FR2885178A1 - Power train for motor vehicle, has exhaust gas recirculation valves and back pressure valve circulating exhaust gas in cleaning circuit and evacuating gas in exhaust pipe, where circuit cleans section of exhaust gas recirculation circuit - Google Patents

Abstract

The train has an exhaust gas recirculation circuit (20) with an exhaust gas recirculation valve (V1) controlling the recirculation of part of an exhaust gas towards an admission circuit. A cleaning circuit cleans a section of the circuit (20) and has an upstream section connecting an exhaust gas outlet and an inlet point (E), where the upstream section is controlled by another valve. The valves and a back pressure valve (24) circulate the gas in the cleaning circuit and evacuate the gas in an exhaust pipe (19).

Description

POWERTRAIN COMPRISING A CIRCUIT FOR CLEANING A CIRCUIT OF

RECIRCULATION OF EXHAUST GASES

  The invention relates to a power unit of a motor vehicle, of the type comprising: an internal combustion engine connected to an intake circuit by an intake manifold and connected to an exhaust circuit by an exhaust manifold, the exhaust circuit comprising a particulate filter and an exhaust pipe, - an exhaust gas recirculation circuit comprising at least one recirculation duct which is connected in parallel between the exhaust circuit and the exhaust circuit. at least one heat exchanger and at least one recirculation valve, called the EGR valve, controlling the recirculation of at least a portion of the exhaust gas to the intake circuit.

  Typically, a low pressure recirculation circuit is connected between the exhaust line at the outlet of the particulate filter, called FAP, and the air intake line at the compressor inlet. This circuit includes a heat exchanger, a valve and an exhaust flap. Patent WO 0192711 describes such a circuit. But the recirculation of the gases in the heat exchanger, the cooler, causes, generally, a fouling that clogs the EGR circuit. To remedy this problem, the elements of the EGR circuit are removed and replaced by new elements such as the heat exchanger, the valve. This method represents a regular maintenance and a significant cost for the user. - 2

  In order to overcome these drawbacks, the invention proposes a powertrain whose recirculation circuit can be cleaned simply and efficiently.

  To this end, the invention proposes a powertrain of the type cited above, characterized in that it comprises a cleaning circuit of a section of the recirculation circuit comprising - the section of the recirculation circuit to be cleaned comprising a point of inlet and outlet point io - an upstream section connecting an exhaust gas outlet and the point of entry - a downstream section connecting the outlet point and the exhaust pipe - control means so as to circulate the exhaust gas at the outlet of the particulate filter in the cleaning circuit and discharge them into the exhaust pipe.

  According to other features of the invention, the section of the recirculation circuit to be cleaned comprises the heat exchanger.

  According to other characteristics of the invention, the recirculation duct is connected downstream of the particulate filter to the intake circuit.

  According to other features of the invention, the cleaning circuit comprises: a part of the recirculation circuit formed by the upstream section, the section of the recirculation circuit to be cleaned and a line formed by the downstream section; control means and the exit point are the EGR valve - and an exhaust pipe control means downstream of the particulate filter is a backpressure flap located downstream of the junction of the upstream section with the exhaust pipe in downstream of the particulate filter and located upstream of the junction of the downstream section with the exhaust pipe downstream of the particulate filter.

  According to other features of the invention, the recirculation duct is connected to the exhaust manifold and the intake manifold of the engine.

  According to other characteristics of the invention, the cleaning circuit comprises a duct 25 formed by the upstream section 10, the section of the recirculation circuit to be cleaned, a duct 23 formed by the downstream section, a section control means. downstream and the exit point are the EGR valve, a control means of the upstream section is a valve V2 and a means of control of the exhaust pipe downstream of the particle filter is a backpressure flap located downstream of the junction of the upstream section with the exhaust pipe downstream of the particle filter and located upstream of the junction of the downstream section with the exhaust pipe downstream of the particle filter.

  According to other features of the invention, the valve V2 is the entry point.

