DE102008022998A1 - Exhaust gases cleaning device for exhaust section of e.g. V8-engine, has metering mechanism attached to counter flow area in such way that reducing agent is metered in counter flow area by metering mechanism - Google Patents

Abstract

The device has an exhaust gas channel provided with a set of partial gas strands (4, 5), which are in flow connection with each other in a preset counter-flow area such that exhaust gas flows (15, 16) are guided against each other in counter-flow. A metering mechanism e.g. metering valve (13), meters a reducing agent e.g. ammonia, in the exhaust gas channel in an area before a catalyzer arrangement. The metering mechanism is attached to the counter flow area in such a way that the reducing agent is metered in the counter flow area by the metering mechanism. An independent claim is also included for a method for operating a device for cleaning of exhaust gases of an internal-combustion engine.

Description

The The invention relates to a device according to the preamble of the claim 1 and a method for purifying exhaust gases according to the preamble of claim 15.

From the generic DE 10 2005 046 316 A1 a device for purifying exhaust gases for an exhaust system of an internal combustion engine with an exhaust duct is already known, which is formed double-flow, wherein a mixing member is provided which has two inlet openings and two outlet openings and which is inserted into the twin-flow exhaust system such that the four Openings of the mixing member are interconnected so that each inlet port is fluidly connected to both outlet ports. In this way it should be achieved that exhaust gases entering through an inlet opening in the mixing member, exit through both outlet openings of the mixing member again. Likewise, those exhaust gases which enter via the other inlet openings of the mixing member, should exit from the mixing member again via both outlet openings. In the mixing element itself, the individual exhaust gas streams flow partly in countercurrent to one another, so that such a mixing of the exhaust gas flows in the mixing member that emerges from the two outlet openings of the mixing element, a gas mixture, which is composed of the two individual gas streams. The term countercurrent is to be understood here as well as in the following in connection with the representation of the idea of the invention in a broader sense and expressly includes more or less, especially at a predetermined angle crossing exhaust gas streams or partial exhaust gas streams. In each of the partial exhaust strands of this twin-flow exhaust system, a catalyst arrangement is installed upstream of the mixing member, which comprises an oxidation catalyst and an SCR catalyst arranged downstream thereof. Furthermore, the catalyst arrangement comprises a urea supply device, which introduces urea into the respective exhaust gas line upstream of the SCR catalytic converter.

A Such exhaust system design is particularly suitable for Use in so-called V-engines, especially in so-called vertwisteten Exhaust systems in which the respective exhaust partial strands the cylinder banks meet in the rear of the vehicle and each lead to the outside on the opposite side, however, is component technology and thus also relatively expensive manufacturing technology and therefore expensive.

In contrast, It is an object of the present invention, an apparatus and a method for purifying exhaust gases for an exhaust line an internal combustion engine, in particular for a vertwisteten Exhaust line to provide, by means of the one Exhaust gas purification in a structurally simple way with high reliability can be carried out.

These Task is solved with respect to the device with the features of claim 1 and with respect to the method solved with the features of claim 15. Advantageous Further developments are the subject of the dependent claims.

According to claim 1 it is provided that the at least one metering device the Countercurrent region is assigned so that by means of this at least a metering device, the reducing agent, preferably a liquid, aqueous urea solution or Ammonia is, can be added in the countercurrent area. With a such structure according to the invention are the generated by the meeting of the exhaust or partial exhaust gas streams Turbulence and turbulence and thus, so to speak, the kinetic energy the mutually guided exhaust or partial exhaust gas mass flows exploited for a simple and reliable mixing the metered, in particular injected reducing agent in the respective exhaust gas mass flows or partial exhaust gas mass flows Achieve, where by an effective reduction in the exhaust gas mass flow contained nitrogen oxides is possible.

One particular advantage of this device according to the invention or process control is also that the dosing the reducing agent for the multiple partial exhaust gas strands only with a single metering device in a functionally reliable manner can be done so not for every sub exhaust line a separate metering device is required. Leave it the component cost and at the same time the control the individual Zudosiereinrichtungen required control effort significantly reduce.

