WO2019233669A1

WO2019233669A1 - Intake manifold for heat engine with optimized recirculated gas mixing device

Info

Publication number: WO2019233669A1
Application number: PCT/EP2019/059794
Authority: WO
Inventors: Thomas VENEZIANI
Original assignee: Renault S.A.S; Nissan Motor Co., Ltd.
Priority date: 2018-06-08
Filing date: 2019-04-16
Publication date: 2019-12-12
Also published as: FR3082241B1; FR3082241A1; CN112437835A; KR20210016467A; JP2021525847A; EP3803093A1

Abstract

Intake circuit (10) for a heat engine comprising a burned gas recirculation system (30) intended to be positioned between an air compression element and an upper portion of a combustion chamber (11) which is hollowed out of a cylinder head (20) of the engine, said air intake circuit comprising the cylinder head, an intake manifold (12) comprising a plenum (16) and air intake ducts (22), characterized in that the recirculation system (30) comprises a burned gas injection duct (17) opening into the plenum (16), said duct (17) being capable of transporting said burned gas against the flow of intake air (32).

Description

Title of the Invention: Intake manifold for a heat engine with an optimized mixed recirculated gas device Technical field

The present invention relates to an internal combustion engine or thermal engine of a motor vehicle.

The present invention relates more particularly to an intake manifold of the engine with a burnt gas mixing device.

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

Prior art

The present invention relates to internal combustion engines intended in particular to equip motor vehicles, which implement burnt gas recirculation means.

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

The standards relating to pollution and consumption of internal combustion engines equipping including motor vehicles, become increasingly severe in industrialized countries. The automotive industry is now busy finding technical solutions to meet these obligations and without penalizing neither the performance of the engines nor their cost price. A known technique of depollution of said internal combustion engines consists in operating the recirculation of the flue gas at the inlet in order to reduce the nitrogen oxides, that is to say to bring back a portion of the flue gas at the inlet and by mixing them with fresh air captured. This technique consists in reinjecting, according to the operating conditions of the engine, a part of the exhaust gases into the combustion chambers of the engine, which has the effect of reducing in proportion the quantity of oxidizing gas and thus of lowering the temperature of the combustion engine. combustion, resulting in a decrease in the production of NOx or oxides of nitrogen.

For example, the method relating to low pressure flue gas generally

adopted is the "external recirculation" of exhaust gases using a valve EGR (Exhaust Gas Recirculation) pilot, also called EGR valve for Exhaust Gas Recirculation, closing or opening a pipe connecting the collector

exhaust to the engine intake manifold. The EGR valve makes it possible to inject a certain amount of exhaust gas into the intake according to the operating conditions of the engine.

[0008] The flue gases are injected at the engine intake, generally in a combustion chamber.

engine intake manifold or directly into the engine intake ducts between the intake manifold and a combustion chamber of the engine.

The publication EP1447533-A1 thus proposes a direct injection of blow-by gases in an air intake duct to a combustion chamber of the engine. Said gases pass through a channel that opens into the intake duct.

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

[0011] In known manner, said flue gases can be collected in a recirculation ramp which extends substantially parallel to the longitudinal axis X of the engine. In said ramp open intake channels connecting said ramp to one of the air intake ducts of the engine.

The publication US 20090301448-A1 and proposes a blow-by gas collection ramp to be injected into the air intake ducts of the engine.

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

The publication FR2946699-A1 discloses a ramp for collecting burnt gases.

extending parallel to the axis of the engine and connected to an air intake manifold plenum arranged downstream of an air-water heat exchanger in the direction of flow of air. Said connection is made through channels opening into the plenum.

The disadvantage of this type of burned gas injection is also a mixture of flue gases and air that is not optimal and may affect the performance of the engine.

The document US2015002078-A1 proposes an injection of burnt gases in the plenum of a thermal engine air intake distributor through a duct penetrating upstream in the plenum of the intake distributor, said duct comprising a gas injection port facing the combustion chamber.

A disadvantage of this type of injection is on the one hand that the penetrating conduit generates losses in the flow of air to the combustion chamber and secondly that the mixture is not optimal that may affect the performance of the engine.

The object of the present invention is to provide an air intake circuit with recirculation of burned gas for engine to thermal, gasoline or diesel, overcoming the disadvantages above and improving the intake circuits of air with a mixture of burnt gases for heat engines known from the state of the art, to provide an optimal mixture of recirculated flue gases with the air before admission into the combustion chamber while generating little or no pressure loss 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 stitching of the burnt gases which can be high pressure flue gases from a combustion circuit. engine exhaust upstream of a pollution control system, for example from a collector

engine exhaust, or from a decontamination system or downstream of said system, or taken downstream of an oil settler from oil vapors. The recirculation system allows an admission of said flue gases to the intake of the engine by an injection of said gases in an intake manifold plenum by minimizing the pressure losses and optimizing the mixing of the gases with the fresh air of the engine. admission.

