DE202013102603U1 - exhaust aftertreatment device - Google Patents

Abstract

Exhaust after-treatment device for an internal combustion engine, characterized in that it has a filter passage (9) with in the operation of the exhaust aftertreatment device temporally variably adjustable passage for the exhaust gas flow.

Description

The present invention relates to an exhaust aftertreatment device.

In diesel motor vehicles whose exhaust aftertreatment device is equipped with a NO _x storage catalytic converter, operation with a rich air / fuel mixture takes place in certain operating phases. Here, a comparatively low lambda value (eg, 0.96) is set, which is used to release and convert nitrogen oxides (NO _x ) stored in the NO _x storage catalyst, as well as to release sulfur at relatively low catalyst temperatures (typically 600 ° C-700 ° C) is needed.

In low-load operation, the ability to stably adjust for rich-air-fuel mixture operation is limited by the stability of the combustion process. This is especially true in combustion concepts based on a lean air-fuel mixture and as applied in direct injection diesel engines. This limits the robustness required to achieve low total hydrocarbon (THC) emissions. Further, when operating under low to medium load and constant engine speed, the stability of the rich air-fuel mixture is also a function of the driver's torque demand uniformity (i.e., accelerator operation), which in turn depends on the roadway, e.g. B. when driving on a slope or a gradient, may vary. In addition, when operating at medium to high load (typically for transient acceleration or continued high-performance operation), the ability to set and maintain rich-air-fuel mixture operation is limited by exhaust gas temperature limits at the turbocharger and exhaust gas recirculation circuits (EGR circle) limited.

A problem encountered in practice is the pronounced formation of wet soot, which is caused by the transition from lean to rich operation and the low lambda value at the beginning of the cleaning process. This wet soot may deposit on the exhaust components downstream of the diesel particulate filter (DPF) and adhere to some extent, for example, as a deposit on the turbine of the turbocharger, which may affect operating characteristics and performance of the exhaust after-treatment device.

Out DE 10 2010 026 868 A1 Among other things, a soot filter is known, which has inclined corrugation layers with parallel ridges to improve the retention of particles, wherein the soot filter can also be configured so that the hydraulic surface for the exhaust gas flow as a function of the distance through the soot filter or from the inlet changes to the outlet.

Out EP 0 205 755 B1 Among other things, an exhaust gas filter for a diesel engine is known, which has a corrugated web and a flat sheet of each porous ceramic material, which together form a composite web, which is wound to form a honeycomb structure with cell channels, wherein inserted into the channels tubular inserts with relatively smaller openings are.

Out WO 2009/065572 A1 Among other things, a soot particle filter is known in which deposit the soot particles on high-temperature resistant noble metal discs, wherein z. B. with a glow ignition a self-fire of the stored soot particles can be set in motion.

The further prior art is exemplified US 2006/0059899 A1 and EP 2 405 109 A2 directed.

It is an object of the present invention to provide an exhaust aftertreatment device which enables stable adjustment of rich air-fuel mixture operation while avoiding the problems described above.

This object is achieved according to the features of the independent claims.

An exhaust gas aftertreatment device according to the invention for an internal combustion engine has a filter passage with a passage for the exhaust gas flow that is variably variable in time during operation of the exhaust gas aftertreatment device.

The invention is based in particular on the concept of achieving support for operation with a rich air-fuel mixture by providing a filter passage with passage variable in time during operation of the exhaust aftertreatment device, so that wet soot generated in particular during operation with a rich air-fuel mixture is at least partially absorbed while the filter passage may be set in the "normal" mode of operation (ie, in stoichiometric or lean air-fuel mixture operation) with relatively greater passage, so that in the "normal" mode of operation the exhaust flow is less or not obstructed.

According to one embodiment, the filter passage is arranged in the exhaust manifold of the internal combustion engine.

According to one embodiment, the internal combustion engine comprises a turbocharger with a compressor and a turbine, wherein the filter passage is arranged relative to the exhaust gas flow upstream of the turbine. As a result of this arrangement of the filter passage upstream of the turbine, wet soot generated during operation of the internal combustion engine or the exhaust aftertreatment device can be at least partially captured and prevented from reaching the turbine of the turbocharger and sticking there as deposit.

This arrangement of the filter passage upstream of the turbine is advantageously independent of the above-described embodiment of the filter passage with variable-time passage adjustable realized.

In another aspect, therefore, the invention also relates to an exhaust aftertreatment device for an internal combustion engine, wherein the internal combustion engine comprises a turbocharger having a compressor and a turbine, and wherein the exhaust aftertreatment device comprises a filter passage disposed upstream of the turbine relative to the exhaust gas flow.

According to one embodiment, the exhaust aftertreatment device further comprises a control device, which is configured to vary the passage of the filter passage in response to a set in the operation of the internal combustion engine lambda value of the air-fuel mixture.

According to one embodiment, with this variation, as the lambda value of the air-fuel mixture is reduced, the passage of the filter passage is reduced.

