EGR system with particulate filter for gasoline engines

Abstract

Exhaust gas recirculation system (1) for a gasoline engine (2), comprising: an exhaust pipe (1.1) connectable to an exhaust manifold (2.1) of the gasoline engine (2), an inlet line (1.2) connectable to an inlet manifold (2.2) of the gasoline engine (2), a compressor (4, 4a, 4b) arranged in the inlet line (1.2), wherein a turbine (3, 3a, 3b) is provided in the exhaust line (1.1), characterized in that an exhaust gas recirculation line (1.3) is provided, which branches off from the exhaust gas line (1.1) upstream of the turbine (3, 3a, 3b) and opens into the inlet line (1.2) downstream of the compressor (4, 4a, 4b), a particle filter (1.4x) is arranged in the exhaust gas recirculation line (1.3), and the particulate filter (1.4x) has a catalytic 3-way coating for the conversion of NOx, CO and HC, and a 3-way exhaust gas catalyst (1.6) is provided upstream of the particulate filter (1.4x), wherein the 3-way exhaust gas catalyst (1.6) is placed within the exhaust line (1.1), and wherein a cooler (1.7) is provided within the exhaust gas recirculation line (1.3) downstream of the particulate filter (1.4x).

Description

The invention relates to an exhaust gas recirculation (EGR) system for a spark ignition engine, having an exhaust line which can be connected to an exhaust manifold, having an inlet line for charge air or combustion air which can be connected to an intake manifold. In the case of a turbo-charged engine, a compressor is arranged in the inlet line, which compressor, in the case of a turbo-charged engine, is connected to a turbine arranged in the exhaust line. The compressor can also be driven alternatively.U.S. Pat. No. 5,671,600 A discloses an exhaust gas recirculation system for diesel engines. At the exhaust gas outlet or at the exhaust gas line, a particle filter is provided, to which a gas recirculation line connects. The exhaust gas recirculation line opens into the inlet line upstream of a charge air compressor. A valve for changing the exhaust gas mass flow is provided within the exhaust gas recirculation line. The particle filter serves to protect the charge air compressor or the charge air cooler from dirt.DE 10 2011 015 629 A1 describes the use of a three-way catalytic converter within an exhaust gas recirculation line of a spark ignition engine for improving pollutant emission, and therefore a reduction of HC, NOx and CO.EP 2 194 351 B1 discloses a charge air cooler with an integrated diesel charge pump for protecting the charge air compressor.DE 10 2012 107 649 B4 describes a particle filter in the exhaust gas line upstream of an exhaust gas recirculation line for supplying a pressure wave supercharger, as is used for diesel engines.US 2014 / 0 165 560 A1 describes an exhaust gas recirculation line of a diesel engine, into which a particle filter and an AMOX catalyst are integrated. According to paragraph

[0025] , this is also intended to be used for a spark ignition engine. However, if ammonia is not required as a reducing agent for the reduction of NOx in a spark ignition engine which is always operated stoichiometrically or rich, the use of an AMOX catalyst in the exhaust gas recirculation line for the oxidation of excess ammonia or of an SCR catalyst in the main exhaust gas line is not considered to be possible for such a spark ignition engine. In addition, it is described that a cooler can be provided in the exhaust gas recirculation line.GB 2 484 495 A describes an exhaust gas recirculation line for a spark ignition engine in which a catalytic converter is contained downstream of a cooler and further downstream of an oxidation catalytic converter. The oxidation catalyst serves for the oxidation of hydrocarbons additionally supplied upstream for the purpose of burning particles.DE 697 37 838 T2 describes an EGR system for a diesel engine with a filter inside the EGR line and with a heat exchanger placed upstream of the filter for cooling the exhaust gas to be filtered and with an oxidation catalyst upstream of the heat exchanger.DE 10 2010 046 900 A1 describes two variants of an exhaust gas recirculation line for a spark ignition engine, wherein a catalytic converter and a downstream particle filter are provided in the main exhaust gas line downstream of the turbine. An exhaust gas recirculation line_I branches off upstream of the turbine and opens downstream of the compressor. Within this exhaust gas recirculation line_I, only one cooler is placed. An exhaust gas recirculation line_II branches off downstream of the particulate filter and opens upstream of the compressor. Within this