FR3082241A1 - INTAKE DISTRIBUTOR FOR A HEAT ENGINE WITH RECIRCULATED GAS MIXING DEVICE - Google Patents

Description

Description

Title of the invention: Intake distributor for a heat engine with an optimized mixing device for recirculated gases Technical field [0001] The present invention relates to an internal combustion or thermal engine of a motor vehicle.

The present invention relates more particularly to an intake distributor of the heat engine with a device for mixing the burnt gases.

The present invention also relates to a recirculation system of the burnt gases of a heat engine.

PRIOR ART The present invention relates to internal combustion engines intended in particular to equip motor vehicles, which use means for recirculating burnt gases.

The present invention relates more particularly to means for recirculating burnt gas from an internal combustion engine. The burnt gases are either from an engine exhaust system and can either be taken directly from the exhaust manifold, they are said to be high pressure, or taken from a pollution control system downstream of the manifold exhaust, they are called low pressure, either from a deoiling step through an oil decanter, they are known as blow-by gas.

The standards concerning pollution and consumption of internal combustion engines fitted in particular to motor vehicles are becoming more and more stringent in industrialized countries. The automotive industry is therefore now busy finding technical solutions to meet these obligations, without penalizing either the performance of thermal engines or their cost price. A known technique for cleaning up said internal combustion engines consists in operating the recirculation of the burnt gases at the intake in order to reduce the nitrogen oxides, that is to say at reducing a portion of the burnt gases at the intake and by mixing them with captured fresh air. This technique consists in reinjecting, depending on the operating conditions of the engine, part of the exhaust gases into the combustion chambers of the engine, which has the effect of proportionally reducing the amount of oxidizing gas and therefore of lowering the combustion temperature. , hence a reduction in the production of NOx or nitrogen oxides.

For example, the process for low pressure burnt gases generally adopted is the external recirculation of the exhaust gases using an RGE (Exhaust Gas Recycling) valve, also called EGR valve acronym for "Exhaust Gas Recirculation" for recirculation of exhaust gases, closing or opening a pipe connecting the exhaust manifold to the engine intake distributor. The EGR valve allows the injection of a determined quantity of gas taken from the exhaust according to the engine operating conditions.

The burnt gases are injected at the engine intake, generally in an engine intake manifold or directly in the engine intake ducts between the intake manifold and an engine combustion chamber.

Publication EP1447533-A1 thus proposes a direct injection of blow-by gases into an air intake duct towards a combustion chamber of the engine. Said gases pass through a channel which opens into the intake duct.

A drawback of this type of injection is that the mixture formed by the blow-by gases and the air is not optimal, which can limit the performance of the engine.

In known manner, said burnt gases can be collected in a recirculation ramp which extends substantially parallel to the longitudinal axis X of the engine. Into said ramp open inlet channels connecting said ramp to one of the engine air intake ducts.

The publication US 20090301448-Al thus proposes a manifold for collecting blow-by gases to be injected into the air intake ducts of the engine.

As in the previous type of injection, the burnt gas intake channels open directly into the air intake ducts leading to a combustion chamber, and do not allow optimal mixing of the burnt gases and air before entering the combustion chamber, which can reduce engine performance.

Publication FR2946699-A1 discloses a burnt gas collection ramp extending parallel to the axis of the engine and connected to an air intake distributor plenum arranged downstream of an air- heat exchanger. water according to the air flow direction. Said connection is made through channels opening into the plenum.

The drawback of this type of burnt gas injection is also a mixture of burnt gases and air which is not optimal and is likely to affect engine performance.

Document US2015002078-A1 proposes an injection of burnt gas into the plenum of an intake distributor of heat engine air by means of a conduit penetrating upstream in the plenum of the intake distributor, said conduit comprising a gas injection orifice facing the combustion chamber.

A drawback of this type of injection is on the one hand that the penetrating duct generates pressure losses when the air flows to the combustion chamber and on the other hand that the mixture is not optimal that may affect engine performance.

