FR2920822A1 - SYSTEM FOR INTRODUCING VAPORIZED FUEL WITHIN AN EXHAUST COMPONENT - Google Patents

Abstract

The invention relates to a system (6) for introducing a vaporized fuel into an exhaust element, in particular a catalyst (2), which comprises an exhaust line (1) of a motor vehicle with a heat engine, this system (6) comprising, on the one hand, means (7) for vaporizing the fuel, on the other hand, a means for introducing the vaporized fuel into the exhaust element (2) and, on the other hand still, means (8) for supplying fuel to the vaporization means (7) .This system (6) is characterized in that it comprises means (12) for draining at least the vaporization means (7), at least a part of the feed means (8).

Description

The present invention relates to a system for introducing a vaporized fuel into an exhaust element which comprises a motor vehicle exhaust line with a heat engine.

This invention relates to the field of the automotive industry and, more particularly, that of the manufacture of equipment to ensure the escape of gases from the combustion of a fuel within an internal combustion engine.

Such equipment is in the form of an exhaust line connected to this engine and having a plurality of exhaust elements succeeding each other along this exhaust line, this in accordance with the direction of the flow of gases within it.

In the usual manner, such an exhaust line comprises, then and successively, exhaust elements consisting of a catalyst (more particularly an oxidation catalyst), a particulate filter (FAP) and a silencer.

It will be observed that such a particle filter comprises, in fact, a multitude of channels into which particles, usually consisting of soot or the like, enter and are trapped, and which, after a certain period of operation of the engine, tend to clog these channels.

In order to overcome this drawback, it is known to use a system installed upstream of the oxidation catalyst and designed, on the one hand, to vaporize fuel (especially gas oil) and, on the other hand, to introducing the fuel vapors into this oxidation catalyst which has the effect of increasing the temperature of the exhaust gas entering the particulate filter. This increase in temperature of the exhaust gas then makes it possible to cause combustion of the particles contained in this particulate filter and thus to ensure a regeneration of the latter.

However, this way of proceeding has certain disadvantages. Indeed, the fuel consists of a mixture of hydrocarbons whose carbon chains have different lengths and, therefore, different vaporization temperatures. Thus, when the fuel is constituted by gas oil, the shortest carbon chains vaporize around 160 ° C while the longest carbon chains vaporize around 380 ° C. It will be observed that the means of vaporization of the fuel is supplied with fuel by a supply means connected to the fuel tank in which the fuel is stored at ambient temperature.

Thus, the fuel contained in the supply circuit of the vaporization means as well as in this vaporization means then has a temperature between that, ambient, of storage (at the reservoir) and that of vaporization (at the level of a heating element that includes this means of vaporization). However, when the fuel supply of this vaporization means is cut off, this means of vaporization and the part of the feed circuit close to this vaporization means contain fuel whose temperature is lower than the maximum vaporisation temperature. even between the extreme temperatures of vaporization (for example between 160 and 380 ° C in the case of gas oil). This fuel, especially when its temperature is between the extreme values of vaporization, is only partially degraded and contains, then, a large concentration of heavy hydrocarbons (that is to say, long carbon chain) which confers to this fuel a texture of mud or tar. However, the vaporization means and the part of the supply circuit close to this vaporization means are located in the immediate vicinity of the exhaust line (or even directly fixed thereto) which has a sufficient operating temperature to transform the sludge. or this tar in carbon elements very stable and adherent to the wall of the vaporization means or that of the conduit of the supply circuit. The presence of these carbon elements is detrimental to the operation of the vaporizer by limiting the amount of fuel to be introduced into the vaporization means, or even preventing such introduction. 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 system for introducing a vaporized fuel into an exhaust element, in particular a catalyst, which comprises a motor vehicle exhaust line with a combustion engine, this system comprising, on the one hand, a means for vaporizing the fuel, on the other hand, means for introducing the vaporized fuel into the exhaust element and, on the other hand, means for supplying fuel to the vaporization means, characterized in that it comprises means for draining at least the vaporization means, or even at least a part of the feed means. Another feature is that the draining means is at least partly constituted by a fuel discharge conduit connected, on the one hand, by means of vaporization or by means of supply and on the other hand , to a fuel storage tank. In fact, a first embodiment consists in that the evacuation duct is constituted by a specific tube extending between the fuel tank and, as the case may be, the vaporization means or the supply means. However, according to another embodiment, this exhaust duct is constituted, on the one hand, by a portion of a fuel return duct connecting the engine to the tank and, on the other hand, by a tube for the connecting, at this portion of the return duct, the vaporization means or the feed means.

