DE102006043151A1 - Regeneration device for particle filter has reducer generating system including valve system via which hydrogen- or carbon-monoxide-rich mixture is supplied - Google Patents

Abstract

The regeneration device has a reducer generating system (10) including a valve system (40), via which the hot gas mixture created in the system, which may be rich in hydrogen and/or carbon monoxide, goes through a regenerating gas path (18) to the exhaust gas channel (30) of the engine (20) in flow direction befor an oxidation catalytic converter (31) followed by the particle filter (32).

Description

was standing of the technique

The The invention relates to a device for the regeneration of a particulate filter in an exhaust passage of an internal combustion engine, wherein the exhaust passage ammonia generated by a reductant generation system for the reduction of nitrogen oxides a standard gas path can be fed in front of an SCR catalytic converter, wherein the reductant generation system is a multitron unit, that of a nitrogen oxide generating unit, a mixture forming chamber and an oxidation reforming unit (cPOx), and a arranged in a gas path combined nitrogen oxide storage / ammonia generating unit is constructed and wherein the multitron unit via an air / exhaust gas supply and a fuel feeder Starting materials for generating the ammonia are at least temporarily fed.

The The invention further relates to a method for the regeneration of a Particulate filter in an exhaust passage of an internal combustion engine, wherein produced by a reducing agent generation system ammonia and for the reduction of nitrogen oxides over a Standard gas path is supplied into the exhaust passage in front of an SCR catalyst, wherein the reductant generation system is a multitron unit, that of a nitrogen oxide generating unit, a mixture forming chamber and an oxidation reforming unit (cPOx), and a constructed in a gas path arranged combined nitrogen oxide storage / ammonia generating unit is and wherein the multitron unit via an air / exhaust gas supply and a fuel feeder Starting materials for generating the ammonia is supplied at least temporarily.

The selective catalytic reduction (SCR) can be used to reduce the NO _x emission (denitrification) of internal combustion engines, in particular diesel engines, with temporally predominantly lean, ie oxygen-rich exhaust gas. In this case, a defined amount of a selectively acting reducing agent is added to the exhaust gas. This can be, for example, in the form of ammonia, which is added directly in gaseous form or is also obtained from a precursor substance in the form of urea or from a urea-water solution (HWL).

In the DE 10139142 A1 is described an exhaust gas purification system of an internal combustion engine, in which an SCR catalyst is used to reduce the NO _x emission, which reduces the nitrogen oxides contained in the exhaust gas with the reagent ammonia to nitrogen. The ammonia is recovered in a urea-water solution (HWL) hydrolysis catalyst upstream of the SCR catalyst. The hydrolysis catalyst converts the urea contained in the HWL to ammonia and carbon dioxide. In a second step, the ammonia reduces the nitrogen oxides to nitrogen, with water being produced as a by-product. The exact procedure has been adequately described in the specialist literature (see WEISSWELLER in CIT (72), pages 441-449, 2000). The HWL is provided in a reagent tank.

adversely in this method is that HWL in the operation of the internal combustion engine is consumed. The consumption is about 4% of fuel consumption. The supply of urea-water solution would have correspondingly large area, for Example at gas stations, be assured. Another disadvantage of the method is in the necessary operating temperature range. The hydrolysis reaction of the urea-water solution is quantitatively first from temperatures of 200 ° C. These temperatures in the exhaust gas are, for example, in diesel engines only after a long time Operating time reached. Because of deposits, it can be at temperatures below 200 ° C come to blockages on the dosing unit, which the supply the urea-water solution in hinder the exhaust tract at least. Furthermore, a metered addition the urea-water solution at Temperatures below 200 ° C due to a polymerization to inhibit the necessary catalytic Properties on hydrolysis or SCR catalyst lead.

In the DE 199 22 961 C2 is an exhaust gas purification system for purifying the exhaust gas of a combustion source, in particular an automotive internal combustion engine, at least nitrogen oxides contained therein with an ammonia generation catalyst for generating ammonia using components of at least a portion of the exhaust gas emitted from the combustion source during ammonia generation operating phases and downstream of the ammonia generation catalyst Nitrogen oxide reduction catalyst for the reduction of nitrogen oxides contained in the emitted exhaust gas of the combustion source using the generated ammonia described as a reducing agent. In this case, a combustion-source-external nitrogen oxide generation unit is provided for enriching the exhaust gas supplied to the ammonia generation catalyst with nitrogen oxide produced by it during the ammonia generation operating phases. As a nitrogen oxide generating unit, for example, a plasma generator for plasma-technical oxidation of nitrogen contained in a gas stream supplied in nitrogen oxide is proposed. The hydrogen needed for ammonia production is generated during the ammonia generation operating phases by the operation of the combustion source produced with a rich, ie fuel-rich air ratio.

One Plasmachemisches process for producing a hydrogen-rich Gas mixture is described in WO 01/14702 A1. It will be in an arc a rich fuel-air mixture, preferably under POx conditions.

Around to carry with you to avoid another fuel has now been in an unpublished one Document of the applicant a plasma method for on-board generation proposed by reducing agents. This will be the reduction The nitrogen oxides required ammonia from non-toxic substances as needed produced in the vehicle and then fed to the SCR process. A in terms of the fuel consumption acceptable solution offers a discontinuous operated method for ammonia production, as well proposed in this document. In this case, the reducing agent Ammonia pulsed provided. This method or device is referred to below as the reducing agent generation system.

