FR2930000A1 - Elements i.e. soot, penetration preventing method for internal combustion engine of motor vehicle, involves evacuating trapped elements in exhaust gas evacuation circuit arranged in downstream of exhaust gas treating device - Google Patents

Abstract

The method involves trapping of elements in an upstream of an exhaust gas recirculation circuit (5) by filtration of the elements issued from an exhaust gas treating device (4), and evacuating the trapped elements in an exhaust gas evacuation circuit (6) of an exhaust line (3), where the evacuation circuit is arranged in downstream of the exhaust gas treating device. An exhaust gas treating unit (42) of the exhaust gas treating device is connected to an internal combustion engine (1). An independent claim is also included for an exhaust gas treating device comprising an exhaust gas treating unit connected to an internal combustion engine.

Description

The present invention relates to a method for preventing the entry, within an exhaust gas recirculation circuit, of elements from an exhaust gas treatment device. This invention also relates to such a device for the treatment of exhaust gases that includes an exhaust line, which incorporates a circuit for recirculation of these gases. This invention relates to the field of the automotive industry and, more particularly, that of the manufacture of equipment designed to ensure the escape of gases from the combustion of a fuel within an internal combustion engine. Already known exhaust lines, connected to the internal combustion engine of a motor vehicle, and comprising, on the one hand, an exhaust gas exhaust system out of this exhaust line and in the atmosphere and, secondly, a circuit for recirculating a portion of these exhaust gases. In fact, such a circuit for recirculating the gases is usually connected to the exhaust gas evacuation circuit and makes it possible to collect a part of the gases discharged and flowing in this evacuation circuit for the exhaust gas. route upstream of the engine and to introduce it into this engine. In this connection, it should be noted that the exhaust gases at the engine outlet contain solid particles (in particular soot) which, when they enter the gas recirculation circuit, are capable of cause damage to a compressor and / or valve that includes this recirculation circuit.

In order to remedy such a disadvantage, the exhaust line may comprise, interposed between the engine and the gas recirculation circuit, a device for the treatment of exhaust gases, usually constituted by a particulate filter or the like .

Such an exhaust line has been described in document EP-1.589.213 but has the drawback of permitting penetration, in this recirculation circuit, of elements coming from this gas treatment device (particularly elements used in the composition of this device and / or elements to ensure the maintenance of this device) and resulting from the degradation thereof. Such elements are, again, likely to cause damage to the compressor and / or the valve that includes the recirculation circuit. This disadvantage has been remedied by the device described in document DE 10 2006 038 706 by equipping the gas recirculation circuit with a second particle filter capable of collecting such elements. This second particulate filter must, however, be regularly maintained and emptied under penalty of being closed by the elements which causes an inactivation of the recirculation circuit of the gases. Another solution, described in US-7.121.081, is to position, within the gas recirculation circuit, a device adapted to ensure the combustion of some of these elements. If such a device is capable of ensuring the combustion of a holding element of a ceramic sheet for the treatment of exhaust gas, this device does not in any way to burn a piece of such a ceramic or a chip of metal resulting from the degradation of the gas treatment device.

The present invention is intended to overcome the disadvantages of devices of the state of the art. For this purpose, the invention relates to a method for preventing the penetration, inside a recirculation circuit of the exhaust gases that comprises a gas exhaust line of a motor vehicle combustion engine internal, elements derived, including degradation, a device for the treatment of these exhaust gas that includes the exhaust line, characterized in that ensures a trapping of the elements upstream of the circuit of re gas circulation and an evacuation of these trapped elements only in a gas evacuation circuit that includes the exhaust line downstream of the treatment device. The invention also relates to a device for the treatment of exhaust gases that comprises a gas exhaust line of a vehicle with internal combustion engine, this device comprising, internally, at least one means for the treatment of exhaust gas and being connected, on the one hand and upstream of the treatment means, to the engine and, on the other hand and downstream of the treatment means, to a circuit for re-circulation of the gases as well as to a exhaust circuit for these gases, characterized in that it comprises, internally and downstream of the processing means, means for trapping elements derived, in particular by degradation, of this device and to remove these elements out of this device and only in the exhaust gas evacuation circuit, in order to prevent these elements from entering the recirculation circuit of gases. Finally, the invention relates to an exhaust device, having the above-mentioned characteristics, and constituted by a particulate filter or by a device combining a catalyst and such a particulate filter. The advantages of the present invention are that the elements from the exhaust gas treatment device (in particular resulting from the degradation of this device) are trapped before being discharged only into the exhaust gas circuit. to be released into the atmosphere, especially after undergoing additional treatment in this evacuation circuit. This advantageously makes it possible to prevent such elements from entering the gas recirculation circuit and thus avoids causing damage to an element (compressor, valve, exchanger, etc.) that this circuit comprises. Advantageously, the gas treatment device comprises, itself and internally, a means for ensuring the trapping of these elements and their evacuation, automatically, out of the gas treatment device and in the circuit d evacuation of these gases. This advantageously makes it possible to avoid any accumulation of these elements inside the treatment device (or even inside the exhaust line) and thus makes it possible to avoid any maintenance or repair intervention on this exhaust line to remove such elements. In addition, such a trapping means is shaped and / or positioned inside the gas treatment device so as to advantageously allow such evacuation by gravity or by entrainment by the evacuated gas flow. Another advantage is that this trapping means is integrated in the gas treatment device so that it does not require any additional external device or additional volume.