The object of the present invention is to provide an air intake circuit with a recirculation of burnt gases for an internal combustion engine, petrol or diesel, overcoming the above drawbacks and improving the intake circuits of air with a mixture of burnt gases for an internal combustion engine known from the state of the art, in order to provide an optimal mixture of the recirculated burnt gases with the air before admission to the combustion chamber while generating little or no pressure drop to the flow of gases.

The internal combustion engine according to the invention comprises a gas recirculation system, that is to say that said system comprises a nozzle for the burnt gases which may be high pressure burnt gases from a circuit of engine exhaust upstream of a pollution control system, for example from an engine exhaust manifold, or from a pollution control system or downstream of said system, or taken downstream of an oil decanter with from oil vapors. The recirculation system allows said burnt gases to be admitted to the engine intake by injecting said gases into an intake manifold plenum while minimizing pressure drops and optimizing the mixing of gases with fresh intake air .

PRESENTATION OF THE INVENTION The present invention relates to an air intake circuit for a heat engine, said air intake circuit comprising a burnt gas or blow-by recirculation system and being positioned between an air compression element and at least an upper combustion chamber part of an engine cylinder head, said air intake circuit comprising the cylinder head, an air intake distributor, and at least one air intake duct, characterized in that the recirculation system comprises at least one flue gas injection duct opening into a plenum of the distributor which is delimited by side walls, an upper wall, a wall lower according to the air flow, said duct being adapted to bring said gases to counter flow of the intake air flow.

Advantageously, the system comprises at least one flue gas injection conduit, which conduit opens into the plenum of the distributor and is able to bring the gases against the flow of air flow to improve the mixture of air and gas before entering the engine combustion chambers. The gases are first directed against the flow of the intake air flow and then returned to the intake duct, which improves the mixing of the gases and the intake air. The layout of the injection duct in the plenum is intended to generate little pressure drop at the air flow.

According to other characteristics of the invention:

-The at least one injection duct opens into the plenum in the extension of the axis of at least one associated intake duct.

Advantageously, the injection duct extends substantially in the extension of the axis of at least one intake duct in order to bring burnt gases to be mixed and directed into said duct. admission.

-The outlet of the at least one injection duct in the plenum is distant from the outlet in said plenum of the at least one associated intake duct.

Advantageously, the outlet of the at least one injection duct in the plenum is distant from the outlet in said plenum of the at least one associated intake duct to allow better mixing between the burnt gases and the intake air before entering the at least one associated intake duct.

-The at least one injection conduit has a tubular channel penetrating into the plenum of the distributor.

Advantageously, the injection pipe is cylindrical and straight to generate a minimum pressure drop during the flow of the burnt gases and in particular during injection into the plenum of the distributor.

Advantageously, the injection pipe comprises a tubular channel penetrating into the plenum of the distributor in order to obtain an optimal position for the injection of the burnt gases into the plenum in the middle of the air flow d admission and improve mixing.

The tubular channel has an opening facing upstream of the air flow.

Advantageously, the tubular channel has an opening facing upstream of the air flow which allows better injection of the burnt gases and better diffusion and mixing of the burnt gases in the air flow.

-The tubular channel includes a bevel opening facing upstream of the flow of intake air.

Advantageously, the tubular channel has an opening cut in a bevel, said opening section is turned upstream of the air flow in order to allow optimal mixing of the burnt gases with the air of admission.

-The tubular channel extends upstream of the air flow, from a deflecting wall capable of directing the air flow towards an opening connected to the air intake duct.

Advantageously, the plenum is delimited by side walls, an upper wall, a lower wall and a deflecting wall downstream of the air flow capable of directing the air flow towards an opening connected with the air intake duct to reduce pressure losses at the intake of the air and burnt gas mixture in the intake duct.

The tubular channel extends from said deflecting wall, upstream of the flow of gases to direct the gases upstream of the flow of intake air and therefore against the flow of l flow of intake air.

-The deflecting wall and the tubular channel come from one piece.

Advantageously, the deflecting wall and the tubular channel come from one piece to facilitate on the one hand the manufacture and on the other hand the establishment in the cylinder head and the formation of the plenum.

The recirculation system comprises a supply rail extending transversely to the air flow axis, said rail is connected to at least one gas injection duct.