Especially if desired inhomogeneously occurring mixture formation processes occur during operation an internal combustion engine, especially in diesel engines, particles, which dissipated with the exhaust stream become. In order to limit the particle emission, can in the exhaust duct the internal combustion engine may be provided a particulate filter, which filter out the particles with high efficiency. The particle filter must be doing this at irregular intervals, for example dependent on be regenerated from the exhaust back pressure.

The Regeneration of the particulate filter takes place by oxidation of the attached Particle. To achieve a sufficient oxidation rate, the temperature of the particulate filter during regeneration must be above of about 600 ° C lie. This temperature is without additional measures and depending on the installation position the particulate filter only in the upper medium pressure / speed map reaches the internal combustion engine.

at lower load conditions the internal combustion engine can be a necessary increase in temperature of the Particulate filter can be achieved by fuel at one the particle filter in the flow direction the catalytic converter upstream of the exhaust gas oxidation catalyst and the energy thus released is supplied to the particulate filter. The provision of the fuel can be via a motor post-injection (PoI), an external fuel evaporation and subsequent dosing in the exhaust gas full flow before the oxidation catalyst or by a direct liquid dosage, as known for example under HCI (hydrocarbon injection) is done.

adversely in these methods of increasing the exhaust gas temperature and thus the temperature of the particulate filter is that in some engines in the lower load range no sufficiently high temperatures can be generated because here by a PoI or over the HCI provided hydrocarbons with cold oxidation catalyst only conditionally with release of heat energy can be set. additionally can under these conditions too high a fuel dosing a lubricating oil dilution and lead to a full suction of the oxidation catalyst. The fuel will not Completely implemented. A subsequent one uncontrolled desorption or combustion of the fuel can cause damage the catalytic components of the oxidation catalyst and to an elevated one Carbon monoxide emissions to lead.

In Scripture DE 199 23 299 A1 a method for controlling an internal combustion engine is described, which comprises means which influence the exhaust gas of the internal combustion engine, wherein a special operating state is introduced when certain conditions in which an increased energy content of the exhaust gas is desired, wherein in the special operating state, a combustion focus is so influenced, that the exhaust gas temperature increases. Among other things, the means are a particulate filter, the special operating state being initiated when a variable which characterizes the load state of the particulate filter exceeds a threshold value.

Such the temperature increasing engine process interventions could, as other known methods, for example the use of auxiliary burners in Abgasvoll- or exhaust gas by-pass or the use of electrical Auxiliary heaters or a fuel additive, from technical, economical and / or environmental health, in particular when used in dynamic operation of the internal combustion engine.

It is therefore an object of the invention, an apparatus and a method to provide a sufficient increase in temperature of the Exhaust gases of an internal combustion engine to start the regeneration of a Particle filter even in low load ranges of the internal combustion engine enable.

Disclosure of the invention

Advantages of the invention

The device-related object of the invention is according to the features of the claim 1 solved.

After that the reducing agent generation system has a valve system over which a hydrogen-rich generated in the reductant generation system and / or carbon monoxide rich and / or hot gas mixture over a Regeneration gas path to the exhaust passage of the internal combustion engine in the flow direction before an oxidation catalyst and the subsequent particle filter or is at least temporarily fed before the particulate filter.

to Generation of a hydrogen-rich and / or carbon monoxide-rich Gas mixture becomes the multitron unit of the reductant generation system operated in rich mode, that is, it becomes fuel for example in a hot Mixture zone metered and at the oxidation reforming unit (cPOx) to the hydrogen-rich and / or carbon monoxide-rich gas mixture implemented. Is this gas mixture by a corresponding valve position dosed to the exhaust passage upstream of the oxidation catalyst, so is the gas mixture to the oxidation catalyst to water and / or carbon dioxide oxidized. The released heat of reaction is via the exhaust gas to the particulate filter fed. The Partkielfilter can do so, regardless of the operating parameters the internal combustion engine, which is necessary for the start of regeneration Temperature warmed up become.

Also the utilization of the stored heat energy of the in the reductant generation system produced hot Gas mixture can be used for heating of the particulate filter until the regeneration temperature is reached be used. It can on the one hand for the production of the hydrogen-rich and / or carbon monoxide-rich gas mixture introduced energy used become. On the other hand, the gas mixture by the operation of a Start burner, as typically arranged in the Multitron unit is and for heating the regenerant generation system used in its startup phase, be heated. It can the hot Gas mixture directly in front of the particle filter or in front of the oxidation catalyst be introduced into the exhaust passage.

We that from a starting burner of the reductant generation system generated hot gas mixture before the oxidation catalyst the exhaust passage of the internal combustion engine supplied so can unburned or partially burned fuel components the gas mixture to the oxidation catalyst with release of energy implemented and thus the exhaust gas temperature can be further raised. In this case, by a rich operation of the starting burner, a gas mixture with a high proportion of unburned or partially burned Fuel shares are generated.

The for one Regeneration of the particulate filter necessary temperature of about 600 ° C can through the feed the hydrogen-rich and / or carbon monoxide rich and / or hot gas mixture also at very low load points of the map of the internal combustion engine be achieved. There is no danger compared to a PoI the lubricating oil dilution and the full suction of the oxidation catalyst with hydrocarbons and an uncontrolled burning with the risk of damage to the Oxidation catalyst. The hydrogen-rich and / or carbon monoxide-rich and / or name is Gas mixture leaves Thus, at lower temperatures of the oxidation catalyst and thus clearly before a PoI or a dosing of hydrocarbons deploy.