Finally, the trapping means that internally comprises the gas treatment device is advantageously designed and / or dimensioned so as to avoid generating a back pressure and / or a pressure drop in the recirculation circuit. which is usually of the low pressure type. Other objects and advantages of the present invention will become apparent from the following description relating to embodiments which are given by way of indicative and non-limiting examples.

The understanding of this description will be facilitated with reference to the appended drawings in which: FIG. 1 is a schematic representation of an exhaust line comprising a gas treatment device according to the present invention; - Figure 2 is a schematic view in cross section, in perspective and in detail of the treatment device, this according to a first angle of view; - Figure 3 is a view similar to Figure 2 and corresponding to a second angle of view.

The invention relates to the field of manufacturing equipment intended to ensure the escape of gases from the combustion of a fuel within the internal combustion engine of a motor vehicle. As can be seen in FIG. 1, such a vehicle comprises an internal combustion engine 1, a supply circuit 2 (in fuel as well as at least in oxygen, in particular in air) of this engine 1 as well as a fuel line. exhaust 3 of the gases resulting from the combustion of this fuel in the engine 1. This exhaust line 3 is connected to the engine 1 and comprises, in accordance with the direction of flow of the exhaust gases in this exhaust line 3 , on the one hand and downstream from this engine 1, a device 4 for treating these exhaust gases and, on the other hand and downstream of this processing device 4, a circuit 5 for recirculating a part of the treated exhaust gas (connected to said supply circuit 2) as well as a circuit 6 for discharging another part of these processed exhaust gases (opening into the atmosphere). This exhaust line 3 may also comprise a turbocharger 7 comprising, on the one hand, a turbine driven in rotation by the flow of the gases from the engine 1, and interposed between the engine 1 and the treatment device 4 and on the other hand, a compressor, implanted in the gas recirculation circuit 5, driven by said turbine, and designed to compress a gas (constituted by air and / or by an exhaust gas from the treatment device 4), or even a mixture gas + fuel, before its introduction into the engine 1. With regard to the device 4 for the treatment of exhaust gas, it is designed to provide a chemical depollution and / or physical of these exhaust gases.

In this regard, it will be observed that such a treatment device 4 may (preferably) be constituted by a particulate filter (usually called FAP) or by a device combining a catalyst (especially for the removal of oxides of nitrogen) and such a particulate filter (usually called cata-FAP).