Advantageously, the recirculation system comprises a supply rail connected with a burnt gas circuit, said rail extends transversely to the direction of air flow and parallel to the axis of the engine to be able water all the engine intake ducts.

The supply rail is hollowed out in the cylinder head or fixed to the lower wall of the plenum or is fixed to the upper wall of the plenum.

Advantageously, the supply rail extending transversely to the flow of the intake air is hollowed out in the cylinder head or is fixed to the bottom wall, or is fixed to one of the lower or upper walls of the plenum, which allows in the first mode a compactness of the circuit and in the second mode an ease of implementation.

The supply rail is connected to an outlet of a blow-by gas settling tank.

Preferably, the supply rail is connected to an outlet of a blow-by gas decanter to bring the blow-by gases back to the inlet.

The supply rail is connected to an exhaust gas circuit.

Preferably, the supply rail is connected to a burnt gas circuit from the engine exhaust, said gases can be high pressure burnt gases or low pressure burnt gases.

BRIEF DESCRIPTION OF THE DRAWINGS Other characteristics and advantages of the invention will appear on reading the following description of particular embodiments of the invention given by way of nonlimiting examples and shown in the appended drawings, wherein :

[Fig.l] is a schematic sectional view of an intake circuit of a heat engine.

[Fig.2] is a schematic sectional view of the cylinder head and the intake manifold according to a first embodiment of the invention.

[Fig.3] is a schematic top view of the cylinder head with the intake circuit according to the invention.

[Fig.4] is a schematic sectional view of the cylinder head and the intake manifold according to another embodiment of the invention.

Detailed description of the figures In the following description, identical reference numerals designate identical parts or have similar functions.

In this document, the term “opening section” is understood to mean a surface of a conduit for the passage of gases, said section may be transverse to the axis of the conduit or at an angle to the axis of the leads.

The terms upstream / downstream relate to the direction of flow of air in the intake circuit.

The upper / lower terms refer to a vertical axis perpendicular to a horizontal plane parallel to the joint plane of a cylinder block with a cylinder head of an engine of the description.

The internal combustion or internal combustion engines of a motor vehicle comprise, on the one hand, systems for reducing the pollution of the burnt gases coming from the engine combustion chambers and, on the other hand, supercharging systems in order to improve the efficiency of said motors.

In order to reduce pollution, it is known to return at least part of the burnt gases to the engine intake, said part is then mixed with fresh air before entering the engine cylinders. There are several types of burnt gas recirculation: low pressure recirculation which includes a sample of burnt gas downstream of pollution control devices such as a catalytic converter depending on the direction of flow of the exhaust gas, or recirculation in high pressure where the burnt gases are captured upstream of the pollution control devices and preferably at the outlet of an engine cylinder head. The so-called high pressure burnt gases are then taken from an exhaust manifold fixed against an exhaust face of an engine cylinder head.

The burnt gases can also come from an oil vapor decanter, they are called blow-by gases. Said settling tank is generally arranged in the upper part of the engine. It allows the separation of the oil contained in the said vapors from the gases. Then, the oil is returned by an oil return circuit preferably to an oil receiving casing located at the bottom of the engine, and the gases can be brought back to the engine intake.

In general, according to Figure 1, a heat engine 100 comprises a cylinder block 101 comprising at least one cylinder 102 in which a piston is movable by sliding along the axis of the at least one cylinder and a cylinder head 20 covering the upper part of the cylinder block and therefore closing at least one combustion chamber 11. Said combustion chamber is delimited by the wall of each of the cylinders, the piston and the cylinder head 20. In the cylinder head are hollowed out ducts intake 21 and exhaust pipes which connect the combustion chamber 11 of each cylinder respectively to an intake circuit 10 and to an exhaust circuit. The intake circuit 10 is fixed to the cylinder head 20 by an intake face 23. The exhaust circuit is fixed to the cylinder head by its exhaust face (not shown) symmetrically opposite the intake face according to a vertical median plane passing through the longitudinal axis X of the engine.

The longitudinal axis X of the engine is substantially parallel to the axis of a crankshaft housed in the engine.