As already described in the introductory part of the description, The term countercurrent should be understood here in a broader sense and expressly cross-flow situations or Conditions in which the exhaust gas mass flows or the partial exhaust gas mass flows below a predetermined Angle cross-shaped coincide and again under flow away from each other at a predetermined angle in a cross shape.

The flow connection in the countercurrent region can basically be designed in many ways, for. B. by a separate connection element or even by an integrally formed with the partial exhaust gas lines connecting region, each leading to this connection element or connection area is fluidically connected to and with this connecting element or connecting portion leading away Teilabgasstrangabschnitten. In this case, the connecting element or the connecting region is preferably formed by a connection element or common connection region common to all partial exhaust gas strands, which makes possible a particularly compact and space-consuming construction or arrangement, in particular in the underbody region or rear region of a motor vehicle. According to a specific embodiment for this purpose, it is particularly advantageous if the partial exhaust strands cross each other in a countercurrent region forming or having crossover area, in particular to form a vertwistete exhaust system, in which meet especially in conjunction with two exhaust gas strands these two gas strands from the rear of the vehicle and in each case based on their cylinder bank-side starting point on the opposite side open into the open.

According to one first concrete and particularly preferred invention Embodiment may be provided that the partial exhaust gas strands Geodetic over each other in the crossing area lying arranged and by means of a countercurrent region forming Connecting pipe are fluidly connected. Such a thing Connecting tube may particularly preferably by a spreader tube be formed, the z. B. in a dual function at the same time also installed for pressure equalization. For a little space-consuming and compact arrangement can also be provided here that the at least one metering device directly on the connecting pipe is arranged, and preferably in a middle region between the superposed Teilabgasstrangabschnitten. With Such a connecting pipe can also be realize a short mixing section, with which an effective treatment of the reducing agent can be achieved.

alternative but also in particular in conjunction with two Partial exhaust gas trains provided crossover areas be that form an x-shaped exhaust line section as a countercurrent region, in the two partial exhaust strands with a first strand section lead and from the two partial exhaust gas streams with a branch off second strand section. Such an X-shaped one Exhaust line section can either be integral by the two partial exhaust gas lines or by a separate component to which the two partial exhaust gas strands are to be connected accordingly to be trained. In connection with such a configuration, it is in particular from space engineering View of significant advantage when the partial exhaust strands at least in the crossover area substantially in one through the vehicle longitudinal axis and the vehicle transverse axis horizontal vehicle plane spanned lying.

to targeted influencing of the mixing section for the reducing agent forming countercurrent area can in this means be provided for flow control. In particular are Such agents in the mouth region of a connecting pipe between geodesically superimposed and cross over the sub-exhaust section of advantage. Such means for influencing the flow can z. B. by baffles, projections, bevels, edge geometries, in particular in the mouth area, be formed. With such Means can, for. B. in a particularly simple manner in an exhaust stream turbulence is generated or alternatively or additionally a desired partial exhaust gas flow in the countercurrent region be diverted. The latter is particularly associated with a connecting pipe between intersecting Teilabgasstrangabschnitten advantageous.

According to one particularly preferred embodiment of the invention is provided that the individual, in particular two partial exhaust gas strands from the internal combustion engine or a defined branch point after the internal combustion engine starting up to the countercurrent area and from the countercurrent area to at least inclusive the catalyst area designed essentially identically equipped and thus in the figurative sense identical in the manner of Similar parts are formed. With such an identical or symmetrical design of the exhaust strands are on simply way essentially identical flow conditions generated in the individual exhaust strands, so that in each Exhaust line achieved a substantially identical reduction performance can be. In particular in connection with such more or less identically designed exhaust gas strands or partial exhaust gas strands There is another special advantage: So here just needs in one of the partial exhaust gas trains a corresponding sensor, in particular a NOx sensor, be provided because of the in this Exhaust line arranged sensor or sensor devices results can be detected, which are essentially identical and therefore comparable with the conditions in the other partial exhaust gas strands are.