Such a treatment device 4 comprises a housing 41 and, internally to this housing 41, a means 42 for the treatment of exhaust gas, more particularly constituted by a ceramic block provided with longitudinal channels. This processing means 42 is usually held in position inside this housing 41 by means of a holding means (more particularly constituted by a holding ply, in particular a fibrous ply, and / or by a joint, in particular metal)) interposed between the housing 41 and the processing means 42. This processing device 4 comprises, again and upstream of the processing means 42, a means 43 for connecting the treatment device 4 to the engine 1. Such a means connection 43 is usually constituted by a conduit or the like. Downstream of this processing means 42, said processing device 4 comprises, on the one hand, a means 44 for its connection to the circuit 5 for recirculating gases and, on the other hand, a means 45 for its connection to the circuit 6 for evacuating these gases (FIGS. 2 and 3). Such connecting means (44, 45) may, again, be constituted by a conduit or the like. Thus, when the engine 1 is running, the exhaust gases from this engine 1 and treated by the processing means 42 are likely to flow, downstream of this processing means 42, into the evacuation circuit 6 and / or in the recirculation circuit 5. The flow of a part of these gases in the recirculation circuit 5 can be controlled by means of an EGR valve 51 included in this recirculation circuit 5. As can be seen in FIG. 41 of this processing device 4 is provided, downstream of the processing means 42, on the one hand, with a first opening 411, in communication with the gas evacuation circuit 6, and at which 411 opens the means 45 for connection to this evacuation circuit 6 and, secondly, a second opening 412, in communication with the gas recirculation circuit 5, and at which 412 opens the connection means 44 for this purpose. recirculation circuit 5. A preferred embodiment illustrated in Figures 2 and 3 is that these two openings (411, 412) are defined by a single cutout 413 formed at the wall of the housing 41. It is, more particularly, at the level of this single cutout 413 that come into play itionner, sealingly and tightly, the connecting means (44, 45).

Another feature of this housing 41 is that it comprises, downstream of the processing means 42, an outlet cone 414 at which at least the second opening 412 is defined, or even (and preferably) the first opening. 411.

In this regard, it will be observed that this processing device 4 is subjected, on the one hand, to the vibrations generated by the operation of the engine 1 and / or by the displacement of the vehicle and, on the other hand, to the particularly high temperature of the engines. exhaust gas from the engine 1 and a particularly large temperature range. In addition, the exhaust gases leaving the engine 1 prove to be particularly corrosive. All of these phenomena (vibration, temperature, corrosion) as well as the aging of the treatment device 4 are liable to lead to a degradation of this treatment device 4 resulting in the production of elements (in particular in the form of chips or metal parts or even particles or ceramic pieces) likely to end up in the exhaust line 3 downstream of the processing means 42.

According to the invention, this gas treatment device 4 comprises, internally and downstream of this gas treatment means 42, a means 46 for trapping elements coming from this device 4 and for evacuating these elements out of this device 4 and only in the exhaust gas circuit 6.

This has the result of preventing such elements from entering the recirculation circuit 5 of the gases and advantageously makes it possible to avoid any degradation of a component of the recirculation circuit 5 (EGR valve, exchanger, compressor), the supply circuit 2, or the motor 1. Another feature of the invention is that the trapping means 46 is shaped and / or positioned inside the treatment device 4 so as to enable the evacuation of the trapped elements in the circuit 6 for evacuating gases by gravity or (and preferably) by driving by the flow of the gases discharged into the evacuation circuit 6. A preferred embodiment consists in that the trapping means 46 then comprises means 461 for orienting at least a portion of the flow of the exhaust gases from the means 42 for treating these gases, in the direction of the circuit 6. exhaust gas. According to a first embodiment not shown, such an orientation means 461 may consist of a planar shape of this trapping means 46, this planar shape being oriented toward the processing means 42, in particular by forming an angle between 10 and 80 °, preferably between 30 and 60 °, with the direction of flow of the gas flow through this processing means 42. However, and according to a preferred embodiment of the invention illustrated in FIGS. such an orienting means 461 is constituted by a concave shape of this trapping means 46, this concavity then being oriented towards the processing means 42. Another feature of the invention is that this means 46 of trapping extends to the front of the second opening 412, communicating with the circuit 5 for recirculation of gas, and arranged at the housing 41 of the device 4 for gas treatment. Such a characteristic advantageously makes it possible to trap all the elements and prevent them from reaching this second opening 412.

An additional feature is that this trapping means 46 is delimited by a peripheral rim 462 positioned around the second opening 412 and applies sealingly to the elements against a portion 415 of the inner wall of the housing 41 of the device 4. gas treatment at which is formed the second opening 412 communicating with the circuit 5 for recirculation of gases. In this regard, it will be observed that a particular embodiment consists in that the second opening 412 is located upstream of the first opening 411, this with respect to the means 42 of gas treatment. In such a case, said trapping means 46 may be designed to completely cover the second opening 412. However, according to another embodiment, the second opening 412 is located at or (and preferably as illustrated in FIGS. 2 and 3) downstream of the first opening 411, this with respect to the gas treatment means 42. In such a case, the trapping means 46 is interposed between the first 411 and the second opening 412 and delimits, with the portion 415 of the inner wall of the housing 41 against which this trapping means 46 is applied, a sealed compartment elements to be evacuated. Another characteristic illustrated in FIGS. 2 and 3 is that, more particularly, it is the outlet cone 414 of the housing 41 which receives the trapping means 46 of the elements. Such an embodiment advantageously makes it possible to take advantage of the volume of this outlet cone 414 to integrate the trapping means 46 inside the casing 41 of the gas treatment device 4.