Fresh air 40 is collected outside the vehicle and then mixed with burnt gas 41 at an intake manifold 12 which is fixed against an intake wall 22, on the side of the intake face 23 of the cylinder head 20 of the engine. The mixture is then led to the combustion chamber 11 of the engine via the intake ducts 21. The air and burnt gas mixture is injected into the combustion chamber, at the top of each cylinder of the cylinder block 101 and mixed with fuel. to generate an explosion in said chamber then generating burnt gases. Said burnt gas is then pushed outside the combustion chamber via the exhaust pipes to an exhaust circuit attached to said cylinder head on the side of the engine exhaust face.

The present invention relates to an intake circuit 10 for a heat engine comprising a recirculation system 30 of the burnt gases to be returned to the engine intake.

By burnt gas is meant gases from the exhaust system or blowby gases.

In the following description, we will describe a return to the admission of blowby gas to facilitate understanding of the invention, but the burnt gases can also be burnt gases at high pressure or low pressure or a mixture of burnt gases.

In known manner, fresh intake air 40 is collected from a front face of the vehicle and passes through the intake circuit to be injected into the combustion chamber 11 of each of the cylinders. The intake air is first filtered by an air filter to remove dirt and dust carried in the intake air. Then, to improve engine performance, it is also known to increase the pressure of the admitted gases and allow better filling of the at least one engine cylinder with air / fuel mixture. The power density of the engine is thus increased as well as its power, with a reduction in the consumption of the engine. An intake air compression stage is thus arranged between the air filter and the engine. This compression stage (not shown) can be formed either by a compression stage of a turbocharger or by an electric compressor.

Downstream of the compression stage, the compressed air is at high temperature and its density is reduced, which is detrimental to the performance of the engine. It is therefore useful to add to said compressor (not shown) and downstream, according to the direction of circulation of the air of the compressor, a stage for cooling the intake air. This cooling stage can be composed of a cooler 14 and more precisely of an air / water exchanger. Water at moderate temperature passes through the exchanger 14 and removes part of the heat from the compressed air.

The compressed and cooled air 40 is then directed to an air intake distributor 12 to control the air flows admitted into the combustion chamber. Said distributor is fixed by a flange 13 to the fixing wall 22 of the intake face 23 of the cylinder head 20 of the engine and directs the compressed and cooled air to intake ducts 21 hollowed out in the cylinder head. Said intake ducts 21 in the cylinder head are of particular shape and profile depending on the type of engine, for example diesel fuel or spark ignition.

The cooler 14 is also called WCAC acronym for "Water Charge Air Cooler" meaning water / air cooler. The distributor 12 is essentially distinguished by a plenum 16 or air reserve chamber before entering the intake ducts 21 of the cylinder head. The distributor 12 is downstream of the WCAC exchanger 14 and in our embodiment, they share the same casing. Said housing is fixed to the fixing wall 22 of the cylinder head. Said fixing wall 22 extends on a plane and has an inclination relative to a horizontal plane, which is parallel for example to a joint plane 25 between the cylinder head and the cylinder block. Said inclination allows a simpler installation and a more reliable maintenance of the cooler.

The plenum 16 is delimited by side walls, an upper wall 36 and a lower wall 35 in the direction of the air flow.

According to Figures 1 to 4, the cooler 14 and the air intake distributor 12 are in one piece 15.

The following description is made for a cylinder to facilitate understanding, but the engine according to the invention comprises at least one cylinder and the invention provides an injection pipe for each cylinder.

According to Figures 1 to 4, the recirculation system 30 comprises a supply rail 31 of burnt gas which is connected to the exhaust circuit or to a gas outlet of a decanter (not shown) of vapors d 'oil.

Preferably, the inlet rail 31 extends parallel to the longitudinal Ion axis X of the engine. Said rail can be obtained by drilling the cylinder head, that is to say that the rail is disposed inside said cylinder head as shown in FIGS. 1 and 2, or fixed to an element of the intake circuit 10 of the engine. , that is to say that the rail is arranged outside the engine as shown in FIG. 4. The intake rail allows the routing of the burnt gases to the intake of the engine.

