FR3032485A1 - TURBOCOMPRESSED ENGINE ASSEMBLY WITH TWO EXHAUST DUCTS WITH RECIRCULATION LINE - Google Patents

Abstract

The invention relates to an engine assembly comprising an exhaust system with a first exhaust duct by the turbine (2), a second discharge duct and a quilting (12) for a recirculation line. The first conduit opens into a main expansion passage (4 ') through an inlet face of a turbine casing (2c) and the second conduit opens through the inlet face (2a) of the casing (2c) into the minus a branch portion (8) internal to the casing (2c) bypassing the main relief passage (4 '). The tapping of the at least one recirculation line is carried out in the turbine (2) on a stitching portion (8) of at least the main expansion passage (4 ') or of said bypass portion (8) via at least one stitching end (12).

Description

The present invention relates to an engine assembly for a motor vehicle comprising an internal combustion engine, an exhaust gas recirculation line at the engine intake. The invention relates to a motor assembly for a motor vehicle comprising an internal combustion engine, an exhaust gas recirculation line to the engine intake. , an air intake system at an engine inlet and an exhaust system at an engine outlet.  Engine turbocharging is provided by a turbine and a compressor, the turbine being integrated in the exhaust system and the compressor in the air intake system, the exhaust system comprising two exhaust pipes extended in the turbine by joining portions.  The exhaust system of such a motor assembly is connected to an output of the turbocharged engine, also called supercharged engine, for an exhaust gas exhaust from combustion in the engine, the engine being advantageously but not only a four-stroke gasoline engine.  [0003] FIG. 1 shows a supercharged gasoline engine assembly according to the closest prior art described in particular in the document WO-A-2009/105463.  Such an engine assembly is known under the name VEMB, abbreviation of the English name of "Valve Event Modulated Boost", translated into French by supercharging controlled by motor distribution.  This type of engine assembly will be detailed after the general presentation of a conventional supercharged engine and an engine equipped with an exhaust gas recirculation line at the engine intake, also called EGR line.  Referring to Figure 1 for a portion of the elements illustrated in this figure, a thermal combustion engine comprises a cylinder block provided with at least one cylinder, preferably several cylinders and an air intake inlet or an air intake manifold for the gasoline air mixture in each cylinder and an exhaust gas outlet resulting from the combustion of the mixture in each cylinder.  The output of the engine is connected to an exhaust manifold 5 supplying an exhaust duct 4, 9 exhausting the exhaust gases to the outside.  The fact that two exhaust manifolds 5, 7 each with an associated exhaust duct 4, 6 are shown for the engine assembly in Figure 1 is not applicable to any turbocharged engine assembly, such an engine generally comprising only one manifold 5 and a single exhaust duct 4, 9 extended inside the turbine 2.  [0006] The turbocharged engine comprises a turbine 2 and a compressor 3.  The turbine 2 is disposed downstream of the exhaust manifold 5 in the exhaust pipe 4 while the compressor 3 is disposed upstream of the air intake manifold to the engine.  The turbine 2 comprises a turbine wheel recovering at least partially a kinetic energy created in the exhaust gas passing therethrough, the rotary member or wheel of the turbine being rotated by the exhaust gases leaving the exhaust manifold .  The turbine 2 drives the compressor 10 3 by being secured to it by an axis, the compressor 3 is traversed by fresh air for supplying air to the engine, air compressor 3 compresses.  At the outlet of the compressor 3, the air which is then called charge air is supplied by the air supply line to a charge air cooler 25 to cool the air leaving the compressor 3.  On this line is also positioned a throttle valve 26 regulating the flow of air into the air intake manifold of the engine forming the engine air inlet.  On the exhaust side of the engine assembly 1, at the outlet of the turbine 2, the exhaust gas exhausted from the engine enters the exhaust duct 9 of the motor vehicle after passing through the turbine 2 and The exhaust gas cleaning means 10 pass through them, for example one or more catalysts, in particular oxidation, reduction or three-way catalysts, whether or not associated with a particulate filter.  A selective catalytic reduction system or RCS system may also be provided in the exhaust duct 9.  [0009] It is also common to provide an engine assembly with a recirculation line for the exhaust gas to the engine air intake, also called EGR line, such a line being referenced 11 in FIG.  It is indeed known for spark ignition and compression ignition engines to recirculate the exhaust gases to the engine air intake to reduce nitrogen oxide emissions.  Such a system is also known by the Anglo-Saxon acronym EGR 30 for "Exhaust Gas Recirculation" which means Recirculation of Exhaust Gas.  An EGR line 11 has a stitching on the exhaust duct to withdraw a portion of the exhaust gas of the duct and a cooler 23 of the exhaust gas passing through this line 11, these gases then being very hot. .  Line 3032485 3 RGE 11 opens on the intake of air upstream of the compressor 3 it feeds.  A valve 24 called EGR valve equips the EGR line 11, advantageously downstream of the cooler 23, to open or close the flow of gas to the inlet.  For any type of RGE line 11, the recirculation of the exhaust gases to the air intake of the heat engine makes it possible to improve the thermodynamic efficiency of the engine because of the reduction in heat transfer by reintroduction. of gas recirculated through line EGR 11 into the intake manifold.  Such recirculation may also allow a decrease in enrichment related to the exhaust temperature and a decrease in pump losses when the engine is associated with a turbocharger.  With regard to the reduction of losses by pumping, this has not been entirely satisfactory and the pumping phenomena still persist in the turbine 2.  It has been proposed to use a relief valve inside the turbine.  It was then proposed an exhaust system for a motor-driven supercharger engine with two exhaust pipes as shown in FIG.  The thermal combustion engine forming part of the set 1 said supercharging controlled by engine distribution has at least one cylinder, in Figure 1 three cylinders.  Each engine cylinder is provided with an intake valve and two exhaust valves.  These exhaust valves may be selectively associated with a first or second exit passage in a cylinder and selectively open and close their associated passage.  