The invention also relates to an exhaust line comprising, on the one hand, a catalyst, more particularly an oxidation catalyst, on the other hand, a particulate filter and, secondly, a system, implanted upstream of this catalyst, and designed to introduce a vaporized fuel into this catalyst, characterized in that the system for introducing a vaporized fuel into the catalyst is in accordance with the above characteristics. The advantages of the device according to the invention 10 consist in that it comprises means for draining at least the vaporizer after use of the latter. The presence of this emptying means avoids, apart from the normal operation of the vaporizer, the non-vaporized fuel from decomposing under the effect of the temperature of the exhaust line and / or the heating element of the vaporizer. medium of vaporization. This allows, advantageously, to ensure operation without fouling of this vaporizer. 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 by referring to the attached drawing in which the single figure is a schematic and partial view of an exhaust line to which is associated a system according to the invention and designed to introduce a vaporized fuel. The present invention relates to the field of the automotive industry and, more particularly, that of the manufacture of equipment making it possible to ensure the escape of gases resulting from the combustion of a fuel within an internal combustion heat engine. . Such equipment is in the form of an exhaust line 1 connected to this engine and comprising a plurality of exhaust elements succeeding each other along this exhaust line 1, this in accordance with the meaning of the flow of gases within it.

In particular and as shown in the appended figure, such an exhaust line 1 comprises, in the direction of the gas flow, at least one catalyst 2, more particularly an oxidation catalyst, as well as a filter. 3. According to a particular embodiment not shown, such a catalyst 2 and such a particulate filter 3 can be defined at the same exhaust element, usually called cata-fap.

However, and as illustrated, this catalyst 2 and this particulate filter 3 are each defined at a separate exhaust element, these exhaust elements then being connected to one another via a In addition, such an exhaust line 1 may also comprise a turbocompressor 5, implanted upstream of the catalyst 2, in the direction of the gas flow, and connected, of a on the other hand, to the engine 2 and an exhaust pipe 4 '. Such an exhaust line 1 is, furthermore, completed by a system 6 making it possible to ensure the regeneration of the particulate filter 3 which, as the engine operates, is fouled by particles (in particular soot) which are deposited in the channels of the particulate filter 3 and which, in the absence of such a regeneration system 6, would cause clogging. To do this, such a system 6 is, in fact, designed to introduce a vaporized fuel (more particularly vaporized gas oil) inside the oxidation catalyst 2 which has the effect of increasing the temperature of the gases of exhaust in the exhaust line 1, in particular in the particle filter 3, causing degradation of the particles contained therein 3 and, thus, its regeneration. As can be seen in the appended figure, this system 6 is implanted upstream of the oxidation catalyst 2, more particularly between this oxidation catalyst 2 and the turbocompressor 5, preferably close to the latter. is in communication with the internal volume of said catalyst 2 to allow the introduction of the vaporized fuel inside thereof 2. As shown in the appended figure, this system 6 comprises, on the one hand, a average 7 to vaporize the fuel. Such a means 7 of vaporization is in the form of a housing receiving, internally, a heating element designed to vaporize the fuel and is provided, on the one hand, with a liquid fuel inlet and, on the other hand, a vaporized fuel outlet. This vaporized fuel outlet is in communication with the internal volume of the catalyst 2, through a means that comprises the system 6 and which is designed to introduce the vaporized fuel into the catalyst 2, this means being, more particularly, constituted by a pipe, connected to the vaporizing means 7 and stitched on the aforementioned exhaust tube 4 '.