  According to other features of the invention, the cleaning circuit comprises a part of the recirculation circuit formed by the upstream section, the section of the recirculation circuit to be cleaned, a line formed by the downstream section, and a means control and the point of exit (S) are the valve (V1).

  Other features and advantages of the invention will appear on reading the description of exemplary embodiments with reference to the appended figures.

  FIG. 1 illustrates a powertrain comprising a low pressure EGR circuit according to the invention.

  FIG. 2 illustrates a powertrain 5 comprising a high pressure EGR circuit according to a first embodiment of the invention.

  FIG. 3 illustrates a powertrain comprising a high-pressure EGR circuit according to a second embodiment of the invention.

  Identical or similar elements are designated by the same reference numerals.

  As represented in FIGS. 1, 2 and 3, a powertrain is generally designated 1 and the general structure of which will not be fully detailed hereinafter.

  The powertrain 1 comprises an internal combustion engine 4, for example a diesel engine with four cylinders 2 and supercharged type. The engine 4 comprises, in particular, an intake circuit, an exhaust circuit, a control system, and a recirculation circuit.

  The intake circuit comprises an intake duct 9, an intake throttling valve 13, an intake manifold 8, an air filter 10 and an intercooler 16. The intake duct 9 guides the intake manifold intake air introduced by the air filter 10 to the intake manifold 8. The intake manifold 8 is connected to the engine 4 to supply the cylinders 2 with air. The inlet throttling valve 13 is arranged upstream of the intake manifold 8 and makes it possible to increase or decrease the quantity of air flowing in the cylinders 2.

  The compressor 15a of a turbocharger 15 and an intercooler 16 are arranged in the intake duct between the air filter 10 and the inlet throttling valve 13. The intercooler 16 is arranged in the intake duct 9 downstream of the compressor 15a.

  The intake air cleaned by an air filter 10 flows to the compressor 15a through the intake duct 9 to be compressed. Then, it is cooled in the intercooler 16 and reaches the intake manifold 8 at a rate controlled by the inlet throttling valve 13.

  The control system, not shown, comprises an electronic control unit ECU. Different sensors are connected to the ECU. Their output signals are used by the ECU to control control means such as the intake throttling valve 13.

  The exhaust circuit forms an exhaust passage through which the exhaust gas from each cylinder 2 is ejected outwardly from the engine body 4. This exhaust system includes an exhaust manifold 18, which is connected to the engine 4 and the turbine 15b of the turbocharger 15, this circuit also includes a post-processing system. An exhaust pipe 19 connects the turbine 15b to the after-treatment system and continues downstream of the post-treatment system. The post-treatment system comprises, in particular, a particulate filter 3.

  The recirculation circuit connects the exhaust circuit to the intake circuit.

  The recirculation circuit comprises a heat exchanger which is a cooler 26, and a valve VI.

  The recirculation circuit can be cleaned on a section by a cleaning circuit. This cleaning circuit comprises: the section to be cleaned which comprises an entry point E and an exit point S; an upstream section connecting an exhaust gas outlet 18, 19 and the entry point E; a downstream section connecting the outlet point S and the exhaust pipe 19; - Control means for circulating the exhaust gas in the cleaning circuit and to evacuate in the exhaust pipe 19.

  According to a first operating mode, as represented in FIG. 1, the recirculation circuit is a low-pressure recirculation circuit. Through a conduit, called recirculation conduit 20, a part of the gases from the particulate filter 3 returns upstream of the intake circuit, downstream of the air filter 10.

  A section of the recirculation circuit comprising the cooler 26 is cleaned by a cleaning circuit. The cleaning circuit comprises: the section to be cleaned which is delimited by the entry point E arbitrarily positioned upstream of the cooler 26 and the outlet point S corresponding to the valve V1, disposed downstream of the cooler 26; the upstream section which corresponds to a section of the recirculation duct 20 connecting the exhaust pipe 19 downstream of the particle filter and the entry point E; - The downstream section, called duct 23, connecting the outlet point S or V1 and the exhaust pipe 19 downstream of the particle filter 3 The valve V1 is three-way A, B, C. The channel A is directed towards the intake circuit, the track B is directed towards the cooler 26 and the valve C is directed towards the conduit 23.