It is the same for the intake valve associated with an inlet passage in each cylinder.  The two outlet passages of each cylinder which are closed and opened sequentially by their associated exhaust valve open on a different exhaust manifold 5, 7, each supplying a dedicated exhaust duct 4, 6, the two ducts 4, 6 exhaust does not follow the same course as it will be detailed below.  The first exhaust passage of each cylinder is connected to the first manifold 5 and the second exhaust passage is connected to the second manifold 7.  A motor assembly 1 said supercharging controlled by engine distribution therefore comprises a first duct 4 said exhaust turbine 2 leaving a first exhaust manifold 5 and a second duct 6 said discharge from a The exhaust manifolds 7, 7 each being respectively connected to one of the two series of first or second exhaust passages provided with their exhaust valves provided for each cylinder.  The first duct 4 leads to an inlet face of the turbine 2 of the turbocharger being extended by a main expansion passage inside the turbine 2 housing a turbine wheel for recovering the kinetic energy. contained in the exhaust gas passing through it.  The second duct 6 bypasses the turbine 2 without penetrating but joins further downstream of the turbine 2 a third duct 9 connected to an outlet face of the turbine 2 for the exhaust gas evacuation of the main expansion passage 10 having has been in exchange for energy with the turbine wheel so that there is only one exhaust duct 9 passing through the decontamination elements 10 placed at the end of the exhaust system.  It follows that, in such a motor-controlled supercharging engine assembly according to the state of the art, the second duct 6 has no penetrating extension in the turbine 2.  The function of the first duct 4, said turbine exhaust duct, is to allow a first flow of exhaust gas to pass through the turbine 2 and its rotary energy recovery member in the form of a wheel to provide power to the compressor 3.  The function of the second duct 6, said discharge duct and fed by a second exhaust manifold 7, different and independent of the first exhaust manifold 5 of the first duct 4, is to allow a second independent exhaust flow. and different from the first flow to bypass the turbine 2 and in particular its wheel and thus discharge the turbine 2 of the total flow of exhaust gas by decreasing the flow of exhaust gas therethrough by subtraction of the second flow to the total flow.  This makes it possible to discharge and / or control the power of the turbine, as would in a conventional operating condition for regulating the motor load a discharge valve, a previously known element of the state of the art for an engine. turbocharged.  This makes it possible in particular to avoid the pumping phenomenon of the engine consisting essentially of a return of the hot gases to the intake air inlet.  For a conventional turbocharged engine, a discharge valve which may be internal or external to the turbine serves to limit the pressure of the exhaust gas on the turbine wheel of the turbocharger by opening a bypass of the exhaust gas to that they no longer pass through the turbine and its wheel.  A limitation of the speed of the wheel 3032485 5 of the turbine is thus obtained, which also limits the speed of rotation of the wheel provided in the compressor being integral with the wheel of the turbine, where also a limitation of the compression of the intake air.  [0020] A relief valve associated with a turbine for regulating the flow of exhaust gas therethrough is no longer necessary with a motor-controlled supercharging engine assembly having two exhaust ducts each starting from a respective exhaust manifold.  [0021] Thus, such an engine assembly makes it possible to improve the efficiency of the engine cycle by reducing the engine pumping during the exhaust phase of a four-stroke cycle, which has a favorable impact on fuel consumption. engine.  Better control of the energy recovered by the turbine is therefore performed, which implies better management of the engine load.  In such an engine assembly, a high pressure RGE 11 recirculation line can simultaneously coexist, which can be stitched, for example, on the second discharge duct 6 and a low pressure recirculation line 11 which can be stitched for example on the first exhaust duct 4 per turbine, this advantageously downstream of the turbine 2.  It may also exist only one EGR 11 recirculation line stitched on one of the two ducts 4, 6.  [0023] One of the major drawbacks of the combination of an EGR line with a two-exhaust engine assembly starting from a respective exhaust valve of two exhaust valves per cylinder is that the connection of the EGR line 11 on the exhaust front of such an engine assembly can be complex.  In addition, in the low-pressure connection configuration for the EGR line, if the backpressure of the exhaust at the outlet of the turbine 2 is not high enough, the flow capacity of the line EGR to the circuit air intake of the engine is reduced, this especially in situations of low engine speed and / or low engine load.  Thus, the maximum level of flow of the EGR line acceptable by the engine is no longer achievable, which limits the efficiency of the recirculation of the exhaust gas to the air intake.  FR-A-2 992 353 discloses a motor unit comprising a combustion engine with an exhaust system comprising a high pressure exhaust manifold 3032485 6 feeding an exhaust line and a low pressure exhaust manifold supplying a recirculation line.  The system also includes a gas tank which is connected to the engine by an isolation valve which can assume a communication configuration allowing a flow of gas between the engine and the tank and an insulation configuration preventing this circulation.  This exhaust system is however complex with the presence of a reservoir and a conduit connecting it to the manifold, the valve being disposed in this conduit.  Therefore, the problem underlying the invention is to improve a motor assembly said supercharging controlled by two exhaust ducts engine distribution, the supercharged engine being associated with a recirculation line of the exhaust gases. the so-called EGR line exhaust, on the one hand, by reducing the complexity of the connection of the EGR line to the exhaust system of the engine assembly and, on the other hand, by obtaining that the operation of the EGR line optimally in all driving conditions of the motor vehicle.  