Internal combustion engine equipped with an oil separator and at least one lower crankcase gas exhaust stack including a blade device promoting oil condensation.

Abstract

Powertrain comprising an internal combustion engine (1), an air intake circuit (3), an engine lower crankcase gas recirculation circuit (5) comprising a pump (5a) directing gases from at least one lower crankcase gas exhaust stack (5d) from the lower crankcase (1b) to an oil separator (5b) connected at outlet by a clean oil gas line (5c) tapped from 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) supplying fresh air to the lower crankcase (1b), characterized in that it comprises a blade device (5e) at the outlet of the lower crankcase gas exhaust stack (5d) and upstream of the pump (5a),comprising at least two louvers arranged so that the oil contained in the lower crankcase gases condenses at least partially on their surface and flows into the lower crankcase gas exhaust stack (5d). Figure for the abbreviation: [Fig 3],

Description

Title of the invention: Internal combustion engine equipped with an oil separator and at least one lower crankcase gas exhaust stack comprising a blade device promoting oil condensation. technical field

[0001] The invention relates generally to a gas treatment architecture in an internal combustion engine, particularly for gases originating from the lower crankcase of said engine, known as "blow-by" gases. It finds a particularly advantageous application in a spark-ignition internal combustion engine of a motor vehicle operating on hydrogen. Previous techniques

[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 rings and located under the cylinders.

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

[0004] In particular, it is necessary to separate the oil droplets from the gases laden with unburned fuel, that is to say, to de-oil the gases, before reintroducing them into the engine intake. Indeed, reintroducing the gases as is would lead to contamination of the combustion chambers, as well as significant oil consumption by the engine. Furthermore, the oil would tend to make the combustion of the mixture incomplete in the combustion chambers and create more pollutant emissions.

[0005] Furthermore, it is prohibited to release crankcase gases containing unburned hydrocarbons into the external atmosphere, which requires recycling them at the engine intake.

[0006] To achieve this, a large number of devices for removing oil from the 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, are known from the prior art.

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

[0008] However, more specifically on spark-ignition internal combustion engines operating on hydrogen, the blow-by gases recirculate in the The lower crankcase of the engine, through the piston rings, is loaded with hydrogen that has not been burned in the combustion chamber at a hydrogen concentration that can exceed the flammability threshold of 4%.

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

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

[0011] Figures [Fig.1] and [Fig.2] representing the prior 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 la and a lower crankcase 1b and is associated with an air intake circuit referenced 3 and an exhaust gas circuit referenced 4.

[0012] The intake circuit 3 includes successively 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 system 4 comprises successively an exhaust manifold 4a and the turbine 2b of the turbocharger 2 mounted on a shaft common to the compressor 2a and a vent. Depending on the embodiment, the exhaust line may include pollution control devices not shown.

[0014] The lower crankcase gas recirculation circuit, referred to as the "blow-by" circuit, includes an active pump referenced 5a directing gases from at least one lower crankcase gas exhaust stack, referred to as the "blow-by" stack, from the lower crankcase 1b to an oil separator 5b. In Figure [Fig. 2], illustrating a cross-sectional view of the internal combustion engine 1, a stack 5d connects the lower crankcase 1b of the engine with an intermediate crankcase 3e upstream of the pump 5a.

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

[0016] The oil separator 5b is connected at the outlet by a clean gas line 5c, 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 from the lower crankcase 1b (the "scavenging line") brings fresh air into the lower crankcase 1b, drawn in by the pump 5a. ventilation line 8 is tapped downstream of air filter 3a and upstream of clean gas line 5c.

[0018] However, with this system, tests have led to the observation of an excessive upwelling of hydrogen-laden oil H2 in the combustion gases (blow-by gases) from the lower crankcase 1b of the engine through the blow-by chimneys to be treated in the separator 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 unsolved.

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

[0021] The invention relates to a powertrain comprising an internal combustion engine, an air intake circuit, a gas recirculation circuit for a lower crankcase of the engine comprising a pump directing gases from at least one exhaust stack from the lower crankcase to an oil separator connected at the outlet to a clean oil gas line, tapped into the air intake circuit, an oil return circuit allowing the oil decanted in the oil separator to join an oil pool present in the lower crankcase of the internal combustion engine located under the cylinders, and a ventilation line tapped upstream of the clean gas line and bringing fresh air into the lower crankcase, drawn in by the pump.The powertrain includes a blade device at the outlet of the crankcase exhaust stack and upstream of the pump, the blade device comprising at least two louvers arranged so that the oil contained in the crankcase gases condenses at least partially on their surface, and flows down the crankcase exhaust stack to the internal combustion engine.

