EP2232034A1 - Method for post-processing exhaust gases of a combustion engine - Google Patents

Method for post-processing exhaust gases of a combustion engine

Info

Publication number
EP2232034A1
EP2232034A1 EP08868902A EP08868902A EP2232034A1 EP 2232034 A1 EP2232034 A1 EP 2232034A1 EP 08868902 A EP08868902 A EP 08868902A EP 08868902 A EP08868902 A EP 08868902A EP 2232034 A1 EP2232034 A1 EP 2232034A1
Authority
EP
European Patent Office
Prior art keywords
injection
post
exhaust
fuel
combustion engine
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP08868902A
Other languages
German (de)
French (fr)
Inventor
Aurélien CLEMENT
Cédric PASCAL
Jean Guermann
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Renault SAS
Original Assignee
Renault SAS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Renault SAS filed Critical Renault SAS
Publication of EP2232034A1 publication Critical patent/EP2232034A1/en
Withdrawn legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/021—Introducing corrections for particular conditions exterior to the engine
    • F02D41/0235—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus
    • F02D41/027—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to purge or regenerate the exhaust gas treating apparatus
    • F02D41/029—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to purge or regenerate the exhaust gas treating apparatus the exhaust gas treating apparatus being a particulate filter
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/30—Controlling fuel injection
    • F02D41/38—Controlling fuel injection of the high pressure type
    • F02D41/40—Controlling fuel injection of the high pressure type with means for controlling injection timing or duration
    • F02D41/402—Multiple injections
    • F02D41/405—Multiple injections with post injections
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2250/00—Engine control related to specific problems or objectives
    • F02D2250/11—Oil dilution, i.e. prevention thereof or special controls according thereto
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/40—Engine management systems