Injection pipes 17 fluidly connect the inlet rail 31 and the plenum 16. Said pipes are substantially cylindrical and straight in order to generate a minimum pressure drop when said burnt gases flow. Preferably, an injection pipe 17 is arranged to open into the plenum 16 of the distributor upstream of an intake pipe connected to an associated cylinder. Said injection conduit allows the injection of burnt gases 41 to be mixed with the intake air, said mixture is then directed to the associated intake conduit leading to the cylinder. In the description, there is an intake duct 21 per engine cylinder. In general, said intake duct 17 then being extended by two secondary intake branches (not shown) which open into the combustion chamber of the cylinder.

According to Figure 3, the intake circuit comprises the intake rail 31 which extends parallel to the longitudinal axis X of the engine and transversely to the direction E of the flow of intake air in plenum 16 of the intake manifold. The injection conduits 17 whose axis is substantially orthogonal to the axis of said intake rail 31 open at a first end in the intake rail 31 and at the second opposite end in the plenum 16. The number of conduits injection 17 is preferably equal to the number of cylinders of the engine. The injection duct 17 therefore extends perpendicular to the axis X of the engine, from the injection rail 31, at the level of an associated cylinder along the axis X of the engine. Each injection pipe opens into the plenum 16 in the extension of the axis of the intake pipe 21. More precisely, the projection on a horizontal plane of the outlet of the injection pipe 17 in the plenum 16 is arranged in the projection of the axis of the associated intake duct on the same horizontal plane as shown in FIG. 3. The outlet in the plenum of the intake duct is disposed substantially in front of an inlet section of the associated intake duct 21. Each of said injection conduits 17 extends in a rectilinear manner and opens out from the wall of the plenum 16 in the upstream direction A _m of the flow of the intake air to bring the burnt gases against the flow of the direction intake air flow.

According to Figures 2 to 4, the air flow is represented by arrow 32 and the injection of burnt gases into the plenum by arrow 33.

The injection conduit 17 comprises a tubular channel 18 penetrating into the plenum to optimally position the point of injection of the burnt gases 41 in the flow of the intake air 40, preferably in the extension of the intake duct 21 and preferably distant from the outlet of said intake duct 21 in the plenum 16. The tubular channel extends from the wall of the plenum towards the upstream Am of the air flow intake. The distance can be greater than 20 mm, for example, to allow optimal mixing of the burnt gases with the intake air before entering the intake duct 21 leading to the cylinder.

Preferably, the tubular channel 18 is substantially inclined relative to the flow axis E of the intake air 40 along a vertical plane as shown in Figures 2 and 4.

The tubular channel 18 has at its free end 18 'an opening directed upstream A _m of the air flow. Said opening can for example be cut at a bevel and have the opening section directed upstream A _m of the air flow.

The burnt gases 41 are therefore directed against the flow of the intake air flow 40 and then returned in the direction of admission to the intake ducts 21, which substantially improves the mixture of said burnt gases with the air before they enter said intake ducts 21.

According to FIG. 2, the tubular channel 18 extends from an inclined deflecting wall 34 delimiting downstream the plenum 16. According to the preferred embodiment, the plenum 16 comprises a part hollowed out in the cylinder head 20.

According to Figures 1 to 4, the deflecting wall 34 is inclined relative to the axis of flow of air E; more precisely, the axis orthogonal to said deflecting wall intersects with the air flow axis E in a vertical plane. Said tubular channel 18 may have an inclination relative to the axis orthogonal to the surface of the deflecting wall 34 or be substantially parallel to said axis to present an inclination relative to the axis of flow of the gases E.

Preferably, the tubular channel 18 and the deflecting wall 34 come from the same part obtained for example by molding. They can be made of plastic because they are not exposed to high temperatures.

According to Figure 4, the supply rail 31 is fixed below the bottom wall 35 defining the plenum. The injection conduit 17 passes through said lower wall 35 substantially at an angle relative to the axis orthogonal to the interior surface of the wall in the direction of upstream A _m of the air flow. It is extended by the tubular channel 18 extending preferentially from the lower wall 35 at an angle in a direction directed upstream A _m from the flow of the intake air or towards the exchanger 12.