exhaust gas recirculation line_II, only one cooler is also placed.Further, EP 2 808 518 A1 relates to an exhaust gas circulation device for an internal combustion engine.DE 10 2011 100 295 A1 discloses a heat exchanger method and a corresponding device for an engine exhaust gas recirculation system.The present invention is directed to overcoming one or more of the problems or disadvantages associated with the prior art.The object of the present invention is achieved by an exhaust gas recirculation system according to claim 1 and by an exhaust system according to claim 5. The dependent claims relate to preferred embodiments of the invention. The invention is based in particular on the object of configuring and arranging an EGR system for a spark ignition engine in such a way that less contamination of components in the intake system and improved combustion are achieved, which thereby enable increased operating reliability and, in addition to reduced pollutant emissions, at the same time improved efficiency of the engine.An EGR system typically consists of at least an exhaust gas recirculation (EGR) line, an exhaust gas recirculation (EGR) cooler, and an exhaust gas recirculation (EGR) flap.According to the invention, the object is achieved in that an exhaust gas recirculation line is provided which branches off at the exhaust gas line upstream of the turbine and opens out in the inlet line downstream of the compressor, wherein a particle filter is arranged in the exhaust gas recirculation line or in the exhaust gas line upstream of the exhaust gas recirculation line, said particle filter having a catalytically active 3-way coating for the conversion of NOx, CO and HC. A 3-way exhaust catalyst is provided upstream of the particulate filter, the catalyst being placed inside the exhaust line, a cooler being provided downstream of the particulate filter inside the exhaust gas recirculation line.Deposits are observed in the EGR system and in the intake system of spark-ignition engines, which deposits are referred to as "wet soot" or "fouling", which can result in serious effects such as blockage, poor uniform distribution and irregular combustion. Therefore, EGR systems have hitherto been used only rarely and with restrictions in spark ignition engines.In EGR systems for spark-ignition engines, cooling of the recirculated exhaust gas is advantageous for optimizing the combustion, since recirculation of non-cooled exhaust gases, in particular at higher loads and at full load, leads to higher intake temperatures on account of the hot exhaust gases supplied. This in turn results in charge losses and an increase in the knocking tendency of the spark ignition engine. This is accompanied by undesirable power losses of the motor. These disadvantages can be reduced by cooling the recirculated exhaust gas. However, this results in the formation of an increased amount of condensates--consisting of water and incompletely burnt combustion residues--in the recirculated exhaust gas, which leads to an increased degree of sottling in the form of wet, adhesive deposits in the EGR system and in the intake air system. A combination of the particle filter with the charge air cooler, as described in EP 2 194 351 B1 for a diesel particle filter, is therefore not considered in order to avoid a risk of blockage due to the deposits in the particle filter described above. In addition, a cooled particle filter in the spark ignition engine leads to a considerable limitation of the engine operating range, since the minimum operating temperature in the particle filter, which is required for the self-regeneration of the particle filter, is not reached outside this range without an active regeneration measure. In contrast to the wet constituents entrained in the Otto exhaust gas, diesel particles are generally drier constituents which have a lower tendency to stick. In addition, active regeneration measures for the particle filter in the diesel engine are generally required in very wide engine operating ranges because of the lower exhaust gas temperatures prevailing there.Particulate filters for spark ignition engines, as well as diesel particulate filters, retain particulates. For regenerating the particle filter, i.e. for burning off filtered particles, sufficiently high exhaust gas temperatures and oxygen excess are required. After a heating phase, these requirements for the exhaust gas properties are available in EGR systems of spark ignition engines. However, in wide operating ranges of the spark ignition engine, i.e. in the fired state (lambda=1 in the case of spark ignition engines operated stoichiometrically), there