FR3048023A1 - ENGINE ASSEMBLY COMPRISING A CYCLON FILTER EXHAUST GAS RECIRCULATION DEVICE - Google Patents

Abstract

Engine assembly comprising a motor (1) connected to an air intake (3) and an exhaust (4), an exhaust gas recirculation device comprising: a cyclonic filter (6), comprising an inlet (E) of gas to be filtered, a first filtered gas outlet (S1), a second enriched gas outlet (S2), gas distribution means arranged in such a way that in a first operating mode the filter (6) receives by its input (E) an incoming flow of exhaust gas and separates this incoming flow into a first filtered stream exiting through the first outlet (S1) to join the exhaust (4) and a second enriched stream exiting through the second outlet (S2) to join the inlet (3), the exhaust gas distribution means are further arranged so that in a second mode the first filtered flow joins the intake inlet (3) and the second flow the exhaust (4).

Description

ENGINE ASSEMBLY COMPRISING A CYCLON FILTER EXHAUST GAS RECIRCULATION DEVICE

The present invention relates to the field of internal combustion engines. The invention more particularly relates to an engine assembly comprising a cyclonic filter exhaust gas recirculation device.

To reduce the emission of polluting substances from a motor vehicle with a combustion engine, it is known to equip motor vehicles with a circulation of exhaust gases in order to recover the exhaust gases from the engine and reinject them into the engine. motor inlet to the air intake. This circulation of exhaust gas is commonly known as EGR (Exhaust Gas Recirculation).

The polluting substances emitted by a motor vehicle are mainly oxides and in particular nitrogen oxides, also known under the abbreviation NOx, formed by the high temperature reaction of oxygen with nitrogen. The exhaust gases, already used by the engine, are relatively low in oxygen and the fact of recirculating them in the admission of the engine in the place of the fresh air supplying the engine decreases the quantity of oxygen available and therefore the formation of NOx.

The particles and hydrocarbons present in the exhaust gas recirculated through the EGR line to be reintroduced to the engine air intake are largely burned or burnt in the combustion chamber of the engine.

However, as the amount of gas recirculated by the EGR line is relatively small, the majority of the particles and hydrocarbons, which can be in a combined state, for example in the form of soot, leaving the engine must be treated by the depollution elements present in the the exhaust line.

The more particles are loaded into the gas, the greater the regeneration frequency of the pollution control elements, which has a negative impact on the engine's fuel consumption and emissions. The unburned hydrocarbons present in the exhaust gases can be considered as causing a loss of energy, whereas it would be desirable to recirculate them to the intake of the engine in larger quantities than a conventional EGR line allows. .

Document DE2833481 discloses the use of a cyclonic separator disposed on an exhaust line with an outlet of the filter connected to a bypass on the exhaust line of the engine for the removal of a part of the exhaust gases. enriched with the particles extracted from the exhaust gases by the filter at the inlet of the engine. Such a device makes it possible to lighten the heavy particles content of the exhaust gases intended for the exhaust line, however the EGR line of the engine can be subject to fouling. The temperature of the gases collected, the temperature of the elements of this line (valve, ducts), the mode of combustion of the engine and the quantity of recirculated gas are important factors for the fouling but strongly variable according to the conditions of engine operation (starting cold, transient, operating point ...).

An object of the present invention is to solve the aforementioned drawback and to propose an engine assembly comprising a cyclonic filter which makes it possible to overcome or limit the problem of fouling of the EGR line.

To achieve this objective, there is provided according to the invention an engine assembly comprising: a heat engine connected to an air intake line and an exhaust line,

A device for recirculating the exhaust gas from the exhaust line to the air intake line, this device comprising: a cyclonic filter, comprising a gas inlet comprising elements to be filtered, a first gas outlet, filtered, a second enriched gas outlet, -gas distribution means comprising valves and gas passages arranged so that in a first mode of operation, the cyclonic filter receives at its inlet an inflow of exhaust gas from the heat engine and separates the incoming flow into a first particulate filtered stream exiting the first exit to join the exhaust line and a second stream, more concentrated in particles than the incoming stream, out the second exit to join the intake line, the exhaust gas distribution means are further arranged so that in a second mode of operation the first stream filtered in pa rticules exiting through the first exit join the intake line and the second stream joins the exhaust line. The technical effect of this arrangement is to allow to choose between returning the unburned particles and hydrocarbon to the exhaust when the engine operating conditions are deemed too foul for the EGR device and return to the intake to recover their energy.