According to another embodiment not shown, the injection rail 31 is fixed above the upper wall 36 of the plenum. The injection conduit 17 passes through said upper wall 36 substantially at an angle relative to the axis orthogonal to the interior surface of the wall in the direction of upstream Am of the air flow. It is extended by the tubular channel 18 extending preferentially from the upper wall 36 at an angle in a direction directed upstream Am of the flow of the intake air or towards the exchanger 12.

The tubular channel 18 has at its free end 18 'preferably an opening directed upstream A _m of the gas flow.

Said opening can be formed by a bevel cut of the tubular channel, the opening section being opposite the upstream A _m of the intake air flow or here facing the exchanger 12 .

Preferably, the tubular channel 18 is of reduced passage section to generate small parts of the charges in the flow of air.

The objective is achieved: the recirculation system 10 of the burnt gases of the air intake circuit according to the invention allows mixing of said gases with the improved air without generating too much pressure drop at the flow intake air.

As it goes without saying, the invention is not limited to the sole embodiments of this socket, described above by way of examples, on the contrary it embraces all variants.

For example, the tubular channel can be replaced by a protuberance on the inner surface of the deflecting or lower wall of the distributor.

The tubular channel 18 can also extend parallel to the axis orthogonal to the bottom wall 36 or deflector 34 and have an opening for the injection of the burnt gases directed upstream A _m from the flow of the 'air.

Another embodiment may be that the tubular channel has a radial opening at its free end 18 ′ facing upstream A _m from the air flow.

Claims (12)

1. Inlet circuit (10) for a heat engine comprising a recirculation system (30) of burnt gases intended to be positioned between an air compression element and an upper part of the combustion chamber (11) hollowed out in a engine cylinder head (20), said air intake circuit comprising the cylinder head, an intake distributor (12) comprising a plenum (16), and air intake ducts (21), characterized in that that the recirculation system (30) comprises at least one flue gas injection pipe (17) opening into the plenum (16) which is delimited by side walls, an upper wall, a lower wall according to the flow d 'air, said conduit (17) being adapted to bring said burnt gases against the flow of the intake air flow (32). 2. Intake circuit (10) according to claim 1, characterized in that the at least one injection duct (17) opens into the plenum (16) in the extension of the axis of at least one associated intake duct (21). 3. Inlet circuit (10) according to claim 2, characterized in that the outlet of the at least injection pipe (17) in the plenum is distant from the outlet in said plenum of the at least one inlet pipe (21) associated. 4. Intake circuit (10) according to any one of claims 1 to 3, characterized in that the at least one injection duct (17) is extended by a tubular channel (18) penetrating into the plenum ( 16) of the distributor (12). 5. Intake circuit (10) according to claim 4, characterized in that the tubular channel (18) has an opening facing upstream (A _m ) of the air flow. 6. Intake circuit (10) according to claim 4 or 5, characterized in that the tubular channel (18) has a bevel opening facing upstream (A _m ) of the air flow. 7. Intake circuit (10) according to any one of claims 4 to 6, characterized in that the tubular channel (18) extends upstream of the air flow, from a deflecting wall ( 34) capable of directing the air flow towards an opening connected with the intake duct (21). 8. Intake circuit (10) according to claim 7, characterized in that the deflecting wall (34) and the tubular channel (18) come from the same part. 9. intake circuit (10) according to any one of claims 1 to 8, characterized in that the recirculation system (30) comprises a supply rail (31) extending transversely to the axis of air flow (E), said rail is connected to the at least one gas injection pipe (17). 10. Intake circuit (10) according to claim 9, characterized in that the supply rail (31) is hollowed out in the cylinder head (20) or fixed to one of the lower (35) or upper (36) walls. ) of the plenum (16). 11. Inlet circuit (10) according to claim 9 or 10, characterized in that the supply rail (31) is connected to an outlet of a blow-by gas settling tank. 12. Intake circuit (10) according to claim 9 or 10, characterized in that the supply rail (31) is connected to an exhaust gas circuit.