is a lack of an oxygen excess as a basis for combustion of the particles in the particle filter. Thus, only particles are supplied to the particle filter by the exhaust gas flow and retained there. A regeneration, and therefore a combustion of the particles, can only take place in overrun phases of the engine when the injection is switched off. In this overrun phase, i.e., with the engine continuing to rotate and with the intake and exhaust valve actuation, oxygen reaches the EGR system when the EGR valve is open and flows through the particle filter integrated there. When the temperature in the particle filter is sufficient, the particles are then burned to CO2. Under certain circumstances, CO and NOx are also formed.Irrespective of this cleaning step, an advantageous use of recirculated exhaust gas is possible only by cooling the exhaust gas close to the level of the drawn-in fresh air in the intake pipe, utilizing the mentioned advantages. If such a filter is now used in the exhaust gas recirculation line, this not only leads to protection of the intake air system from becoming clogged by the particles and further substances entrained in the exhaust gas, but also ensures the extensive use of an exhaust gas cooler within the EGR line in order to avoid losses of charge, increased tendency to knocking and associated power losses.The catalytically active coating of the particle filter in turn leads to reduced pollutant emissions in the intake system, which can additionally advantageously influence the combustion. The coating of the particle filter acts during fired engine operation. The same applies to the filtering effect of the particle filter. In overrun mode, the particulate filter can be regenerated. A catalytic effect is not absolutely necessary because of the excess air or lack of fuel supply in the overrun phase. As a result of the combination of particle filtering and catalytic conversion of further incomplete combustion products, the exhaust gas which is fed back to the engine has a high degree of purity both with respect to the combustion products and with respect to the particles. This has a positive effect on the formation of deposits in the intake system and on the combustion, and consequently on the pollutant emission of the spark ignition engine.The 3-way catalyst or the oxidation catalyst achieves the aforementioned advantages of reduced pollutant emissions. In this case, alternatively, an uncoated particulate filter may be placed separately before or preferably after the catalyst in the exhaust gas recirculation line. This prevents an additional increase in pressure in the exhaust line and thus a higher fuel consumption of the spark ignition engine.If the exhaust gas to be recirculated is taken in front of the catalytic converter of the exhaust system, an additional 3-way catalytic converter or also an oxidation catalytic converter can be integrated in the exhaust gas recirculation line. However, these catalytic converters represent a further component part which can alternatively be avoided with a catalytically coated particle filter.In any case, the oxidation of pollutant components leads to the generation of heat and thus to the heating of the particle filter located downstream. This extends the use of the independent regeneration of the particle filter in overrun operation to further operating states of the engine.The cooler is separated spatially or at least thermally from the particle filter, so that the particle filter has high temperatures as far as possible in wide engine operating states, so that it regenerates by oxidation of the filtered constituents in the event of an oxygen excess in the exhaust gas (lambda >1). This achieves the largest possible working range of the particle filter for regeneration. The radiator is configured as either an exhaust gas-air radiator, an exhaust gas-engine cooling water radiator, or an exhaust gas-low temperature cooling water radiator. In particular embodiments, a plurality of coolers, which can also be designed to be connectable, can be arranged in series or in parallel with the exhaust gas recirculation.The branch upstream of the turbine ensures higher exhaust gas temperatures, which overall have a positive effect on the particulate filter regeneration and the pollutant reduction. The orifice downstream of the compressor has the advantage that the control path is shorter. This combination of upstream branch of the turbine and downstream orifice of the compressor is referred to as high pressure EGR (HP-EGR). However, a sufficiently high pressure gradient may not be available between the exhaust system and