Presentation of the invention

The present invention relates to an air intake circuit for an engine

thermal, said air intake circuit comprising a system for recirculating burnt gas or blow-by and being positioned between an air compression element and at least a combustion chamber top part of a cylinder head engine, said air intake circuit comprising the cylinder head, a distributor

air intake, and at least one air intake duct,

Characterized in that the recirculation system comprises at least one burned gas injection duct opening into a plenum of the distributor which is delimited by side walls, an upper wall, a lower wall according to the air flow. said duct being adapted to supply said gases against the flow of the intake air flow.

Advantageously, the system comprises at least one burned gas injection duct, which duct opens into the plenum of the distributor and is adapted to bring the gas against the flow of air flow to improve the mixture of air and gas before entering the combustion chambers of the engine. The gases are initially directed against the flow of the intake air flow and then brought back to the intake duct, which improves the mixing of gases and air intake. The arrangement of the injection duct in the plenum is designed to generate low pressure losses to the air flow.

According to other features of the invention:

The at least one injection conduit 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 prolongation of the axis of at least one intake duct in order to bring burned gases to be mixed and directed into said duct. 'admission.

[0026] the outlet of the at least one injection duct in the plenum is remote 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 remote from the outlet in said plenum at least one associated intake duct to allow a better mixture between the flue gases and the flue gas. intake air before entering the at least one associated intake duct.

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

Advantageously, the injection duct is cylindrical and straight to generate a minimum of losses to the flow of burnt gases and in particular during the injection in the plenum of the distributor.

Advantageously, the injection conduit 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 flow of air. admission and improve the mixture.

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 a better injection of burnt gases and better diffusion and mixing of the burnt gases in the air flow.

[0033] the tubular channel comprises a bevel opening facing upstream of

the flow of the intake air.

Advantageously, the tubular channel comprises an aperture cut bevel, said opening section is facing upstream of the air flow to allow optimal mixing of the flue gases with the air of admission.

[0035] the tubular channel extends upstream of the air flow, from a deflecting wall capable of directing the flow of air towards a connected opening the duct

air intake.

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

The tubular channel extends from said deflecting wall, upstream of

the flow of gases to direct the gas upstream of the flow of the intake air and therefore against the flow of the flow of the intake air.

The baffle wall and the tubular channel are from the same room.

Advantageously, the baffle wall and the tubular channel are from the same room to facilitate the first hand manufacture and secondly the establishment in the cylinder head and the formation of the plenum.

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

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

[0042] the feed rail is dug in the cylinder head or attached to the bottom wall of the

plenum or is attached to the upper wall of the plenum.

[0043] Advantageously, the feed rail extending transversely to the flow of the intake air is hollowed out in the cylinder head or is fixed to the lower wall, or is fixed to one lower walls or upper plenum, which allows in the first mode a compact circuit and in the second mode ease of implementation.

[0044] the feed rail is connected to an outlet of a blow-by gas settler.

Preferably, the feed rail is connected to an output of a

blow-by gas clarifier to bring back to the intake the blow-by gases.

[0046] the supply rail is connected to an exhaust gas circuit.

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

Brief description of the drawings

Other features and advantages of the invention will appear on reading the following description of particular embodiments of the invention given as non-limiting examples and shown in the accompanying drawings, in which:

[Fig. 1] is a schematic sectional view of an intake circuit of an engine

thermal. [0050] [fig.2] is a schematic sectional view of the cylinder head and the inlet distributor according to a first embodiment of the invention.

[Fig.] Is a schematic view from above of the cylinder head with the intake circuit according to the invention.

Is a schematic sectional view of the cylinder head and the intake distributor according to another embodiment of the invention.

Detailed description of the figures

In the following description, identical reference numerals designate identical parts or having similar functions.

In this document is meant by the terms "opening section" a surface of a duct, passage of gas, said section may be transverse to the axis of the duct or obliquely to the axis of the leads.

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

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

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

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

The flue gases can also come from a decanter of oil vapors, they are called blow-by gas. Said decanter is generally arranged in the upper part of the engine. It allows the separation of the oil contained in said vapors, gases. Then, the oil is returned by an oil return circuit preferably to an oil receiving housing disposed at the bottom of the engine, and the gases can be returned to the engine intake.