In order to achieve this objective, an engine assembly with an engine comprising at least one cylinder, at least one exhaust gas recirculation line at an engine intake, a turbocharger comprising a turbine is provided according to the invention. and a compressor, and an exhaust system connected by a first and a second exhaust manifold to an engine outlet for exhaust gas exhaust from combustion in the engine, the exhaust system comprising a first said exhaust duct by the turbine leaving the first exhaust manifold and a second duct said discharge from the second exhaust manifold, the turbine being provided with a housing having a main relief passage in which is housed a turbine wheel and the first conduit 25 opening into the main expansion passage through an inlet face of the housing, characterized in that the second conduit opens by the inlet face of the housing in at least one internal bypass portion to the casing bypassing the main expansion passage and in that the stitching of said at least one recirculation line is in the turbine on a stitch portion of at least the expansion passage or said at least one bypass portion via at least one stitching end.  The technical effect is to obtain at least one stitching end of at least one integrated recirculation line to the turbine, this through a housing surrounding the turbine.  It is thus possible to increase the rate of gas recirculation under both low pressure and high pressure connection conditions, depending on whether the stitching is performed on the main expansion passage or the at least one branch portion.  In addition, the fact of connecting the expansion passage and said at least one branch portion respectively extending the first or the second conduit in the turbine makes it possible to maintain the same conventional exhaust aftertreatment system. of the engine than that preceding the improvement of a motor assembly by supercharging controlled by motor distribution.  Compared to a conventional turbocharger engine assembly, according to the present invention, a discharge valve is advantageously replaced by the branching portion or portions extending the second conduit inside the turbine, the flow rate of which can easily be controlled. .  Even the stitching end opening into the recirculation line can be used for the discharge of the turbine, especially when the stitching end is formed on the expansion passage extending the first exhaust duct in the turbine.  This is advantageously controlled by the motor control which has all the necessary parameters for determining whether a discharge of the turbine wheel is necessary or not.  Advantageously, the stitching portion on which the stitching is made via at least one stitching end is said at least one branch portion extending the second conduit and bypassing the wheel of the turbine, the exhaust system comprising a third conduit outside the turbine and connected to an outlet face of the turbine casing for exhaust gas discharge out of the turbine.  Advantageously, the stitching portion comprises at least one regulating valve for regulating at least one exhaust gas flow therethrough, said at least one regulating valve being operable between at least a first position of closing the flow in the stitching portion at or after said at least one stitching end and a second opening opening position in the stitching portion at or after said at least one stitching end.  [0033] Advantageously, the control valve is disposed towards at least one outlet end of said at least one tapping portion at the outlet face of the turbine, intermediate opening positions of the regulating valve making it possible to regulate the flow rate in said at least one stitching portion according to the degree of opening of the regulating valve corresponding to each respective intermediate position.  Advantageously, the control valve is operable between at least four positions, namely: a first closing position of said at least one stitching portion and at least one stitching end with a zero flow rate in said at least one tapping portion and in said at least one recirculation line; a second closing position of said at least one tapping portion with a zero flow in said at least one tapping portion; the exhaust gases; flowing fully into said at least one recirculation line via said at least one stitching end, a third closing position of said at least one recirculation line via closure of said at least one stitching end with a throughput zero in said at least one recirculation line, the exhaust gases in this stitching portion flowing fully to said at least one outlet end of said at least one stitching portion, fourth fourth opening positions of said at least one stitching portion and said at least one recirculating stitching end, said intermediate opening positions for adjusting the flow rate to said at least one stitching portion; minus one outlet end in said at least one stitching portion and in said at least one recirculation line according to the degree of opening of said at least one stitching portion and said at least one stitching end corresponding to each position respective intermediary.  Advantageously, when the stitching portion is said at least one branch portion, the regulating valve comprises a disk displaceable in translation or in rotation by an actuator, the disk bearing said at least one output end of said at least one bypass portion and said at least one stitching end of said at least one recirculation line.  Advantageously, the disk of the regulating valve is either: - I-shaped plate, - of U-shaped section for which said at least one outlet end 30 of said at least one branch portion is radial internal to the disk while said at least one stitching end is radially external to the disk, or - of inverted L-shaped section for which said at least one output end of said at least one branch portion is axially internal to the disk while said at least one stitching end is radially external to the disk or said at least one output end of said at least one branch portion is radially internal to the disk while said at least one stitching end is axially external to the disk .  [0037] Advantageously, the output disc is disposed around an outlet end of the first conduit, the output disc having an internal hollow recess 5 opposite the exit end of the first conduit.  Advantageously, said at least one outlet end of said at least one branch portion is of circular section, oval or half-moon shaped.  Advantageously, the casing of the turbine surrounds at a distance the wheel of the turbine and comprises an intermediate portion interconnecting its inlet face and an outlet face of the casing, the intermediate portion comprising at least one opening for said at least one stitching of said at least one recirculation line.  