Various additional features may be provided, alone or in combinations:

In a variant, the exhaust gas distribution means are furthermore arranged in such a way that in a third mode of operation the cyclonic filter does not receive an exhaust gas flow through its inlet but is traversed by a flow of gas. exhaust gas from the heat engine entering through the first exit and exiting through the second exit to join the intake line.

Preferably, the exhaust gas distribution means comprise: a passage of gas extending from the inlet of the cyclonic filter to a first tapping on the exhaust line; a first valve arranged at the intersection between the exhaust line and this passage for the control of the distribution of exhaust gas flow from the engine between the downstream of the exhaust line and the inlet of the cyclonic filter, -a gas passage s' extending from the second outlet of the cyclonic filter to a third tapping on the exhaust line, -a gas passage extending from the second outlet of the cyclonic filter to the inlet line, -a third valve disposed at the intersection between the second outlet, the passage extending towards the intake line and the passage extending towards the exhaust line, for the control of the distribution of the flow of exhaust gas between the second outlet and these d they gas passages, -a gas passage extending from the first outlet of the cyclonic filter to a second stitching on the exhaust line, -a gas passage extending from the first outlet of the cyclonic filter to a fourth quilting on the passage extending from the second outlet of the cyclonic filter to the inlet line, -a second valve disposed at the intersection between the first outlet, the passage extending towards the exhaust line and the passage s' extending to the fourth tapping, for controlling the distribution of the gas flow between the first outlet and these two gas passages, the first tapping being on the exhaust line upstream than the second and third tapping.

More preferably, the motor assembly comprises a control unit configured to control the valves so that for the first mode of operation: the first valve directs the flow of gas from the heat engine to the inlet of the cyclonic filter, the second valve communicates the first outlet with the passage extending towards the second tapping on the exhaust line; the third valve communicates the second outlet to the passage that leads to the intake line;

More preferably, the control unit is further configured to control the valves so that for the second mode of operation: the first valve directs the flow of gas from the heat engine to the inlet of the cyclonic filter; the second valve communicates the first outlet with the passage extending to the fourth stitching, the third valve communicates the second outlet with the passage which leads via the third stitching to the exhaust line.

Alternatively, the control unit is further configured to control the valves so that for the third mode of operation: the first valve directs the flow of gas from the engine to the exhaust line, the second valve communicates the first outlet with the passage extending to the second tapping on the exhaust line, -the third valve communicates the second outlet to the passage that leads to the inlet line.

Alternatively, the second valve and the third valve are controlled by the same actuator.

In another variant, the exhaust gas distribution means comprise a fourth gas flow control valve in the passage extending from the second outlet of the cyclonic filter to the intake line, the control unit being in position. further configured to open this fourth valve in the three modes of operation.

Alternatively, the engine assembly comprises a turbocharger having a turbine disposed in the exhaust line, the first, second and third connections being all arranged upstream or all arranged downstream of the turbine.

Alternatively, the engine assembly comprises an oxidation catalyst disposed in the exhaust line upstream of the first tapping. Other features and advantages will appear on reading the description below of a particular embodiment, not limiting of the invention, with reference to the figures in which: - Figure 1 is a schematic representation of a motor assembly of the invention, this assembly comprising a heat engine and an exhaust gas recirculation device incorporating a cyclonic filter. - Figure 2 is a schematic representation of a first mode of operation of the motor assembly of the invention. - Figure 3 is a schematic representation of a second mode of operation of the motor assembly of the invention. - Figure 4 is a schematic representation of a third mode of operation of the motor assembly of the invention.

