DE10341143A1 - Process for cleaning a particle filter used in a motor vehicle engine comprises adding a reactive gas to the exhaust gas line at an exhaust gas temperature below the regeneration temperature of the filter to initiate a reaction - Google Patents

Abstract

The process for cleaning a particle filter (12) used in a motor vehicle engine (2) comprises adding a reactive gas (6) to the exhaust gas line (3) running between the filter and the engine at an exhaust gas temperature below the regeneration temperature of the filter to initiate a reaction of the particles. An independent claim is also included for a cleaning device (1) for a particle filter used in a motor vehicle engine.

Description

The The present invention relates to a method and a device for cleaning a particulate filter of an internal combustion engine, in particular a Diesel engine of a motor vehicle.

To reduce the particle emissions of diesel motor vehicles soot filter systems are used. By collecting the soot in the filter, the exhaust back pressure increases, thereby deteriorating the fuel consumption and driving dynamics of the vehicle. In order to prevent blocking of the particulate filter, intermittent or continuous combustion of the soot deposited in the soot filter is required. This is also called regeneration of the particulate filter. For example, an intermittent, thermal regeneration is achieved in that the exhaust gas flowing into the soot filter is raised to the required temperature level for the filter system used. The required high temperature level is about 650 ° C, provided the particle filter is provided without a catalytic coating. Furthermore, it is known to be able to lower the temperature, for example by adding additives that allow combustion at a lower temperature level. This goes for example from the DE 199 04 736 A1 as well as from the DE 40 411 27 C2 out.

If the motor vehicle is used mainly in short-distance or winter operation, there is the possibility that the necessary temperature level for regeneration of the particulate filter is not or not regularly achieved. To ensure an increase in the exhaust gas temperature, internal engine as well as off-engine possibilities are therefore known. In the engine inside possibility, for example, the exhaust gas temperature increase takes place by engaging in the combustion process management. For example, the injection parameters can be adapted. For this purpose, it is known, for example, to perform an additional fuel injection, such as by means of a delayed injection in the expansion stroke. Such funds go for example from the DE 199 26 138 A1 , of the DE 199 481 56 A1 and the DE 101 59 479 A1 out. Furthermore, there is the possibility that the NO _x content is raised in order to achieve a burning of the collected particles in the particulate filter. This is for example from the DE 199 611 66 A1 as well as from the DE 101 19 431 A1 known. As part of the off-engine possibilities for raising the exhaust gas temperature for the regeneration of the particulate filter, it is again known to exploit an exothermic reaction, which are achieved by adding unburned fuel into the exhaust gas before the catalyst or indirectly by means of a burner. For example, goes from the DE 100 62 956 A1 a diesel fuel injection in front of the particulate filter. From the DE 40 25 017 C2 It is known to arrange a burner in the exhaust system in front of the particulate filter, which raises the exhaust gas temperature such that burning of the soot particles in the particulate filter is ensured.

The internal engine measures to raise the temperature levels have due to their very late injection timing the disadvantage that it to a very early oil dilution in the Internal combustion engine comes. Furthermore, strong heat losses due to the design of the exhaust system, so that on the one hand high engine component loads can occur to a sufficient extent Ensure temperature level at the particle filter. On the other hand requires such a regeneration strategy a higher fuel use, which increases consumption. The outside the engine Temperature increase by means of a catalyst, before the fuel is injected, requires that the light-off temperature of the catalyst exceeded to prevent breakthrough of unburned fuel have to be. For this usually temperatures above 230 ° C are required. The use in turn, a burner arranged in front of the particle filter requires in particular a big Effort in terms of space and flame stability.

task It is the object of the present invention to provide particulate filter regeneration to allow at low exhaust gas temperatures and in particular a exhaust gas optimized operation of the internal combustion engine in always to ensure recurrent short-distance operation.

These Task is with a method for cleaning a particulate filter an internal combustion engine, in particular a diesel engine, a motor vehicle with the features of claim 1 and 2 and with a cleaning device for a particle filter one Internal combustion engine, in particular a diesel internal combustion engine a motor vehicle with the features of claim 11 solved. Further advantageous embodiments and further developments are specified in the respective subclaims.

An inventive method for cleaning a particulate filter of an internal combustion engine of a motor vehicle is carried out by metered addition of a reactive gas in an exhaust gas line leading between the engine and the Particulate filter runs at an exhaust gas temperature below the regeneration temperature of the particulate filter to initiate a reaction of the particles. This allows regeneration of the particulate filter to take place, in particular at idle or on short distances, although the exhaust gas temperature transferred from the internal combustion engine to the particulate filter is generally insufficient in such operating points to cause combustion of the particulates. By controlled metered addition of the reactive gas is made possible to increase the exhaust gas temperature such that an initiation of a reaction of the particles is made possible. In particular, the metered reactive gas can only be added until the particle combustion is so exothermic that further addition of the reactive gas is no longer necessary.

According to one Another idea of the invention is a process for purification a particulate filter of an internal combustion engine of a motor vehicle to disposal in which by adding a metered reactive gas in an exhaust gas leading Line between the internal combustion engine and the particle filter runs, the reactive gas prior to the addition of the entrained in the motor vehicle fuel is reformed. This has the advantage of being a very high quality reactive Gas provided which allows a very short reaction time, for the sufficient temperature for to achieve a particle filter regeneration. On the other hand allowed a very high quality reactive gas, the restriction to a low addition of the same, to be able to initiate a sufficient particle filter regeneration. The Addition takes place, for example, according to the method described above.