Other features, objects and advantages of the present invention will appear on reading the detailed description which follows and with reference to the accompanying drawings given as non-limiting examples and in which: FIG. a schematic representation of a turbocharged engine assembly comprising an exhaust system with two exhaust pipes and an EGR line according to the closest state of the art; - FIG. 2 is a schematic representation of a turbocharged engine assembly; comprising an exhaust system with two exhaust ducts 20 and an EGR line according to the present invention, the turbine being traversed by extensions of the two ducts, - Figure 3 is a schematic perspective representation of an embodiment of the invention. a turbine surrounded by its casing, this turbine forming part of the exhaust system according to the present invention and FIGS. 3a and 3b showing embodiments of the outlet face of the turbine through which the exhaust gases exit; FIG. 4 shows a longitudinal section of a turbocharger, the turbine of the turbocharger being integrated into the exhaust system of the assembly; motor according to the present invention by illustrating a first embodiment of a control valve for the branch portion extending in the turbine the second conduit and Figure 4a shows an outlet face of the turbine according to Figure 4, - the FIG. 5 shows a section of a turbocharger with the turbine provided with a control valve but according to another embodiment in FIG. 4 and FIG. 5a shows an outlet face of the turbine according to FIG. A turbine forming part of the exhaust system of the engine assembly according to the present invention, FIGS. 6, 6a to 6e show a control valve in the branch portion extending the xth duct inside the turbine respectively in various positions in the closed position and opening in the motor assembly according to the invention and this for two embodiments with or without stitching of the line EGR, 5 - the figure 7 is a diagrammatic representation in perspective of another embodiment of a turbine provided with a control valve on an internal bypass portion; FIGS. 8, 9 and 9a show a respective embodiment of a disc. carrying out outlet end openings of the branch and tipping end portion for an exhaust gas recirculation line, which disc may be part of a turbine element of the engine assembly according to the present invention .  It is to be borne in mind that the figures are given by way of examples and are not limiting of the invention.  They are schematic representations of principle intended to facilitate the understanding of the invention and are not necessarily at the scale of practical applications.  In particular, the dimensions of the various elements illustrated are not representative of reality.  In what follows the words downstream and upstream are to be taken in the direction of the flow of exhaust gas out of the engine or again to the engine inlet for the recirculation line, an element in the system. exhaust downstream of the engine being further away from the engine than another element upstream of the element.  What is called the engine assembly includes the engine as well as its auxiliaries for the intake of air into the engine and for the exhaust of gases out of the engine, a turbocharger also forming part of the engine assembly, the turbine being included in the exhaust system of the engine assembly.  FIG. 1 has already been described in the introductory part of the present patent application.  Referring to all the figures except Figure 1 and in particular in Figure 2, there is shown an engine assembly according to the present invention which incorporates some of the characteristics of the engine assembly of the state of the art with, however, a different exhaust system.  The engine assembly 1 comprises an internal combustion engine and a turbocharger comprising a turbine 2 and a compressor 3.  The turbine 2 comprises a wheel 3032485 11 recovering at least partially the kinetic energy of the gases passing through it and transmits this energy to the compressor 3.  For this, the turbocharger is provided with an axis connecting the wheel of the turbine 2 to a wheel in the compressor 3 ensuring the compression of the air passing through the compressor 3.  This shaft can be lubricated, cooled by water and / or oil and installed on bearings with or without bearings.  This axis may also be equipped with an electrical assistance, either directly on the axis, or with the help of gears, for example a transmission or a gearbox.  The exhaust system is connected to an output of the engine for exhausting exhaust gases from combustion in the engine and comprises a first exhaust duct 4 by the turbine 2 starting from a first exhaust manifold 5 and a second duct 6 said discharge from a second exhaust manifold 7.  The first and second collectors 5, 7 are connected to the outlet of the internal combustion engine for the exhaust gas channeling through the first and second conduits 4, 6.  The output of the motor may consist of two output passages per cylinder on the engine each associated with an exhaust valve, but this is not limiting, although this is illustrated in FIG.  In FIG. 2, the engine comprises at least one cylinder having two outlet passages for evacuation of exhaust gases from combustion in the engine, the first outlet passage being connected to the first collector 5 while the second outlet passage is connected to the second manifold 7.  The present invention can also be applied to an engine with at least one cylinder having only one outlet passage, the first and second collectors 5, 7 being connected to this single passage.  The two exhaust manifolds 5, 7 may be close to each other 25 to be connected to the turbine 2, for example by the same exhaust manifold connection flange with a turbine housing 2c 2 .  The exhaust manifolds 5, 7 may be cooled by a cooling liquid, in particular water, the liquid flowing in a common cooling circuit or not common to the two collectors 5, 7.  The cooling circuit (s) may also be used for cooling the interior of the turbine 2.  The turbine 2 is provided with a casing 2c surrounding it by having at least one input face 2a and 2b output face.  The turbine 2 has a main relief passage 4 'in which is housed a turbine wheel and the first conduit 4 opens into the main passage of relaxation 4' by the inlet face 2a of the housing 2c.  The main relief passage 4 'is particularly visible in Figures 3, 4 and 5.  The exhaust system also comprises a stitching with a stitching end 12 on the second duct 6 or its extension in the turbine 2 for a line 5 of recirculation 11 of the exhaust gas at the inlet of the engine.  This tapping may also be on the first conduit 4 or its extension in the turbine 2 in replacement or in association with the tapping on the second conduit 6.  