One Another advantage is that an initiated regeneration program not interrupted by an idle operation of the internal combustion engine must, but the necessary temperature in the exhaust duct through Addition of the hydrogen-rich and / or carbon monoxide-rich and / or be called Gas mixture can be maintained.

By the addition of the hydrogen-rich and / or carbon monoxide-rich and / or hot gas mixture from the regeneration agent generation system before the oxidation catalyst the oxidation catalyst is also heated. This allows the Cold start phase of the oxidation catalyst can be shortened, resulting in a reduction the hydrocarbon emissions of the internal combustion engine leads.

Next the particulate filter is described by the, from the operation the internal combustion engine independent heating measures the SCR catalyst with heating and one for a maximum nitrogen oxide conversion necessary operating temperature brought. The nitric oxide slip can be reduced.

in the Compared to known methods for increasing the exhaust gas temperature by a discontinuous additive by means of oxidation accelerators is not another according to the invention Fuel required.

According to a preferred embodiment variant of the invention, the valve system is arranged downstream of the oxidation reforming unit (cPOx) and with the valve system the gas path for the gas flow emerging from the oxidation reforming unit (cPOx) can be switched between the combined nitrogen oxide storage / ammonia production unit and the exhaust gas duct. In an ammonia-producing In this way, during a lean phase, the nitrogen-containing gas generated in the multitron unit can be fed to the nitrogen oxide storage / ammonia production unit and temporarily stored there. Likewise, the hydrogen-rich gas produced in the fat phase subsequent to the lean phase can be fed to the nitrogen oxide storage / ammonia production unit and converted there with the cached nitrogen oxide to ammonia, which is then fed via the standard gas path to the exhaust duct of the internal combustion engine upstream of the SCR catalytic converter. In a particulate filter regeneration phase, the gas leaving the oxidation reforming unit (cPOx) is supplied via the valve system and the regeneration gas path to the exhaust gas duct upstream of the oxidation catalytic converter or upstream of the particulate filter for heating the exhaust gas and thus of the particulate filter. The Multitron unit is operated in rich operation, so it is at the oxidation reforming unit (cPOx) implemented a fuel-air mixture to hydrogen and carbon monoxide. This operation is maintained until the desired temperature is reached in the exhaust gas full flow at the particulate filter. The ammonia production rests during this phase. At the oxidation catalyst, the metered hydrogen and the carbon monoxide react at temperatures from about 150 ° C to water and carbon dioxide, thereby releasing heat energy, which leads to an increase in exhaust gas temperature and thus to increase the temperature of the particulate filter. The supply of hydrogen-rich and carbon monoxide-rich gas into the exhaust duct can be reduced or stopped as soon as the heat of reaction released during the regeneration of the particulate filter is sufficient to maintain the regeneration.

To an alternative embodiment The invention may be provided that the valve system according to the combined nitrogen oxide storage / ammonia generating unit arranged is and that with the valve system the gas path for the out of the nitrogen oxide storage / ammonia production unit escaping gas flow between the introduction into the exhaust duct before the SCR catalyst and the introduction into the exhaust passage before the oxidation catalyst or is switchable before the particulate filter. During the ammonia production phase is over the corresponding valve position, the ammonia fed to the SCR catalyst. During one Particulate filter regeneration phase becomes the hydrogen and carbon monoxide rich Gas mixture from the multitron unit by the extended after Fat phase nitrogen oxide-free nitric oxide storage / ammonia production unit and then routed the exhaust passage upstream of the oxidation catalyst or upstream of the particulate filter fed. Advantageous in this embodiment is that the nitric oxide storage / ammonia generating unit during the Particle filter regeneration phase flows through the warm gas mixture and thus longer on Operating temperature is maintained, resulting in a prolonged Operational readiness of the reducing agent generation system leads.

is it provided that the valve system between the nitric oxide generating unit and the oxidation reforming unit (cPOx) is arranged and that with the valve system of the gas path for the from the nitrogen oxide generating unit leaking gas stream between the introduction into the oxidation reforming unit (cPOx) and the introduction into the exhaust port before the oxidation catalyst or before the particulate filter is switchable, so can during a Particle filter regeneration phase that from the nitrogen oxide generation unit escaping hot gas used to heat the exhaust stream and thus the particulate filter become. In this case, the gas in the Multitron unit by the regular operation or by a start burner provided in the Multitron unit to be provided. An advantage of this arrangement is that while the particulate filter regeneration phase, the oxidation reforming unit (cPOx) is bypassed and thus when setting the burner gas temperature no consideration on the temperature resistance the oxidation reforming unit (cPOx) must be taken.

A increase the hydrogen content while reducing the carbon monoxide content in the exhaust duct supplied Gas can be achieved by placing in the gas path after the oxidation reforming unit (cPOx) a catalytic shift stage and then the valve system is arranged and that with the valve system of the gas path for the off the catalytic shift stage exiting gas flow between the Combined nitric oxide storage / ammonia generating unit and the Exhaust gas channel is switchable. The increase of the hydrogen content takes place by reaction of carbon monoxide with water to carbon dioxide and hydrogen at the shift stage.