Preferably is the heat release either via a, achieved upstream of the particulate filter, oxidation catalyst or over generated directly on a catalytically coated particle filter. The coating preferably has a purely oxidizing component on. According to one Further, the coating may have a Denox functionality.

in the following will be executions in particular with regard to diesel internal combustion engines. However, the invention is also working on the Otto principle can be used direct injection internal combustion engines. Therefore are the subsequent ones based on a diesel engine Explanations are not limited to these but can also transferred to other internal combustion engines become.

Preferably, it is desirable that hydrogen is generated during the reforming as a reactive gas, in particular hydrogen in molecular form, such as H ₂ . In particular, the reforming is made possible by the fact that the reactive gas is generated from, for example, a diesel fuel, in particular reformed. However, another gas can be used for this purpose. If, for example, a hybrid motor vehicle is used, the reactive gas can be generated, for example, from a corresponding filling, in particular a natural gas filling by reforming.

The Use of very reactive components, such as hydrogen, Already allowed in conjunction with one or more catalytic surfaces at very low ambient temperatures due to exothermic oxidation to generate high temperatures. These temperatures are sufficient to at least initiate a regeneration of a particulate filter, but especially complete to support. The reactive components can either stored in the vehicle or out of the vehicle Fuel such as diesel fuel to be reformed.

Preferably if a regeneration is carried out, when the vehicle is idling and / or in low load operation the diesel engine is. Then the reactive gas is metered added. However, the regeneration can also over an entire map area executed in all load ranges especially if no other regeneration measure is pending. Preferably, an addition below an exhaust gas temperature of 200 ° C. Especially is the reactive gas even at an exhaust gas temperature of less as 160 ° C, in particular below 100 ° C fed, to a sufficient increase due to an exothermic reaction to allow the temperature to a level by which the regeneration of the particulate filter allows becomes. Preferably, such an increase in the temperature level made in diesel internal combustion engines, for example, over heat meabgebende Facilities in the exhaust system. This can, for example Turbochargers, exhaust gas cooling devices, long exhaust pipes and / or similar be.

The reactive gas is obtained, for example, from fuel, in particular diesel fuel. It is also possible to recover the reactive gas from methane, propane, sodium borohydride, methanol as well as ethanol. For example, as a reformer for reforming the reactive gas suitable for use in a fuel cell reformer available. The reformer can, for example, work according to the "catalytic partial oxidation" principle or according to the "autothermal reformer" principle. There is also the possibility that in a hybrid motor vehicle, a corresponding reformer for a fuel cell is shared, so gewonn to the NEN hydrogen can be used for the regeneration of the particulate filter.

One Reforming to produce the reactive gas may also be different Done way. You can do this one or more different catalysts are used. For example, this can also be at a higher pressure than the occur in the exhaust system prevailing, under which the reactive Gas also supplied, for example becomes. It is also possible to use a plasma fuel reformer, such as from the publication "Integrated micro plasmatron fuel converter - exhausted catalyst Bromberg, Kohn and Rabinowitz of the MIT is known (reference: www.psfc.mit.edu/plasmatech/plasmetron1.html)

Furthermore, the reforming can be carried out by means of a partial oxidation (POX), in which oxygen is added substoichiometrically to a fuel gas. Heat is released in the incoming water gas shift reaction. According to one example, in an operating range of the internal combustion engine at a working temperature around 800 ° C. and at a lambda value between 0.3 and 0.4 diesel fuel is refurbished according to POX. In this way, a reactive gas can be achieved as a gas mixture, for example, at least H _{2 has} between 15 mol% and 20 mol% and CO between 17 mol% and 23 mol%.

Also A steam reforming (WDR) can be carried out by adding of steam the fuel can be reformed. This reaction is endothermic and can therefore, for example, from the internal combustion engine Use waste heat. A mix of POX and WDR leads for autothermal reforming (ATR), in which a heat balance balanced between the input and output of the reformer, thereby the temperature remains constant. The reforming can in particular also under pressure, depending on carried out by Method may be between 3 bar and 35 bar. As fuels for the Reforming come, for example, methanol, natural gas, gasoline, diesel as well as ethanol in question.

Especially The reactive gas can also come from a reformer, for example for one APU (Auxiliary Power Unit) is used. For example, the APU will for a On-board network of the motor vehicle used, for example, for a 42V electrical system. Belonging to the APU can be a memory for be the reactive gas, so that directly at the start of the internal combustion engine a feeder ensures the reactive gas can be.

The Reactive gas can essentially be one or more gas components Have gas components. According to one Embodiment is used as a reactive gas hydrogen that at least the vast majority Makes up part of the reactive gas. Preferably, the reactive Gas at least approximate Completely from hydrogen. According to one In another embodiment, the reactive gas has two or more reactive Gas components, for example at least hydrogen and CO. Besides For example, the gas may include other components necessary for particulate filter regeneration to classify as inert compared to the reactive gas components are. Preferably the proportion of reactive gas components at least 25 mol% of the reactive Gas, in particular over 30 mol%, preferably over 35 mol%.

A Continuing provides that a adjustable proportion of the exhaust gas flow at the particulate filter at least immediately before initiation of the regeneration of the particulate filter is bypassed. This takes place, for example, in a temperature range below the regeneration temperature of the particulate filter. This allowed that one smaller exhaust partial flow impinges on the particle filter. This lower exhaust partial flow needed a lower addition of the reactive gas to an increase in the Temperature levels for initiating the regeneration of the particulate filter to enable. If the regeneration of the particulate filter has started, the diverted partial exhaust gas stream can immediately as well as gradually be reduced and fed to the particulate filter. Preferably for the Vorbeileitung the exhaust gas partial stream used a bypass system, which in Exhaust line is arranged. A bypass of a partial exhaust gas stream At the particulate filter is preferably carried out only for a very short period, the is sufficient to initiate the regeneration of the particulate filter. The following the resulting exothermic energy is sufficient, on the one hand the particle filter continue to regenerate, on the other hand that necessary for regeneration Keep temperature level, even if now the complete exhaust gas flow through the particle filter flows.