Definitions

  • the present invention relates to the field of aftertreatment of exhaust gases and more particularly relates to a post-treatment process of the exhaust gas.
  • diesel engines are designed to produce as little exhaust emissions as possible, with the rest to be converted by exhaust aftertreatment systems.
  • Diesel engines by their specific operation, emit in their exhaust gas polluting soot or particles.
  • a filter called particulate filter
  • This filter retains the particles that accumulate within it as and when the engine is used. This accumulation of particles eventually clogs the filter, creating a strong counter pressure to the engine exhaust, which significantly reduces its performance.
  • the particles contained in the particulate filter are burned during a regeneration phase. Initialization and maintenance of particle combustion in the filter is achieved by raising the internal temperature of the particulate filter.
  • the activation of the various regeneration assistance means is controlled by the engine control computer (ECU) which determines, as a function of several parameters including the soot loading of the particulate filter, the instant of regeneration as well as its duration and the injection parameters during this phase.
  • ECU engine control computer
  • the thermal necessary for the regeneration of the particle storage elements is obtained by means of additional injections, either during the expansion phase of the cylinder, or directly in the exhaust line.
  • the adjustment of the injection is carried out for example by a loop on the temperature at the outlet of the oxidation catalyst, or on the upstream temperature of the particulate filter.
  • the exotherm for providing the temperature necessary for the regeneration of the particulate filter is achieved by a post-injection in the combustion chamber of the engine, or by an additional injection directly into the exhaust line called for example injection of the fifth injector.
  • the postinjection is performed in the engine cylinders, the introduction of the amount of fuel is achieved through the addition of two post injections.
  • the first post injection or near post injection is to inject the fuel after the main injection, the crankshaft having an angle between 20 and 70 ° after top dead center. This injection is intended to burn completely in the cylinder so as to produce a rise in the temperature before the turbine and therefore at the inlet of the catalyst.
  • the close post injection thus allows a sensible production of energy on the crankshaft.
  • the combustion is only partial and generates a quantity of reducing agents, that is to say the exotherm in the oxidation catalyst.
  • the second post injection or post injection remote is to inject the fuel, the crankshaft having an angle between 100 and 150 ° after the top dead center.
  • This injection is intended to produce the amount of reducing agents (unburned hydrocarbons (HC)) necessary to reach the input temperature level of the particulate filter required during their treatment in the catalyst (DOC).
  • HC unburned hydrocarbons
  • DOC catalyst
  • the computer adapts the use of the post-injection and / or the fifth injector depending on the operating point.
  • WO200757268 proposes for example to divide the post-injection in order to limit the dilution of the fuel in the oil at low flow points.
  • JP2007023961 proposes to adapt the post-injection according to the cylinders.
  • the document FR2660012 proposes to spray the fuel directly into the particulate filter to expand the use of the fifth injector at low speeds and temperatures, which does not necessarily imply points of low operating speed / load.
  • the document US20050000209 proposes a system with a pre-chamber of heating for spraying heated fuel directly into the exhaust line to improve the thermals on certain operating zones.
  • the present invention proposes a strategy aimed at reducing the cost of dilution related to the use of post-injection while increasing the area of use of the injector in the exhaust line.
  • an object of the invention is a method of post-treatment of the exhaust gases of a combustion engine, characterized in that during the regeneration phases of an oxidation means, at least one post is carried out fuel injection into a combustion chamber coupled to an injection from an exhaust injector disposed in the exhaust line.
  • a method combining the use of the fifth injector and the post-injection extends the range of use of the fifth injector and limits dilution at low speed / load.
  • the post-injection and the exhaust injection can be carried out on specific operating points, the post-injection and the exhaust injection can be carried out on operating points of low speed / load,
  • a close post-injection and at least one remote post-injection can be carried out, the distant post-injection can be divided into two injections,
  • the volume of fuel to be injected during the post-injection can be divided into a post-remote injection number.
  • the invention also relates to a device for post-treatment of exhaust gases implementing such a method, said device being disposed in an exhaust line of a combustion engine, and comprising a first oxidation means, a second oxidation means, placed downstream of said first oxidation means, a fuel introduction means, arranged upstream of the first oxidation means relative to the direction of flow of the exhaust gas, between the output of the combustion engine and the inlet of the first oxidizing means, characterized in that the first oxidizing means is an oxidation catalyst for a diesel engine.
  • the second oxidation means may be a particulate filter.
  • the invention also relates to a use of an injection of an injector at the exhaust and at least one remote post-injection during a regeneration phase of an oxidation means, the oxidation means being preferably a particulate filter.
  • the invention also relates to a vehicle comprising such a device for aftertreatment of the exhaust gases.
  • - Figure 1 is a schematic overview of the device according to the invention.
  • - Figure 2 shows an injection diagram depending on the crankshaft angle of the combustion engine, for example for a setting where the main injection "main” is keyed substantially at 0 ° v (crankshaft), the "post-close” substantially at 50 ° v, and the “post-far” substantially at 120 ° v.
  • FIG. 1 shows an exhaust gas after-treatment device disposed on a duct or an exhaust line 10, downstream of a combustion engine 4, for example four-cylinder engine equipped with a injection system 5.
  • the exhaust line 10 comprises oxidation means 1, 2 formed by a diesel catalytic oxidation catalytic converter called DOC, downstream of which is disposed a particulate filter 2.
  • oxidation means 1, 2 formed by a diesel catalytic oxidation catalytic converter called DOC, downstream of which is disposed a particulate filter 2.
  • the exhaust line 10 comprises a fuel introduction means 3, such as a fuel injector called the fifth injector, upstream of the catalytic oxidation catalyst 1 relative to the direction of flow of the exhaust gas, between the exit of the combustion engine and the inlet of the oxidation catalyst 1.
  • a fuel introduction means 3 such as a fuel injector called the fifth injector
  • an exhaust gas post-treatment process comprises a stage in which at least one fuel injection post-injection coupled to an injection from the injector is carried out. 3. At least one post-injection and the exhaust injection are preferably carried out at specific operating points. Indeed, as specified in the description above, in areas where the thermal is sufficient, for example substantially between 3 bars and 13 bars of effective average pressure (PME), the injection from the fifth injector is sufficient.
  • PME effective average pressure
  • Post-injection and supplemental injection are performed on low speed / load operating zones.
  • close post-injection and at least one remote post-injection are performed.
  • the post-injection is divided into two distant post injections.
  • the use of the fifth injector coupled to this "triple post-injection" advantageously preserves the thermal created by the close post injection while decreasing the dilution related to the post-injection remote.
  • the number of remote post injection is given by way of example, the total volume of fuel to be injected during the remote post-injection can be divided into several injections so as to obtain a better homogeneity of the gas mixture. exhaust - fuel and less exchange with cylinder walls.
  • This "triple post-injection" allows an increase in the inlet temperature of the engine turbine, which causes an increase in the inlet temperature of the catalytic oxidation catalyst 1 to a level higher than the temperature that allows the priming of the catalyst, which makes it possible to burn the hydrocarbons passing through the catalytic oxidation catalyst 1.
  • This exhaust gas aftertreatment process both reduces hydrocarbon emissions and decreases fuel dilution in the oil while ensuring effective regeneration of the particulate filter in low operating zones. /charge.
  • Such a method allows a better control of the regeneration of the particulate filter on operating zones at low speed / load, and an efficient treatment of hydrocarbons in these zones by increasing the temperature before turbine and the inlet temperature. from DOC 1.
  • This method can advantageously be implemented by any post-treatment device that requires a high thermal associated with a DOC, such as a trap of nitrogen oxide (NOx-T rap) or hydrogen sulphide (H2S-Trap) or other.
  • a DOC such as a trap of nitrogen oxide (NOx-T rap) or hydrogen sulphide (H2S-Trap) or other.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
  • Processes For Solid Components From Exhaust (AREA)

Abstract

The invention relates to a method for the post-processing of exhaust gases of a combustion engine, characterised in that, during the regeneration phases of an oxidation means (2), it comprises carrying out at least one fuel post-injection into a combustion chamber coupled to an injection from an exhaust injector (4) arranged in the exhaust line.