  The exhaust pipe 19 downstream of the particle filter 3 comprises downstream of the upstream section and upstream of the conduit 23 a counterpressure flap 24 which directs the gas from the particle filter 3 to the recirculation circuit.

  The three-way valve VI A, B, C and the counterpressure flap 24 make it possible to choose one of the following two modes: a mode of recirculation of the gases, called depollution mode when the channels A and B are open and the channel C is closed and when the counter-pressure shutter 24 is partially closed; a cleaning mode of the recirculation circuit when the channels B and C are open and the channel A is closed and when the counter-pressure shutter 24 is partially closed.

  To control these operations, the valve V1 and the counterpressure flap 24 are connected to the ECU.

  In pollution control mode, the backpressure flap 24 is partially closed and the valve V1 is open on the side of the particle filter 3 (channel B) and the intake circuit (channel A). A part of the exhaust gas leaving the particle filter 3 is introduced into the recirculation circuit 20 at a flow rate controlled by the valve V1 and the counterpressure flap 24. The portion of the exhaust gas is cooled by the cooler 26 and is mixed with fresh intake air in the intake duct 9. This mixture then flows to the compressor 15a through the intake duct 9 to be compressed. Then, it is cooled in the intercooler 16 and reaches the intake manifold 8 at a rate controlled by the intake throttle valve 13 so as to be introduced into the combustion chambers of each cylinder 2 of the engine 4. The combustion temperature of the mixture becomes relatively low in this way NOX nitrogen oxide generation is reduced.

  In cleaning mode, the backpressure flap 24 is partially closed and the valve VI is open on the side of the particulate filter 3 (path B) and the conduit 23 (path C). The gases leaving the particle filter 3 are introduced into a part of the recirculation circuit, that is to say the gases pass through the inactive cooler 26, the valve VI. Then these gases circulate in the conduit 23 to the exhaust pipe 19 downstream of the counterpressure flap 24. The temperature of the gas leaving the particle filter 3 reaches about 500 C which prevents the clogging of the cooler 26 and the valve V1. In fact, in depollution mode, material may remain stuck to the walls of the valve V1 and the cooler 26. In cleaning mode, the flow of gas leaving the particle filter 3 makes it possible to dry the material and to evacuate it towards the exhaust.

  According to a second mode of operation, as shown in Figure 2 and Figure 3, the recirculation circuit is a high pressure recirculation circuit. Part of the gases from the exhaust manifold 18 returns to the intake manifold 8. A section of the recirculation circuit including the cooler 26 is cleaned by a cleaning circuit.

  Two embodiments are proposed for this second mode of operation.

  According to a first embodiment, as represented in FIG. 2, the cleaning circuit comprises: the section to be cleaned which is delimited by the entry point E which is arbitrarily positioned upstream of the cooler 26 and which corresponds to a valve V2 and the - 9 outlet point S which corresponds to the valve V1, disposed downstream of the cooler 26; the upstream section, called duct 25, connecting the exhaust pipe 19 downstream of the particle filter 3 and the entry point E or V2; the downstream section, called duct 23, connecting the outlet point S or V1 and the exhaust pipe 19 downstream of the particulate filter 3.

  The valve VI is three-way. Lane A is directed to the intake circuit, Track B is directed to cooler 26 and Track C is directed to conduit 23.

  A valve V2 is three-way P, Q, R. The path P is directed towards the cooler 26, the path Q directed towards the exhaust manifold 18 and the path R is directed towards the conduit 25.

  The exhaust pipe 19 downstream of the particulate filter 3 comprises downstream of the duct 25 and upstream of the duct 23 a counterpressure flap 24 which directs the gas from the particulate filter 3 to the recirculation circuit.