Especially can one or more buildings are provided in the exhaust line, the Divide exhaust stream in the exhaust line such that a medium, for example Area of the exhaust stream by supplying the reactive gas in This area is heated, one in the outer area of the exhaust line flowing through By contrast, exhaust gas flow only through the exothermic reaction of the reactive gas by appropriate heat conduction heating experiences. In this way it is avoided that a bypassing a Exhaust partial flow takes place on the particle filter.

Preferably, a regeneration of a particulate filter is monitored. In particular, the Regeneration also controlled or regulated done, for example, can be used on a control unit of the motor vehicle. Exemplary controls the regeneration as well as structures of the exhaust line with corresponding sensors as well as exhaust gas converting facilities are exemplified in the DE 101 30 633 A1 , of the DE 100 56 034 A1 and the DE 199 52 830 A1 referred to in the context of this disclosure with respect to the control, the operation of the regeneration, appropriate measures, facilities and the like.

According to one Control strategy becomes a loading condition of the particulate filter as well as a temperature of the particulate filter detected. Dependent on thereof a dosage of reactive gas to be added is determined and accordingly added, with formation of hot spots in the Particle filter monitored and avoided.

A Procedure for the regeneration of the particulate filter provides that during a Heating phase, optionally also during the soot oxidation phase, a portion of the exhaust stream is passed around the particulate filter. In this way, it is possible to reduce the heat transfer from the particle filter to steer out. In particular, to avoid a thermal damage of the particulate filter, it has proved to be advantageous when the temperature of the particulate filter at least during the Regeneration is determined and depending on this temperature an influence on the exhaust gas flow flowing through the particle filter he follows. The influence can be many ways. For example, the exhaust gas flow can be influenced, for example, by a diversion along a bypass line. It is also possible to change an addition of the reactive gas to cool the particulate filter. Preferably is at an undesirable Increasing the temperature will enrich the particle filter flowing Exhaust gas through an increase achieved the addition of the reactive gas. Preferably, different activities for influencing the flowing through Combined exhaust gas flow. According to a development is provided that one increase or lowering the addition of the reactive gas in conjunction with a division of the exhaust gas flow and / or in particular bypass the particulate filter takes place. For example, a breakdown the exhaust stream into different partial exhaust streams by means of an exhaust flap take place, which is arranged in the exhaust line in front of the particle filter.

A surveillance the temperature of the particulate filter, for example, via a Temperature sensor and / or over a, arranged behind the particulate filter sensor done. Farther it is possible a statement about the regeneration of the particulate filter or the state of the particulate filter by means to get a lambda probe. The lambda probe is preferably arranged before and / or after the particulate filter. Also, one can Lambda probe in the particulate filter itself be present. For example is a regeneration period of the particulate filter by means of a difference value formation calculated from two or more lambda values. The lambda values can be from one or more lambda probes are derived. Preferably, the lambda signal measured after the particle filter. This is related to a value set, either by calculation and / or by means of a corresponding sensor is recorded before or along the particulate filter.

For example, it is provided that an addition of the reactive gas in dependence on a predeterminable temperature window during the regeneration of the particulate filter is increased or decreased. For this purpose, a control unit may have an operating map of the particulate filter. This operating map has, for example, one or more pressures, pressure differences, temperatures, gas values such as HC, NO _x , CO, CO ₂ or other gas values, operating points, values such as speeds, torques, injection times, injection quantities, acceleration values, air mass and the like. By means of such an operating map, a control or regulation of the regeneration, the duration of which as well as initiation in different operating states of the internal combustion engine, in particular in idle or in partial load operation can be carried out.

According to a further aspect of the invention, a cleaning device for a particle filter of an internal combustion engine, in particular a diesel internal combustion engine, of a motor vehicle is provided, which has an exhaust pipe which is arranged between the internal combustion engine and the particle filter. The exhaust pipe has at least one reactive-gas injection orifice, the injection orifice being in line-connected communication with a reactive gas-generating reformer of fuel carried in a fuel tank of the motor vehicle. This cleaning device has the advantage that in particular a refurbished, reactive gas can be used which releases a high exothermic energy during the reaction. This makes it possible to effect a high effect on the particle filter with relatively small amounts. In particular, the cleaning device allows an initiation of the regeneration step, which continues automatically, for example, after initiation due to the amounts of heat released by the combustion of the particles. Preferably, the regeneration of the particulate filter is monitored. The surveillance allowed on the Regeneration to be able to act. Should the temperature be too high or too low, the regeneration behavior can be changed, for example, by means of a control or regulation of the reactive gas. The cleaning device allows regeneration to be enabled, in particular in states of low exhaust gas temperature. If the internal combustion engine, in particular the diesel internal combustion engine frequently used in city traffic and short distances, there is a risk that the particulate filter is added, but without experiencing a necessary regeneration due to the low exhaust gas temperatures. The cleaning device allows by raising the reactive gas in the exhaust pipe raising the temperature level to initiate the regeneration as well as for example to achieve the "light-off" temperature of an existing catalyst.