the intake system for supplying the desired recirculated exhaust gas quantity in all desired operating states. In the event that additional cooling of the recirculated exhaust gas is required, the purified exhaust gas can also be supplied to the intake system downstream of the compressor and upstream of the charge air cooler. The exhaust gas is thus cooled not only in the EGR cooler but additionally also in the charge air cooler. An arrangement is also conceivable in which the charge air cooler is designed so effectively that no EGR cooler is required in the EGR line for the recirculated exhaust gas.The upstream branch of the turbine in combination with the upstream orifice of the compressor is referred to as maximum pressure EGR (MD-EGR) and ensures a large pressure difference within the EGR line even for larger demanded exhaust gas recirculation amounts. However, this makes the controlled system longer than in the case of HP-EGR, and the compressor and the turbine may have to be adapted to the changed mass flow rates.The downstream branch of the turbine in combination with the upstream orifice of the compressor is referred to as low pressure EGR (LP-EGR). This arrangement has the advantage that it can also return exhaust gas into the intake system in operating states in which the pressure gradient is not sufficient for HP-EGR. Furthermore, the LP-EGR is characterized by a lower exhaust gas temperature, since the exhaust gas is taken from behind the turbine, as a result of which the required cooling capacity of the EGR cooler is reduced. In addition, the compressor in the intake section must be designed for the greater mass flow rate.In the event that the exhaust gas is taken from the exhaust line downstream of the catalytic converter, the particulate filter arranged in the exhaust gas recirculation line does not require a coating for converting further pollutants.In this case, it can advantageously be provided that a charge air cooler and / or a charge air throttle valve are provided, wherein the orifice of the exhaust gas recirculation line is placed downstream of a position for a charge air cooler and / or downstream of a position of the charge air throttle valve. It can furthermore be advantageous if a controllable throttle valve is provided in or on the exhaust gas recirculation line, by means of which a mass flow of exhaust gas within the exhaust gas recirculation line can be set as a function of the operating point, wherein the throttle valve is placed downstream or upstream of the particle filter. During engine overrun phases, the regeneration of the particulate filter can be influenced via the quantity of recirculated fresh air quantity using the regulating flap. In special embodiments, the throttle valve can also be arranged directly after the particle filter. For this purpose, a construction arranged in a common housing is also possible. Positioning in front of the particle filter leads to increased contamination of the throttle valve and can only be considered in exceptional cases.It may also be advantageous if the throttle valve is provided downstream of the cooler. Thus, it is protected from excessive temperature stress.The object is also achieved by an exhaust system and / or a spark ignition engine having an exhaust gas recirculation system as described above.Further advantages and details of the invention are explained in the patent claims and in the description and are illustrated in the figures. The following are shown: FIG. 1 shows a schematic diagram of a combined HP and LP EGR; FIG. 2 shows a schematic diagram of an MD-EGR; FIGS. 3 a, 3 b show schematic diagrams of a combined HP and IP EGR with different cooler arrangement and inlet line inflow lines; FIGS. 4 a, 4 b show schematic diagrams of a combined HP, IP and LP EGR with different cooler arrangement and inlet lines; FIGS. 5 a, 5 b show schematic diagrams of a partial HP or IP EGR, in which all the exhaust gas of a cylinder is recirculated.All the schematic diagrams according to FIGS. 1-5b show an exhaust gas recirculation (EGR) system 1 which is integrated into the exhaust gas and charge air system of a spark ignition engine 2 with an exhaust manifold 2.1 and an intake manifold 2.2 as well as an exhaust gas turbine 3 and charge air compressor 4. The exhaust gas and charge air system has an exhaust gas line 1.1, which is connected to the exhaust manifold 2.1 of the spark ignition engine 2 and in which the turbine 3 is integrated. At the end of the exhaust line 1.1, exhaust gas 8 leaves the exhaust gas recirculation system 1 and flows into the further exhaust gas section, not shown. In addition, an