Description

PROCEDE DE POST TRAITEMENT DES GAZ D'ECHAPPEMENT D'UN MOTEUR A COMBUSTION METHOD FOR POST PROCESSING OF EXHAUST GASES OF A COMBUSTION ENGINE
La présente invention concerne le domaine des post traitement des gaz d'échappement et concerne plus particulièrement un procédé de post traitement des gaz d'échappement.The present invention relates to the field of aftertreatment of exhaust gases and more particularly relates to a post-treatment process of the exhaust gas.
Afin de répondre aux futures réglementations européennes, les moteurs diesel sont mis au point de façon à produire le moins possible d'émissions toxiques à l'échappement, le reste devant être converti par des systèmes de post-traitement des gaz d'échappement.In order to meet future European regulations, diesel engines are designed to produce as little exhaust emissions as possible, with the rest to be converted by exhaust aftertreatment systems.
Les moteurs Diesel, par leur fonctionnement spécifique, émettent dans leur gaz d'échappement des suies polluantes ou particules. Afin de limiter les émissions de ces particules dans l'atmosphère, un filtre, appelé filtre à particules, est implanté dans la ligne d'échappement, en aval des chambres de combustion du moteur. Ce filtre retient les particules qui s'accumulent en son sein au fur et à mesure de l'utilisation du moteur. Cette accumulation de particules finit par boucher le filtre, créant une forte contre pression à l'échappement du moteur, ce qui diminue considérablement ses performances. Pour recouvrer les performances du moteur, on brûle les particules contenues dans le filtre à particules lors d'une phase de régénération. L'initialisation et le maintien de la combustion des particules dans le filtre s'obtiennent par élévation de la température interne du filtre à particules.Diesel engines, by their specific operation, emit in their exhaust gas polluting soot or particles. In order to limit the emissions of these particles into the atmosphere, a filter, called particulate filter, is located in the exhaust line, downstream of the combustion chambers of the engine. This filter retains the particles that accumulate within it as and when the engine is used. This accumulation of particles eventually clogs the filter, creating a strong counter pressure to the engine exhaust, which significantly reduces its performance. To recover the performance of the engine, the particles contained in the particulate filter are burned during a regeneration phase. Initialization and maintenance of particle combustion in the filter is achieved by raising the internal temperature of the particulate filter.
La mise en action des différents moyens d'aide à la régénération est pilotée par le calculateur de contrôle moteur (ECU) qui détermine, en fonction de plusieurs paramètres dont le chargement en suies du filtre à particules, l'instant de la régénération ainsi que sa durée et les paramètres d'injection pendant cette phase.The activation of the various regeneration assistance means is controlled by the engine control computer (ECU) which determines, as a function of several parameters including the soot loading of the particulate filter, the instant of regeneration as well as its duration and the injection parameters during this phase.
Pour améliorer l'efficacité de la régénération, il est nécessaire de produire une température interne au filtre à particules sensiblement comprise entre 570 et 6500C, favorable à l'oxydation des suies et supérieure à la température normale de l'échappement, et ce quelque soit le point de fonctionnement du moteur.To improve the efficiency of the regeneration, it is necessary to produce an internal temperature of the particulate filter substantially between 570 and 650 0 C, favorable to the oxidation of soot and greater than the normal temperature of the exhaust, and this whatever the point of operation of the engine.
Pour optimiser le traitement de l'ensemble des polluants, il est nécessaire de gérer au mieux les phases de stockage et de régénération de ces pièges, c'est-à-dire contrôler précisément la température en entrée du filtre à particules. Or, la thermique nécessaire à la régénération des éléments de stockage de particules est obtenue au moyen d'injections supplémentaires, soit pendant la phase de détente du cylindre, soit directement dans la ligne d'échappement. Le réglage de l'injection s'effectue par exemple par un bouclage sur la température en sortie du catalyseur d'oxydation, ou encore sur la température amont du filtre à particules.To optimize the treatment of all pollutants, it is necessary to better manage the storage and regeneration phases of these traps, that is to say accurately control the inlet temperature of the particulate filter. However, the thermal necessary for the regeneration of the particle storage elements is obtained by means of additional injections, either during the expansion phase of the cylinder, or directly in the exhaust line. The adjustment of the injection is carried out for example by a loop on the temperature at the outlet of the oxidation catalyst, or on the upstream temperature of the particulate filter.
Actuellement, l'exotherme permettant de fournir la température nécessaire à la régénération du filtre à particules est réalisé par une post-injection dans la chambre de combustion du moteur, ou par une injection supplémentaire directement dans la ligne d'échappement appelée par exemple injection du cinquième injecteur. Lorsque la postinjection est effectuée dans les cylindres du moteur, l'introduction de la quantité de carburant est réalisée grâce à l'ajout de deux post injections.Currently, the exotherm for providing the temperature necessary for the regeneration of the particulate filter is achieved by a post-injection in the combustion chamber of the engine, or by an additional injection directly into the exhaust line called for example injection of the fifth injector. When the postinjection is performed in the engine cylinders, the introduction of the amount of fuel is achieved through the addition of two post injections.