Preferably is a reformer to the flow arranged with exhaust gas at least partially in the exhaust pipe. This allows the existence heat exchange between the arranged in the exhaust pipe reformer or reformer component and the passing one Exhaust possible is. This has an advantage for a reduction of heat loss of the reformer. For example, the generation of the reactive gas for heat release to lead in the reformer. This amount of heat is heated by placing the reformer in the exhaust pipe of the flowing exhaust gas used. If, for example, a reforming by means of a partial carried out catalytic oxidation, can according to a Another embodiment, the exhaust gas flowing around the reformer this cool and thus against overheating protect.

According to one Further development is provided that the cleaning device a bypass system having. The bypass system preferably has a discharge from the exhaust pipe upstream of the injection port. This allows, with a corresponding actuating means, a partial exhaust stream at least at the injection port and in particular can also be conducted past the particle filter. The bypass system and the associated one Adjusting agents are preferably over led a control or regulation, which performs and monitors the regeneration of the particulate filter. This allows playing in the game together with the dosage of the addition of the reactive gas regeneration dependent on from the respective operating states not only of the internal combustion engine but also, for example, of the particulate filter itself, of as well as downstream facilities such as catalysts and the like allows becomes.

A Continuing provides that the bypass line a buffer, for example in the form of another particle filter having. This allows to go back and forth between both particle filters to be able to switch. The particle buffer in the bypass line is needed preferably a smaller storage volume than the main used one Particle memory.

Of the Caching may in particular be designed such that it is in is capable for short operating states to have sufficient storage capacity. This is however less than the one for a permanent operation would be necessary. The cache will preferably regenerated itself at a time when the first Particle storage in the regeneration is, or has been regenerated. For this purpose, the buffer can also be acted upon by reactive gas become.

Preferably is provided that a Derivation of the bypass system downstream From the particulate filter opens into the exhaust pipe. This allows the particle filter for one short time to initiate the regeneration can be bypassed. However, this bypassing means no significant increase in the Particulate emissions, because this bridging of the Particulate filter only for a short period, preferably only for the initiation of regeneration the particulate filter takes place.

Especially the cleaning device has a device for regulating the Adjustment of a particle filter temperature. By means of this is on the one hand, it is possible an overheating to avoid the particulate filter. On the other hand forms the device the possibility, monitor the regeneration behavior of the particulate filter and, for example, according to a specification such as a regeneration map to be able to adapt an actual value to a setpoint. This allows in particular that at a trigger the regeneration, for example, due to an excessive pressure difference above the Particulate filter an addition of the reactive gas in adaptation to the respective particle degradation in the particulate filter, as well as at each present exhaust stream and its components can be made.

For example, a determination of a temperature as well as a corresponding control according to the DE 101 08 720 A1 known technical teaching, which is referred to in the context of this disclosure in this regard. There is also the possibility of regeneration using a lambda control, as for example from the DE 100 56 035 A1 and referred to in the context of this disclosure.

In particular, a regulation of the rules avoid the formation of hot spots in the particle filter. A corresponding monitoring is carried out for example by means of a lambda probe.

To the An example is to monitor a surface temperature to avoid hot spots executed the particulate filter, preferably by means of a sensor of high temporal resolution in a range preferably between 100 and 300 msec. The temperature is preferably determined inside the particulate filter. For example a sensor disposed inside the particulate filter. Especially there is also the possibility the use of a surface sensor, which is able to capture not only a punctual measured value but also about a width and / or length and / or height of one Section in the particle filter determines the temperature. This allows The supervision whole critical areas, as the temperature at hot spots temperature gradients of, for example, 100 ° C / cm and the areal surveillance make the occurrence detectable as such. For example, can in the case of a ceramic particle filter, this at least on its surface one, preferably have a plurality of corresponding sensors embedded.

A support the regeneration of the particulate filter is carried out by a catalytic acting coating of the particulate filter. This allows that in the particulate filter even exothermic energy is released and this is about the Particle filter can spread. For example, first a middle one Particle filter one sufficient for regeneration Have temperature. By heat transfer can subsequently the farther out Areas of the particulate filter also necessary for regeneration Temperature received. The catalytic coating accelerates the Regeneration and sets the exothermic energy in the area of soot particles even free. This reduces heat losses, as for example when releasing the exothermic energy upstream of the particulate filter may be present.

A further embodiment provides that upstream of the particle filter upstream of an oxidation catalyst. The oxidation catalyst is capable of reacting the reactive gas and thereby raising the temperature of the exhaust gas to a temperature level sufficient for regeneration of the particulate filter. This allows, for example, that an exhaust gas temperature measured after the oxidation catalyst is higher than an exhaust gas temperature measured upstream of the oxidation catalyst. In particular, an ignition temperature of the soot can be achieved faster. This allows, for example, to initiate the regeneration in the particle filter. Preferably, the regeneration of Parti kelfilters in correlation with the control behavior of the oxidation catalyst and the mixture formation of the internal combustion engine via the lambda control. Also, the addition of the reactive gas, particularly H ₂ , allows the light-off temperature to be reached very quickly, even though the system has cooled to minus temperatures due to environmental conditions, for example due to prolonged service life.

Farther It has proved to be advantageous that for different operating conditions of Internal combustion engine different measures for the regeneration of the Particulate filters are integrated on the motor vehicle. This allows depending on the operating condition of the internal combustion engine the appropriate measure choose to be able to. For example activities be provided, as in the above-mentioned state the technique cited and closer explained are. These techniques are expressly referred to in the context of this disclosure.

