Internal combustion engine equipped with an oil separator and at least one lower engine crankcase gas discharge chimney comprising a blade device promoting oil condensation.

Abstract

Power unit comprising an internal combustion engine (1), an air intake circuit (3), a circuit for recycling the engine crankcase gases (5) comprising a pump (5a) directing gases coming from at least one chimney (5d) for discharging the crankcase gases coming from the crankcase (1b) to an oil separator (5b) connected at the outlet by a pipe (5c) for clean oil gases, connected to the air intake circuit (3), an oil return circuit (7) from the oil separator (5b) to the internal combustion engine (1), and a ventilation line (8) bringing fresh air into the crankcase (1b), characterized in that it comprises a blade device (5e) at the outlet of the crankcase gas discharge chimney (5d) and upstream of the pump (5a),comprising at least two louvers arranged so that the oil included in the lower crankcase gases condenses at least partially on their surface and flows into the lower crankcase gas discharge chimney (5d). Figure for abstract: [Fig 3],

Description

Title of the invention: Internal combustion engine equipped with an oil separator and at least one exhaust duct for lower crankcase gases of the engine, comprising a blade device promoting oil condensation. Technical field

[0001] The invention generally relates to a gas treatment architecture in an internal combustion engine, in particular gases coming from the lower crankcase of said engine, called "blow by" gases. It finds a particularly advantageous application in an internal combustion engine of a spark-ignition type motor vehicle operating with hydrogen. Prior art

[0002] An internal combustion engine generates leaks of unburned combustion gases during its operation from the combustion chambers into a lower crankcase of the engine, at the level of the piston segments and located under the cylinders.

[0003] These gases are charged with both unburned fuel and oil droplets resulting from the contact of the gases in the combustion chamber with engine parts lubricated with oil. These oil-laden gases accumulate in the lower crankcase and must be evacuated and recycled into the engine.

[0004] In particular, it is necessary to separate the oil droplets from the gases charged with unburned fuel, that is to say, to defuel the gases, before reintroduction into the engine intake. Indeed, the reintroduction of the gases as they are would cause pollution of the combustion chambers, as well as significant oil consumption by the engine. In addition, the oil would tend to make the combustion of the mixture in the combustion chambers incomplete and to create more pollutant emissions.

[0005] Furthermore, it is prohibited to discharge crankcase gases loaded with unburned hydrocarbons into the outside atmosphere, which requires them to be recycled to the engine intake.

[0006] To achieve this, a large number of devices are known from the state of the art for de-oiling lower crankcase gases, known as "blow-by" gases, and for reintroducing these fuel-laden gases into the engine intake, where they contribute to the richness of the air-fuel mixture.

[0007] The state of the art consists in particular of decantation devices arranged outside the engine to treat the combustion gases by separating the oil from the gases.

[0008] However, more particularly on internal combustion engines with spark ignition operating on hydrogen, the "blow-by" gases recirculating in the The engine crankcase through the segmentation are charged with hydrogen that has not been burned in the combustion chamber at a hydrogen concentration that may exceed the flammability threshold of 4%.

[0009] Unlike conventional fuels (petrol, alcohol, etc.) where the concentration of gases in the fuel does not pose a particular risk of ignition, in the case of hydrogen, it becomes necessary to lower the concentration.

[0010] To achieve this, it is known to dilute the gases with fresh air by using a pump located on the engine decantation circuit, the pump taking clean air from the engine air intake circuit downstream of the air filter and sending it into the lower crankcase of the engine to dilute the gases there.

[0011] In figures [Fig.l] and [Fig.2] representing the state of the art for a hydrogen internal combustion engine, a three-cylinder in-line engine referenced 1, supercharged by a turbocharger referenced 2, is shown. In figure [Fig.2], the engine 1 comprises cylinders 1a and a lower crankcase 1b and is associated with an air intake circuit referenced 3 and a burnt gas exhaust circuit referenced 4.

[0012] The intake circuit 3 successively comprises an air filter 3a, a hydrogen concentration sensor 3b, the compressor 2a of a turbocharger 2, an air intake valve (or throttle body) referenced 3c and a distributor (or intake manifold) referenced 3d.

[0013] The exhaust circuit 4 successively comprises an exhaust manifold 4a and the turbine 2b of the turbocharger 2 mounted on a shaft common to the compressor 2a and an air vent. According to the embodiments, the exhaust line possibly comprises pollution control devices not shown.

[0014] The lower crankcase gas recycling circuit, called the “blow-by” circuit, comprises an active pump referenced 5a directing gases coming from at least one lower crankcase gas evacuation chimney, called the “blow-by” chimney coming from the lower crankcase 1b towards an oil separator 5b. In the figure [Fig.2] illustrating a sectional view of the internal combustion engine 1, a chimney 5d connects the lower crankcase 1b of the engine with an intermediate casing 3e upstream of the pump 5a.