According to the present invention, the second duct 6 opens through the inlet face 2a of the housing 2c in at least one branch portion 8 internal to the casing 10 2c bypassing the main relief passage 4 'and the stitching of said at least one recirculation line 11 is made in the turbine 2 on a stitching portion 8 of at least the expansion passage 4 'or said bypass portion 8 via at least one stitching end 12.  Thus, a bypass portion 8 extending the second duct 6 inside 15 of the turbine 2 is integrated in the turbine 2 but is not in exchange for kinetic energy with the wheel of the turbine, which provides a more efficient discharge effect of the turbine than the discharge effect obtained with a relief valve.  In addition, the fact that a bypass portion 8 extending the second duct 6 inside the turbine 2 is integrated in the turbine 2 reduces the size of the exhaust system and reduces the expense of the exhaust system. for the ducts 4, 6, the junction of the first and second ducts 4, 6 being in the turbine 2 and not after the turbine 2, resulting in a shortening of the length of the second duct 6.  According to the invention, the stitching of the recirculation line RGE 11 is done on at least a portion 8 of one of the first and second conduits 4, 6 internal to the turbine 2 via 25 at least one stitching end 12 said portion 8 advantageously comprising a regulating valve 13, 13a for the regulation of at least one flow of exhaust gas passing therethrough.  If in Figure 2 the stitching portion is the branch portion 8 extending the second conduit 6 inside the turbine 2, this is not necessarily the case within the scope of the invention.  [0056] Thus, it is possible to obtain a high pressure RGE line 11, in which case it is in the extension of the second discharge duct 6 by at least one bypass portion 8 not passing through the impeller wheel 2 that the stitching is done.  It can also be obtained a line RGE 11 low pressure, in which case it is in the extension of the first duct 4 said exhaust through the main passage of expansion 4 'inside the turbine 2 that stitching is done.  It is also possible to cumulate the taps at the same time on the respective extensions 4 ', 8 in the turbine 2 of the first ducts 4 and second duct 6 which are respectively the main relief passage 4' and said at least one branch portion in which case high and low pressure RGE lines 11 are obtained, these lines being stitched inside the turbine 2.  Preferably, the portion or portions on which the stitching is done via at least one stitching end 12 are one or more bypass portions 8 of the second duct 6 bypassing the impeller of the impeller 2, so as to obtain a line EGR 11 high pressure.  This allows an optimization of the distribution of the flows initially passing through the second duct 6 with respect to the flow initially passing through the first duct 4, which allows better aerodynamics at the outlet of the turbine 2.  In a first embodiment of the present invention, the control valve 13, 13a may be operable between at least a first flow closure position in the at least one branch portion serving as a stitching portion 8 after stitching. 12 and a second open position of the flow in the branch portion or portions 8 after stitching 12.  In this embodiment, it should be noted, on the one hand, that there may be several branch portions that are stitched.  On the other hand, if in the figures the control valve 13, 13a is integrated in a bypass portion 8, this is not limiting, such a control valve can be integrated in the main relief passage 4 'in association with or replacing a tapping in the bypass portion (s).  This is also valid for the second embodiment which will now be detailed.  In a second embodiment of the invention, which is preferred to the first mentioned, the control valve 13, 13a may be disposed towards the outlet end or ends 8b of the at least one branch portion 8 portions of tapping on the outlet face 2b of the turbine 2, intermediate opening positions of the control valve 13, 13a can be used to adjust the flow in the branch portion or portions 8 according to its degree of opening corresponding to each respective intermediate position.  There are thus several degrees of opening possible with the result of a modulation of the output flow of the branch portion or portions 8 serving as stitching portions.  As shown in particular in FIGS. 3 and 7, the turbine 2 of the turbocharger may be integrated in a casing 2c having at least one inlet face 2a for the exhaust gases receiving the ends of the first and second ducts 4, 6 and an outlet face 2b for the exhaust gases leaving the turbine 2.  The casing 2c may have a quilting outlet 12a passing through the turbine 2.  In FIGS. 3, 4a, 5a and 7, the inlet end 8a and the outlet end 8b of a bypass portion 8 are shown.  FIG. 3a shows an outlet face of the casing with a single outlet end 8b of a bypass portion while FIG. 3b shows an outlet face of the casing with several outlet ends 8b of a portion of derivation, these output ends being adjacent to this figure but can be equally distributed uniformly and concentrically on the output face of the housing.  [0064] In a first embodiment of the invention, which is not limited to the control valve, as shown in FIG. 4, the regulation valve 13 can only close the outlet end of the bypass portion 8 as that stitch portion to prevent the second flow through this branch portion 8 to lead to the outlet face 2b of the housing 2c.  In this embodiment, the control valve 13 does not control the closing or opening of the EGR line by its stitching end.  FIGS. 4a and 5a illustrate an inlet face 2a of the casing of the turbine with the inlet opening of a main expansion passage 4 'and a bypass portion 8 respectively extending the first duct 4 or the second leads 6 in the turbine.  In a preferred embodiment of the invention concerning the control valve, the control valve 13, 13a may be arranged at the outlet end or ends 8b of the at least one branch portion 8 serving as portions. stitching on the outlet face 2b of the turbine 2, the control valve 13, 13a being operable between at least four positions.  Figure 5, while referring to Figure 2 for some of the references, shows in particular three positions a, b, c of a control valve 13a.  The first position, referenced c, may be a closing position of the outlet of said at least one branch portion 8 and of said at least one stitching end 12 with a zero flow in said at least one branch portion 8 and in said at least one recirculation RGE line 11.  The second position, referenced b, may be a closed position of the output of said at least one bypass portion 8 with a zero flow at the output of said at least one branch portion 8, the exhaust gases. exhaust of the second duct 6 flowing completely in said at least one recirculating RGE line 11 via said at least one quilting end 12.  