The Dosing device itself is preferably characterized by a with a control and / or regulating device coupled metering valve, wherein the control and / or regulating device prefers an already existing one Engine control unit is, so the metered addition is very good Controlled in the context of the anyway to be provided engine management can be regulated.

The Catalyst arrangement itself can by one in each Teilabgasstrang arranged catalyst may be formed, in particular an SCR catalyst is, with which under the so-called selective catalytic Reduction (SCR) a lean NOx conversion he follows. In principle, however, there would also be here the possibility of the individual partial exhaust gas strands after the countercurrent area to merge into a single-flow exhaust system and then the catalyst, in particular the SCR catalyst, in the single-flow Provide area. Basically, however, is the use the device according to the invention and process control preferred in connection with a vertwisteten exhaust system. The Reducing agent is preferably in liquid form, z. B. as an aqueous urea solution or in the form of ammonia. In principle, however, would also be one Metering of the reducing agent in finely atomized or gaseous Kind possible. In conjunction with a diesel internal combustion engine can be provided, a diesel particulate filter upstream or provide downstream of the counterflow region. Merely as an example can the countercurrent area between a diesel particulate filter and the catalyst arrangement of each partial exhaust gas line can be arranged. In the case of the downstream of the countercurrent region arranged Diesel particulate filter can also be diesel fuel as a reducing agent be used by means of the additional regeneration of the diesel particulate filter takes place.

Of another can be provided for even more effective mixing to use static mixers of the metered reducing agent, z. B. in the catalytic converter close range of the respective partial exhaust gas strands.

As already set forth, is the use of the invention Device and process management, especially in with several Cylinder banks equipped internal combustion engines of particular Advantage, z. B. in V-type engines such as V8, V10 or V12 engines or in conjunction with W motors or Boxer engines. This in particular also in conjunction with diesel internal combustion engines.

The The invention will be described in greater detail below with reference to a drawing explained.

It demonstrate:

1 2 is a schematic plan view of a vertical exhaust system for a diesel internal combustion engine designed as a V8 engine;

2 schematically an enlarged view of the detail A of 1 .

3 a schematic schematic diagram of the crossover of the 2 together with exemplarily arranged baffles, and

4 schematically an alternative embodiment of a crossover region according to the invention.

The 1 schematically shows a diesel internal combustion engine 1 , which is designed as a V8 engine. From each cylinder bank 2 . 3 branches off a partial exhaust line 4 . 5 so that thereby a double-flow exhaust system 6 is formed, wherein the two partial exhaust gas strands 4 . 5 in the area behind the internal combustion engine 1 are guided in the direction of the opposite cylinder bank or vehicle side and each other in a crossover area 7 cross over before the two partial exhaust strands 4 . 5 Then, in the direction of the internal combustion engine away again are guided substantially straight backwards and accordingly form a so-called vertwistete exhaust system.

As shown in the schematic representation of 1 it can be seen that the two partial exhaust gas strands 4 . 5 designed and constructed substantially identical in terms of shaping, curvature, cross-section and functional parts, ie that in each of the partial exhaust gas strands 4 . 5 at an identical point in the flow path of the partial exhaust gas strands 4 . 5 a substantially identically designed diesel oxidation catalyst 8th is arranged, in each case before the crossover area 7 a diesel particulate filter 9 downstream, which are also formed substantially identical, while in the region downstream of the crossover region 7 each a substantially identical SCR catalyst 10 in each of the partial exhaust strands 4 . 5 is arranged.

How this in particular the 2 can be seen, are the two partial exhaust gas lines 4 . 5 in the crossover area 7 geodetically one above the other and are by means of a countercurrent forming connecting pipe 11 , the countercurrent area explained in more detail below 12 trains, fluidically connected.

Like this one 2 can be further removed, is directly on the connecting pipe, preferably in the central region, between the superimposed partial exhaust gas strands 4 . 5 a metering valve 13 arranged, by means of the reducing agent 14 , z. As a liquid, aqueous urea solution or a diesel fuel, at predetermined times and in predetermined amounts by means of a corresponding control and / or regulating device can be added.