If it is provided that the lambda value can be set between 0.3 and 1.0, preferably between 0.33 and 0.66, during a rich operating phase of the multitron unit, then this can be used to control the system for a low carbon monoxide Slip achieved and thus an additional carbon monoxide emission can be avoided. Furthermore, this can be a deterioration of the DeNO _x process on the subsequent SCR catalyst, as it can be caused by carbon monoxide avoided.

According to a particularly preferred embodiment variant of the invention, it is provided that the valve system is constructed from a 3/2 valve or two 2/2 valves, wherein a 2/2-valve in a standard gas path and a 2/2 valve in the regeneration gas path. The 3/2 valve offers the advantage that the valve system can be realized with only one valve. An advantage of the variant with two 2/2 valves is that a complete shutdown of the gas flow through the reducing agent generation system is possible by closing the two 2/2 valves. This is otherwise possible only by switching off the gas supply to the reducing agent generation system, for example directly by an upstream compressor, compressor or a blower.

Corresponding a further embodiment variant of the invention can be provided that the valve system consists of at least two 2/2 valves with a first 2/2 valve in the regeneration gas path and a second 2/2 valve in the flow direction according to at least one further component of the reductant generation system is arranged in the standard gas path.

Thereby, that the valve system is connected to a control unit and that the control unit signals over the regeneration needs of the particulate filter are supplied and / or in the control unit regeneration cycles for the particulate filter are deposited If necessary, the necessary valve positions for regeneration be made of the particulate filter.

The Device leaves to use particularly advantageous in diesel engines, the one Reductant generation system and a particulate filter have.

The The object of the invention relating to the method is according to the features of claim 10 solved.

After that it is envisaged that one in the reductant generation system produced rich in hydrogen and / or carbon monoxide and / or hot Gas mixture during Ammonia production phases via a valve system of the nitrogen oxide generating unit or the exhaust duct before supplied to the SCR catalyst and that the gas mixture during Particle filter regeneration phases via the valve system and a Regeneration gas path to the exhaust passage of the internal combustion engine in the flow direction before an oxidation catalyst and the subsequent particle filter or fed in front of the particle filter becomes.

During the Ammonia production phase may thus be ammonia after for reducing agent generation systems manufactured known method and fed to the SCR catalyst.

While particulate filter regeneration phases can the gas mixture the exhaust passage upstream of the oxidation catalyst or fed in front of the particle filter become. In both cases there is a warming of the particulate filter by the heat energy stored in the gas mixture. If the gas mixture in front of the oxidation catalyst to the exhaust passage supplied this is done by the reaction of the hydrogen, the carbon monoxide and of any non-combusted hydrocarbons present to carbon dioxide and water to the oxidation catalyst released reaction heat and supplied to the exhaust stream. This allows the subsequent particle filter to be heated so far that a sufficient oxidation rate of the in the particulate filter stored particles is achieved.

According to one preferred embodiment of Invention may be provided that additional measures to increase the exhaust gas temperature performed be and / or that the feeder of the hydrogen-rich and / or carbon monoxide-rich and / or hot gas mixture during operating states the internal combustion engine is carried out with low exhaust gas temperatures. Such an extra measure may for example be a moderate PoI, which then switched on is, if by the supply of the gas stream from the reducing agent generation system the temperature of the particulate filter is so high that the disadvantages of PoI, such as the lubricating oil dilution or increased hydrocarbon emissions avoided can be. The feeder of the hydrogen-rich and / or carbon monoxide-rich and / or hot gas mixture during operating states the engine with low exhaust gas temperatures causes that even in these operating conditions reaches a sufficient temperature for particle filter regeneration can be.

The hot gas mixture can be generated by operating a start burner in the multitron unit. The starting burner is an already provided in the Multitron unit component with which when starting the reducing agent generation system, the components of the reducing agent generation system are heated to the required temperature. The valve position during the heating phase is such that the gas flow is along the standard gas path. If the hot gas stream of the starting burner is supplied via the valve system and the regeneration gas path to the exhaust gas channel in front of the particle filter, then the particle filter can be heated to the temperature necessary for the regeneration of the particle filter. If the hot gas stream is supplied to the exhaust gas passage in front of the oxidation catalytic converter, it can there by oxidation of unburned or partially combusted fuel components and the reaction thus released Heat in addition heat energy to the exhaust stream and be delivered to the particulate filter.

Becomes the starting burner with excess oxygen operated, so the oxygen excess for oxidation or Combustion of the particles stored in the particulate filter used become. The regeneration of the particulate filter can thus also at complete standstill the internal combustion engine performed become.

He follows an increased Exhaust gas recirculation of the internal combustion engine, so lets thereby the amount emitted by the internal combustion engine Reduce nitrogen oxides. The associated higher particle emissions can through the particulate filter are stored. By the method proposed by the proposal possible, of the operating conditions of the internal combustion engine as far as possible independent regeneration of the particulate filter can the regeneration intervals are shortened significantly. Therefore, too an elevated one Particle emission of the Internal combustion engine with the particulate filter to be filtered out.