La première post injection ou post injection proche consiste à injecter le carburant après l'injection principale, le vilebrequin ayant un angle entre 20 et 70° après le point mort haut. Cette injection est destinée à brûler complètement dans le cylindre de façon à produire une élévation de la température avant turbine et par conséquent en entrée du catalyseur. La post injection proche permet ainsi une production sensible d'énergie sur le vilebrequin.The first post injection or near post injection is to inject the fuel after the main injection, the crankshaft having an angle between 20 and 70 ° after top dead center. This injection is intended to burn completely in the cylinder so as to produce a rise in the temperature before the turbine and therefore at the inlet of the catalyst. The close post injection thus allows a sensible production of energy on the crankshaft.
Toutefois, sur certains points de fonctionnement, la combustion n'est que partielle et génère une quantité de réducteurs, c'est-à-dire de l'exotherme dans le catalyseur d'oxydation.However, on some operating points, the combustion is only partial and generates a quantity of reducing agents, that is to say the exotherm in the oxidation catalyst.
La deuxième post injection ou post injection éloignée consiste à injecter le carburant, le vilebrequin ayant un angle entre 100 et 150° après le point mort haut. Cette injection est destinée à produire la quantité de réducteurs (hydrocarbures (HC) imbrûlés) nécessaire pour atteindre le niveau de température en entrée du filtre à particules requis lors de leur traitement dans le catalyseur (DOC). L'énergie produite sur le vilebrequin est généralement nulle ou très faible.The second post injection or post injection remote is to inject the fuel, the crankshaft having an angle between 100 and 150 ° after the top dead center. This injection is intended to produce the amount of reducing agents (unburned hydrocarbons (HC)) necessary to reach the input temperature level of the particulate filter required during their treatment in the catalyst (DOC). The energy produced on the crankshaft is generally zero or very low.
Ces post injections permettent d'obtenir une très bonne thermique en entrée du filtre à particules mais sont très pénalisantes du point de vue de la dilution - causée par le mélange de carburant avec l'huile moteur dû à la condensation sur les parois du cylindre - et du rendement puisqu'elles ont lieu dans des conditions de pression et de température dans le cylindre faibles. Lorsque l'injection est effectuée dans la ligne d'échappement, l'injecteur supplémentaire ou cinquième injecteur, ne produit pas de dilution, mais son utilisation est limitée. En effet, son utilisation est restreinte par le débit et la température des gaz d'échappement provenant du moteur. Des problèmes de vaporisation, d'homogénéisation ou encore d'émission de polluants peuvent survenir sur de nombreux points de fonctionnement du moteur, ce qui ne permet pas de régénérer le filtre à particules sur une plage étendue par ce cinquième injecteur, et constitue une contrainte d'utilisation.These post injections allow to obtain a very good thermal input of the particulate filter but are very penalizing from the point of view of dilution - caused by the mixing of fuel with the engine oil due to condensation on the walls of the cylinder - and yield since they occur under low pressure and temperature conditions in the cylinder. When the injection is made in the exhaust line, the additional injector or fifth injector, does not produce dilution, but its use is limited. Indeed, its use is restricted by the flow and temperature of the exhaust gas from the engine. Problems of vaporization, homogenization or pollutant emission can occur on many points of operation of the engine, which does not allow to regenerate the particle filter over a wide range by the fifth injector, and is a constraint use.
Lors d'une phase de régénération du filtre à particules, le calculateur adapte l'utilisation de la post-injection et/ou du cinquième injecteur en fonction du point de fonctionnement.During a regeneration phase of the particulate filter, the computer adapts the use of the post-injection and / or the fifth injector depending on the operating point.
Dans les zones de fonctionnement où la thermique est suffisante, l'utilisation du cinquième injecteur est habituellement efficace. On maintient cette stratégie et on n'utilise pas de post-injection. Cette méthode classique permet donc un traitement efficace des hydrocarbures (HC) puisque la thermique dans le moyen d'oxydationIn operating areas where the thermal is sufficient, the use of the fifth injector is usually effective. This strategy is maintained and no post-injection is used. This conventional method therefore allows efficient treatment of hydrocarbons (HC) since the thermal in the oxidation means
(DOC) est suffisante et la régénération du filtre à particules est réalisée dans de bonnes conditions.(DOC) is sufficient and the regeneration of the particulate filter is carried out under good conditions.