On the other hand, this system 6 comprises a means 8 for supplying liquid fuel with this vaporization means 7. Such a supply means 8 is, at least in part, constituted by a supply duct 9 connected, a on the other hand, by means of vaporization 7 (more particularly at the liquid fuel inlet of this vaporization means 7) and, on the other hand, to a tank 10 for storing the fuel, more particularly that for supplying the engine. This supply means 8 can, again, comprise means 11 to ensure a flow of fuel in the feed duct 9, such a circulation means 11 may be constituted by a pump or the like. Another feature of this system 6 is that it may further comprise means for determining the flow rate of the fuel introduced into the vaporization means 7. Such a dosing means may be defined at this vaporization means. 7, even (and preferably) at said supply means 8 and be more particularly constituted by a solenoid valve or the like. According to the invention, this system 6 also comprises a means 12 for draining at least the vaporizing means 7, or even at least a portion of the supply means 8 (more particularly a portion of the supply duct 9). In fact and as shown in the appended figure, such a draining means 12 is, at least in part, constituted by a discharge pipe 13 of the fuel contained in the vaporization means 7, or even in the means of 8. This exhaust duct 13 is connected, on the one hand, to this vaporization means 7 (directly or indirectly) and, on the other hand, to the fuel storage tank 10, for the reception of the evacuated fuel. .

In this connection, it will be observed that this exhaust duct 13 can then be connected to this vaporization means 7, either directly (more particularly by being connected to the level of the fuel inlet of this vaporization means 7). or (preferably) indirectly by being connected to said supply means 8 (more particularly to the supply duct 9 that comprises the supply means 8). According to a first embodiment (shown in solid lines in the appended figure), this exhaust duct 13 may consist of a specific tube extending between, on the one hand, the fuel tank 10 and, on the other hand, on the other hand, the vaporization means 7 or (and preferably) the supply duct 9 of the supply means 8. In such a case, the pressure prevailing in the catalyst 2 being greater than that prevailing in the means 7 of vaporization , the fuel contained in this vaporization means 7 is pushed back a sufficient distance to no longer be in contact with a heating element of this vaporization means 7. According to a second embodiment (shown in dashed line in the appended figure this exhaust duct 13 may consist, on the one hand, of a portion 14 of a fuel return duct 15 connecting the engine to the tank 10 and, on the other hand, by a tube 16 for connection, at this portion 14 of condu it returns 15, the vaporization means 7 or (and preferably) the supply means 8 (more particularly the supply duct 9 of the supply means 8). In this respect, it will be observed that, in the case where the fuel injection system in the engine operates with a low return flow (low pressure part integrated with the high pressure pump), the gravity and the exhaust backpressure will be sufficient to repel the fuel at a distance sufficient to no longer be in contact with the heating element of the vaporization means. However, and in the case where the fuel injection system in the engine operates with a strong return flow (low pressure pump separated from the high pressure pump), the exhaust pipe 13 can be completed by means for sucking, in this exhaust duct 13, the fuel contained at least in the vaporization means 7.

Such suction means is preferably constituted by a Venturi-type element defined at this exhaust duct 13, more particularly at the portion 14 of the return duct 15. According to another characteristic of the According to the invention, and irrespective of the above-mentioned draining means 12, the system 6 may also comprise means 17 for reversibly closing off the evacuation pipe 13. Such a sealing means 16 is preferably constituted by by a valve, more particularly by a solenoid valve.

This shutter means 17 is designed to be, on the one hand, in the closed position in the case of supply of fuel to the vaporization means 7 to prevent the circulation of fuel in the exhaust duct 13 (thus to prevent the evacuation of this fuel) and, secondly, in the open position in case of emptying this to allow the flow of fuel in the exhaust pipe 13 (so to allow the evacuation of the fuel). According to the invention, the system 6 further comprises means for managing the emptying means 12 (more particularly the shut-off means 17), or even the fuel supply means 8 (more particularly the pump and / or the dosing means) and / or the vaporizing means 7 (more particularly the heating element that it comprises). Thus, such a management means may be designed to actuate the supply means 8 to supply fuel to the vaporization means 7 while closing the closure means 17 and by actuating the heating element of the vaporization means 7, this during the regeneration of the particulate filter 3.