The Procedure leaves used particularly advantageous in diesel engines, the one Reductant generation system and a particulate filter have.

short Description of the drawings

The Invention will be described below with reference to the figures shown in the figures Embodiments explained in more detail. It demonstrate:

1 1 is a schematic representation of an exhaust aftertreatment system of an internal combustion engine with a reducing agent generation system and a 3/2 valve,

2 in a further embodiment, a schematic representation of an exhaust aftertreatment system of an internal combustion engine having a reducing agent generation system and a 3/2 valve,

3 2 a schematic representation of an exhaust aftertreatment system of an internal combustion engine with a reducing agent generation system and two 2/2 valves,

4 a schematic representation of an exhaust aftertreatment system of an internal combustion engine with a reducing agent generation system and a 3/2-valve and a catalytic shift stage and

5 in a further embodiment, a schematic representation of an exhaust aftertreatment system of an internal combustion engine having a reducing agent generation system and a 3/2 valve.

embodiments the invention

1 shows a schematic representation of an exhaust aftertreatment system 1 an internal combustion engine 20 with a reductant generation system 10 and a 3/2 valve 41 the example of a diesel engine.

The exhaust gas of the internal combustion engine 20 is via an exhaust system 30 guided, wherein in the flow direction of the exhaust gas, an oxidation catalyst 31 in the execution of a diesel oxidation catalyst, a particulate filter 32 in the version of a diesel particulate filter and a downstream SCR catalytic converter 33 are provided. For the reduction of nitrogen oxides is before the SCR catalyst 33 from a reductant generation system 10 Ammonia can be fed as a reducing agent. SCR catalysts 33 work on the principle of selective catalytic reduction, in which by means of the reducing agent ammonia in oxygen-containing exhaust gases nitrogen oxides are reduced to nitrogen and water.

The reductant generation system 10 has a multitron unit 11 from a nitric oxide generating unit 12 , a non-illustrated mixture forming chamber and an oxidation reforming unit 15 (cPOx), such as a combined nitric oxide storage / ammonia production unit 16 in a standard gas route 17 of the reductant generation system 10 on.

The multitron unit 11 are via an air / exhaust gas supply 13 and a fuel feeder 14 Starting materials for generating the ammonia, at least temporarily fed. The ammonia is generated from air, exhaust gas or a mixture of air and exhaust gas and in the example shown from diesel fuel.

The production of ammonia occurs within the reductant generation system 10 in which nitric oxide NO in a lean phase (λ> 1) in a plasma within the nitric oxide generating unit 12 is generated from air. These nitrogen oxides flow through the subsequent oxidation reforming unit 15 (cPOx) and then in the example shown the combined nitrogen oxide storage / ammonia production unit 16 supplied and stored. In a second phase of operation following the lean phase, the fat phase (0.33 <λ <1), becomes in the range of the multitron unit 11 metered liquid fuel in an evaporation and mixture formation zone, not shown, and in the oxidation reforming insurance unit 15 (CPOx) reacted to a hydrogen and carbon monoxide-containing gas mixture, which then in the field of nitrogen oxide storage / ammonia generating unit 16 converts the previously stored nitrogen oxides to ammonia. This generated gaseous ammonia is then in the exhaust gas flow of the exhaust passage 30 before the SCR catalyst 33 added.

Because the SCR catalyst 33 has an ammonia storage capacity, it is possible to continuously achieve via a batch process for ammonia production, the reduction of nitrogen oxides by means of the SCR process in the exhaust stream. In the temperature range between 150 ° C and 450 ° C, catalysts of titanium dioxide (TiO ₂ ) and vanadium pentoxide (V ₂ O ₅ ) convert the nitrogen oxides with the ammonia produced at a high rate. But there are other SCR catalysts here 33 conceivable.

In the illustrated embodiment, the reductant generation system 10 a valve system 40 in the form of a 3/2 valve 41 which after the oxidation reforming unit 15 (cPOx) is arranged. With the help of the 3/2 valve 41 may be from the oxidation reforming unit 15 (cPOx) emerging gas stream optionally via the standard gas path 17 the nitric oxide storage / ammonia production unit 16 for generating ammonia or via a regeneration gas path 18 the exhaust duct 30 before the oxidation catalyst 31 be supplied.

Will the from the Oxidationsreformierungseinheit 15 (cPOx) emerging gas flow through the corresponding valve position the exhaust duct 30 before the oxidation catalyst 31 supplied, the reducing agent generation system 10 to support the regeneration of the particulate filter 32 be used in the exhaust gas flow. For this purpose, in a first operating mode, the rich operation of the reducing agent generation system 10 with the implementation of the fuel / air mixture at the Oxidationreformierungseinheit 15 (cPOx) to hydrogen and carbon monoxide over a longer period of time maintained. During this phase, the ammonia production is at rest. The hydrogen and carbon monoxide become attached to the oxidation catalyst 31 reacted at temperatures from about 150 ° C to water and carbon dioxide. The released heat of reaction is transferred to the particulate filter via the exhaust gas flow 32 passed on. This is the particle filter 32 heated until the temperature for regeneration of the particulate filter 32 sufficient, for diesel particulate filters, for example, about 600 ° C.

In a second operating mode, one in the multitron unit 12 included, not shown starting burner, with which the components of the reducing agent generation system 10 in the start phase are warmed up to the required operating temperature, for heating the particulate filter 32 be used. This will be the starting burner, which is in the Multitron unit 12 before the oxidation reforming unit 15 (cPOx) is arranged, operated and the hot exhaust gas generated thereby via the valve system 40 and the regeneration gas path 18 the exhaust duct 30 and thus the particle filter 32 fed. If the hot exhaust gas of the starting burner, as shown in the illustrated embodiment, before the oxidation catalyst 31 the exhaust duct 30 fed, so can in the oxidation catalyst 31 additionally unburned or partially burned fuel components, which are contained in the exhaust stream of the starting burner, are oxidized with the release of the heat of reaction liberated. The starting burner can be operated so that its exhaust gas contains a sufficient amount of unburned or partially burned fuel components.