The third position, referenced a, may be an open position of the control valve 13a leaving open the outlet end 8b of the bypass portion 8 extending the second conduit 6 inside the turbine 2 opening towards the outlet face 2b of the turbine 2 and the stitching end 12, the flow of the second duct 6 being divided between a flow towards the outlet face 2b of the turbine 2 and a flow in the EGR line 11 for recirculation of the exhaust gas.  Another position may be a closed position of said at least one recirculation line RGE 11 by closing said at least one stitching end 12 with a zero flow rate in said at least one recirculating RGE line 11, the exhaust gas flowing towards the outlet of said at least one branch portion 8 extending the second duct 6 inside the turbine 2 towards the outlet face 2b of the turbine 2.  Finally, intermediate positions are possible by being partial opening positions of said at least one bypass portion 8 and said at least one tapping end 12 recirculation, these intermediate opening positions to adjust the flow rate at the outlet of said at least one bypass portion 8 and in said at least one recirculation RGE line 11 according to the degree of opening of said at least one branch portion 8 and said at least one corresponding stitching end 12 at each respective intermediate position.  Thus, the regulating valve 13, 13a may, in some embodiments of the present invention, control the flow rate of the bypass portion 8 and the recirculating RGE line 11 beginning of the stitching 12.  There is thus an economy of means obtained by these characteristics.  This is illustrated in particular in FIGS. 6 and 6a to 6e, which show various positions of a regulating valve 13, according to the present invention, respectively for a first embodiment in which the regulation valve 13 operates in the stitch portion 8 separating an upstream portion of the stitching portion of a downstream portion 8 'at the end of stitching portion 8 or respectively for a second embodiment in which the control valve 13 operates between, on the one hand, an upstream part of the stitching portion 8 and the end of the stitching 12 and, on the other hand, the downstream part 8 'at the end of the stitching portion 8.  These representations are diagrammatic, the downstream part 8 'at the end of the stitching portion 8 opening towards the exit face of the casing of the turbine, the casing of the turbine and its outlet face not however being represented in FIG. these figures.  In addition, as previously mentioned, the stitching portion 8 may be a bypass portion extending the second conduit or the main expansion passage extending the first conduit.  In these figures, the control valve 13 is in the form of a cone that can completely obstruct the end of the upstream portion of the stitching portion 8 and, where appropriate, the end of the stitching 12. of the EGR line.  The control valve 13 can be moved by an actuator 15 to these figures by translation.  It should be borne in mind that all these features are not limiting and that another arrangement of the EGR stitching and stitching portion 8 and another form of regulating valve 13 may be adopted.  In a first embodiment shown in FIGS. 6, 6a and 6b, the regulation valve 13 is displaceable in translation between a closed position and an open position of the end of the upstream portion of the portion of stitching 8.  In the first case, the flow of the upstream portion of the stitching portion 8 does not result in the downstream portion 8 'at the end of the stitching portion 8 and in the second case, the flow of the upstream portion of the staple portion 8 in the downstream part 8 'at the end of the stitching portion 8, its throughput is adjustable by translation of the regulating valve 13, a progressive transverse widening of the downstream part 8' leading to a greater flow rate due to 25 greater opening between the valve 13 and the walls of the downstream portion 8 '.  In FIG. 6, the upstream part of the stitching portion 8 is closed by the regulation valve 13.  No flow of exhaust gas from the upstream portion of the stitching portion 8 reaches the downstream portion 8 'at the end of the stitching portion 8.  In FIG. 6a, the regulation valve 13 has begun its translation towards the downstream part 8 'at the end of the stitching portion 8 but still closes the upstream part of the stitching portion 8.  In FIG. 6b, the control valve 13 has continued its translation, has reached the level of the transverse widening of the downstream part 8 'at the end of the stitching portion 8 and no longer closes the upstream portion of the stitching portion 8 .  The flow therefore passes from the upstream portion of the stitching portion 8 into the downstream portion 8 'at the end of the stitching portion 8.  In a second embodiment shown in FIGS. 6c to 6e, the stitching end 12 and the upstream portion of the stitching portion 8 extend in parallel while being traversed by the exhaust gases in the opposite direction. one with respect to the other.  The control valve 13 is interposed between, on the one hand, the stitching end 12 and the upstream part of the stitching portion 8 and, on the other hand, the downstream part 8 'at the end of the stitching portion 8 .  In FIG. 6c, the regulation valve 13 which is of conical shape has its tip adjacent to the edge of the separation duct between the stitching end 12 and the upstream part of the stitching portion 8.  The upstream portion of the stitching portion 8 is closed by the regulating valve 13 and the stitching end 12.  No flow of exhaust gas from the upstream portion of the stitching portion 8 thus leaves neither by the downstream portion 8 'at the end of stitching portion 8 nor by the stitching end 12 to feed the EGR line.  In FIG. 6d, the upstream part of the stitching portion 8 does not always communicate with the downstream part 8 'at the end of the stitching portion 8 because of the position of the regulating valve 13, although this it has carried out a translation taking off its tip from the edge of the separation duct between the stitching end 12 and the stitching portion 8.  The conical tip of the control valve 13 no longer closes the end of the inlet tap 12 of the EGR line.  The flow of exhaust gas from the upstream portion of the stitching portion 8 passes only through the stitching end 12 to feed the EGR line.  In FIG. 6e, the regulation valve 13 has continued its translation, has reached the level of the transverse widening of the downstream part 8 'and no longer closes the communication between the upstream part and the downstream part of the stitch portion 8.  The flow 25 therefore passes from the upstream portion of the stitching portion 8 into the downstream portion 8 'but also through the stitching end 12 input.  