EP3472441B1 - Particle filter for an internal combustion engine - Google Patents

Description

The invention relates to a particle filter for an internal combustion engine according to the preamble of patent claim 1.

Particle filters for internal combustion engines, in particular for compression-ignition internal combustion engines, are known. The particle filter is distinguished in particular by the fact that several channels are arranged next to one another, in particular parallel to one another, the channels being alternately closed. The exhaust gas flowing in via a filter inlet flows through the particle filter in its extension direction in that it passes from a channel opened at the filter inlet into a channel opened at the filter outlet via a porous wall arranged between these two channels. Solid particles of the exhaust gas are deposited in and / or on the wall. Since these particles reduce a free flow cross-section of the particle filter and because the potential for excessive temperature increases in the particle filter as a result of exothermic soot burn-off increases with increasing load, these particles must be removed from the particle filter by a so-called regeneration, in other words by converting the soot particles.

The patent specification EP 2 161 420 B1 a particle filter for an internal combustion engine can be removed, which is uncoated in areas of the channels in which mainly solid particles are deposited. Thus, a coated section and an uncoated section are each formed in the channels, the uncoated section of a channel being formed adjacent to the coated section of a further channel.

From the publication EP 1 250 952 A1 shows a particle filter for an internal combustion engine designed as a diesel engine, which has a coating for soot oxidation, the reaction temperature of which is below 500 ° C. This is done with the help of preferred materials of the particle filter, in the form of Alkaline earth metal compounds, an oxygen-storing substance and platinum, palladium or rhodium achieved.

The patent specification US 7,691,339 B2 discloses a particle filter for an internal combustion engine which uses microwave energy to reduce the soot particles accumulating in the particle filter. A microwave generator is provided, which heats up the microwave-absorbing material received in the soot filter.

The disclosure document DE 10 2006 032 886 A1 a particle filter with a functional material coating can be removed. The channels of the particle filter through which flow is to be carried out are coated on their wall surfaces with the functional material, the functional material transitioning from a first modification to a second modification in an exothermic reaction and leading to an increase in the temperature in the particle filter.

The disclosure document DE 101 35 341 A1 discloses a particulate filter coated with a noble metal catalyst and with an oxygen occluding and releasing agent. By changing the oxygen content in the exhaust gas flowing through the particle filter, the temperature of the particle filter can be influenced.

The disclosure document EP 1 857 947 A1 a method for increasing the temperature of exhaust gas cleaning systems, in particular a particle filter and a nitrogen oxide trap, can be found. The particle filter is provided with an oxygen-storing layer; a variation in the oxygen content of the exhaust gas flowing through the filter leads to an exothermic reaction and thus to an increase in the temperature of the filter.

The object of the present invention is to provide an improved particle filter for an internal combustion engine.

According to the invention, this object is achieved by a particle filter for an internal combustion engine with the features of claim 1. Advantageous configurations with expedient and non-trivial developments of the invention are specified in the respective subclaims.

A particle filter according to the invention for an internal combustion engine has a filter body, the filter body having a filter inlet through which a flow can flow and a filter outlet which can flow through it. The filter body comprises at least one through-flowable first channel, with a first end formed facing the filter inlet and a second end formed facing the filter outlet, and a through-flow second channel, with one facing the filter inlet formed third end and a trained fourth end facing the filter outlet. The second end and the third end are impermeable or difficult to flow in a certain way, whereby the channels can be divided into a flow-through channel section and a non-flow-through or in a certain way difficult-to-flow channel section.

As a result, first channels with a blocked or hindered flow inlet at the filter inlet and second channels with a blocked or hindered flow outlet at the filter outlet are formed. A flow of exhaust gas flowing through the particle filter, starting from the first channel into the second channel, takes place via a common channel wall formed between the first channel and the second channel. The channel wall is designed to be separable soot particles from the exhaust gas.

In the following, an impermeable channel section is not necessarily to be understood as a completely sealed channel section closed against any permeability, but rather a channel section that is in a certain way difficult to flow through - z. B. a so-called diffusion-open channel section, in particular oxygen molecules can penetrate this difficult-to-flow channel section.

To increase a reaction temperature present in the particle filter for burning off the soot particles, the first channel and / or the second channel has a heating element, the heating element being arranged in the channel section of the channel through which there is no flow.