An additional feature is that the trapping means 46 consists of a filter. According to a first embodiment illustrated in FIGS. 2 and 3, such a filter is constituted by a lattice, preferably of metallic type.

However, according to a second embodiment not shown, this filter is constituted by a sintered medium, preferably of composite type. Whatever the nature of this filter, it has openings (more particularly constituted by meshes in the case of a lattice) whose dimensions are chosen to trap elements whose size is greater than a certain size. In this respect, when it is desired to trap elements of at least 200 microns, the size of the openings is preferably of the order of 150 microns, so as to take account of a safety coefficient and the geometry of these elements. It will be observed that the presence of such a filter generates, downstream of this filter and in the circuit 5 of recirculation of the gases, a loss of charge and / or a back pressure which is directly related, for a flow of gas given to the size of the openings of this filter and the size thereof, more particularly to the surface thereof provided with said openings. However, the specifications for a gas treatment device 4 intended to equip a motor vehicle specifies the maximum permissible value of this pressure drop and / or this back pressure.

Thus, according to an additional characteristic of the invention, the filter is then and preferably sized (more particularly as regards its surface and, more precisely, the surface of this filter provided with openings) as a function of a on the one hand, the size of these openings and, on the other hand, the back pressure and / or the maximum allowable pressure drop in the recirculation circuit 5 of the gases. This dimensioning can, again (and preferably), be ensured according to the characteristics of the exhaust gas from the engine 1, more particularly the temperature and / or the flow rate of these gases.

In this respect, it will be observed that the positioning of this filter inside the gas treatment device 4 advantageously makes it possible to suitably size such a filter, in order to respond optimally to the aforementioned specifications. Such a dimensioning is in no way possible for a filter of the state of the art positioned inside a conduit 5 of recirculation of the gases, in particular constituted by an EGR tube having, usually, a diameter of order of 30 mm.

As mentioned above, the invention also relates to an exhaust gas treatment device 4 having the above-mentioned characteristics. Such a device 4 is then and preferably consists of a particulate filter or a device combining a catalyst and such a particulate filter. The invention also relates to a gas exhaust line 3 comprising a motor vehicle 1 with internal combustion. This exhaust line 3 comprises an exhaust gas treatment device 4 having the above-mentioned characteristics, a circuit 5 for re-circulating these gases and a circuit 6 for evacuation of these gases, these circuits (5, 6) being connected to this processing device 4, downstream thereof. In this connection, it will be observed that the supply circuit 2 and / or the circuit 5 for recirculating the gases are designed so that the pressure of the exhaust gases flowing in the recirculation circuit 5 is low. (Low pressure EGR). In order to allow proper operation of this gas recirculation circuit 5, the trapping means 46 internally provided by the gas treatment device 4 is designed and / or dimensioned so as to avoid generating a counter-pressure. and / or a pressure drop in this recirculation circuit 5. Finally, the invention also relates to a method for preventing the penetration, inside an exhaust gas recirculation circuit (EGR) that comprises a gas exhaust line 3 of a motor vehicle 1 with internal combustion engine, elements derived, including degradation, a device 4 for the treatment of these exhaust gases that includes the exhaust line 3.

According to the invention, this process consists in ensuring that these elements are trapped upstream of the gas recirculation circuit 5 and that these trapped elements are discharged only into a gas evacuation circuit 6 that includes the exhaust line 3 downstream of the treatment device 4. In fact, such trapping of the elements is ensured by filtration of these elements, more particularly by means of a filter constituted by the aforementioned trapping means 46. More specifically, the trapping of the elements inside the exhaust gas treatment device 4 is ensured, more particularly at the outlet of a housing 41 which this device 4 comprises and which internally comprises a means 42 for the treatment of these gases.