The flow of the exhaust gas from the second conduit is distributed between the downstream portion 8 'at the end of the stitching portion 8 and the EGR line through its stitching end 12 inlet.  The flow rate in the downstream part 8 'at the end of the stitching portion 8 increases with the progression of the transverse widening of this downstream part.  FIGS. 7, 8, 9 and 9a illustrate a control valve which is movable in rotation by an actuator 15.  The casing 2c of the turbine 2 shown in FIG. 7 is substantially the same as that shown in FIG. 3 and differs from the latter only in a position different from the stitching end 12, this stitching end 12 not being 3032485 18 not visible in Figure 7.  The elements inside the housing 2c are also substantially similar except the control valve 13.  In these figures, the control valve 13 comprises a closure disk, referenced 29 in FIGS. 8, 9 and 9a, movable in rotation by an actuator 15.  The shutter disk 29 carries the outlet end (s) 8b of the at least one branch portion (8) and the stitching end (s) 12 of the recirculation EGR line.  The shutter disk 29 of the control valve 13 may be flat I-shaped.  It may also be of inverted U-shape for which the outlet end or ends 8b of the at least one branch portion 8 are radially internal to the closure disc 29 while the at least one end of the stitching ends 12 are radially external to the disc shutter 29.  The shutter disc 29 may be of inverted L-shape for which the outlet end or ends 8b of the at least one branch portion 8 are axially internal to the closure disk 29 while the at least one tapping end 12 is radial. external to the shutter disc 29 or the outlet end or ends 8b of the at least one branch portion 8 are radially internal to the shutter disc 29 while the at least one stitching end 12 is axially external to the shutter disc 29.  The shutter disk 29 receives at its inside a disk carrying the outlet ends 8b of the at least one branch portion.  Depending on the rotation of the shutter disk 29, the exit ends 8b carried by the disk can be brought to face the exit ends of the shutter disk 29 to ensure a passage of the flow either towards the face of the shutter disk 29. outlet of the turbine or to the quilting ends 12 of the EGR line.  The outlet shutter disk 29 may also be arranged around the outlet end of the main expansion passage, referenced 4 'in FIG. 7, the outlet shut-off disc 29 having an internal hollow recess in FIG. vis-à-vis the outlet end 4b 25 of the main channel of relaxation 4 'as shown in Figure 7 for these two references.  With such a closure disc 29, the closures, the complete or partial openings of the outlet ends 8b are reached at the same time for all the exit ends, all the exit ends 8b simultaneously having the same degree of opening when the rotation of the shutter disc 29.  Referring to all the figures except Figure 1, the outlet ends 4b, 8b of the main expansion passage 4 'and said at least one branch portion 8 within the turbine housing 2c 2 can lead to the same level of the turbine 2 to the outlet face 2b of the casing 2c of the turbine 2, that is to say upstream of this outlet face 2b in the turbine 2.  The third duct 9 which is outside the casing 2c of the turbine has a mouth on the outlet face 2b of the casing 2c away from the turbine 2 starting from this outlet face 2b of the exhaust gas of the turbine 2 .  In a conventional manner, the third duct 9 comprises elements 10 for cleaning up the exhaust gases flowing through it.  As previously mentioned, the flow of exhaust gas passing through the casing 2c of the turbine by at least one bypass portion 8 extending the second duct 4 said discharge can be subtracted from the total flow of exhaust gas outgoing of the engine and only remains the flow of the first duct 4 said exhaust turbine which passes 10 in the main channel of relaxation 4 'housing the wheel of the turbine 2.  This decreases the available power for the turbocharger and substantially serves as a conventional turbocharger relief valve.  In one embodiment of the motor assembly according to the present invention, the output of the engine comprises, by cylinder, two outlet passages closed by a respective exhaust valve, an outlet passage feeding the first duct 4, which is exhaust turbine and the other outlet passage feeding the second conduit 6 dump via the collectors 5 and 7 exhaust.  [0089] However, the opening of the exhaust valve connected to the second duct 6 occurs very often after the opening of the exhaust valve connected to the first duct 4 and still during the exhaust phase of the four cycle. engine time, even on the latest phasing of the opening of the exhaust valve connected to the second duct 6.  There is thus a period of time for which the two exhaust valves are open at the same time, which makes the function of the second discharge duct 6 still operational.  This is disadvantageous since on operating points of the engine assembly 1 corresponding to operating points of a turbocharger with closed discharge valve, in particular the points at low engine speed and full load, the closure the relief valve being necessary to maximize the power to the turbine 2, the second exhaust duct 6 of the exhaust system according to the invention is not closed to him, while it would be advantageous to pass all the flow of exhaust gas through the turbine 2 by its rotary energy recovery member in the form of a wheel.  Thus, the continuous opening of the second discharge duct 6 decreases the power available to the turbine 2, due to a lower flow rate of gas passing through the turbine wheel, which results in degradation of the engine response under transient and steady state conditions.  It is therefore advantageous to close the second duct 6, in particular in its bypass portion 8, in order to improve the response of the motor assembly 1 under transient conditions, in particular under a full load and low transient life situation. diet.  This can be done by the control valve 13, 13a by closing the outlet end 8b of the bypass portion 8 with or without supply of the RGE line 11 by the stitching end 12.  With a second conduit 6 extended discharge in the turbine 2 by one or more bypass portions 8, themselves having one or more output ends 8b, the section of the output ends 8b can take several different forms to know for example: 15 - a round shape such as, for example, in a conventional turbocharger system, - an optimized shape for the optimization of the turbine assembly 2 and its associated casing 2c and the optimization of the turbulence opposite outlet 2b of the turbine 2, for example a crescent shape, an oval or triangle shape, etc.  The invention is in no way limited to the described and illustrated embodiments which have been given by way of example only.