Lors des points à faible régime/charge , l'utilisation d'un cinquième injecteur seul est problématique car le manque de thermique en entrée du DOC empêche l'amorçage de celui-ci et le traitement des HC est inexistant ce qui entraîne des pénalités sur l'émission de HC en sortie échappement. Il est possible d'utiliser la post-injection seule, ce qui permettrait d'augmenter la température en sortie du moteur, donc d'amorcer le catalyseur et d'avoir une bonne thermique en entrée du filtre à particules.During points at low speed / load, the use of a fifth injector alone is problematic because the lack of input thermal DOC prevents the boot of it and the treatment of HC is non-existent which results in penalties on the emission of HC at the exhaust outlet. It is possible to use the post-injection only, which would increase the temperature at the output of the engine, so to prime the catalyst and have a good thermal input filter particle.
Cependant, cette approche est très pénalisante en terme de dilution du carburant dans l'huile. Plusieurs solutions proposent de limiter la dilution dans l'huile du carburant lors des stratégies de régénération du filtre à particules.However, this approach is very penalizing in terms of dilution of the fuel in the oil. Several solutions propose to limit the dilution in the fuel oil during regeneration strategies of the particulate filter.
Le document WO200757268 propose par exemple de diviser la post-injection dans le but de limiter la dilution du carburant dans l'huile sur des points à faible débit.WO200757268 proposes for example to divide the post-injection in order to limit the dilution of the fuel in the oil at low flow points.
Le document JP2007023961 propose d'adapter la post-injection en fonction des cylindres.JP2007023961 proposes to adapt the post-injection according to the cylinders.
Les documents US20060016424 et EP1541844 proposent de diviser la postinjection pour diminuer la dilution. D'autres solutions permettent d'améliorer la régénération du filtre à particules sur des points de fonctionnement à faible régime/charge ou pour augmenter la plage d'utilisation du cinquième injecteur.Documents US20060016424 and EP1541844 propose to divide the postinjection to decrease the dilution. Other solutions make it possible to improve the regeneration of the particulate filter at points of operation at low speed / load or to increase the range of use of the fifth injector.
Le document FR2660012 propose de pulvériser le carburant directement dans le filtre à particules pour élargir l'utilisation du cinquième injecteur aux vitesses et températures faibles, ce qui n'implique par obligatoirement des points de fonctionnement faible régime/charge.The document FR2660012 proposes to spray the fuel directly into the particulate filter to expand the use of the fifth injector at low speeds and temperatures, which does not necessarily imply points of low operating speed / load.
Le document US20050000209 propose un système avec une préchambre de chauffage permettant de pulvériser du carburant chauffé directement dans la ligne d'échappement pour améliorer les thermiques sur certaines zones de fonctionnement.The document US20050000209 proposes a system with a pre-chamber of heating for spraying heated fuel directly into the exhaust line to improve the thermals on certain operating zones.
Ces solutions actuelles ne permettent pas diminuer la dilution du carburant dans l'huile. De plus, l'utilisation du cinquième injecteur notamment en faible régime/charge est impossible, et ses zones de fonctionnement sont limitées.These current solutions do not reduce the dilution of the fuel in the oil. In addition, the use of the fifth injector including low speed / load is impossible, and its operating areas are limited.
Afin de pallier tous ces inconvénients, la présente invention propose une stratégie visant à diminuer le coût en dilution lié à l'utilisation de la post-injection tout en augmentant la zone d'utilisation de l'injecteur dans la ligne d'échappement.In order to overcome all these drawbacks, the present invention proposes a strategy aimed at reducing the cost of dilution related to the use of post-injection while increasing the area of use of the injector in the exhaust line.
Dans ce but, un objet de l'invention est un procédé de post traitement des gaz d'échappement d'un moteur à combustion caractérisé en ce que lors des phases de régénération d'un moyen d'oxydation, on effectue au moins une post-injection de carburant dans une chambre de combustion couplée à une injection provenant d'un injecteur à l'échappement disposé dans la ligne d'échappement.For this purpose, an object of the invention is a method of post-treatment of the exhaust gases of a combustion engine, characterized in that during the regeneration phases of an oxidation means, at least one post is carried out fuel injection into a combustion chamber coupled to an injection from an exhaust injector disposed in the exhaust line.
Un procédé associant l'utilisation du cinquième injecteur et de la post-injection permet d'étendre la plage d'utilisation du cinquième injecteur et permet de limiter la dilution à faible régime/charge.A method combining the use of the fifth injector and the post-injection extends the range of use of the fifth injector and limits dilution at low speed / load.
Selon d'autres caractéristiques,According to other characteristics,
- on peut effectuer la post-injection et l'injection à l'échappement sur des points de fonctionnement déterminés, - on peut effectuer la post-injection et l'injection à l'échappement sur des points de fonctionnement de faible régime/charge,the post-injection and the exhaust injection can be carried out on specific operating points, the post-injection and the exhaust injection can be carried out on operating points of low speed / load,