Figure 1 shows a motor assembly of the invention. This comprising a heat engine 1, for example a spark ignition internal combustion engine or compression ignition. Such an engine assembly can equip a vehicle, for example a motor vehicle to allow a displacement thereof. The engine 1 may comprise several cylinders 2, for example here four cylinders.

The thermal engine 1 is connected to an air intake line 3 and to an exhaust line 4 for the evacuation of the exhaust gases produced during operation of the engine 1. The circuit of the exhaust line 4 is in the figure shown by the thickest lines in Figure 1. The engine assembly further comprises a device 5 for recirculating exhaust gas to the air intake line 3.

This exhaust gas recirculation device 5 comprises a cyclonic filter 6, known per se. The cyclonic filter 6 has an inlet E intended to receive an exhaust gas stream to be filtered. The cyclonic filter 6 is normally intended to separate, by forming one or more cyclones, the exhaust gases passing through it into a first stream and a second stream of exhaust gas. The first stream is a filtered stream of the particles, condensates and hydrocarbons contained in the exhaust gases entering through the inlet E, this first outflow through a first outlet S1 of the filter 6. The second stream is therefore a stream enriched with particles , condensates and hydrocarbons removed from the first stream, this second stream exiting through a second outlet S2 of the filter 6. The inlet E is the normal inlet for the generation of a cyclone inside the filter 6.

This exhaust gas recirculation device 5 further comprises exhaust gas distribution means comprising valves and gas passages arranged so as to implement the modes of operation to be described later. The opening and closing of the valves of the recirculation device 5 are controlled by an electronic control unit, UCE. The control unit, UCE comprises the acquisition means, processing by software instructions stored in a memory and controlling the valves of the recirculation device. The implementation of the different modes of operation by the LICE is based on engine operating conditions.

In this embodiment, the inlet E of the cyclonic filter 6 is connected by a passage 7 of gas, which may comprise a pipe, at a first tapping P1 on the exhaust line 4. A first bypass valve V1 is disposed at the intersection between the exhaust line 4 and the passage extending between the inlet E and the first connection P1 for controlling the distribution of exhaust gas flow from of the engine between the downstream of the exhaust line 4 and the inlet E of the cyclonic filter 6. The upstream and the downstream are defined here relative to the direction of flow of the exhaust gas in the exhaust line 4.

In this embodiment again, the second outlet S2 of the cyclonic filter 6 is connected by a gas passage 9, which may comprise a pipe, to the intake line 3 and another gas passage 8, which may comprise a driving, at a third stitching P3 on the exhaust line 4. A third valve V3 is disposed in the recirculation device 5 at the intersection between the second outlet S2, the passage 9 extending towards the inlet and the passage 8 extending towards the exhaust, for the control of the distribution of the flow of exhaust gas between the second outlet S2 and these two passages 8, 9 of gas.

In the path of the gas passage 9, between the third valve V3 and its intake tap PA on the intake line 3, a fourth recirculated exhaust gas flow control valve V4 is disposed in this passage 9 of gas.

In this embodiment again, the first outlet S1 of the cyclonic filter 6 is connected by a gas passage 10 which may comprise a pipe, a second tapping P2 on the exhaust line 4 and another gas passage 11. , which may comprise a pipe, at a fourth tapping P4 disposed on the passage 9 extending from the second outlet S2 of the cyclonic filter 6 to the inlet line 3, more precisely between the third valve V3 and the intake tap PA. More specifically still, this fourth stitching P4 is disposed between the third valve V3 and the fourth valve V4. A second valve V2 is arranged in the recirculation device 5 at the intersection between the first outlet S1, the passage 10 extending towards the exhaust and the passage 11 extending towards the fourth connection P4, for the control of the distribution of the filtered exhaust stream between the first outlet S1 and these two passages 10, 11, of gas.

In this embodiment, first, second and third tappings, P1, P2, P3, the first tapping P1 is the most upstream on the exhaust line 4.

The second stitch P2 is upstream of the third stitch P3, but the opposite is possible.

The exhaust line 4 may comprise one or more depollution devices disposed downstream of the third quilting P3.

