the internal combustion engine (18) comprises a combustion space, a cylinder head for at least one-sided limitation of the combustion chamber and a cylinder head cover (17) according to claim 13 for externally covering the cylinder head.