The arrangement of the heating element in the non-flowable channel section has several advantages. For example, a flow through the particle filter is not impaired due to the heating element, which has a flow resistance. Another advantage is to be seen in the use of the unused areas of the particle filter with regard to the flow: an increase in the reaction temperature for burning off the soot particles can be achieved while maintaining the original Size of the particle filter. In other words, that means that an intended installation space for the particle filter is retained and no constructive change measures need to be taken with regard to the installation space. If, for example, the channels of the particle filter are coated, this can have the consequence that, compared to uncoated channels, a channel cross section of the channel is reduced due to the coating. However, so that through-flow conditions of the particle filter having the coating corresponding to the uncoated particle filter can be achieved, the channel cross section of the particle filter must be enlarged, whereby the required installation space of the particle filter having the coating is also increased.

In one embodiment of the particle filter according to the invention, the heating element is formed from a functional material which reacts exothermically when oxygen is stored. In other words, this means that the heating element is designed to be quasi self-igniting. The advantage is to be seen in the fact that only the heating element itself is required without, for example, as is known from the prior art, an auxiliary means in the form of an ignition device, such as, for example, the microwave generator. It is only necessary to adapt the operation of the internal combustion engine so that the exothermic reaction of the functional material is initiated based on a corresponding temperature of the exhaust gas and / or a corresponding composition of the exhaust gas. The heating element is arranged in a cross section of the first channel and / or the second channel which is orthogonal to a longitudinal axis along which the channels are designed to extend and wherein the heating element is directly acted upon by the exhaust gas.

The heating element can preferably be excited to give off heat with the aid of a change in a combustion air ratio of the exhaust gas. For this purpose, the combustion air ratio of the exhaust gas can be changed by adding or reducing fuel or air. In particular, a so-called sub-stoichiometric composition, which corresponds to a combustion air ratio with a value less than 1, or an over-stoichiometric composition, which corresponds to a combustion air ratio with a value greater than 1, is caused by a so-called rich operation Internal combustion engine or a lean operation of the internal combustion engine can be achieved.

The heating element can preferably be excited to give off heat by changing the combustion air ratio of the exhaust gas from a combustion air ratio with a value less than 1 to a combustion air ratio with a value greater than 1. This change in the combustion air ratio can be achieved, for example, starting from a load operation of the internal combustion engine with only slightly substoichiometric operation, e.g. with a value of the combustion air ratio of approx. 0.98 and a subsequent overrun operation of the internal combustion engine, in particular with an overrun cutoff.

Such an operation of the internal combustion engine can already be achieved, for example, by driving downhill or by decelerating a motor vehicle with the internal combustion engine. This is already with a short-term, z. B. due to the downhill drive or a delay realizable overrun operation, in particular with an overrun cut-off, a temperature increase due to the heat emission of the heating element in the particle filter can be brought about. In other words, the heating element can react to brief lean operation of the internal combustion engine, for example due to overrun fuel cutoff, with a sharp rise in temperature. The advantage is that an engine control for operating the internal combustion engine does not have to be adapted or has to be adapted only slightly.

In a further embodiment of the particle filter according to the invention, the heating element has an element cross-section which corresponds to a cross-section of the channel. In addition to its temperature-increasing function, the heating element can thus be used to seal the duct on one side.

The heating element is preferably designed at least on the basis of cerium oxide and / or cerium-zirconium mixed oxides. With the appropriate composition and concentration, these oxides have a pronounced oxygen storage capacity, which enables a high temperature increase to be achieved due to the exothermic reaction.

If the heating element has noble metals such as palladium and / or rhodium, they also have a direct oxygen storage capacity, at least in a certain temperature range.

In a further preferred embodiment of the particle filter according to the invention, the heating element of the first channel is made of a first material and the heating element of the second channel is made of a second material that differs from the first material. The advantage is the formation of differently high temperature increases in the particle filter.

The particle filters of the prior art have, in principle, a comparatively low reaction speed of the burning off of the soot particles. This can have the consequence that, for example, due to a burning off almost simultaneously in all filter areas of the same soot load at all points of the particle filter, very high temperatures are present in areas of the particle filter which, starting from a filter inlet, are in the direction of a filter outlet of the particle filter that can lead to damage to the particle filter and / or a possibly existing coating. In such a case, the temperature near the filter outlet of the particle filter can be highest. It can be assumed that also with z. B. 800 ° C the burn is relatively slow and so the heat released in the filter inlet area is in the downstream areas, thus also in the area before the filter outlet, accumulates with the heat released there.