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

[0023] The base can 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 blade device to be positioned in the lower crankcase gas exhaust chimney.

[0024] At least part of the louvers may extend by a blade forming an inclination with respect to the base different from the inclination of the louvers with respect to the base.

[0025] The base may be fitted with domed keys, all the blades being connected in pairs by means of a pin, the blade furthest from the base supporting then a domed upper button, the domed buttons and the domed upper button allowing the blade device to be positioned in the lower gas exhaust chimney.

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

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

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

[0029] Other objects, features and advantages of the invention will become apparent from the following description, given solely by way of non-limiting example and made with reference to the accompanying drawings in which:

[0030] - Figure [Fig. 1] illustrates the main elements of an internal combustion engine controlled ignition powered by hydrogen and equipped with a "blow-by" circuit including an oil separator,

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

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

[0033] - Figure [Fig.4] illustrates the lower crankcase gas exhaust stack 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 against which the oil-laden combustion gases impact in order to reduce their velocity and promote oil condensation, returning to the lower crankcase 1b in the form of droplets flowing 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 5th blade device positioned between the lower crankcase gas exhaust chimney, known as 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 contained in the lower crankcase gases, known as "blow-by" gases, charged with hydrogen rising from the lower crankcase 1b of the engine before their arrival in the pump 5a and the oil separator 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 pre-decanted gases have their oil content reduced before being admitted into pump 5a and oil separator 5b. Since the H2 molecule is very small, it also incorporates into the oil. Thus, separating a certain amount of oil minimizes the quantity of oil to be treated by the main decantation process upstream of the pump.

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

[0042] The blade device 5e comprises a base 10 provided with domed keys 11 so as to be positioned in the blow-by chimney 5d. At least two louvers 12 are fixed to the base by a first proximal end. The other distal end of the louvers 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 with domed keys 11 so as to be positioned in the blow-by chimney 5d. At least two louvers 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 extends into a blade 12a. The blades 12a have the particularity of forming an inclination with respect to the base 10 different from the inclination of the louvers 12 with respect to the base 10. This difference in inclination makes it possible to slow down the gases even more and possibly create turbulence, thus promoting the condensation of the oil by increasing the contact time of the gases with the louvers and the blades.

[0045] In this embodiment, all the blades 12a are connected in pairs via a pin 12b, the blade 12a furthest from the base then supporting a domed upper touch lia allowing the positioning in the "blow-by" chimney.

[0046] The blade device 5e reduces the amount of oil in the gases admitted into the pump 5a, thereby decreasing damage to the pump and the risk of fire. By reducing the amount of oil to be treated, the concentration of H2 is minimized, which must be kept below the 4% limit. Indeed, this limit is a flammability limit; beyond this value, there is a risk of detonation.

Claims

Demands

1. Powertrain comprising an internal combustion engine (1), an air intake circuit (3), a crankcase gas recirculation circuit for a lower engine crankcase (5) comprising a pump (5a) directing gases from at least one crankcase gas exhaust stack (5d) (1b) to an oil separator (5b) connected at its outlet to a clean oil gas line (5c) tapped into the air intake circuit (3), an oil return circuit (7) allowing the oil decanted in the oil separator (5b) to rejoin an oil pool present in the lower crankcase (1b) of the internal combustion engine (1) located below the cylinders (1a), and a ventilation line (8) tapped upstream of the clean gas line (5c) and supplying fresh air into the lower crankcase (1b), drawn in by the pump (5a),the powertrain being characterized in that it comprises a blade device (5e) at the outlet of the lower crankcase gas exhaust stack (5d) and upstream of the pump (5a), the blade device (5e) comprising at least two louvers (12) arranged so that the oil contained in the lower crankcase gases condenses at least partially on their surface and flows into the lower crankcase gas exhaust stack (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. Powertrain according to claim 2, wherein the base is provided with domed keys (11), an upper domed key (lia) being fixed on a second distal end of the louvers (12), the domed keys (11) and the upper domed key (lia) enabling the positioning of the blade device (5e) in the lower crankcase gas exhaust chimney (5d).

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

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

6.

7. (lia), the domed keys (11) and the upper domed key (lia) allowing the positioning of the blade device (5e) in the lower crankcase gas exhaust chimney (5d). 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, wherein the exhaust line includes at least one pollution control device.

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