Further advantageous embodiments and developments show the following Drawing. However, the features shown there are not on the individual embodiments limited. Rather, you can this example, with the embodiments described above merged into further education that will not be closer explained are. Show it:

1 a schematic diagram of a cleaning device of a particulate filter of a diesel engine,

2 a further schematic diagram of a second cleaning device,

3 a development of the second cleaning device 2 with a bypass system,

4 a third cleaning device,

5 a diagram showing the course of a regeneration of a particulate filter by way of example,

6 a second diagram showing an exemplary operation of a lambda probe in conjunction with a particle filter, and

7 a catalyst efficiency versus temperature depending on the gas used.

1 shows a schematic diagram of a first cleaning device 1 , An internal combustion engine, in particular a diesel internal combustion engine 2 , has an exhaust pipe 3 on, over which an exhaust gas flow 4 from the diesel engine 2 is led away. In the exhaust pipe 3 is an injection port 5 arranged over which a reactive gas 6 in the exhaust pipe 3 is supplied. The reactive gas 6 mixes with the exhaust stream 4 and continues to flow along the exhaust pipe 3 , The injection port 5 is for example at an angle to the exhaust pipe 3 built-in, which has a good mixing of the reactive gas 6 with the exhaust gas flow 4 allows. The injection port 5 In particular, a fanning of the incoming reactive gas 6 cause. The reactive gas 6 becomes from a device, in particular a reformer 7 , provided, wherein the reformer, for example, a metering device 8th having. By way of a regulating or control device, which is not shown in detail, at least one state of the particulate filter is determined as a function of at least one condition 12 an inflow of the reactive gas 6 in the exhaust pipe 3 controlled. The reformer 7 for example, via a fuel line 9 Fuel supplied in a, arranged in the motor vehicle fuel tank 10 is carried. The fuel tank 10 For example, it may be a diesel fuel tank. Furthermore, the fuel tank 10 be designed for the storage of a gas, in particular hydrogen or hydrogen-containing gas such as methane, propane or the like. This allows, for example, without a reformer 7 directly the highly reactive gas 6 over the injection port 5 in the exhaust pipe 3 to be able to admit. In particular, liquid fuel is used, this is preferably by means of the reformer 7 edited. For neces-ended media such as air are on additional lines, such as an air supply 11 , to the reformer 7 fed. The admixture of the reactive gas 6 to the exhaust stream 4 downstream of a particle filter is downstream 12 arranged, which is shown in dashed lines schematically. The particle filter 12 preferably has a coating which forms a catalytic surface. The catalytic surface is capable of producing the mixture of reactive gas 6 and the exhaust stream 4 with heat release in the particle filter 12 implement such that a regeneration of the particulate filter 12 he follows. The reactive gas 6 uses it in the exhaust stream 4 existing oxygen during the catalytic reaction. The particle filter 12 may have as a coating in addition to an oxidation coating an additional function as Denoxfilter. Furthermore, the particle filter 12 preferably at least one sensor 13 on. The sensor 13 is for example a temperature sensor, via the corresponding, the exhaust gas or the particulate filter 12 characteristic parameters can be recorded and implemented.

Alternatively to the dashed line indicated particle filter 12 is in 1 For this purpose, a device made of an oxidation catalyst 14 and a particle filter 12 arranged. The oxidation catalyst 14 is capable of catalytically reacting the exhaust gas flowing through it, so that the exhaust gas temperature is raised to a sufficient temperature for a regeneration of the particulate filter. Such a separation has the advantage that the light-off temperature of the oxidation catalyst 14 is achieved earlier for the implementation of further exhaust gas components. In particular, such an arrangement has the advantage that already heated to a sufficient temperature for the regeneration temperature exhaust gas to the particulate filter 12 incident. As a result, it can be avoided that an upstream region is flown with a lower temperature level than a subsequent region of the particulate filter 12 , in which already an exothermic heat supply by catalytic conversion of the exhaust gas in Par particle filter 12 has used. Incidentally, with respect to the structure, the arrangement, the coating as well as with respect to additional devices such as catalysts, measuring points and the like on the DE 199 599 55 A1 , the DE 199 55 324 A1 , the DE 101 53 284 A1 , the DE 101 53 283 A1 and the DE 101 18 327 A1 whose contents in this regard belong fully to the present disclosure.

The particle filter 12 in 1 downstream is a second sensor 15 , For example, a lambda probe in the exhaust system 16 , The second sensor 15 recorded parameters with respect to the filtered exhaust gas 17 can by means of a monitoring device, not shown, in particular a motor control, in interaction with the sensor 13 recorded parameters are evaluated to a control strategy for at least the regeneration of the particulate filter 12 to obtain. A first control strategy provides, for example, that the particulate filter 12 when reaching a specific pressure gradient across the particulate filter 12 by adding the reactive gas 6 is cleaned. According to a further regeneration strategy, an initiation of the regeneration is triggered over time. Another strategy provides that the regeneration depending on the composition of the exhaust stream 4 or the filtered exhaust gas 17 , The individual strategies can be combined with each other and supplemented by one or more, other unspecified regulatory strategies.