According to one embodiment, the filter passage in at least one setting leaves the exhaust flow unaffected.

According to one embodiment, the filter passage in their relative distance to each other adjustable filtration walls.

According to one embodiment, the filter passage at least partially on a lamellar structure.

Further embodiments of the invention are described in the description and the dependent claims.

The invention is explained below with reference to preferred embodiments with reference to the accompanying drawings.

Show it:

1 a schematic representation for explaining a possible construction of an exhaust aftertreatment device according to the invention; and

2a -B are schematic representations for explaining the function of a present in an exhaust aftertreatment device according to the invention filter passage.

1 shows a schematic representation for explaining the structure of an exhaust aftertreatment device 1 according to an embodiment of the invention.

According to 1 refers to an internal combustion engine 2 in the form of a diesel engine with turbocharger 3 Fresh air from an air filter 4 that of a compressor 3a of the turbocharger 3 is pre-compressed. The exhaust gases of the internal combustion engine 2 flow through the exhaust pipe 5 downstream of the turbine 3b of the turbocharger 3 successively an exhaust aftertreatment device 6 with an oxidation catalyst and / or a NO _x storage catalyst, a diesel particulate filter 7 as well as a rear silencer 8th ,

According to 1 is further in the exhaust aftertreatment device according to the invention 1 in the exhaust manifold upstream of the turbine 3b of the turbocharger 3 a filter passage 9 provided, which, as hereinafter with reference to 2 is described during operation of the exhaust aftertreatment device 1 is adjustable in time.

In this case, a control device is preferably provided, which is configured to the passage of the filter passage 9 depending on a during operation of the internal combustion engine 2 adjusted lambda value of the air-fuel mixture to vary.

About this control device, the filter passage 9 in "normal" operating mode (ie in stoichiometric or lean air-fuel mixture mode) as in 2a schematically indicated "open" are set, ie the exhaust gas flow is not limited or hindered there.

During operation of the internal combustion engine 2 with a rich air-fuel mixture, however, as in 2 B indicated schematically, the filter passage 9 so far closed or narrowed that a passage restriction of the hot Exhaust stream or the rich air-fuel mixture takes place.

Here, the filter passage points 9 In the exemplary embodiment, a lamellar structure with fins 9a . 9b on which form Filtrationswandungen, where especially wet soot can deposit. Due to the narrowed passage cross-section in the area of the filter passage 9 The generated wet soot is at least partially captured and prevented from the turbine 3b of the turbocharger 3 to reach and stick there in the form of deposits.

The increased back pressure also allows the mass flow rate in the exhaust aftertreatment device 1 which is desirable in that it reduces the additional fuel demand for producing the rich air-fuel mixture.

The deposited soot particles can then during the normal regeneration of the diesel particulate filter 7 be eliminated. Furthermore, even a short-term high-temperature operation, a cleaning of the filter passage 9 be brought about.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102010026868 A1 [0005]
• EP 0205755 B1 [0006]
• WO 2009/065572 A1 [0007]
• US 2006/0059899 A1 [0008]
• EP 2405109 A2 [0008]

Claims (9)

Exhaust after-treatment device for an internal combustion engine, characterized in that it has a filter passage ( 9 ) having in the operation of the exhaust aftertreatment device temporally variable adjustable passage for the exhaust gas stream. Exhaust after-treatment device according to claim 1, characterized in that the filter passage ( 9 ) in the exhaust manifold of the internal combustion engine ( 2 ) is arranged. Exhaust after-treatment device according to claim 1 or 2, characterized in that the internal combustion engine is a turbocharger ( 3 ) with a compressor ( 3a ) and a turbine ( 3b ), wherein the filter passage ( 9 ) relative to the exhaust gas flow upstream of the turbine ( 3b ) is arranged. Exhaust after-treatment device for an internal combustion engine, the internal combustion engine having a turbocharger ( 3 ) with a compressor ( 3a ) and a turbine ( 3b ), characterized in that the exhaust aftertreatment device a filter passage ( 9 ), which with respect to the exhaust gas flow upstream of the turbine ( 3b ) is arranged. Exhaust after-treatment device according to one of the preceding claims, characterized in that it further comprises a control device, which is configured to block the passage of the filter passage ( 9 ) in dependence on a during operation of the internal combustion engine ( 2 ) set lambda value of the air-fuel mixture to vary. Exhaust gas aftertreatment device according to claim 5, characterized in that in this variation with a reduction of the lambda value of the air-fuel mixture, the passage of the filter passage ( 9 ) is reduced. Exhaust after-treatment device according to one of the preceding claims, characterized in that the filter passage ( 9 ) in at least one setting leaves the exhaust flow unaffected. Exhaust after-treatment device according to one of the preceding claims, characterized in that the filter passage ( 9 ) Has in their relative distance mutually adjustable Filtrationswandungen. Exhaust after-treatment device according to one of the preceding claims, characterized in that the filter passage ( 9 ) has at least partially a lamellar structure.

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