In a general manner, according to FIG. 1, a heat engine 100 comprises a crankcase cylinders 101 comprising at least one cylinder 102 in which a piston is slidably movable along the axis of at least one cylinder and a cylinder head 20 covering the upper part of the cylinder block and thus 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 dug intake ducts 21 and exhaust pipes which connect the chamber to

combustion 11 of each cylinder respectively to an intake circuit 10 and an exhaust circuit. The intake circuit 10 is fixed to the cylinder head 20 by an intake face 23. The exhaust system is fixed to the cylinder head by its face

exhaust (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 captured outside the vehicle and then mixed with flue gas 41 at an inlet distributor 12 which is fixed against an inlet wall 22, on the side of the vehicle. intake face 23 of the cylinder head 20 of the engine ,. The mixture is then fed to the combustion chamber 11 of the engine via the intake ducts 21. The air and flue 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 flue gas. Said flue gases are then pushed out of the combustion chamber via the exhaust pipes to an exhaust system attached to said cylinder head on the exhaust side of the engine.

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 intake of the engine.

The term "flue gas" means the gases coming from the exhaust system or the blow-by gases.

In the following description, we will describe a return to the admission of blow-by gas to facilitate understanding of the invention but the flue gas may also be high pressure or low pressure flue gas or mixture of flue gases.

In known manner, the fresh air intake 40 is captured 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 through an air filter to remove dirt and dust carried into the intake air. Then, to improve the performance of the engine, it is also known to increase the pressure of the admitted gases and allow a better filling of the at least one engine cylinder air / fuel mixture. The power density of the engine is thus increased as well as its power, with a reduction in engine consumption. An intake air compression stage is thus disposed 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 engine performance. It is therefore useful to add to said compressor (not shown) and downstream in the direction of circulating air of the compressor, a cooling stage of the intake air. This cooling stage can be composed of a cooler 14 and more precisely of an air / water heat exchanger. Water at moderate temperature passes through the exchanger 14 and takes away some of the heat of the compressed air.

Compressed and cooled air 40 is then directed to an air intake manifold 12 to control the flow of air admitted into the combustion chamber. Said reactor is fixed by a flange 13 to the attachment wall 22 of the intake face 23 of the cylinder head 20 of the engine and directs the compressed air and cooled to intake ducts 21 dug 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 cooler water / air. 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 a same housing. Said casing is fixed to the fixing wall 22 of the cylinder head. Said fixing wall 22 extends over a plane and has an inclination with respect 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 implementation 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 distributor 12 of the air intake 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 conduit for each cylinder.

According to FIGS. 1 to 4, the recirculation system 30 comprises a rail

feedstock 31 which is connected to the exhaust system or a gas outlet of a decanter (not shown) of oil vapors.

Preferably, the intake rail 31 extends parallel to the longitudinal axis. longitudinal X of the engine. Said rail can be obtained by drilling the cylinder head that is to say that the rail is disposed within said cylinder head as shown in Figures 1 and 2, or attached to an element of the engine intake circuit 10 , that is to say that the rail is disposed outside the engine as shown in Figure 4. The intake rail allows the flow of burnt gases to the engine inlet.

Injection ducts 17 fluidly connect the intake rail 31 and the plenum 16. Said ducts are substantially cylindrical and straight to generate a minimum of losses to the flow of said flue gas. Preferably, an injection duct 17 is arranged to open into the plenum 16 of the distributor upstream of an intake duct connected to an associated cylinder. Said injection duct allows the injection of burnt gases 41 to be mixed with the intake air, said mixture is then directed to the associated intake duct leading to the cylinder. In the description, there is an intake duct 21 per cylinder of the engine. In general, said intake duct 17 is then 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 the intake air in plenum 16 of the intake manifold. The injection ducts 17 whose axis is substantially orthogonal to the axis of said intake rail 31 open at a first end into the intake rail 31 and the second end opposite into the plenum 16. The number of ducts injection 17 is preferably equal to the number of cylinders of the engine. The injection duct 17 therefore extends perpendicularly to the X axis of the engine, from the injection rail 31, at an associated cylinder along the X axis of the engine. Each injection duct opens into the plenum 16 in the extension of the axis of the intake duct 21. More specifically, the projection on a horizontal plane of the outlet of the injection duct 17 in the plenum 16 is disposed in the projection the axis of the associated intake duct on the same horizontal plane as shown in Figure 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 ducts 17 extends rectilinearly and opens out of the wall of the plenum 16 towards the upstream A _m of the flow of the intake air to bring the flue gases against the flow of the direction. flow of intake air.