[0015] The internal combustion engine 1 is provided with an oil return circuit 7 allowing the oil decanted in the oil separator 5b to return to the oil pool. Such a circuit is illustrated in figure [Fig.l] and figure [Fig.2].

[0016] The oil separator 5b is connected at the outlet by a pipe 5c of clean gases, composed of burnt gases and hydrogen, without oil, tapped into the air intake circuit 3 downstream of the air filter 3a.

[0017] A ventilation line 8 of the lower casing 1b (“scavenging line” in English) brings fresh air into the lower casing 1b, sucked in by the pump 5a. The ventilation line 8 is tapped downstream of the air filter 3a and upstream of the clean gas line 5c.

[0018] However, with this system, tests have led to the observation of an excessive rise of oil charged with hydrogen H2 in the combustion gases (blow-by gas) from the lower crankcase 1b of the engine through the blow-by chimneys to be treated in the decanter by means of an air pump.

[0019] The technical problem of decanting oil-laden blow-by gases in a hydrogen-powered internal combustion engine thus remains unresolved.

[0020] Another technical problem is to minimize the concentration of hydrogen H2 for safety reasons. Statement of the invention

[0021] The subject of the invention is a powertrain comprising an internal combustion engine, an air intake circuit, a circuit for recycling gases from a lower crankcase of the engine comprising a pump directing gases coming from at least one chimney for discharging gases coming from the lower crankcase towards an oil separator connected at the outlet to a clean oil gas pipe, tapped on the air intake circuit, an oil return circuit allowing the oil decanted in the oil separator to join an oil layer present in the lower crankcase of the internal combustion engine located under the cylinders, and a ventilation line tapped upstream of the clean gas pipe and bringing fresh air into the lower crankcase, sucked in by the pump.The powertrain comprises a blade device at the outlet of the lower crankcase gas discharge chimney and upstream of the pump, the blade device comprising at least two louvers arranged so that the oil included in the lower crankcase gases condenses at least partially on their surface, and flows into the lower crankcase gas discharge chimney to the internal combustion engine.

[0022] The blade device may comprise a base on which at least two louvers are fixed by a first proximal end.

[0023] The base may be provided with domed keys, an upper domed key being fixed on a second distal end of the louvers, the domed keys and the upper domed key allowing the positioning of the blade device in the lower crankcase gas exhaust chimney.

[0024] At least a portion of the shutters may be extended by a blade forming an inclination relative to the base different from the inclination of the shutters relative to the base.

[0025] The base may be provided with domed keys, all the blades being connected two by two by means of a pin, the blade furthest from the base supporting then an upper domed key, the domed keys and the upper domed key allowing the positioning of the blade device in the lower gas exhaust chimney.

[0026] The internal combustion engine can operate at least partially on dihydrogen.

[0027] The exhaust line may comprise at least one pollution control device.

[0028] The blade device has the advantage of a particularly low cost, particularly in view of the advantage generated, and is applicable to all internal combustion engines. Brief description of the drawings

[0029] Other aims, characteristics and advantages of the invention will appear on reading the following description, given solely by way of non-limiting example and made with reference to the appended drawings in which:

[0030] - Figure [Fig.l] illustrates the main elements of an internal combustion engine with controlled ignition powered by hydrogen and equipped with a blow-by circuit including an oil decanter,

[0031] - Figure [Fig.2] is a sectional view of an internal combustion engine powered by hydrogen and equipped with a gas recycling circuit from a lower engine crankcase including an oil decanter,

[0032] - Figure [Fig.3] is a sectional view of an internal combustion engine powered by hydrogen and provided with a lower crankcase gas recycling circuit comprising an oil decanter and a blade device according to the invention,

[0033] - figure [Fig.4] illustrates the lower crankcase gas exhaust chimney and the placement of a blade device according to the invention,

[0034] - Figure [Fig.5] illustrates the main elements of a blade device according to a first embodiment, and

[0035] - Figure [Fig.6] illustrates the main elements of a blade device according to a second embodiment. Detailed description

[0036] The internal combustion engine according to the invention comprises a blade device on which the oil-laden combustion gases impact in order to reduce their speed and promote condensation of the oil, returning to the lower casing 1b in the form of droplets trickling down the chimneys. This achieves a first separation of the oil from the combustion gases.

[0037] The gases then continue their journey to be treated by decantation in a conventional manner.

[0038] The internal combustion engine according to the invention comprises a blade device 5e arranged between the lower crankcase gas evacuation chimney, called the “blow-by” chimney 5d, and the pump 5a. Figure [Fig.4] illustrates the placement of this blade device 5e.