inlet line 1.2 connected to the inlet manifold 2.2 of the spark ignition engine 2 is provided, into which the compressor 4 is integrated. The inlet line 1.2 is supplied with fresh air 7 via an air supply system, not shown. In addition, at least one exhaust gas recirculation line 1.3, 1.3a (EGR line) is provided, which branches off at the exhaust gas line 1.1 and opens out into the inlet line 1.2.Either a particle filter 1.4, 1.4x is arranged in the EGR line 1.3 or a particle filter 1.4, 1.4x is arranged in the exhaust line 1.1, which filter filters the recirculated or recirculated exhaust gas 8. Furthermore, at least one EGR cooler 1.7, 1.7a is provided in the EGR line 1.3 downstream of the particle filter 1.4, 1.4x. Downstream of the respective EGR cooler 1.7 or upstream of the opening into the inlet line 1.2, an EGR throttle valve 1.8 for regulating the mass flow is placed inside the EGR line 1.3, 1.3 a.In principle, a distinction is made between three variants of the exhaust gas recirculation, depending on the branching of the EGR line from the exhaust line 1.1 and the opening of the EGR line in the inlet line 1.2.The combination of the branch of the EGR line 1.3 upstream of the turbine 3 and the orifice of the EGR line 1.3 downstream of the compressor 4 is referred to as high-pressure EGR (HP-EGR).The combination of the branch of the EGR line 1.3 upstream of the turbine 3 and the orifice of the EGR line 1.3 upstream of the compressor 4 is referred to as maximum pressure EGR (MD-EGR).The combination of the branch of the EGR line 1.3 downstream of the turbine 3 and the orifice upstream of the compressor 4 is referred to as low-pressure EGR (LP-EGR).The three EGR variants referred to above can be used individually or combined with one another.To further influence the recirculated exhaust gas quantity, a throttle valve can be installed in the inlet line 1.2 upstream of the point of introduction of the exhaust gas recirculation line 1.3 into the inlet line 1.2.In the diagram according to FIG. 1, different EGR variants are shown additionally or alternatively. Inside the inlet line 1.2, downstream of the compressor 4, a charge air cooler 5 and a charge air throttle valve 6 are provided.There is an HP EGR formed by the EGR line 1.3 which branches off upstream of the turbine 3 and which opens out downstream of the compressor 4. The opening takes place downstream of the charge air throttle valve 6, Alternatively, the EGR line 1.3' can open upstream of the charge air throttle valve 6 and upstream of the charge air cooler 5.Downstream of the turbine 3, a catalytic converter 1.6, which is designed as a 3-way catalytic converter or as an oxidation catalytic converter, is provided in the exhaust line 1.1. Regardless of the exemplary embodiments described below, the catalyst 1.6 used in each case can in principle be a 3-way catalyst or an oxidation catalyst. An oxidation catalytic converter 1.6 is particularly suitable when it is a lean-burn spark ignition engine 2.Downstream of the catalytic converter 1.6, a further EGR line 1.3a additionally branches off, which opens upstream of the compressor 4 and forms an LP-EGR. The particle filter 1.4 and the EGR cooler 1.7 and an EGR throttle valve 1.8 are provided within the latter. Alternatively, an EGR line 1.3a' may branch off upstream of the catalyst 1.6.Alternatively, an EGR line 1.3a' may branch off upstream of the catalyst 1.6. In this case, the particle filter 1.4x is concerned with a 3-way catalyst coating or an oxidation coating in order to compensate for the bypass of the catalyst 1.6. It should also be noted here that, regardless of the exemplary embodiments described below, the coating of the particle filter applied in each case can in principle be a 3-way catalyst coating or an oxidation coating. An oxidation coating is considered in particular when it is a lean-burn spark ignition engine 2.As an alternative A1 to this LP-EGR, the catalytic converter 1.6 and downstream of the particle filters 1.4 are provided in the exhaust gas line 1.1, wherein the EGR line 1.3 only branches off downstream of the particle filter 1.4. The EGR cooler 1.7 and the EGR throttle valve 1.8 are arranged in the EGR line 1.3.As a further alternative A2 for LP-EGR, the exhaust line 1.1 is equipped with two exhaust line sections 1.1a, 1.1b which are guided in parallel and can be switched via a controllable valve 1.9. In the exhaust pipe portion 1.1a, the catalyst 1.6 is placed. In the parallel exhaust gas line section 1.1b, the coated particle filter 1.4x and the branch for the EGR line 1.3a are arranged. A switchable bypass is thus available for the EGR line 