- on peut effectuer une post-injection proche et au moins une post-injection éloignée, - on peut diviser la post-injection éloignée en deux injections,a close post-injection and at least one remote post-injection can be carried out, the distant post-injection can be divided into two injections,
- on peut diviser le volume de carburant à injecter lors de la post-injection en un nombre d'injection post éloignée.the volume of fuel to be injected during the post-injection can be divided into a post-remote injection number.
L'invention concerne également un dispositif de post traitement des gaz d'échappement mettant en œuvre un tel procédé, ledit dispositif étant disposé dans une ligne d'échappement d'un moteur à combustion, et comportant un premier moyen d'oxydation, un deuxième moyen d'oxydation, placé en aval dudit premier moyen d'oxydation, un moyen d'introduction de carburant, disposé en amont du premier moyen d'oxydation relativement au sens de circulation des gaz d'échappement, entre la sortie du moteur à combustion et l'entrée du premier moyen d'oxydation, caractérisé en ce que le premier moyen d'oxydation est un catalyseur d'oxydation pour moteur diesel.The invention also relates to a device for post-treatment of exhaust gases implementing such a method, said device being disposed in an exhaust line of a combustion engine, and comprising a first oxidation means, a second oxidation means, placed downstream of said first oxidation means, a fuel introduction means, arranged upstream of the first oxidation means relative to the direction of flow of the exhaust gas, between the output of the combustion engine and the inlet of the first oxidizing means, characterized in that the first oxidizing means is an oxidation catalyst for a diesel engine.
Selon une autre caractéristique, le deuxième moyen d'oxydation peut être un filtre à particules.According to another characteristic, the second oxidation means may be a particulate filter.
L'invention concerne également une utilisation d'une injection d'un injecteur à l'échappement et d'au moins une post-injection éloignée lors d'une phase de régénération d'un moyen d'oxydation, le moyen d'oxydation étant de préférence un filtre à particules.The invention also relates to a use of an injection of an injector at the exhaust and at least one remote post-injection during a regeneration phase of an oxidation means, the oxidation means being preferably a particulate filter.
L'invention concerne également un véhicule comportant un tel dispositif de post traitement des gaz d'échappement.The invention also relates to a vehicle comprising such a device for aftertreatment of the exhaust gases.
D'autres caractéristiques, buts et avantages de la présente invention apparaîtront à la lecture de la description détaillée qui va suivre, et en regard du dessin annexé, donné à titre d'exemple non limitatif et sur lequel :Other features, objects and advantages of the present invention will appear on reading the detailed description which follows, and with reference to the appended drawing, given by way of non-limiting example and in which:
- la figure 1 est une vue d'ensemble schématique du dispositif selon l'invention. - la figure 2 représente un schéma d'injection en fonction de l'angle du vilebrequin du moteur à combustion, par exemple pour un réglage où l'injection principale "main" est calée sensiblement à 0°v (vilebrequin), la "post-proche" sensiblement à 50°v, et la "post-éloignée" sensiblement à 120°v.- Figure 1 is a schematic overview of the device according to the invention. - Figure 2 shows an injection diagram depending on the crankshaft angle of the combustion engine, for example for a setting where the main injection "main" is keyed substantially at 0 ° v (crankshaft), the "post-close" substantially at 50 ° v, and the "post-far" substantially at 120 ° v.
A la figure 1 , on a représenté un dispositif de post-traitement des gaz d'échappement disposé sur un conduit ou une ligne d'échappement 10, en aval d'un moteur à combustion 4, par exemple à quatre cylindres muni d'un système d'injection 5.FIG. 1 shows an exhaust gas after-treatment device disposed on a duct or an exhaust line 10, downstream of a combustion engine 4, for example four-cylinder engine equipped with a injection system 5.
La ligne 10 d'échappement comporte des moyens d'oxydation 1 , 2 formés par un catalyseur d'oxydation catalytique pour moteur Diesel appelé DOC, en aval duquel est disposé un filtre à particules 2.The exhaust line 10 comprises oxidation means 1, 2 formed by a diesel catalytic oxidation catalytic converter called DOC, downstream of which is disposed a particulate filter 2.
La ligne d'échappement 10 comporte un moyen d'introduction en carburant 3, tel qu'un injecteur de carburant appelé cinquième injecteur, en amont du catalyseur d'oxydation catalytique 1 relativement au sens de circulation des gaz d'échappement, entre la sortie du moteur à combustion et l'entrée du catalyseur d'oxydation 1.The exhaust line 10 comprises a fuel introduction means 3, such as a fuel injector called the fifth injector, upstream of the catalytic oxidation catalyst 1 relative to the direction of flow of the exhaust gas, between the exit of the combustion engine and the inlet of the oxidation catalyst 1.