Figure 2 illustrates a first mode of operation. In this first mode of operation, the engine 1 operates with a recirculation of exhaust gas whose concentration of particles, condensates and unburned hydrocarbons is higher than in the exhaust gas entering the cyclonic filter 6. In this first mode of operation, the cyclonic filter 6 receives, via its inlet E, an incoming flow of exhaust gas coming from the engine 1. The incoming flow forms a cyclone (schematized by the vortex-shaped arrow in FIG. 2) which separates in a first particulate filtered stream exiting the first exit, S1, to join the exhaust line 4 and a second stream, more concentrated in particles than the incoming stream through the inlet E, this second stream exiting through the second exit , S2, to join the line 3 of admission.

In this first mode of operation which will also be referred to as the so-called "enrichment to EGR" mode: the first valve V1 directs the flow of gas from the engine to the inlet E of the cyclonic filter 6 (arrow F1), the second valve V2 directs the stream of filtered gas discharged through the first outlet S1 to the second tapping P2 (arrow F2) and the exhaust line 4 (arrow 6); the third valve V3 directs the flow of enriched gas evacuated by the second output S2 to the passage 9 which leads to the intake line 3 (arrow F3), the fourth valve V4 of the passage 9 is open to allow (arrow F4) the enriched flow to return in the line 3 of admission (arrow F5).

This operating mode aims to protect or allow a good functioning of the element or the elements of depollution present in the portion of the line 4 of exhaust downstream of the third stitching P3 and to perform a recovery of energy to the engine, by recovery of hydrocarbons and particles such as previously unburned soot particles.

Figure 3 illustrates a second mode of operation. In this second mode of operation, the engine 1 operates with an exhaust gas recirculation whose concentration of particles, condensates and unburned hydrocarbons is lower than in the exhaust gas entering the cyclonic filter 6. In this second mode of operation, the cyclonic filter 6 receives by its inlet E an incoming flow of exhaust gas from the heat engine 1. The incoming stream forms a cyclone (shown schematically by the vortex-shaped arrow in FIG. 3) which separates into a first particulate filtered stream exiting through the first outlet, S1, to join the inlet line 3 and a second stream, more concentrated in particles than the incoming stream, exiting through the second outlet, S2) to join the line 4 exhaust.

In this second mode of operation, which will also be referred to as the "enrichment to exhaust line" mode: the first valve V1 directs the flow of gas from the engine to the inlet E of the cyclonic filter 6 (arrow F7) the second valve V2 directs the flow of filtered gas discharged through the first outlet S1 to the passage 11 leading to the fourth connection P4 (arrow 8); the third valve V3 directs the flow of enriched gas evacuated by the second exit S2 towards the passage 8 (arrow F9) which leads via the third stitch P3 to the exhaust line 4 (arrow 10), -the fourth valve V4 of the passage 9 is open to allow (arrow F11) the enriched flow to return to the line 3 intake (arrow F12).

This mode of operation is intended to protect the device 5 for recirculating the exhaust gases from a major fouling. In this mode of operation, the particles, condensates and unburned hydrocarbons are concentrated towards the exhaust line 4 in order to have a flow of gas returning to the cleaner intake.

Figure 4 illustrates a third mode of operation. In this third mode of operation, the cyclonic filter 6 does not receive, through its inlet E, an incoming flow of exhaust gas coming from the heat engine 1. The cyclonic filter 6 is traversed by an exhaust gas flow coming from the engine , this flow entering through the first output, S1, and out through the second output, S2, to join the line 3 admission. In this case, no cyclone is generated in the cyclonic filter 6.

In this third mode of operation which will also be referred to as the so-called "cyclonic filter short-circuit" mode: the first valve V1 directs the flow of gas from the engine no longer to the inlet E of the cyclonic filter 6 but towards the exhaust line 4 (arrow F13), the second valve V2 is oriented as in the first operating mode known as "enrichment towards EGR" but the flow of exhaust gas passing through the cyclonic filter 6 coming from the line the exhaust via the second tapping P2 enters the cyclonic filter 6 by the first output S1 (arrow 14), -the third valve V3, is also oriented as in the first operating mode called "enrichment to EGR" and orients the flow gas to be discharged through the second outlet S2 to the passage 9 which leads to the intake line 3 (arrow F15), in this operating mode, the cyclonic filter 6 is therefore traversed by exhaust gas in a sense that does not generate a cyclone and therefore does not have a concentration of heavy particles. the fourth valve V4 of the passage 9 is open to allow (arrow F16) the flow of gas to be returned in the intake line 3 (arrow F17).