This management means can also be designed to inactivate the supply means 8 and open the closure means 17, this during an emptying operation of the vaporization means 7, or the supply means 8. A In this regard, it will be observed that this management means may, again, be designed to actuate (or maintain actuated) the heating element of the vaporization means 7 for at least part of the duration of a draining operation of the latter 7 The invention also relates to an exhaust line 1 comprising, on the one hand, a catalyst 2, more particularly an oxidation catalyst, on the other hand, a particulate filter 3 and, on the other hand, , a system 6 designed to introduce a vaporized fuel into this catalyst 2 and having the above characteristics.

This system 6 is implanted upstream of this catalyst 2, or even (and preferably when this exhaust line 1 comprises a turbocharger 5) implanted between such a catalyst 2 and a turbocharger 5, preferably near this turbocharger 5.35

Claims (12)

1. System (6) for introducing a vaporized fuel inside an exhaust element, in particular a catalyst (2), which comprises an exhaust line (1) of a motor vehicle with a heat engine, this system ( 6) comprising, on the one hand, means (7) for vaporizing the fuel, on the other hand, means for introducing the vaporized fuel into the exhaust element (2) and, on the other hand, a means (8) for supplying fuel to the vaporization means (7), characterized in that it comprises means (12) for draining at least the vaporization means (7), or at least a part of at least one of the means feeding (8). 2. System (6) according to claim 1, characterized in that the means (12) for draining the vaporization means (7) is at least partly constituted by a conduit (13) for discharging the connected fuel on the one hand by means of vaporization (7) or on the feed means (8) and on the other hand to a fuel storage tank (10). 3. System (6) according to claim 2, characterized in that the discharge duct (13) consists of a specific tube extending between the fuel tank (10) and, as the case may be, the means of vaporization (7) or the feeding means (8). 4. System (6) according to claim 2, characterized in that the discharge duct (13) is constituted, on the one hand, by a portion (14) of a connecting fuel return duct (15). the motor to the reservoir (10) and, on the other hand, a tube (13) for connecting, to this portion (14) of the return duct (15), the vaporization means (7) or the means for power supply (8). 5. System (6) according to claim 4, characterized in that the exhaust duct (13) is completed by means for sucking, in this exhaust duct (13), the fuel contained at least in the means Spraying (7). 6. System (6) according to any one of claims 2 to 5, characterized in that the means (12) for draining comprises, further, means (17) for closing, reversibly, the exhaust duct (13). 7. System (6) according to any one of the preceding claims, characterized in that the means (8) for supplying the vaporization means (7) with fuel is at least partly constituted by a supply duct (9). ) connected, on the one hand, by means of vaporization (7) and, on the other hand, to a tank (10) for storing the fuel. 8. System (6) according to any one of the preceding claims, characterized in that the fuel supply means (8) comprises means (11) for ensuring a flow of fuel in the feed duct (9). ). 9. System (6) according to any one of the preceding claims, characterized in that it comprises a means for dosing the flow of fuel introduced into the vaporization means (7). 10. System (6) according to any one of the preceding claims, characterized in that it comprises a means for managing the emptying means (12), or even the supply means (8) in fuel and / or the vaporization means (7). 11. Exhaust line (1) comprising, on the one hand, a catalyst (2), more particularly an oxidation catalyst, on the other hand, a particulate filter (3) and, secondly, a system (6), implanted upstream of said catalyst (2), and adapted to introduce a vaporized fuel into said catalyst (2), characterized in that the system (6) for introducing a vaporized fuel into the catalyst (2) ) is according to any one of the preceding claims. 12. Exhaust line (1) according to claim 11 comprising, upstream of the catalyst (2), a turbocharger (5), characterized in that the system (6) for introducing a vaporized fuel into the exhaust line ( 1) is located near this turbocharger (5).