Claims (10)

1. An engine assembly (1) comprising an internal combustion engine comprising at least one cylinder, at least one exhaust gas recirculation line at an engine intake, a turbocharger comprising a turbine (2) and a compressor ( 3), and an exhaust system connected by a first and a second exhaust manifold (5, 7) to an engine outlet for exhaust gas exhaust from combustion in the engine, the engine exhaust system. exhaust comprising a first duct (4) said exhaust by the turbine (2) from the first exhaust manifold (5) and a second duct (6) said discharge from the second exhaust manifold (7), the turbine (2) being provided with a housing (2c) having a main expansion passage (4 ') in which is housed a turbine wheel and the first conduit (4) opening into the main relief passage (4') by an inlet face (2a) of the housing (2c), characterized in the second duct (6) opens through the inlet face (2a) of the casing (2c) in at least one branch portion (8) internal to the casing (2c) bypassing the main expansion passage (4 ') and in that the tapping of said at least one recirculation line (11) is carried out in the turbine (2) on a stitching portion (8) of at least the main expansion passage (4 ') or said at least one a branch portion (8) via at least one stitching end (12). 2. The assembly of claim 1, wherein the stitching portion (8) on which the stitching is performed via at least one stitching end (12) is said at least one branch portion (8) extending the second conduit (6). ) and bypassing the wheel of the turbine (2), the exhaust system comprising a third duct (9) outside the turbine (2) and connected to an outlet face (2b) of the turbine casing (2c) for evacuation of the exhaust gases out of the turbine (2). 3. An assembly according to claim 1 or 2, wherein the stitching portion (8) comprises at least one regulating valve (13, 13a) for regulating the flow of exhaust gas therethrough, said at least one valve of control (13, 13a) being operable between at least a first flow closure position in the stitching portion (8) at or after said at least one stitching end (12) and a second open position of the flow in the stitching portion (8) at or after said at least one stitching end (12). 4. The assembly of claim 3, wherein the control valve (13, 13a) is disposed towards at least one outlet end (8b) of said at least one portion of a stitching (8) at an outlet face ( 2b) of the turbine (2), intermediate opening positions of the control valve (13, 13a) for adjusting the flow rate in said at least one nozzle portion (8) according to the degree of opening of the valve of regulation (13, 13a) corresponding to each respective intermediate position. 5 5. The assembly of claim 3, wherein the control valve (13, 13a) is operable between at least four positions, namely: - a first closed position of said at least a stitching portion (8) and said at least one stitching end (12) with a zero flow in said at least one stitching portion (8) and in said at least one recirculation line (11), - a second closing position of said at least one portion stitching (8) with a zero flow in said at least one stitching portion (8), the exhaust gas flowing completely into said at least one recirculation line (11) via said at least one stitching end ( 12), a third closing position of said at least one recirculation line (11) by closing said at least one stitching end (12) with a zero flow in said at least one recirculation line (11) , the exhaust in this portion of piqua ge (8) flowing fully to at least one outlet end (8b) of said at least one stitching portion (8), - fourth opening positions of said at least one stitching portion (8) and said at least one recirculating stitching end (12), said intermediate opening positions for adjusting the flow to said at least one outlet end (8b) in said at least one stitching portion (8) and in said at least one recirculation line (11) according to the degree of opening of said at least one stitching portion (8) and said at least one stitching end (12) corresponding to each respective intermediate position. 6. The assembly of claim 4 or 5, wherein, when the stitching portion is said at least one branch portion (8), the control valve (13, 13a) comprises a disc (29) movable in translation or in translation. rotation by an actuator 30 (15), the disc (29) carrying said at least one outlet end (8b) of said at least one branch portion (8) and said at least one stitching end (12) of said at least one least one recirculation line (11). 7. The assembly of claim 6, wherein the disk (29) of the regulating valve (13, 13a) is either: I-shaped plate, of inverted U-shaped section for which said at least an outlet end (8b) of said at least one branch portion (8) is radially internal to the disc (29) while said at least one stitching end (12) is radially external to the disc (29), or - an inverted L-shaped section for which said at least one outlet end (8b) of said at least one branch portion (8) is axially internal to the disc (29) while said at least one stitching end (12) is radial external to the disc (29) or said at least one outlet end (8b) of said at least one branch portion (8) is radially internal to the disc (29) while said at least one stitching end (12) ) is axially external to the disk (29). 8. An assembly according to claim 6 or 7, wherein the outlet disk (29) is disposed around an outlet end (4b) of the main expansion passage (4 '), the outlet disc (29) having a internal hollow recess vis-à-vis the outlet end (4b) of the main relief passage (4 '). 9. An assembly according to any one of claims 4 to 8, wherein said at least one outlet end (8b) of said at least one stitching portion (8) is of circular section, ovalized or in the form of a half-moon . 10. An assembly according to any one of the preceding claims, wherein the casing (2c) of the turbine remotely surrounds the wheel of the turbine (2) and comprises an intermediate portion interconnecting its face face to one face outlet (2a, 2b) of the housing (2c), the intermediate portion comprising at least one opening (12a) for said at least one stitching (12) of said at least one recirculation line (11).