This mode of operation aims to minimize the pressure losses or not to reduce the amount of unburned hydrocarbons, for example, where they would be useful in a process of depollution, such as a particle filter regeneration.

The valves V1 to V4 can be all or nothing or be proportional valves. The invention is not limited to the embodiments described. In a variant where the engine 1 is supercharged, the engine assembly may also comprise a turbocharger comprising a compressor disposed in the intake line 3 and a turbine disposed in the exhaust line 4.

In this variant, the exhaust gas recirculation device 5 may be a "high pressure" exhaust gas recirculation device in which the first, second and third connections P1, P2, P3 are upstream of the turbine. and the intake tap PA is downstream of the compressor. In the intake line 3, the upstream and downstream are defined relative to the direction of flow of the air admitted into the engine 1.

In another variant, the exhaust gas recirculation device 5 may be a "low pressure" exhaust gas recirculation device in which the first, second and third taps P1, P2, P3 are downstream of the exhaust gas recirculation system. Turbine and the intake nozzle PA is upstream of the compressor.

In another variant, the exhaust line 4 may comprise a pollution control member such as an oxidation catalyst upstream of the first quilting P1.

In another variant where the engine 1 is still a compression ignition engine, the exhaust line 4 may comprise a particulate filter and / or a selective reduction catalyst of the nitrogen oxides downstream of the third nozzle P3.

In another variant, the second valve, V2, and the third valve, V3, can be controlled by the same actuator, which has the advantage of facilitating the synchronization of the two valves and minimizing the cost. The technical interest of the invention is to reduce the emissions of particles and hydrocarbons before their treatment. In the case of an exhaust line equipped with a particulate filter that must be periodically regenerated, this may favorably reduce the regeneration frequency of the particulate filter and therefore the overall efficiency of the engine, but potentially this operating mode increases the efficiency of the engine. fouling of the exhaust gas recirculation device 5. The device of the invention therefore provides the possibility of reversing the operation of the filter and thus to make the recirculation of exhaust gas with less charged gas particles, condensates and hydrocarbons, the latter elements will be treated by the line of exhaust including the depollution devices. Thus, depending on the engine operating conditions that may include the combustion mode, engine operating point and / or other engine control information (such as exhaust gas recirculation fouling estimators, state of charge of the particulate filter ...) it is possible to find the best mode of operation of the engine assembly to improve the engine efficiency and / or minimize the fouling of the exhaust gas recirculation device.

Claims (10)