This configuration therefore has the advantage of bringing about a temperature increase in the area of the filter inlet that differs from the temperature increase in the area of the filter outlet. It is advantageous to form the heating element in the area of the filter inlet from a first material which only releases heat at low and medium temperatures in the particle filter, e.g. palladium, and in the area of the filter outlet the heating element made from a second material that releases heat even for even higher temperatures in the particle filter, for example with a high proportion of standard storage materials of today's 3-way catalytic converters.

For example, highly loaded particle filters, i.e. Particle filters, which have a large amount of soot particles, heat them starting from the filter outlet. If the burn-off or regeneration were initiated at the filter outlet, the heat released there would really be released and not imposed as a "thermal burden" in the upstream areas. Under certain boundary conditions, especially if flow velocities are not too high, the so-called soot burn-off front would then run counter to the flow velocity in the direction of the filter inlet and into the areas of the particle filter formed there. It can therefore be advantageous if the first material is designed to react in a medium temperature range and the second material is designed to react over a further temperature range.

A further increase in efficient regeneration can be brought about with the aid of a further heating element if this is arranged in the duct section through which a flow can flow.

The impermeable channel section has a plug, the heating element being designed to completely or partially replace the plug. Particulate filters according to the prior art have plugs which only serve the purpose of sealing off the channel. You are massive formed and have a relatively large length. E.g. Plug lengths of approx. 7 mm are usual for particle filters used or planned in the gasoline engine sector. A mass fraction of the stoppers in the clogged filter inlet and filter outlet areas is approx. 60 - 70%. Therefore, a complete or partial replacement of these plugs with a heating element made of a material with a high proportion of a storage component with high heat of oxidation leads to a sharp rise in temperature when the internal combustion engine is switched from rich operation to lean operation, for example in connection with a Fuel cut-off. A particularly efficient particle filter is thus implemented.

• Fig. 1 in einem t-λ-Diagramm einen Verlauf des Verbrennungsluftverhältnisses λ von Abgas und in einem korrespondierenden t-T-Diagramm Temperaturen in einem Partikelfilter gemäß dem Stand der Technik und in einem erfindungsgemäßen Partikelfilter Temperaturverläufe an unterschiedlichen Positionen des Partikelfilters, ermittelt mit Hilfe einer Simulationsrechnung,
• Fig. 2 in einem x-T-Diagramm Temperaturverläufe zu verschiedenen Zeitpunkten im Partikelfilter gemäß dem Stand der Technik und dem erfindungsgemäßen Partikelfilter,
• Fig. 3 in einer schematischen Darstellung einen erfindungsgemäßen Partikelfilter, und Fig. 4 ein Ellingham-Diagramm der Elemente Palladium und Rhodium und deren Oxide.

Further advantages, features and details of the invention emerge from the following description of preferred exemplary embodiments and with reference to the drawing. The features and combinations of features mentioned above in the description as well as the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figures can be used not only in the respectively specified combination, but also in other combinations or on their own, without the scope of the Invention to leave. Identical or functionally identical elements are assigned identical reference symbols. Show it:

• Fig. 1 in a t-λ diagram a course of the combustion air ratio λ of exhaust gas and in a corresponding tT diagram temperatures in a particle filter according to the prior art and in a particle filter according to the invention temperature curves at different positions of the particle filter, determined with the aid of a simulation calculation,
• Fig. 2 in an xT diagram, temperature curves at different times in the particle filter according to the prior art and the particle filter according to the invention,
• Fig. 3 in a schematic representation a particle filter according to the invention, and Fig. 4 an Ellingham diagram of the elements palladium and rhodium and their oxides.

A sudden temperature increase in a particle filter 1 according to the invention can be brought about with an exothermic reaction of a material that has a high oxygen storage content when an internal combustion engine, not shown, is switched from load to overrun. The proportions of an air-fuel mixture supplied to the internal combustion engine are changed. Starting from what is known as rich operation, which has a combustion air ratio λ of the air-fuel mixture with a value less than 1, it is preferable to switch to lean operation, which has a combustion air ratio λ of the air-fuel mixture with a value greater than 1. As a result, exhaust gas from the internal combustion engine, which flows through the particle filter 1, has an increased proportion of oxygen, which triggers the exothermic reaction. A simultaneous overrun fuel cutoff increases the oxygen content significantly, which also makes it possible to achieve a significant increase in the temperature in the particle filter 1.

Fig. 1 shows in the lower section in a t-λ diagram a curve L1 of a combustion air ratio λ over time t in front of a known particle filter. A sudden change in the combustion air ratio λ from a value of approx. 0.95 here to a value of well over 1 characterizes a point in time when the internal combustion engine is switched from load to overrun with fuel cut-off.