  The valves V1, V2 and the counterpressure flap 24 make it possible to choose one of the following two modes: a mode of recirculation of the gases, called pollution mode when the channels P, Q, A, B are open and the channels C, R are closed and when the backpressure flap 24 is open, - a cleaning mode of the elements of the recirculation circuit when the channels R, P, B, C are open and the channels Q, A are closed and when the counterpressure flap 24 is partially closed.

  To control these operations, the valves VI, V2 and the counterpressure flap 24 are connected to the ECU.

  In pollution control mode, a part of the exhaust gas leaving the exhaust manifold 18 is introduced into the recirculation circuit at a flow rate controlled by the valve V1 and the counterpressure flap 24. This part of the exhaust gas is cooled by the cooler 26 and is mixed with fresh intake air in the intake duct 9 so as to be introduced into the combustion chambers of each cylinder 2 of the engine 4. The combustion temperature of the mixture becomes relatively low in this way the generation of NOX nitrogen oxides is reduced.

  In cleaning mode, the gases leaving the particle filter 3 are introduced into the duct 25 to circulate in a portion of the curing circuit, that is to say the gases pass through the valve V2, the cooler 26 inactive, the valve VI . Then, they circulate in the branch 23 to the exhaust pipe 19 downstream of the particulate filter 3. The temperature of the gases leaving the particle filter 3 reaches about 500 ° C., which makes it possible to prevent clogging of the cooler 26 and valves V1 and V2. Indeed, in pollution control mode, the material can remain stuck to the walls of the valves V1, V2 and the cooler 26. The flow of gas leaving the particle filter 3 allows to dry the material and evacuate to the exhaust .

  According to a second embodiment, as represented in FIG. 3, the cleaning circuit comprises: the section to be cleaned which is delimited by the entry point E arbitrarily positioned upstream of the cooler 26 and by the exit point S corresponding to the valve V1, which is disposed downstream of the cooler 26; the upstream section which corresponds to a section of the recirculation duct 20 connecting the exhaust manifold 18 and the entry point E; the downstream section, called duct 23, connecting the outlet point S or V1 and the exhaust pipe 19 upstream of the particulate filter 3.

  The valve VI is three-way. Lane A is directed to the intake circuit, Track B is directed to cooler 26 and Track C is directed to conduit 23.

  The valve V1 makes it possible to choose one of the following two modes: a mode of recirculation of the gases, called mode to depollution when the channels A, B are opened and the channel C is closed, a mode of cleaning of the elements of the recirculation circuit when channels B, C are open and channel A is closed.

  To control these operations, the valve V1 is connected to the ECU.

  In pollution control mode, a portion of the exhaust gas leaving the exhaust manifold 18 is introduced into the recirculation circuit at a flow rate controlled by the valve VI. This portion of the exhaust gas is cooled by the cooler 26 and is then mixed with fresh intake air in the intake duct 9 so as to be introduced into the combustion chambers of each cylinder 2 of the engine 4. The combustion temperature of the mixture becomes relatively low in this way NOX nitrogen oxide generation is reduced.

  In cleaning mode, the gases leaving the exhaust manifold 18 are introduced into the duct 20 to circulate in a portion of the recirculation circuit, that is to say the gases pass through the cooler 26 inactive, the valve VI. Then, they circulate in the branch 23 to the exhaust pipe 19 upstream of the particulate filter 3. The temperature of the gases leaving the exhaust manifold - 12-18 reaches about 500 C which avoids clogging cooler 26 and valve VI. Indeed, in pollution control mode, the material may remain stuck to the walls of the valve V1 and the cooler 26. The flow of gas leaving the exhaust manifold 18 allows drying this material and evacuate to the pipe d exhaust 19 upstream of the particulate filter 3 to be treated in the particulate filter 3.