Once the burnup of the stored particles on the particulate filter 32 has initiated, due to the released by the combustion heat of reaction, the support by the addition of hydrogen and carbon monoxide or hot exhaust gas from the reducing agent generation system 10 be reduced. Furthermore, from temperatures at which the disadvantages of a PoI, such as the lubricating oil dilution or increased hydrocarbon emissions, are avoided, a moderate PoI be used.

The heating of the particle filter 32 by the reaction of the hydrogen and carbon monoxide-rich gas mixture from the reducing agent generation unit 10 or the addition of hot exhaust gas of the starting burner makes it possible, even at low load points of the engine map 20 , where sufficient exhaust gas temperatures are not reached, regeneration cycles for the particulate filter 32 perform. In this case, the method can be used alone or in support of known methods for raising the exhaust gas temperature. There is no risk of dilution of the lubricating oil or the fact that the particle filter sucks completely with hydrocarbons, which can lead to uncontrolled combustion of the hydrocarbons with the risk of catalyst damage. The gaseous hydrogen and carbon monoxide-containing gas mixture or the addition of the hot gas mixture of the starting burner can therefore be used significantly before a PoI or a metered addition of hydrocarbons via a HCi (hydrocarbon injection). If an initiated regeneration program is endangered by stand-gas operation in the implementation, by adding the hydrogen and carbon monoxide rich or hot gas from the reducing agent generation system 10 the necessary temperature in the exhaust duct 30 be maintained. Furthermore, next to the particle filter 32 also the oxidation catalyst 31 warmed up, resulting in a shortening of the cold start phase of the oxidation catalyst 31 with a reduction in emissions of hydrocarbons. By increasing the exhaust gas temperature can continue the temperature of the SCR catalyst 33 be raised to a suitable temperature for a maximum nitric oxide conversion.

Since the particle filter regeneration largely independent of the operating condition of the internal combustion engine 20 can be carried out, the regeneration intervals can be shortened. It is thus possible, the exhaust gas recirculation of the internal combustion engine 20 increase and thus reduce their nitrogen oxide emission. The associated increased particulate emissions can via the particulate filter 32 and the more frequent regeneration phases are compensated by the exhaust gas.

2 shows in a further embodiment, a schematic representation of an exhaust aftertreatment system 1 an internal combustion engine 20 with a reductant generation system 10 and a 3/2 valve 41 , again using the example of a diesel engine.

Unlike the in 1 illustrated embodiment is the 3/2 valve 41 in the flow direction after the nitrogen oxide storage / ammonia production unit 16 arranged. During the regeneration phase of the particulate filter 32 is via a corresponding valve position, the hydrogen and carbon monoxide-rich gas mixture from the Multitron unit 11 via the nitrogen oxide storage / ammonia recovery unit 16 , the valve system 40 and the regeneration gas path 18 the exhaust duct 30 in the flow direction before the oxidation catalyst 31 fed. As in the nitric oxide storage / ammonia generating unit 16 during the extended fat phase of the Multitron unit 11 no more nitrogen oxide is stored, no ammonia is generated therein and the gas mixture can almost unchanged the nitrogen oxide storage / ammonia generating unit 16 happen. The regeneration of the particle filter 32 takes place according to the 1 described method.

An advantage of this arrangement is that the nitrogen oxide storage / ammonia generating unit 16 during the regeneration phase of the particulate filter 32 from the hot gas stream of the Multitron unit 11 flows through and thus maintained at operating temperature, resulting in a longer operational readiness of the reducing agent generation system 10 leads.

3 shows a schematic representation of an exhaust aftertreatment system 1 an internal combustion engine 20 with a reductant generation system 10 in a further embodiment.

It is different from the one in 1 variant shown the valve system 40 through two 2/2 valves 42 . 43 realized, with the first 2/2 valve 42 in the regeneration gas path 18 and the second 2/2 valve 43 in the standard gas path 17 before the nitric oxide storage / ammonia generation unit 16 is arranged. Furthermore, the regeneration gas path opens 18 between the oxidation catalyst 31 and the particulate filter 32 in the exhaust duct 30 ,

During the ammonia production phase, this is the first 2/2 valve 42 closed while the second 2/2 valve 43 is open. The one from the Multitron unit 11 escaping gas flow is thus the nitric oxide storage / ammonia generating unit 16 fed.

For regeneration of the particle filter 32 becomes the first 2/2 valve 42 opened and the second 2/2 valve 43 closed. The one from the Multitron unit 11 escaping hot gas stream thus passes in front of the particle filter 32 in the exhaust duct 30 ,

In the present embodiment, the oxidation catalyst 31 not from the gas stream from the reductant generation system 10 flows through, it is therefore no additional heat of reaction by reacting hydrogen, carbon monoxide or hydrocarbons on the oxidation catalyst 31 generated. The additional heating of the particle filter 32 takes place purely via the supply line of the hot gas mixture from the Multitron unit 11 , The introduction of the gas mixture immediately before the particle filter 32 is therefore in particular in the operating form, in which a hot gas flow through the operation of the starting burner of the reducing agent generation system 10 is generated, suitable.