2 shows a second cleaning device 18 , In the 2 with the elements 1 matching, already mentioned components have the same reference numerals below. The second cleaning device 18 has a device, in particular the reformer 7 into the exhaust management 3 integrated on. Preferably, the reformer 7 For example, in the middle of the exhaust pipe 3 arranged. This makes it possible, a uniform flow around the reformer 7 to get around. The exhaust gas flow 4 flows around the reformer 7 long along its circumference. This allows, on the one hand, that during generation of the reactive gas 6 Heat losses of the reformer 7 can be reduced. The reformer 7 emitted heat is transferred to the exhaust gas flow 4 passed, and thus serves to additional heating of the exhaust stream. For example, if a reforming carried out by means of partial catalytic oxidation, the exhaust gas stream is used 4 again to cool the reformer 7 , This prevents it from overheating. Preferably, the circumference of the reformer 7 at least partially on a designed for the heat dissipation surface structure. These may be, for example, guide surfaces or other measures that increase the circumferential surface. Furthermore, an arrangement of the reformer 7 in the exhaust pipe 3 the possibility of a special orientation of the injection port 5 on. The injection port 5 in particular, at least approximately one to the exhaust pipe 3 Paraxial injection of the reactive gas 6 enable. In this way, it is possible, for example, a specific area of the subsequent particulate filter 12 or oxidation catalyst 14 preferably with the reactive gas 6 to flow. This may for example be a, based on the cross section of the downstream component, the middle region.

3 shows a schematic view of the second cleaning device 2 in addition to a bypass system 19 , The exhaust pipe 3 has a derivative 20 of the bypass system. By means of a Bypassstellmittels 21 , For example in the form of an exhaust valve, can from the exhaust gas flow 4 an exhaust gas partial stream 22 into the derivative 20 be guided. The partial exhaust gas flow 22 in the illustrated embodiment around the particulate filter 12 as well as around the injection port 5 guided around. Downstream of the particulate filter 12 becomes the partial exhaust gas flow 22 back to the filtered exhaust 17 fed. An exemplary use of the bypass system 19 For example, looks like this: To a heat transfer from the particulate filter 12 during a warm-up phase to initiate regeneration, at the beginning of a regeneration phase, the bypass adjustment means will 21 switched so that only a small flow of exhaust gas 4 must be heated, the particle filter 12 flows through. The partial exhaust gas flow 22 is from the exhaust stream 4 through the bypass adjusting means 21 separated for this purpose.

The regeneration phase is started, for example, by reacting the reactive gas 6 in the exhaust pipe 3 is introduced. Another possibility of starting the regeneration phase is, for example, if this is supported by an electrical heating at least a portion of the particulate filter 12 , Preferably, the bypass adjusting means becomes 21 switched so that the separated exhaust gas partial stream 22 has a larger volume flow, as that in the exhaust pipe 3 remaining exhaust gas flow 4 , By changing the Bypassstellmittels 21 there is the possibility of a change in the ratio between the exhaust gas partial stream 22 and the remaining exhaust stream 4 , In particular, this makes it possible to carry out a volume flow distribution of the exhaust gas adapted to the respective regeneration.

Preferably, after initiation of the regeneration of the particulate filter 12 the partial exhaust stream 22 reduced further, until finally the bypass adjustment means 21 the derivative 20 closes. At this time, the entire exhaust gas flow flows 4 through the particle filter 12 , The partial exhaust gas flow 22 is therefore preferably in the derivation 20 led, thus an excessive heat transport from the particle filter 12 is prevented out. Excessive heat transport would cause regeneration of the particulate filter 12 possibly hamper. Next allows the separation of the exhaust gas partial stream 22 a faster heating phase of the remaining exhaust gas flow 4 and thus the particle filter 12 until initiation of regeneration. The exothermic energy arising after the initiation of the regeneration will be at reduced exhaust gas flow 4 over the wall of the particle filter 12 forwarded, so that the heat released during the soot oxidation is used in addition to regeneration support. During regeneration this is preferably monitored. This allows, for example, that a critical temperature of the particulate filter 12 is detectable. In such a case, the bypass adjusting means 21 be used to the exhaust partial flow 22 to reduce. As a result, flows a higher exhaust gas flow 4 through the particle filter 12 , This performs a larger amount of heat, causing the particulate filter 12 is cooled to a safe range below the critical temperature.

During a regeneration of the particulate filter 12 Thus, it is possible, for example, during the entire regeneration of a partial exhaust stream 22 on the particle filter 12 passing out. Furthermore, it is possible to perform this only to initiate the regeneration phase. Furthermore, there is the possibility of the partial exhaust gas flow 22 to vary according to the needs of the regeneration according to recorded parameters, for example, between complete diversion and partial diversion as well as no diversion. At least one, the particulate filter characterizing, parameters, for example by means of the sensor 13 be recorded. The sensor 13 For example, a temperature sensor or sons be real. According to a development, the sensor 13 a temperature sensor, while the subsequent second sensor 15 is a lambda probe. An operation of a possible regeneration will be described below by way of example with reference to the diagrams in FIG 5 and 6 described.

4 shows a schematic view of a third cleaning device 22 , The third cleaning device 22 again has a center in the exhaust pipe 3 arranged reformers 7 on. The motor vehicle in which the diesel engine 2 is arranged, has an additional power source 23 on. The vehicle is, for example, a hybrid vehicle in which it is possible to switch between and / or switch between different drive concepts. The power source 23 For example, may be a fuel cell or an APU (Auxilia ry Power Unit), which is converted to when driving the motor vehicle. Sufficient energy supply to the fuel cell or the APU is achieved via reforming, in which hydrogen is recovered. This hydrogen can on the one hand for the fuel cell itself, on the other hand for the regeneration of the particulate filter 12 be used.

In the 4 as a reformer 7 illustrated device for injecting the reactive gas 6 preferably has a type of jet pump 24 on. The reactive gas 6 is injected into a mixing part, in the inlet openings via a part of the exhaust gas stream 4 enters the mixing area and there with the reactive gas 6 mixed. This mixture becomes the particle filter 12 preferably supplied in a central region, which heats up immediately due to the liberated exothermic energy for regeneration. The regeneration takes place in this way very quickly in a partial region of the particulate filter 12 , By a possible control of the mixture of reactive gas 6 and the exhaust stream 4 can by appropriate deflection different area of the particulate filter 12 flowed and thus the regeneration be initiated. According to the illustrated embodiment of the third cleaning device 22 This opens up the possibility of forgoing a bypass system. However, this may optionally also in the third cleaning device 22 be provided.