[0039] The blade device 5e has the effect of condensing the oil included in the lower crankcase gases, called "blow-by" gases, loaded with hydrogen rising from the lower crankcase 1b of the engine before their arrival in the pump 5a and the oil decanter 5b. The oil thus condensed falls back by trickling into the lower crankcase 1b of the engine along the "blow-by" chimney 5d.

[0040] The gases thus pre-decanted have their quantity of oil reduced before their admission into the pump 5a and the oil decanter 5b. The H2 molecule being very small, it also inserts itself into the oil. Thus, the fact of separating a certain quantity of oil makes it possible to minimize upstream of the pump the quantity of oil to be treated by the main decantation.

[0041] A first embodiment of the blade device 5e is illustrated by the figure [Fig.5].

[0042] The blade device 5e comprises a base 10 provided with domed keys 11 so as to be arranged in the blow-by chimney 5d. At least two shutters 12 are fixed to the base by a first proximal end. The other distal end of the shutters 12 is fixed to an upper domed key 1 allowing it to be positioned in the blow-by chimney.

[0043] A second embodiment of the blade device 5e is illustrated in figure [Fig.6]. As in the first embodiment, the blade device 5e comprises a base 10 provided with domed keys 11 so as to be arranged in the blow-by chimney 5d. At least two shutters 12 are fixed to the base 10 by a first proximal end.

[0044] However, in this second embodiment, at least one of the louvers 12 is extended by a blade 12a. The blades 12a have the particularity of forming an inclination relative to the base 10 different from the inclination of the louvers 12 relative to the base 10. This difference in inclination makes it possible to slow down the gases even more and possibly create turbulence, thus promoting condensation of the oil by increasing the duration of contact of the gases with the louvers and the blades.

[0045] In this embodiment, all the blades 12a are connected two by two by means of a pin 12b, the blade 12a furthest from the base then supporting an upper curved key 11a allowing positioning in the “blow-by” chimney.

[0046] The blade device 5e makes it possible to reduce the quantity of oil in the gases admitted into the pump 5a so as to reduce damage to the latter as well as the risk of fire. By reducing the quantity of oil to be treated, the concentration of H2 is minimized, which must be contained below the 4% limit. In fact, this limit is a flammability limit, beyond this value there is a risk of detonation.

Claims

Claims

1. Powertrain comprising an internal combustion engine (1), an air intake circuit (3), a circuit for recycling gases from a lower crankcase of the engine (5) comprising a pump (5a) directing gases coming from at least one chimney (5d) for discharging the lower crankcase gases (1b) towards an oil separator (5b) connected at the outlet to a pipe (5c) for clean oil gases, tapped on the air intake circuit (3), an oil return circuit (7) allowing the oil decanted in the oil separator (5b) to join an oil layer present in the lower crankcase (1b) of the internal combustion engine (1) located under the cylinders (1a), and a ventilation line (8) tapped upstream of the pipe (5c) for clean gases and bringing fresh air into the lower crankcase (1b), sucked in by the pump (5a),the powertrain being characterized by the fact that it comprises a blade device (5e) at the outlet of the lower crankcase gas discharge chimney (5d) and upstream of the pump (5a), the blade device (5e) comprising at least two louvers (12) arranged so that the oil included in the lower crankcase gases condenses at least partially on their surface and flows into the lower crankcase gas discharge chimney (5d) to the internal combustion engine (1).,

2. Powertrain according to claim 1, wherein the blade device (5e) comprises a base (10) on which at least two louvers (12) are fixed by a first proximal end.

3. A powertrain according to claim 2, wherein the base is provided with domed keys (11), an upper domed key (11a) being fixed to a second distal end of the louvers (12), the domed keys (11) and the upper domed key (11a) allowing the blade device (5e) to be positioned in the lower crankcase gas exhaust chimney (5d).

4. Powertrain according to claim 2, in which at least a portion of the louvers (11) extends into a blade (12a) forming an inclination relative to the base (10) different from the inclination of the louvers (12) relative to the base (10).

5. Powertrain according to claim 4, in which the base is provided with domed keys (11), all the blades (12a) being connected two by two by means of a pin (12b), the blade (12a) furthest from the base then supporting an upper domed key

6.

7. (11a), the domed keys (11) and the upper domed key (11a) allowing the positioning of the blade device (5e) in the lower crankcase gas evacuation chimney (5d). A powertrain according to any one of claims 1 to 5, wherein the internal combustion engine operates at least partially on dihydrogen. Powertrain according to any one of claims 1 to 6, in which the exhaust line comprises at least one pollution control device.

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