Claims (14)

REVENDICATIONS1. A method for preventing the penetration, within a circuit (5) of recirculation of the exhaust gas that comprises a line (3) for exhausting gases from a motor vehicle 10 (1) to internal combustion, elements derived, in particular by degradation, a device (4) for the treatment of these exhaust gases that includes this exhaust line (3), characterized in that it ensures a trapping of elements upstream of the circuit (5) for recirculating the gases and an evacuation of these elements trapped only in a circuit (6) for evacuation of gases that comprises the exhaust line (3) downstream of the device (4) treatment. 2. Method according to claim 1, characterized in that one ensures the trapping of the elements by filtration of these elements. 3. Method according to any one of claims 1 or 2, characterized in that it ensures the trapping of the elements inside the device (4) for treating the exhaust gas, more particularly at the level of the output of a housing (41) that comprises the device (4) and which has internally means (42) for the treatment of these gases. 4. Device (4) for the treatment of the exhaust gases that comprises an exhaust line (3) of the gases 30 of a motor vehicle (1) with internal combustion, this device (4) comprising, internally, the least means (42) for the treatment of the exhaust gas and being connected, on the one hand and upstream of the processing means (42), to the engine (1) and, on the other hand, and downstream of the means of treatment (42), a circuit (5) for recirculation of gas and a circuit (6) for evacuation of these gases, characterized in that it comprises, internally and downstream of the means of treatment (42), a means (46) for trapping elements derived, in particular by degradation, of this device (4) and for discharging these elements out of this device (4) and only in the circuit (6) for evacuating exhaust gas, this to prevent these elements to enter the circuit (5) of recirculation of gases. 5. Device (4) for the treatment of exhaust gas according to claim 4, characterized in that the means (46) trapping is shaped and / or positioned inside the device (4) treatment so that to allow the evacuation of the trapped elements in the circuit (6) for evacuation of gases by gravity or by driving by the flow of the evacuated gases. 6. Device (4) for treating exhaust gas according to any one of claims 4 or 5, characterized in that the means (46) trapping comprises means (461) for orienting at least a portion of the flow of the exhaust gas from the means (42) for treating these gases, this in the direction of the circuit (6) for evacuation of gases. 7. Device (4) for the treatment of exhaust gas according to any one of claims 4 to 6, characterized in that it comprises a housing (41) receiving internally the means (42) for treating gases and provided, downstream of this means (42) of treatment, on the one hand, a first opening (411) communicating with the circuit (6) for evacuation of gases and, secondly, a second opening (412), communicating with the circuit (5) for recirculation of gases, and in front of which (412) extends the means (46) trapping. 8. Device (4) for the treatment of exhaust gas according to claim 7, characterized in that the means (46) entrapment is delimited by a peripheral edge (462) positioned around the second opening (412) and applied in a sealed manner to the elements, against a portion of the inner wall (415) of the housing (41) of the device (4) for treating gas at which is formed the second opening (412). 9. Device (4) for the treatment of exhaust gas according to claim 8, characterized in that the second opening (412) is located at or, preferably, downstream of the first opening (411) while that the trapping means (46) is interposed between the first (411) and the second (412) opening and delimits, with the portion (415) of the inner wall of the casing (41) against which the trapping means (46) is applied, a compartment sealed to the elements to be evacuated. 10. Device (4) for the treatment of exhaust gas according to any one of claims 7 to 9, characterized in that the housing (41) of the device (4) for treating gas comprises, downstream of the means (42), an outlet cone (414), on the one hand, receiving, internally, the means (46) for trapping the elements and, on the other hand, at which at least the second opening ( 412), or even, and preferably, the first opening (411). 11. Device (4) for the treatment of exhaust gas according to any one of claims 4 to 10, characterized in that the means (46) for trapping the elements is defined by a filter constituted by a lattice, of preferably of metal type, or by a sintered medium, preferably of composite type. 12. Device (4) for the treatment of exhaust gas according to claim 11, characterized in that the filter has openings whose dimensions are chosen to trap elements whose size is greater than a determined size. 13. Device (4) for the treatment of exhaust gas according to claim 12, characterized in that the filter is sized according to, on the one hand, the size of the openings and, on the other hand, the backpressure and / or the maximum allowable pressure drop in the gas recirculation circuit (5), or even depending on the characteristics of the gases from the engine (1). 14. Device (4) for the treatment of exhaust gas according to any one of claims 4 to 13, characterized in that it is constituted by a particulate filter or a device combining a catalyst and a such a particulate filter.