5 shows a diagram for the possible sequence of a regeneration of the particulate filter. The temperature of the filter T _F and the lambda value after the particle filter L _{nF are} plotted on the Y axis. The time is plotted on the X-axis. The diagram shows an example operating principle of a lambda-controlled particle filter generation. This can be carried out, for example, with one of the above-described methods or cleaning devices.

Following the initiation of the regeneration phase at the time t ₁ is increased by the addition of the reactive gas may for example comprise one or more reactive components, the temperature in the particulate filter. In this case, the combustion-air ratio lambda decreases, which manifests itself as waste from time t ₁ . The temperature of the particulate filter increases until time t ₂ . At this time, the particulate filter has a temperature T _F , which coincides with a temperature T _Z for igniting the soot particles. Preferably, the lambda ratio is controlled or regulated in parallel to the rise in temperature so that the value of lambda is still significantly above 1. At least until time t ₂ , preferably until time t ₃ , is therefore present in the particulate filter or thereafter an excess of oxygen. Preferably, the lambda value decreases only from the time t ₃ to a value below 1 from. In particular, in the period t ₂ to t ₃ at the beginning of the initiation of the regeneration, a strong increase in temperature may occur. This is due to the potentially exponentially increasing released thermal energy. According to one embodiment, it is therefore provided that when reaching a critical temperature T _{k of} the particulate filter, as shown at time t ₃ , for example, the amount of reactive gas is increased abruptly. This makes it possible that the residual oxygen content is lowered in the exhaust gas. The soot oxidation in the particulate filter is decelerated due to the thereby scarce oxygen. The released energy is reduced, whereby the further flowing exhaust gases dissipate a higher amount of heat compared to the simultaneously released amount of heat.

According to one embodiment, it is provided that in addition by an appropriate switching of the bypass system and thus the bypass actuator of the flowing through the particulate filter exhaust stream is either increased to achieve increased heat removal from the particulate filter. However, the exhaust gas stream flowing through the particulate filter may also be lowered, for example, to achieve enrichment of the exhaust gas flowing through the particulate filter. Before the supply of the reactive gas, for example, the partial exhaust gas flow is removed. The remaining exhaust gas flow is thereby enriched at the same volume flow of the reactive gas. If the filter temperature T _F falls below a lower threshold again, for example, a supply of the reactive gas is reduced again. As a result, the oxygen content in the exhaust stream increases. The soot oxidation can then be carried out again increased. Such, for example, lambda-controlled particulate filter regeneration preferably takes place until a complete regeneration of the particulate filter is ensured. This is for example in 5 scored at time t ₄ . Due to the implementation of the particles the released exothermic energy decreases more and more. As a result, as the exhaust gas flow through the particulate filter increases, the temperature of the particulate filter decreases more and more until, for example, it approaches a temperature as it existed at time t ₁ . This is detectable.

6 shows by way of example a second diagram showing an interaction of a lambda probe with the particle filter in the context of a regeneration. For example, the lambda probe is arranged behind the particle filter flow. The lambda probe is used to determine at least one start of regeneration or a regeneration end of the regeneration of the particulate filter. For this purpose, the lambda signal is recorded and converted via a suitable evaluation device, for example in a control unit, to corresponding actuating signals or controlled variables, by means of which, for example, the exhaust gas flow, the reactive gas, the bypass system or the like for influencing the particle filter temperature regulated or controlled can be. Also, one or more additional measures can be initiated that support, for example, initiation of the regeneration of the particulate filter as well as a subsequent further soot particle oxidation. The lambda signal is preferably recorded permanently or clocked. If it is determined that the lambda signal drops after the particle filter, it can be concluded that the soot ignition temperature is reached at time t ₂ . This is illustrated by the fact that the lambda value before the particle filter L _{vF has} a higher value than the lambda value after the particle filter L _nF . This signal difference can be used to obtain information about the progress of the regeneration. Increases the lambda value and thus the oxygen content again, for example, until the time t ₄ , it can be concluded that the regeneration of the particulate filter is completed. This can trigger a signal, stopping an influx of reactive gas. The lambda value then increases again, for example, at the time t ₄ to a value as it existed at the beginning of the initiation t ₁ at idle by supplying reactive gas.

7 Figure 12 shows on the Y-axis a conversion efficiency for the possible operation of an oxidation catalyst as well as a catalytic-filtered particulate filter with respect to the temperature plotted on the X-axis. As can be seen from the diagram, even low temperatures suffice to achieve a high conversion rate with the use of H ₂ with corresponding heat release (exothermic process), in particular to produce an initiation of the particle filter regeneration. For other molecules, higher temperatures are needed to initiate particle filter regeneration. Preferably, therefore, it is provided that the reactive gas at a temperature of 200 ° C is able to initiate a regeneration of the particulate filter.

Furthermore, it is off 7 It can be seen that the particle cleaning effect at a lower temperature begins by using a reactive gas than that of CO contained in the exhaust gas, for example, and / or HC used. In particular, this allows that due to the addition of a more reactive gas than CO or HC alone, the exhaust temperature is raised so that possibly a catalytic conversion ("light-off") of CO and HC in the exhaust gas to an exhaust without such a reactive gas enrichment Hydrogen is used to raise the temperature, for example, only a small additional temperature rise is needed from this temperature level to achieve a catalyst "light-off" temperature for, for example, CO and HC conversion. At a start, in particular during a cold start of the internal combustion engine, a shortening of the time span can thereby be achieved, up to which the catalyst begins with its catalytic conversion.