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

The injection duct 17 comprises a tubular channel 18 penetrating into the plenum to optimally position the injection point of the flue gases 41 in the plenum. the flow of the intake air 40, preferably in the extension of the intake duct 21 and preferably remote from the outlet of said intake duct 21 in the plenum 16. The tubular channel extends from the wall from the plenum towards the upstream Am of the flow of the intake air. The distance may be greater, for example, than 20 mm to allow optimal mixing of the flue 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 in 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 may for example be cut bevel and have the opening section directed upstream A _m of the flow of air.

The flue gases 41 are thus directed against the flow of the intake air flow 40 and then brought back in the direction of admission to the inlet ducts 21, which substantially improves the mixing of said flue gases. with air before entering said intake ducts 21.

According to FIG. 2, the tubular channel 18 extends from a deflecting wall 34

inclined delimiting downstream the plenum 16. According to the preferred embodiment, the plenum 16 comprises a portion dug in the cylinder head 20.

According to Figures 1 to 4, the deflecting wall 34 is inclined relative to the axis

air flow E; more precisely, the axis orthogonal to said deflecting wall is intersecting 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 deflector wall 34 or be substantially parallel to said axis to have an inclination with respect to the axis of flow of the gas E.

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

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

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

[0089] Preferably, the tubular channel 18 is of reduced passage section to generate small amounts of charges to the flow of air.

The objective is achieved: the recirculation system 10 of the flue gases of the circuit

air intake according to the invention allows a mixture of said gas with the improved air without generating too much pressure losses to the flow of the intake air.

It goes without saying that the invention is not limited to the embodiments of this outlet, described above as examples, it encompasses all variants.

For example, the tubular channel may be replaced by a protuberance on the inner surface of the baffle or lower wall of the tundish.

The tubular channel 18 may also extend parallel to the axis orthogonal to the lower wall 36 or baffle 34 and have an opening for the injection of flue gas directed upstream A _m of the flow of the 'air.

Another embodiment may be that the tubular channel comprises a

radial opening at its free end 18 'facing upstream A _m of the air flow.

Claims

claims

[Claim 1] Intake circuit (10) for a combustion engine comprising a

a burnt gas recirculation system (30) for positioning between an air compression element and a combustion chamber top (11) in a cylinder head (20) of the engine, said air intake circuit comprising the cylinder head, an intake distributor (12) comprising a plenum (16), and air intake ducts (22),

characterized in that the recirculation system (30) comprises at least one flue gas injection duct (17) opening into the plenum (16) which is delimited by side walls, an upper wall, a bottom wall according to the air flow, said duct (17) being adapted to bring said flue gases against the flow of the intake air flow (32).

[Claim 2] Intake circuit (10) according to claim 1, characterized in that the at least one injection pipe (17) opens into the plenum (16) in the extension of the axis of minus an associated intake duct (21).

[Claim 3] Intake circuit (10) according to claim 2, characterized in that the outlet of the at least one injection duct (17) in the plenum is remote from the outlet in said plenum of at least one duct. admission (21) associated.

[Claim 4] Intake circuit (10) according to any one of claims 1 to

3, characterized in that the at least one injection conduit (17) is extended by a tubular channel (18) penetrating into the plenum (16) of the distributor (12).

[Claim 5] Intake circuit (10) according to claim 4, characterized in that the tubular channel (18) has an upstream opening (A _m ) of the air flow.

[Claim 6] Intake circuit (10) according to claim 4 or 5, characterized in that the tubular channel (18) has an upwardly beveled opening (A _m ) of the air flow.

[Claim 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) adapted to direct the flow of air to an opening connected to the duct of admission (22).

[Claim 8] Intake circuit (10) according to claim 7, characterized in that the deflecting wall (34) and the tubular channel (18) come from the same room.

[Claim 9] Intake circuit (10) according to any one of claims 1 to

9, characterized in that the recirculation system (30) comprises a supply rail (31) extending transversely to the axis

air flow (E), said rail is connected to the at least one gas injection pipe (17).

[Claim 10] Intake circuit (10) according to claim 9, characterized in that the feed rail (31) is cut into the yoke (20) or attached to one of the lower walls (35) or upper (36) of the plenum (16).

[Claim 11] Intake 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 settler.

[Claim 12] Intake circuit (10) according to claim 9 or 10, characterized in that the supply rail (31) is connected to an exhaust gas circuit.