claims An engine assembly comprising: a heat engine (1) connected to an air intake line (3) and an exhaust line (4), an exhaust gas recirculation device of the line (4) exhaust system to the air intake line (3), this device comprising: a cyclonic filter (6), comprising a gas inlet (E) comprising elements to be filtered, a first gas outlet (S1) filtered, a second enriched gas outlet (S2), gas distribution means comprising valves and gas passages arranged so that in a first mode of operation, the cyclonic filter (6) receives at its inlet (E ) an incoming flow of exhaust gas from the heat engine (1) and separates the incoming flow into a first filtered particulate stream exiting the first outlet (S1) to join the exhaust line (4) and a second stream , more concentrated in particles than the incoming flow, leaving by the second exit (S2) for joining the inlet line (3), characterized in that the exhaust gas distribution means are furthermore arranged so that in a second mode of operation the first filtered particulate stream exiting through the first outlet (S1) joins the intake line (3) and the second stream joins the exhaust line (4). 2. Engine assembly according to claim 1, characterized in that the exhaust gas distribution means are further arranged so that in a third mode of operation the cyclonic filter (6) does not receive through its inlet (E). flow of exhaust gas but is traversed by a flow of exhaust gas from the heat engine (1) entering through the first output (S1) and out through the second output (S2) to join the line (3 ) admission. 3. Engine assembly according to claim 2, characterized in that the exhaust gas distribution means comprise: a passage (7) of gas extending from the inlet (E) of the cyclonic filter (6) to a first tapping (P1) on the exhaust line (4), -a first valve (V1) disposed at the intersection between the exhaust line (4) and this passage (7) for controlling the flow distribution of exhaust gas from the engine between the downstream of the exhaust line (4) and the inlet (E) of the cyclonic filter (6), a gas passage (8) extending from the second outlet (S2) of the cyclonic filter (6) at a third stitch (P3) on the exhaust line (4), -a passage (9) of gas extending from the second outlet (S2) of the filter (6) cyclonic at the inlet line (3), -a third valve (V3) disposed at the intersection between the second outlet (S2), the passage (9) extending towards the inlet line (3) and the passage (8) extending towards the exhaust line (4), for controlling the distribution of the flow of exhaust gas between the second outlet (S2) and these two passages (8, 9) of gas, a passage (10) of gas extending from the first outlet (S1) of the cyclonic filter (6) to a second tapping (P2) on the exhaust line (4), -a gas passage (11); extending from the first outlet (S1) of the cyclonic filter (6) to a fourth stitch (P4) on the passage (9) extending from the second outlet (S2) of the cyclonic filter (6) to the line (3) of an inlet, a second valve (V2) disposed at the intersection between the first outlet (S1), the passage (10) extending towards the exhaust line (4) and the passage (11) extending towards the fourth quilting (P4), for controlling the distribution of the gas flow between the first outlet (S1) and these two passages (10, 11) of gas, the first quilting (P1) being on the line (4) of more upstream exhaust than the second and third stitching (P2, P3). 4. Engine assembly according to claim 3, characterized in that it comprises a control unit (ECU) configured to control the valves so that for the first mode of operation: the first valve (V1) directs the gas flow from the heat engine (1) to the inlet (E) of the cyclonic filter (6), the second valve (V2) communicates the first outlet (S1) with the passage (10) extending towards the second quilting (P2) on the line (4) exhaust, the third valve (V3) communicates the second output (S2) to the passage (9) which leads to the line (3) intake. 5. The assembly of claim 4, characterized in that the control unit (ECU) is further configured to control the valves so that for the second mode of operation: the first valve (V1) directs the flow of gas from the heat engine (1) to the inlet (E) of the cyclonic filter (6), the second valve (V2) communicates the first outlet (S1) with the passage (11) extending towards the fourth quilting (P4), the third valve (V3) communicates the second output (S2) with the passage (8) which leads via the third stitching (P3) to the exhaust line (4), 6. An assembly according to claim 4 or claim 5, characterized in that the control unit (ECU) is further configured to control the valves so that for the third mode of operation: the first valve (V1) directs the flow of gas from the heat engine (1) to the exhaust line (4), -the second valve (V2) communicates the first outlet (S1) with the passage (10) extending towards the second quilting (P2) on the line (4) exhaust, the third valve (V3) communicates the second output (S2) to the passage (9) which leads to the line (3) intake. 7. Assembly according to one of claims 3 to 6, characterized in that the second valve (V2) and the third valve (V3) are controlled by the same actuator. 8. Engine assembly according to one of claims 3 to 7, characterized in that the exhaust gas distribution means comprises a fourth valve (V4) for controlling the flow of gas in the passage (9) extending from the second output (S2) of the cyclonic filter (6) to the inlet line (3), the control unit (ECU) being further configured to open this fourth valve (V4) in the three modes of operation. 9. Engine assembly according to one of the preceding claims, characterized in that it comprises a turbocharger comprising a turbine disposed in the line (4) exhaust, the first, second and third connections (P1, P2, P3) being either all arranged upstream are all arranged downstream of the turbine. 10. Engine assembly according to one of the preceding claims, characterized in that it comprises an oxidation catalyst disposed in the line (4) exhaust upstream of the first quilting (P1).