1.3 a, wherein in both cases the 3-way or at least the oxidation catalysis is achieved in the exhaust lines 1.1 a, 1.1 b.The controllable valve 1.9 can also be designed such that partial exhaust gas quantities of different sizes flow simultaneously through the parallel exhaust gas line sections 1.1a, 1.1b.Furthermore, an uncoated particle filter can also be used in the exhaust gas line section 1.1b. In this case, however, the exhaust gas catalytic converter 1.6 is installed in the exhaust gas line 1.1 before being divided into the two exhaust gas line sections 1.1 a, 1.1 bto ensure catalytic purification of the exhaust gas in each position of the valve 1.9.According to FIG. 2, an MD-EGR is formed. The particulate filter 1.4x placed in the EGR passage 1.3 has a catalyst coating. In addition to this, a catalytic converter 1.6, preferably a 3-way catalytic converter, is provided in the exhaust line 1.1 downstream of the turbine 3.According to the embodiment of FIG. 3 a, the exhaust gas recirculation is forwarded starting from the EGR line 1.3, which branches off at the exhaust gas line 1.1, via a plurality of EGR lines 1.3 a- 1.3 darranged in parallel, which each open out at the inlet line 1.2. The particle filter 1.4x with the catalyst coating and the cooler 1.7 are arranged in the EGR line 1.3. Each of these EGR lines 1.3 a- 1.3 dhas a throttle flap 1.8 a- 1.8 ddownstream of the connection to the EGR line 1.3, wherein all throttle flaps 1.8 a- 1.8 dare connected via a control line 9.1 to a control unit 9 for controlling or regulating the position of the respective throttle flap 1.8 a- 1.8 dand can be controlled individually. Downstream of the respective throttle valve 1.8a-1.8d, a further cooler 1.7a-1.7d is provided in the respective EGR line 1.3a-1.3d. The inlet line 1.2 has two compressors 4a, 4b, which are each coupled to a turbine 3a, 3b of the exhaust line 1.1. The EGR lines 1.3a, 1.3b both open downstream of the compressor 4a and form an HP-EGR. The EGR line 1.3 bopens upstream of the charge air cooler 5, while the EGR line 1.3 aopens downstream of the charge air cooler 5.The EGR line 1.3d opens upstream of the compressor 4b and forms an MD EGR. However, the EGR line 1.3c opens between both compressors 4a, 4b and therefore forms a reduced MD EGR.The embodiment of FIG. 3a can also be designed without an EGR cooler 1.7 (not shown).Downstream of the turbines 3 a, 3 b, a 3-way catalytic converter 1.6 is placed, starting from which the exhaust gas 8 is guided into the further exhaust system.The embodiment according to FIG. 3 bis of similar construction. In this case, four coolers 1.7a-1.7c are provided in the EGR line 1.3, in each case upstream of the branch into the respective EGR line 1.3a-1.3d. Thus, a cooler 1.7d is less necessary than is the case in the embodiment according to FIG. 3a.Both exemplary embodiments according to FIGS. 3 aand 3 b ensure an extremely flexible EGR guidance, so that a long-range particle filtering and a regeneration of the particle filter 1.4, on the one hand, and the supply of cooled exhaust gas according to demand into the inlet line for a comprehensive operating range of the engine, on the other hand, are always ensured.The embodiments of FIGS. 4 a, 4 binclude HP-EGR, MD-EGR, and LP-EGR. The charge air cooler 5 and the charge air throttle valve 6 are seated in the inlet line 1.2, while the exhaust line 1.1 is equipped downstream of the turbine 3 with a 3-way catalytic converter 1.6 and a downstream particle filter 1.4.According to the exemplary embodiment of FIG. 4 a, a coated or uncoated particle filter 1.4, 1.4 xis first provided in the EGR line 1.3. A further EGR line 1.3a then branches off. While the EGR line 1.3a opens as HP-EGR downstream of the charge air throttle valve 6 at the exhaust line 1.1, the EGR line 1.3 opens as MD_EGR upstream of the compressor 4. A cooler 1.7a and a downstream throttle valve 1.8a are likewise provided in the EGR line 1.3a.In addition to this, a further EGR line 1.3b is provided, which branches off at the exhaust line 1.1 downstream of the particle filter 1.4, and therefore downstream of the turbine 3. It likewise has a cooler 1.7 band a downstream throttle valve 1.8 b, before it opens out at the inlet line 1.2 upstream of the compressor 4 and thus represents an LP-EGR.Both the HP-EGR, and the IP-EGR and the LP-EGR are realizable in any combination.In contrast to the exemplary embodiment according to FIG. 4 a, in the exemplary embodiment according to FIG. 4 b, the EGR line 1.3 and the EGR line 1.3 bare coupled via a controllable valve 1.9. This has the advantage that a cooler 1.7b is less required. However, in