In the upper and middle section of the Fig. 1 temperature curves Tl, T2, and T3 calculated as a function of the operating changeover are shown for different positions along a flow axis of the particle filter. In the upper section are the temperature profiles of a particle filter 1 according to the prior art and in the middle section of FIG Fig. 1 are temperature profiles of a particle filter 1 according to the invention shown. The temperature profile T0 corresponds to a so-called inlet temperature, i.e. the gas temperature upstream of the OPF.

The particle filter 1 according to the invention, which is shown schematically according to FIG Fig. 3 has throughflow channel sections 13 and impermeable channel sections 14. The temperature curves T1 and T3 show a thermal behavior of the particle filter 1 in a plane near a filter inlet 3 or near a filter outlet 4 of the particle filter 1, i.e. in planes that also impermeable channel sections 14 cut through. The temperature profile T2 shows the thermal behavior of the particle filter 1 near a central plane of the particle filter 1, which is formed centrally between the planes of the filter inlet 3 and the filter outlet 4.

The temperatures T1, T2, T3 in the particle filter 1 according to the prior art follow the cooling inlet temperature T0 with a time delay due to the heat capacity of the particle filter 1 itself. The temperatures T1, T2, T3 in the particle filter 1 according to the invention show different curves. The temperatures T1, T3 of the levels with impermeable channel sections 14 rise immediately after the change from the (slightly) rich to the lean mixture, only slightly delayed, violently, in this example by about 75 ° C. As soon as an exothermic filling of an oxygen reservoir in the duct sections 14 through which there is no flow is completed, these temperatures T1, T3 also follow the inflow temperature T0, which is getting colder and colder, with a time delay.

The calculations were made without taking into account any soot burn-off. Measurements not shown in more detail show that at approx. 700 ° C. of the particle filter 1, the soot burn-off proceeds only slowly. At approx. 850 ° C a regeneration of stored soot can be clearly seen. For the load case shown here, the particle filter 1 has hardly regenerated without soot. The particle filter 1 according to the invention, having the duct sections 14 through which there is no flow, ignites the soot burn-off in such a way that it then accelerates or sustains itself until it is largely regenerated.

Fig. 2 shows in an xT diagram temperature profiles at different times t0, t1, t2, t3, t4 before and after a change from a (slightly) rich load operation of the internal combustion engine to overrun operation with fuel cut-off in the direction of the flow axis of the particle filter 1. In the upper section of Fig. 2 are the temperature profiles t0, t1, t2, t3, t4 in the particle filter 1 according to the prior art and in the lower section of FIG Fig. 2 the temperature curves t0, t1, t2, t3, t4 are shown in the particle filter 1 according to the invention.

The temperature curve t0 corresponds to a curve before the changeover. The temperature curves t1, t2, t3, t4 are temperature curves after the change in operation, the temperature curve t1 20.2 seconds, the temperature curve t2 21.2 seconds, the temperature curve t3 22.2 seconds and the temperature curve t4 23.2 seconds Corresponds to the temperature curve over the flow axis after the change of operation.

The particle filter 1 according to the invention for the internal combustion engine, not shown in detail, is shown in a schematic illustration according to FIG Fig. 3 educated. During operation of the internal combustion engine, which is designed in the form of a direct-injection Otto engine, exhaust gas containing soot particles is produced due to combustion of the air-fuel mixture.

The particle filter 1 has a filter body 2 with a filter inlet 3 and a filter outlet 4 that can be flowed through. A multiplicity of passages 5, 6 through which a flow can flow is formed in the filter body 2. The channels 5, 6 extend along a longitudinal axis L and are designed to be adjacent to one another, with a flow occurring along the longitudinal axis L.

The channels 5, 6 alternately have an end that is closed at the filter inlet 3 and one at the filter outlet 4. In addition, a first channel 5 and a second channel 6, the plurality of channels and the mode of operation of the particle filter 1 described.

The first channel 5 has a first end 7 facing the filter inlet 3 and a second end 8 facing the filter outlet 4. The second channel 6 has a third end 9 facing the filter inlet 3 and a fourth end 10 facing the filter outlet 4 . The second end 8 and the third end 9 are designed such that there is no flow. The exhaust gas flows from the first channel 5 to the second channel 6 via a common channel wall 11 formed between the first channel 5 and the second channel 6.