Now flow the two exhaust gas mass flows 15 . 16 from the respective cylinder banks 2 . 3 towards the crossover area 7 too, is determined by the arrangement of the connecting pipe 11 in the crossover area 7 in both partial exhaust gas lines 4 . 5 flows, such a flow effect causes that of the exhaust gas mass flows 15 . 16 , which are marked here on the one hand with dotted arrows and the other with solid arrows, each a partial exhaust gas mass flow 17 . 18 in the connecting pipe 11 flows in, so that these two partial exhaust gas mass flows 17 . 18 encounter in countercurrent. This results in the connecting pipe 11 Turbulence and turbulence, which is a very good distribution of one in the connecting pipe 11 metered reducing agent 14 in the partial exhaust gas mass flows 17 . 18 allow, so that they form a kind of carrier gas flow for the reducing agent and carry this with them when the respective partial exhaust gas mass flows 17 . 18 in the 2 are shown only very schematically and by way of example, again the connecting pipe 11 leave and in the partial exhaust strands 4 . 5 flow. Turbulence or formation of turbulence also occurs in this area, which results in a further distribution of the reducing agent in the downstream of the crossover region 7 lying Teilabgasstrangabschnitts the respective sub-exhaust line 4 . 5 causes.

How this in particular the one projected into the picture plane representation of the 2 displayed 3 can be removed, in the region of the mouth openings of the connecting pipe 11 in the partial exhaust gas lines 4 . 5 flow guide 19 . 20 be provided, for example ( 3 above) can cause a partial exhaust gas flow from the exhaust gas mass flow 15 is branched off. How this exemplifies the representation of 3 can be seen in the lower part, there provided the flow guide 20 In particular, such turbulence generation cause that also a partial exhaust gas mass flow 17 in the area of the connecting pipe 11 is sucked in, so to speak. Also, any combinations of these only exemplarily indicated flow guide 19 and 20 with each other are possible at any time.

In the 4 is schematically an alternative embodiment of a crossover region 7 shown, which has an x-shaped exhaust line section, in which the two partial exhaust gas strands 4 . 5 with a first strand section 22 . 23 and from which the two partial exhaust gas strands 4 . 5 with a second strand section 24 . 25 branch off again. The partial exhaust gas strands 4 . 5 lie in the crossover area 7 essentially in a plane defined by the vehicle longitudinal axis x and the vehicle transverse axis y vehicle horizontal plane. Immediately in the area of the x-shaped exhaust line section 21 is a metering valve 13 arranged, by means of which the reducing agent in the countercurrent region formed here by the immediate crossing region 12 can be sprayed or injected. Due to the turbulences in the countercurrent area 12 it comes to an effective mixing of the exhaust gas mass flows 15 . 16 , which in turn are characterized by arrows with solid lines and by dashed arrows, before these in turn loaded with reducing agent 14 the x-shaped exhaust gas flow section 21 leave.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• DE 102005046316 A1 [0002]

Claims (15)