Lors des phases de régénérations du filtre à particules 2, un procédé de post traitement des gaz d'échappement selon l'invention comporte une étape où l'on effectue au moins une post-injection de carburant couplée à une injection provenant de l'injecteur supplémentaire 3. On effectue de préférence au moins une post-injection et l'injection à l'échappement sur des points de fonctionnement déterminés. En effet, comme cela est précisé dans la description ci-dessus, dans les zones où la thermique est suffisante, par exemple sensiblement entre 3 bars et 13 bars de pression moyenne effective (PME), l'injection provenant du cinquième injecteur suffit. La température en entrée du catalyseur d'oxydation catalytique 1 permet de traiter efficacement les hydrocarburesDuring the regeneration phases of the particulate filter 2, an exhaust gas post-treatment process according to the invention comprises a stage in which at least one fuel injection post-injection coupled to an injection from the injector is carried out. 3. At least one post-injection and the exhaust injection are preferably carried out at specific operating points. Indeed, as specified in the description above, in areas where the thermal is sufficient, for example substantially between 3 bars and 13 bars of effective average pressure (PME), the injection from the fifth injector is sufficient. The inlet temperature of the catalytic oxidation catalyst 1 makes it possible to effectively treat hydrocarbons
(HC) imbrûlés introduits.(HC) unburnt introduced.
On effectue la post-injection et l'injection supplémentaire sur des zones de fonctionnement de faible régime/charge.Post-injection and supplemental injection are performed on low speed / load operating zones.
Dans ces zones, on effectue une post-injection proche et au moins une post- injection éloignée. Tel que représenté à la figure 2, on divise la post-injection éloignée en deux post injections éloignées. L'utilisation du cinquième injecteur couplé à cette « triple post-injection » permet avantageusement de conserver la thermique créée par la post injection proche tout en diminuant la dilution liée à la post injection éloignée.In these areas, close post-injection and at least one remote post-injection are performed. As shown in Figure 2, the post-injection is divided into two distant post injections. The use of the fifth injector coupled to this "triple post-injection" advantageously preserves the thermal created by the close post injection while decreasing the dilution related to the post-injection remote.
Il sera compris que le nombre de post injection éloignée est donné à titre d'exemple, le volume total de carburant à injecter lors de la post-injection éloignée pouvant être divisé en plusieurs injections de manière à obtenir une meilleure homogénéité du mélange gaz d'échappement - carburant et moins d'échanges avec les parois des cylindres.It will be understood that the number of remote post injection is given by way of example, the total volume of fuel to be injected during the remote post-injection can be divided into several injections so as to obtain a better homogeneity of the gas mixture. exhaust - fuel and less exchange with cylinder walls.
Cette « triple post-injection » permet une élévation de la température en entrée de la turbine du moteur, ce qui provoque une augmentation de la température en entrée du catalyseur d'oxydation catalytique 1 à un niveau supérieur à la température qui permet l'amorçage du catalyseur, ce qui permet de brûler les hydrocarbures traversant le catalyseur d'oxydation catalytique 1.This "triple post-injection" allows an increase in the inlet temperature of the engine turbine, which causes an increase in the inlet temperature of the catalytic oxidation catalyst 1 to a level higher than the temperature that allows the priming of the catalyst, which makes it possible to burn the hydrocarbons passing through the catalytic oxidation catalyst 1.
L'injection provenant du cinquième injecteur combinée à cette « triple post- injection » permet d'étendre les zones de fonctionnement du cinquième injecteur à la zone de fonctionnement à faible régime/charge grâce au traitement des hydrocarbures dans le DOC 1. On crée ainsi une thermique en sortie du DOC 1 propice à une bonne régénération en entrée du filtre à particules, sans augmenter les émissions d'hydrocarbures en sortie échappementThe injection from the fifth injector combined with this "triple post-injection" makes it possible to extend the operating zones of the fifth injector to the operating zone at low speed / load thanks to the treatment of hydrocarbons in the DOC 1. a thermal output of the DOC 1 conducive to good regeneration at the inlet of the particulate filter, without increasing the hydrocarbon exhaust exhaust output
Ce procédé de post traitement des gaz d'échappement permet à la fois de réduire les émissions d'hydrocarbures et de diminuer la dilution du carburant dans l'huile tout en assurant une régénération efficace du filtre à particules dans les zones de fonctionnement à faible régime/charge. Un tel procédé permet une meilleure maîtrise de la régénération du filtre à particules sur des zones de fonctionnement à faible régime/charge, et un traitement efficace des hydrocarbures dans ces zones grâce à l'augmentation de la température avant turbine et la température d'entrée du DOC 1.This exhaust gas aftertreatment process both reduces hydrocarbon emissions and decreases fuel dilution in the oil while ensuring effective regeneration of the particulate filter in low operating zones. /charge. Such a method allows a better control of the regeneration of the particulate filter on operating zones at low speed / load, and an efficient treatment of hydrocarbons in these zones by increasing the temperature before turbine and the inlet temperature. from DOC 1.
Ce procédé peut avantageusement être mis en œuvre par tout dispositif de post- traitement ayant besoin d'une thermique élevée associé à un DOC, tel qu'un piège d'oxyde d'azote (NOx-T rap) ou de sulfure d'hydrogène (H2S-Trap) ou autre. This method can advantageously be implemented by any post-treatment device that requires a high thermal associated with a DOC, such as a trap of nitrogen oxide (NOx-T rap) or hydrogen sulphide (H2S-Trap) or other.