The duct wall 11 is porous and permeable to flow, with the soot particles of the exhaust gas flowing through the duct wall 11 being deposited or deposited on the duct wall 11. The exhaust gas flows through the particle filter 1 in the direction of the arrows shown.

The channels 5, 6 are closed at their ends 8, 9 through which there is no flow with the aid of a plug 12. In other words, that means that the channels 5, 6 each have a channel section 13 through which there is free flow and a channel section 14 through which there is no flow.

The plug 12 has an element cross-section QE which corresponds to a cross-section Q of the channel 5; 6 corresponds. Since the channels 5, 6 have an identical cross section in the illustrated embodiment, the element cross section QE also corresponds to a cross section Q of the second channel 6. In an embodiment not shown in detail, the channels 5, 6 have different cross sections Q. This means that the plug 12 has an element cross-section QE adapted to the cross-section Q of the corresponding channel 5, 6.

The element cross section QE of the plug 12 is constant over a length L of the plug 12 in the illustrated embodiment. The element cross-section QE could also change over its length L. For example, in an exemplary embodiment not shown in detail, the plug 12 has a frustoconical shape with an element cross section QE that changes over the length LE, provided that the channel 5; 6 has a conical shape.

When the internal combustion engine is in operation, the soot particles collect in the particle filter 1, an effective flow cross section of the particle filter 1 being reduced over time. The reduction in the effective flow cross-section leads to an increase in exhaust gas back pressure in the internal combustion engine, which can lead to an increase in gas exchange losses. With constant power, this in turn would result in an increase in the fuel consumption of the internal combustion engine or, with the same fuel consumption, a reduction in the output of the internal combustion engine. A regeneration of the particle filter 1 is thus carried out as a function of a so-called loading of the particle filter 1.

To regenerate the particle filter 1, it has at least one heating element 15, which is arranged in the duct section 14 through which there is no flow. The heating element 15 consists of a functional material which reacts exothermically in the event of an excess of air, in other words emits heat and thus leads to a temperature increase in the particle filter 1.

The heating element 15 is designed in the form of the plug 12 and replaces it. The heating element 15 could also be designed as part of the plug 12. It is made of a material which is designed to trigger an exothermic reaction when oxygen is stored. In other words, this means that the heating element 15 independently releases heat due to its molecular structure, provided that oxygen storage is formed. This means that the heat of the reaction is released.

The material is a solid which can be present in at least two modifications. In rich operation of the internal combustion engine, it is at least partially in a reduced modification, the first modification, and in a lean operation of the internal combustion engine it changes over to an oxidized modification, the second modification. This solid, also called functional material, is preferably a mixed oxide of cerium and zirconium oxides with possibly other substances, such as metals and / or earth metals, lanthanum, presodymium, ytterium, and aluminum oxide.

The "less noble" noble metals palladium and rhodium, which also have a direct oxygen storage capacity, are also suitable. At higher temperatures, for example approx. 900 ° C, they do not oxidize and therefore do not store, and retain their noble metallic state. It is irrelevant here whether it is an exhaust gas with a rich composition corresponding to the rich operation or an exhaust gas with a lean composition corresponding to the lean operation of the internal combustion engine. Rhodium would acc. Fig. 4 Rhodium oxide can form up to approx. 880 ° C and can therefore behave ignoble up to this temperature.

According to its composition, the functional material can be designed for exothermic reaction in different temperature ranges. E.g. a first material has a composition with a reduction / oxidation ability in a low and medium temperature range up to approx. 700 ° C., for example palladium. A second material has a composition with an additional exothermic reaction in a high temperature range, such as, for example, TWC (Three-way-Catalyst) standard storage materials. In other words, this means that the first material is designed to react at low and medium temperatures present in the particle filter 1, and that the second material is designed to react at all temperatures present in the particle filter 1.

It goes without saying that all stoppers 12 can be replaced by one heating element 15 each, which improves regeneration.

A particle filter 1 with a plurality of heating elements 15 which are formed from a single material and / or a material mix is also expedient. The positioning of the heating element (s) 15, on the inlet side or on the outlet side, can also be selected as a function of an installation situation of the particle filter 1, close to or remote from the engine.

In a preferred exemplary embodiment not shown in detail, all of the plugs 12 of the particle filter 1 are replaced by a heating element 15 in each case. Another exemplary embodiment of the particle filter 1 according to the invention, not shown in detail, has the heating element 15 formed from the first material at the second end 8 and the heating element 15 formed from the second material at the third end 9.