  In the first mode of operation, the recirculation circuit valve VI is used to allow both "decontamination" mode operation and "cleaning" mode operation. To allow operation in "cleaning" mode, it is also possible to use another valve, ie a three-way valve at the junction of the recirculation duct 20 and the duct 23, or a two-way valve on the duct 23.

  In the first embodiment of the second mode of operation, the valve V2 can be arbitrarily positioned on the cleaning duct 25.

  In the operating modes mentioned, the cleaning circuit makes it possible to clean both the EGR valve and the heat exchanger, but it is also possible to envisage by a choice of the positioning of the conduit (s) 23, 25 only the cleaning the EGR valve or heat exchanger. For example, in the first embodiment of the second mode of operation, the conduit 25 may be positioned downstream of the cooler 26 and upstream of the valve V1, in this configuration, only the valve V1 may be subject to a cleaning.

  The present invention is not limited to the modes of operation described, provided by way of illustrative and non-limiting example.

Claims (8)

- 13 - CLAIMS   Motor vehicle power train (1), of the type comprising: an internal combustion engine (4) connected to an intake circuit by an intake manifold (8) and connected to an exhaust system by a manifold exhaust system (18), the exhaust system comprising a particulate filter (3) and an exhaust pipe (19), - an exhaust gas recirculation circuit including at least one recirculation duct (20). ) which is connected in shunt between the exhaust circuit and the intake circuit * at least one heat exchanger (26) and * at least one recirculation valve (VI), called the EGR valve, controlling the recirculation of at least a portion of the exhaust gas to the intake circuit characterized in that the powertrain comprises a cleaning circuit of a section of the recirculation circuit comprising - the section of the recirculation circuit to be cleaned comprising an entry point ( E) and an exit point (S ) - an upstream section connecting an exhaust gas outlet (18, 19) and the entry point (E) - a downstream section (23) connecting the outlet point (S) and the exhaust pipe (19); ) - control means (V1, V2, 24) so as to circulate the exhaust gas in the cleaning circuit and to evacuate in the exhaust pipe (19).   - 14 - 2. Power train according to claim 1, characterized in that the section of the recirculation circuit to be cleaned comprises the heat exchanger (26).   3. Power train according to one of claims 1 to 2, characterized in that the recirculation duct (20) is connected downstream of the particulate filter (3) to the intake circuit.   io 4. Power train according to claim 3, characterized in that - the cleaning circuit comprises * a part of the recirculation circuit formed by the upstream section, * the section of the recirculation circuit to clean * a conduit (23) formed by the downstream section - a control means and the outlet point (S) are the valve (V1) - and a control means of the exhaust pipe (19) downstream of the particle filter (3) is a counterpressure flap ( 24) located downstream of the junction of the upstream section with the exhaust pipe (19) downstream of the particulate filter and situated upstream of the junction of the duct (23) with the exhaust pipe (19) downstream of the particulate filter (3).   5. Power train according to one of claims 1 to 2, characterized in that the recirculation duct (20) is connected to the exhaust manifold (18) and the intake manifold (8) of the engine (4).   6. Power train according to claim 5, characterized in that the cleaning circuit comprises - a duct (25) formed by the upstream section * the section of the recirculation circuit to clean * a conduit (23) formed by the downstream section - a control means of the downstream section and the point of exit (S) are the valve (V1), - a control means of the upstream section is a valve (V2).   and a means for controlling the exhaust pipe (19) downstream of the particulate filter (3) is a counterpressure flap (24) located downstream of the junction of the duct (25) with the exhaust pipe (19). ) downstream of the particulate filter and upstream of the junction of the conduit (23) with the exhaust pipe (19) downstream of the particulate filter (3).   7. Power train according to claim 6, characterized in that the valve (V2) is the point of entry (E).   8. Powertrain according to claim 5, characterized in that the cleaning circuit comprises * a part of the recirculation circuit formed by the upstream section, * the section of the recirculation circuit to clean * a conduit (23) formed by the section downstream - and a control means and the exit point (S) are the valve (V1).