Advantageous in the version with two 2/2 valves 42 . 43 compared to a likewise possible construction with a 3/2 valve is that both 2/2 valves 42 . 43 can be closed simultaneously, creating a gas flow for the entire reductant generation system 10 can be prevented. This is otherwise only a shutdown of the gas supply to the Multitron unit 11 directly on an upstream compressor, compressor or blower possible.

In a further, not shown, modification of 3 illustrated embodiment of the exhaust aftertreatment system 1 can the second 2/2 valve 43 in the standard gas path 17 in the flow direction after the nitrogen oxide storage / ammonia production unit 16 be arranged.

4 shows a schematic representation of another embodiment of an exhaust aftertreatment system 1 an internal combustion engine 20 with a reductant generation system 10 and a 3/2 valve 41 ,

In modification to the in 1 illustrated embodiment is between the oxidation reforming unit 15 (cPOx) and the valve system 40 a catalytic shift step 19 arranged. That in the extended fat phase in the Multitron unit 11 produced hot hydrogen and carbon monoxide-rich gas mixture undergoes the shift stage during the regeneration phase 19 and then the exhaust duct 30 before the oxidation catalyst 31 fed. For this purpose, the gas mixture via a corresponding valve position of the 3/2-valve 41 the regeneration gas path 18 fed.

In the shift stage, an increase in the hydrogen content takes place with a simultaneous reduction in the carbon monoxide content of the gas mixture in accordance with a water-gas shift reaction, after which carbon monoxide and water contained in the gas mixture is converted to carbon dioxide and hydrogen. Due to the higher hydrogen content, a higher reaction energy to the oxidation catalyst 31 be achieved at the same time reduced carbon monoxide emission.

By varying the lambda value between 0.33 and 0.66, the exhaust aftertreatment system 1 to a slight additional carbon monoxide slip through the operation of the reductant generation system 10 during the regeneration phases of the particulate filter 32 be optimized. This can impair the denitrification or the removal of nitrogen oxides from the exhaust gas of the internal combustion engine 20 on the SCR catalyst 33 , So an impairment of the so-called DeNOx process, as it can be caused by carbon monoxide, be avoided.

5 shows in a further embodiment, a schematic representation of an exhaust aftertreatment system 1 an internal combustion engine 10 with a reductant generation system 10 and a 3/2 valve 41 ,

Notwithstanding the in 1 The illustrated embodiment is the 3/2 valve 41 between the nitrogen oxide generating unit 12 and the oxidation reforming unit 15 (cPOx) arranged. Through the 3/2 valve 41 This can be done from the nitric oxide generating unit 12 exiting gas mixture for ammonia production along the standard gas path 17 the oxidation reforming unit 16 (cPOx) and then the nitrogen oxide storage / ammonia production unit 16 be supplied. For regeneration of the particle filter 32 This can be done from the nitric oxide generating unit 12 escaping gas mixture through the 3/2 valve 41 and the regeneration gas path 18 the exhaust duct 30 before the oxidation catalyst 31 be supplied.

The arrangement is particularly for the operating form in which the gas mixture by the operation of the, not shown, in the nitrogen oxide generating unit 12 integrated start burner is provided suitable. In this case, the hot exhaust gas of the starting burner is direct, ie without a passage through the Oxidationreformierungseinheit 15 (cPOx), the exhaust duct 30 supplied and can thus directly to the temperature increase of the exhaust gas of the internal combustion engine 20 and thus the particle filter 32 contribute. Furthermore, unburned and partially combusted exhaust components from the exhaust gas of the starting burner to the oxidation catalyst 31 with delivery of the heat of reaction liberated to the exhaust gas flow of the internal combustion engine 20 be oxidized.

An advantage of this embodiment is that the oxidation reforming unit 15 (cPOx) is not flowed through by the hot exhaust gas of the starting burner and thus when setting the burner gas temperature no consideration for Oxidationsreformierungseinheit 15 (cPOx) must be taken.

In principle, the apparatus and method may be applied to all diesel or lean-burn engines powered by other fuels which use a reductant generation system 10 is used and the one particle filter 32 in an exhaust duct 30 exhibit.

Claims (16)