addition to or as an alternative to HP-EGR, only one of MD-EGR and LP_EGR may be realized.In the exemplary embodiments according to FIGS. 5 aand 5 b, the EGR line 1.3 is assigned to an individual cylinder outlet 2.3 of the spark ignition engine 2 and conducts the exhaust gas quantity of this cylinder outlet 2.3. The charge air cooler 5 and the charge air throttle valve 6 are seated in the inlet line 1.2, while the exhaust line 1.1 is equipped downstream of the turbine 3 with a 3-way catalytic converter 1.6 and a downstream particle filter 1.4.According to the exemplary embodiment of FIG. 5 a, an HP-EGR is formed. The EGR line 1.3 has a coated particle filter 1.4x and a downstream cooler 1.7 and a throttle valve 1.8 placed downstream of the cooler 1.7. In an exemplary embodiment not shown, an uncoated particle filter 1.4 can also be provided.According to the exemplary embodiment of FIG. 5 b, an MD-EGR is supplemented. For this purpose, a further EGR line 1.3 abranches off between the coated particle filter 1.4 xand the cooler 1.7, which line opens upstream of the compressor 4. In this EGR line 1.3a, a further cooler 1.7a and a downstream throttle valve 1.8a are likewise placed. In an exemplary embodiment not shown, an uncoated particle filter 1.4 can also be provided.List of reference characters1 Exhaust system / exhaust gas recirculation system 1.1 Exhaust line 1.1a Exhaust line section 1.1b Exhaust line section 1.2 Inlet line, charge air line, fresh air line 1.3 Exhaust gas recirculation line, EGR line 1.3' Exhaust gas recirculation line, EGR line 1.3a Exhaust gas recirculation line, EGR line 1.3a' Exhaust gas recirculation line, EGR line 1.3c Exhaust gas recirculation line, EGR line 1.3d Exhaust gas recirculation line, EGR line 1.4 Particle filter 1.4x Particle filter, coated 1.6 Exhaust gas catalytic converter, 3-way catalytic converter, Oxidation catalyst 1.7 Cooler 1.7a Cooler 1.7b Cooler 1.7c Cooler 1.7d Cooler 1.8 Throttle valve 1.8a Throttle valve 1.8b Throttle valve 1.8c Throttle valve 1.8d Throttle valve 1.9 Valve, Exhaust flap 2 Spark ignition engine 2.1 Exhaust manifold 2.2 Intake manifold 2.3 Cylinder outlet 3 Turbine 3a Turbine 3b Turbine 4 Compressor 4a Compressor 4b Compressor 5 Charge air cooler 6 Charge air throttle valve 7 Fresh air 8 Exhaust gas 9 Control unit 9.1 Control line A1 Alternative A2 Alternative

Claims

Exhaust gas recirculation system (1) for a spark ignition engine (2), which has: an exhaust line (1.1) which can be connected to an exhaust manifold (2.1) of the spark ignition engine (2), an inlet line (1.2) which can be connected to an inlet manifold (2.2) of the spark ignition engine (2), a compressor (4, 4a, 4b) arranged in the inlet line (1.2), wherein a turbine (3, 3a, 3b) is provided in the exhaust line (1.1), characterized in that an exhaust gas recirculation line (1.3) is provided which branches off from the exhaust line (1.1) upstream of the turbine (3, 3a, 3b) and opens out from the inlet line (1.2) downstream of the compressor (4, 4a, 4b), a particle filter (1.4x) being arranged in the exhaust gas recirculation line (1.3), and the particle filter (1.4x) has a catalytically active 3-way coating for converting NOx, CO and HC, and a 3-way exhaust gas catalytic converter (1.6) is provided upstream of the particle filter (1.4x), wherein the 3-way exhaust gas catalytic converter (1.6) is placed inside the exhaust gas line (1.1), and wherein a cooler (1.7) is provided downstream of the particle filter (1.4x) inside the exhaust gas recirculation line (1.3).Exhaust gas recirculation system (1) according to Claim 1, characterized in that a charge air cooler (5) and a charge air throttle valve (6) are provided, wherein the orifice of the exhaust gas recirculation line (1.3) is placed downstream of a position for the charge air cooler (5) and / or downstream of a position for the charge air throttle valve (6).Exhaust gas recirculation system (1) according to one of the preceding claims, characterized in that a throttle valve (1.8) is provided in the exhaust gas recirculation line (1.3), by means of which throttle valve an exhaust gas mass flow within the exhaust gas recirculation line (1.3) can be set as a function of the operating point, wherein the throttle valve (1.8) is placed downstream or upstream of the particle filter (1.4x).Exhaust gas recirculation system (1) according to Patent Claim 3, characterized in that the throttle flap (1.8) is provided downstream of the cooler (1.7).Exhaust system having an exhaust gas recirculation system (1) according to one of the preceding patent claims.

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