Claims

REVENDICATIONS
1. Procédé de post traitement des gaz d'échappement d'un moteur à combustion, au cours duquel, lors des phases de régénération d'un moyen d'oxydation (2), on effectue au moins une post-injection de carburant dans une chambre de combustion couplée à une injection provenant d'un injecteur à l'échappement (4) disposé dans la ligne d'échappement, caractérisée en ce qu'on effectue la post-injection et l'injection à l'échappement sur des points de fonctionnement déterminés de faible régime/charge, la post-injection comportant une post- injection proche et au moins une post-injection éloignée, et en ce que lors de la post-injection éloignée, on divise le volume de carburant à injecter en plusieurs injections.A method of post-treatment of the exhaust gases of a combustion engine, during which, during the regeneration phases of an oxidation means (2), at least one fuel post-injection is carried out in a combustion chamber coupled to an injection from an exhaust injector (4) disposed in the exhaust line, characterized in that the post-injection and the exhaust injection are carried out on determined low-speed / load operation, the post-injection having a close post-injection and at least one remote post-injection, and in that after the remote post-injection, the volume of fuel to be injected is divided into several injections .
2. Procédé de post traitement des gaz d'échappement selon la revendication 1 , caractérisé en ce qu'on divise la post-injection éloignée en deux injections.2. A method of post-treatment of exhaust gas according to claim 1, characterized in that divides the post-injection away into two injections.
3. Dispositif de post traitement des gaz d'échappement mettant en œuvre le procédé selon l'une des revendications 1 à 2, ledit dispositif étant disposé dans une ligne d'échappement d'un moteur à combustion, et comportant a. un premier moyen d'oxydation (1 ), b. un deuxième moyen d'oxydation (2), placé en aval dudit premier moyen d'oxydation (1 ), c. un moyen d'introduction de carburant (3), disposé en amont du premier moyen d'oxydation relativement au sens de circulation des gaz d'échappement, entre la sortie du moteur à combustion et l'entrée du premier moyen d'oxydation (1 ), caractérisé en ce que le premier moyen d'oxydation est un catalyseur d'oxydation pour moteur diesel (1 ).3. Aftertreatment device exhaust gas implementing the method according to one of claims 1 to 2, said device being disposed in an exhaust line of a combustion engine, and comprising a. a first oxidation means (1), b. a second oxidation means (2), located downstream of said first oxidation means (1), c. a fuel introduction means (3) disposed upstream of the first oxidation means relative to the direction of flow of the exhaust gas, between the combustion engine outlet and the inlet of the first oxidation means (1 ), characterized in that the first oxidizing means is an oxidation catalyst for a diesel engine (1).
4. Dispositif selon la revendication 3 caractérisé en ce que le deuxième moyen d'oxydation (2) est un filtre à particules.4. Device according to claim 3 characterized in that the second oxidation means (2) is a particulate filter.
5. Véhicule comportant un dispositif selon la revendication 4. 5. Vehicle comprising a device according to claim 4.
EP08868902A 2007-12-21 2008-12-11 Method for post-processing exhaust gases of a combustion engine Withdrawn EP2232034A1 (en)

Applications Claiming Priority (2)

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FR0760185A FR2925598A1 (en) 2007-12-21 2007-12-21 METHOD FOR POST PROCESSING OF EXHAUST GASES OF A COMBUSTION ENGINE
PCT/EP2008/067278 WO2009083415A1 (en) 2007-12-21 2008-12-11 Method for post-processing exhaust gases of a combustion engine

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ITTO20010786A1 (en) * 2001-08-03 2003-02-03 Fiat Ricerche SELF-PRIMING METHOD OF THE REGENERATION OF A PARTICULATE FILTER FOR A DIRECT INJECTION DIESEL ENGINE PROVIDED WITH AN INI PLANT
WO2006083750A2 (en) * 2005-01-27 2006-08-10 Southwest Research Institute Regeneration control for diesel particulate filter for treating diesel engine exhaust
FR2884872B1 (en) * 2005-04-25 2007-09-14 Renault Sas METHOD FOR CONTROLLING A VEHICLE ENGINE TO REGULATE THE TEMPERATURE OF A PARTICLE FILTER
US20060236680A1 (en) * 2005-04-26 2006-10-26 Wenzhong Zhang Method for regenerating a diesel particulate filter
EP1744042B1 (en) * 2005-07-11 2012-02-22 Ford Global Technologies, LLC Method to regenerate a particulate filter
DE102005054387A1 (en) * 2005-11-15 2007-05-16 Bosch Gmbh Robert Regeneration of a particulate filter by post-injection at intervals

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