Another exemplary embodiment, not shown in detail, of the particle filter according to the invention has heating elements made of a first material at second ends and third ends, which are more distant from the central longitudinal axis. At the second ends and third ends, which are closer to the central longitudinal axis, it has heating elements made of a second material or no heating elements at all.

A further heating element 15 could also be arranged in the flow-through channel section 13. This could be formed from a further material that differs from the first material and the second material. I.e. in other words, it consists of a further material with an oxygen storage capacity that is different from the first material and the second material.

List of reference symbols

1

Particle filter

2

Filter body

3

Filter inlet

4th

Filter outlet

5

First channel

6th

Second channel

7th

First end

8th

Second ending

9

Third ending

10

Fourth end

11

Canal wall

12th

Plug

13

Flow-through channel section

14th

Passage section through which there is no flow

15th

Heating element

L.

Longitudinal axis

LE

length

L1

course

Q

Channel cross-section

QE

Element cross-section

T

temperature

T0

Inlet temperature

T1

first temperature curve

T2

second temperature curve

T3

third temperature curve

t

time

t0

Temperature profile before the changeover

t1

Temperature profile after the change of operation

t2

Temperature profile after the change of operation

t3

Temperature profile after change of company

t4

Temperature profile after change of company

λ

Combustion air ratio

Claims (9)

1. Particle filter for an internal combustion engine, having a filter body (2), wherein the filter body (2) has a filter inlet (3) passable by a flow, and a filter outlet (4) passable by a flow, and wherein the filter body (2) has at least one first duct (5) passable by a flow, having a first end (7) that is configured so as to face the filter inlet (3), and a second end (8) that is configured so as to face the filter outlet (4), and a second duct (6) passable by a flow, having a third end (9) that is configured so as to face the filter inlet (3), and a fourth end (10) that is configured so as to face the filter outlet (4), and wherein the second end (8) and the third end (9) are configured so as to be impassable by a flow, wherein the ducts (5, 6) are capable of being divided into a duct portion (13) passable by a flow, and a duct portion (14) impassable by a flow, and wherein a flow transfer of an exhaust gas flowing through the filter body (2) proceeding from the first duct (5) to the second duct (6) is performed by way of a common duct wall (11) that is configured between the first duct (5) and the second duct (6), and wherein the duct wall (11) is configured so as to be capable of separating soot particles of the exhaust gas, and wherein the first duct (5) and/or the second duct (6) for increasing a reaction temperature present in the particle filter (1) for burning off the soot particles have/has a heating element (15), wherein the heating element (15) is disposed in that duct portion (14) of the duct (5; 6) that is impassable by a flow and is configured from a functional material which reacts in an exothermic manner when storing oxygen, wherein the heating element (15) is disposed in a cross section (Q) of the first duct (5) and/or the second duct (6), said cross section (Q) being orthogonal to a longitudinal axis (L) along which the ducts (5, 6) are configured to extend, and wherein the heating element (15) is impinged directly by the exhaust gas, and wherein the duct portion impassable by a flow has a stopper (12),
   characterized in that
   the heating element (15) is configured so as to completely or partially replace the stopper (12).
2. Particle filter according to Claim 1,
   characterized in that
   the heating element (15) for the release of heat is excitable with the aid of a modification of a combustion air ratio (λ) of the exhaust gas.
3. Particle filter according to Claim 2,
   characterized in that
   the heating element (15) for the release of heat is excitable with the aid of a modification of a combustion air ratio (λ) of the exhaust gas from a combustion air ratio (λ) having a value below 1 to a value above 1.
4. Particle filter according to one of the preceding claims,
   characterized in that
   the heating element (15) has an element cross section (QE) which corresponds to a cross section (Q) of the duct (5, 6).
5. Particle filter according to one of the preceding claims,
   characterized in that
   the heating element (15) is configured at least from cerium and zirconium oxides and/or the mixed oxides thereof.
6. Particle filter according to one of the preceding claims
   characterized in that
   the heating element (15) comprises palladium and/or rhodium.
7. Particle filter according to one of the preceding claims,
   characterized in that
   the heating element (15) of the first duct (5) is configured from a first material, and the heating element (15) of the second duct (6) is configured from a second material that is dissimilar to the first material.
8. Particle filter according to Claim 7,
   characterized in that
   the first material is configured for reacting at low and medium temperatures present in the particle filter (1), and the second material is configured for reacting above all temperatures present in the particle filter (1).
9. Particle filter according to one of the preceding claims,
   characterized in that
   a further heating element (15) is disposed in the duct portion passable by a flow.

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