Claims (24)

Method for cleaning a particulate filter ( 12 ) an internal combustion engine ( 2 ) of a motor vehicle by metered addition of a reactive gas ( 6 ) in an exhaust pipe ( 3 ), between the internal combustion engine ( 2 ) and the particle filter ( 12 ) runs at an exhaust gas temperature below the regeneration temperature of the particulate filter ( 12 ) for initiating a reaction of the particles. Method for cleaning a particulate filter ( 12 ) an internal combustion engine ( 2 ) of a motor vehicle by adding a metered reactive gas ( 6 ) in an exhaust pipe ( 3 ), between the internal combustion engine ( 2 ) and the particle filter ( 12 ), whereby the reactive gas ( 6 ) is reformed prior to the addition of the entrained in the motor vehicle fuel. Process according to claim 1 or 2, characterized in that the reactive gas ( 6 ) metered in idle mode and / or in low-load operation of the internal combustion engine ( 2 ) is added. Method according to claim 1, 2 or 3, characterized that at least in the predominant operating area, preferably dosed throughout the operating range, the reactive gas is added. Method according to one of the preceding Claims, characterized in that below an exhaust gas temperature of 200 ° C, the reactive gas ( 6 ) is supplied. Method according to one of the preceding claims, characterized in that as reactive gas ( 6 ) Hydrogen in a reformer ( 7 ) produced in front of the particulate filter ( 12 ) is added. Method according to one of the preceding claims, characterized in that an adjustable portion of the of the internal combustion engine ( 2 ) emitted exhaust stream ( 4 ) at least immediately before initiation of the regeneration of the particulate filter ( 12 ) on the particle filter ( 12 ) is bypassed. Method according to one of the preceding claims, characterized in that the temperature of the particulate filter ( 12 ) is determined at least during the regeneration and depending on this temperature, an influence of the particulate filter ( 12 ) flowing through the exhaust gas flow, in particular an addition of the reactive gas ( 6 ) for cooling the particle filter ( 12 ) he follows. Method according to claim 8, characterized in that the addition of the reactive gas ( 6 ) as a function of a predeterminable temperature window during the regeneration of the particulate filter ( 12 ) is increased or decreased. A method according to claim 8 or 9, characterized in that depending on the temperature of the particulate filter ( 12 ) the adjustable part of the particle filter ( 12 ) bypassed partial exhaust gas flow is changed. Method according to one of the preceding claims, characterized in that the reactive gas ( 6 ) has at least hydrogen and CO as reactive gas components. Cleaning device ( 1 ; 18 ; 22 ) for a particulate filter ( 12 ) an internal combustion engine ( 2 ) of a motor vehicle with an exhaust pipe ( 3 ), between the internal combustion engine ( 2 ) and the particle filter ( 12 ) is arranged, the at least one injection port ( 5 ) for a reactive gas ( 6 ), wherein the injection port ( 5 ) in line-connected connection with the by means of a metering device ( 8th ) controllable injection of the reactive gas ( 6 entrained fuel stored in a refillable fuel tank ( 10 ) of the motor vehicle is stored. Cleaning device ( 1 ; 18 ; 22 ) according to claim 12, characterized in that a reformer ( 7 ) for generating the reactive gas ( 6 ) between the injection port ( 5 ) and the fuel tank ( 10 ) is interposed. Cleaning device ( 1 ; 18 ; 22 ) according to claim 13, characterized in that the reformer ( 7 ) to the flow with an exhaust gas stream ( 4 ) at least partially in the exhaust pipe ( 3 ) is arranged. Cleaning device ( 1 ; 18 ; 22 ) according to claim 12, 13 or 14, characterized in that a bypass system is a derivative ( 20 ) from the exhaust pipe ( 3 ) upstream of the injection port ( 5 ) having. Cleaning device ( 1 ; 18 ; 22 ) according to claim 15, characterized in that the derivative ( 20 ) downstream of the particulate filter ( 12 ) in the exhaust pipe ( 3 ) opens. Cleaning device ( 1 ; 18 ; 22 ) according to one of claims 12 to 16, characterized in that a control device for adapting a particle filter temperature is present. Cleaning device ( 1 ; 18 ; 22 ) according to one of claims 12 to 16, characterized in that a control device for detecting a start of regeneration and / or regeneration end is present. Cleaning device ( 1 ; 18 ; 22 ) according to one of claims 12 to 18, characterized in that the particulate filter ( 12 ) has a catalytically active coating. Cleaning device ( 1 ; 18 ; 22 ) according to one of claims 12 to 19, characterized in that the particulate filter ( 12 ) has a de-Nox coating. Cleaning device ( 1 ; 18 ; 22 ) according to one of claims 12 to 20, characterized in that the particle filter ( 12 ) upstream of an oxidation catalyst ( 14 ) is arranged upstream. Cleaning device ( 1 ; 18 ; 22 ) according to one of claims 12 to 21, characterized in that a monitoring is provided on hot spots in the particulate filter. Cleaning device ( 1 ; 18 ; 22 ) according to any one of claims 12 to 22, characterized in that this in a selection of various measures for the regeneration of the particulate filter ( 12 ) is integrated on the motor vehicle. Cleaning device ( 1 ; 18 ; 22 ) according to one of the preceding claims 12 to 23, characterized in that an APU is provided by the regenerative gas ( 6 ) can be supplied.