Device for the regeneration of a particle filter ( 32 ) in an exhaust duct ( 30 ) an internal combustion engine ( 20 ), wherein the exhaust duct ( 30 ) of a reductant generation system ( 10 ) produced ammonia for the reduction of nitrogen oxides via a standard gas path ( 17 ) in front of an SCR catalyst ( 33 ), wherein the reducing agent generation system ( 10 ) from a multitron unit ( 11 ) derived from a nitric oxide generating unit ( 12 ), a mixture formation chamber and an oxidation reforming unit ( 15 ) (cPOx), and a combined nitrogen oxide storage / ammonia production unit ( 16 ) and wherein the multitron unit ( 11 ) via an air / exhaust gas supply ( 13 ) and a fuel supply ( 14 ) Starting materials for generating the ammonia are at least temporarily fed, characterized in that the reducing agent generation system ( 10 ) a valve system ( 40 ), via which in the reductant generation system ( 10 ) produced hydrogen-rich and / or carbon monoxide rich and / or hot gas mixture via a Regenerationsgasweg ( 18 ) the exhaust duct ( 30 ) of the internal combustion engine ( 20 ) in the flow direction in front of an oxidation catalyst ( 31 ) and the following particle filter ( 32 ) or in front of the particle filter ( 32 ) is at least temporarily fed. Device according to claim 1, characterized in that the valve system ( 40 ) after the oxidation reforming unit ( 15 ) (cPOx) is arranged and that with the valve system ( 40 ) the gas path for the from the oxidation reforming unit ( 15 ) (cPOx) gas flow between the combined nitrogen oxide storage / ammonia production unit ( 16 ) and the exhaust channel ( 30 ) is switchable. Device according to claim 1, characterized in that the valve system ( 40 ) after the combined nitrogen oxide storage / ammonia production unit ( 16 ) and that with the valve system ( 40 ) the gas path for the from the nitrogen oxide storage / ammonia generating unit ( 16 ) leaving the gas stream between the introduction into the Ab gas channel ( 30 ) before the SCR catalyst ( 33 ) and the introduction into the exhaust gas channel ( 30 ) in front of the oxidation catalyst ( 31 ) or in front of the particle filter ( 32 ) is switchable. Device according to claim 1, characterized in that the valve system ( 40 ) between the nitrogen oxide generating unit ( 12 ) and the oxidation reforming unit ( 15 ) (cPOx) is arranged and that with the valve system ( 40 ) the gas path for the nitrogen oxide production unit ( 12 ) gas stream between the introduction into the oxidation reforming unit ( 15 ) (cPOx) and the introduction into the exhaust gas channel ( 30 ) in front of the oxidation catalyst ( 31 ) or in front of the particle filter ( 32 ) is switchable. Apparatus according to claim 1, characterized in that in the gas path after the oxidation reforming unit ( 15 ) (cPOx) a catalytic shift stage ( 19 ) and then the valve system ( 40 ) and that with the valve system ( 40 ) the gas path for the from the catalytic shift stage ( 19 ) gas stream between the combined nitrogen oxide storage / ammonia production unit ( 16 ) and the exhaust channel ( 30 ) is switchable. Apparatus according to claim 5, characterized in that during a rich operating phase of the Multitron unit ( 11 ) The lambda value between 0.3 and 1.0, preferably between 0.33 and 0.66 is adjustable. Device according to one of claims 1 to 6, characterized in that the valve system ( 40 ) from a 3/2 valve ( 41 ) or two 2/2 valves ( 42 . 43 ), whereby a 2/2 valve ( 43 ) in the standard gas path ( 17 ) and a 2/2 valve ( 42 ) in the regeneration gas path ( 18 ) is arranged. Device according to one of claims 1 to 7, characterized in that the valve system ( 40 ) of at least two 2/2 valves ( 42 . 43 ), wherein a first 2/2-valve ( 42 ) in the regeneration gas path and a second 2/2 valve in the flow direction according to at least one further component of the reductant generation system in the standard gas path ( 17 ) is arranged. Device according to one of claims 1 to 8, characterized in that the valve system ( 40 ) is connected to a control unit and that the control unit signals about the regeneration needs of the particulate filter ( 32 ) and / or that in the control unit regeneration cycles for the particulate filter ( 32 ) are deposited. Application of the device according to one of claims 1 to 9, characterized in that the device is used in diesel engines, the a reducing agent generation system ( 10 ) and a particle filter ( 32 ) exhibit. Process for the regeneration of a particulate filter ( 32 ) in an exhaust duct ( 30 ) an internal combustion engine ( 20 ), wherein a reductant generation system ( 10 ) Ammonia and for the reduction of nitrogen oxides via a standard gas path ( 17 ) in the exhaust duct ( 30 ) in front of an SCR catalyst ( 33 ), wherein the reducing agent generation system ( 10 ) from a multitron unit ( 11 ) derived from a nitric oxide generating unit ( 12 ), a mixture formation chamber and an oxidation reforming unit ( 15 ) (cPOx), and a combined nitrogen oxide storage / ammonia production unit ( 16 ) and wherein the multitron unit ( 11 ) via an air / exhaust gas supply ( 13 ) and a fuel supply ( 14 ) Is at least temporarily supplied to starting materials for generating the ammonia, characterized in that a in the reducing agent generation system ( 10 ) produced hydrogen-rich and / or carbon monoxide rich and / or hot gas mixture during ammonia production phases via a valve system ( 40 ) of the nitrogen oxide production unit ( 16 ) or the exhaust duct ( 30 ) before the SCR catalyst ( 33 ) and that the gas mixture through the valve system during particle filter regeneration phases ( 40 ) and a regeneration gas path ( 18 ) the exhaust duct ( 30 ) of the internal combustion engine ( 20 ) in the flow direction in front of an oxidation catalyst ( 31 ) and the subsequent particle filter ( 32 ) or in front of the particle filter ( 32 ) is supplied. A method according to claim 11, characterized in that in addition further measures to increase the exhaust gas temperature are performed and / or that the supply of the hydrogen-rich and / or carbon monoxide rich and / or hot gas mixture in operating conditions of the internal combustion engine ( 20 ) is carried out with low exhaust gas temperatures. A method according to claim 11 or 12, characterized in that the hot gas mixture by operation of a starting burner in the Multitron unit ( 10 ) is produced. Method according to claim 13, characterized in that that the starting burner is operated with excess oxygen. Method according to one of claims 11 to 14, characterized in that an increased exhaust gas recirculation of the internal combustion engine ( 20 ) he follows. Application of the method according to one of claims 11 to 15, characterized in that the method is used in diesel engines, the a reducing agent generation system ( 10 ) and a particle filter ( 32 ) exhibit.