A device for purifying exhaust gases for an exhaust system of an internal combustion engine having an exhaust duct, which is formed mehrflutig in a predetermined range and a plurality of partial gas strands, which are in a predetermined countercurrent flow in communication with each other so that at least a partial exhaust gas flow of the respective guided in the partial exhaust gas streams in Essentially in countercurrent to one another, and with at least one metering device, by means of which a reductant can be added to the exhaust gas duct in the region upstream of a catalyst arrangement, characterized in that the at least one metering device ( 13 ) the countercurrent area ( 12 ) is assigned so that by means of this the reducing agent ( 14 ) in the countercurrent region ( 12 ) is metered. Apparatus according to claim 1, characterized in that the flow connection in the countercurrent region ( 12 ) by one, preferably all partial exhaust gas strands ( 4 . 5 ) common, connecting element ( 11 ) or one, preferably all partial exhaust gas strands ( 4 . 5 ), which is flow-connected with this leading and with this away leading Teilabgasstrangabschnitten. Apparatus according to claim 1 or 2, characterized in that the partial exhaust gas strands ( 4 . 5 ) in each other in a countercurrent region ( 12 ) forming or having crossover area ( 7 ), in particular to form a vertwisteten exhaust system. Apparatus according to claim 3, characterized in that the partial exhaust gas strands ( 4 . 5 ) in the crossover area ( 7 geodetically arranged one above the other and by means of a countercurrent region ( 12 ) forming connecting pipe are fluidly connected. Apparatus according to claim 4, characterized in that the at least one metering device ( 13 ) directly on the connecting tube ( 11 ), preferably in a central region between the superimposed Teilabgasstrangabschnitten is arranged. Apparatus according to claim 2 and claim 3, characterized in that two partial exhaust gas strands ( 4 . 5 ) are provided in the crossover area ( 7 ) an x-shaped exhaust line section ( 21 ), which in turn forms a counterflow region ( 12 ), in which both partial exhaust gas strands ( 4 . 5 ) with a first strand section ( 22 . 23 ) and from which both partial exhaust strands ( 4 . 5 ) with a second strand section ( 24 . 25 ) branch off. Apparatus according to claim 6, characterized in that the partial exhaust gas strands ( 4 . 5 ) in the crossover area ( 7 ) lie substantially in one of the vehicle longitudinal axis (x) and the vehicle transverse axis (y) spanned vehicle horizontal plane. Device according to one of claims 1 to 7, characterized in that in the countercurrent region ( 12 ), in particular in the mouth region of a connecting tube ( 11 ) between geodetically superimposed and intersecting partial exhaust gas strand sections, at least one means ( 19 . 20 ) is provided for influencing the flow. Apparatus according to claim 8, characterized in that the at least one means ( 19 . 20 ) is formed to influence the flow through a baffle and / or an orifice-side edge geometry, which in an exhaust gas flow ( 15 . 16 ) Generates turbulences and / or the one partial exhaust gas flow ( 17 . 18 ) into the countercurrent area ( 12 ), in particular in a connecting tube ( 11 ) branches off between intersecting Teilabgasstrangabschnitten. Device according to one of claims 1 to 9, characterized in that of the internal combustion engine ( 1 ) or a defined branch point on the basis of the individual, in particular two partial exhaust gas strands ( 4 . 5 ) to the countercurrent area ( 12 ) and the countercurrent area ( 12 ) are designed, equipped and designed to be substantially identical at least up to and including the catalyst region. Device according to one of claims 1 to 10, characterized in that the catalyst arrangement by one in each Teilabgasstrang ( 4 . 5 ) arranged with optionally diesel particulate filter, in particular by an SCR catalyst ( 10 ), most preferably formed by a single SCR catalyst in the exhaust line or partial exhaust line. Device according to one of claims 1 to 11, characterized in that a particle filter downstream or upstream of the countercurrent region ( 12 ) is arranged, in particular in connection with a downstream of the countercurrent region ( 12 ) arranged particle filter diesel fuel is used as a reducing agent. Device according to one of claims 1 to 12, characterized in that a single metering device ( 13 ), which is preferably formed by a metering valve coupled to a control and / or regulating device, and / or a single nitrogen oxide sensor, which is assigned to one of the partial exhaust gas strands, is provided. Device according to one of claims 1 to 13, characterized in that the internal combustion engine ( 1 ) is equipped with a plurality of cylinder banks and / or that the internal combustion engine is a diesel internal combustion engine. Method for operating a device for cleaning exhaust gases of an internal combustion engine, in particular a device according to one of claims 1 to 14, with an exhaust duct, which is formed mehrflutig in a predetermined range and a plurality of countercurrent in a countercurrent flow in a countercurrent and / or countercurrent exhaust gas or partial exhaust gas mass flows, wherein the exhaust gas or partial exhaust gas mass flows at predetermined times a predetermined amount of a reducing agent is added, characterized in that the plurality of exhaust gas or partial exhaust gas mass flows ( 15 . 16 . 17 . 18 ) the reducing agent ( 14 ) in the countercurrent region ( 12 ) is controlled and / or regulated metered in and then with the reducing agent ( 14 ) mixed exhaust or partial exhaust gas mass flows ( 15 . 16 . 17 . 18 ) are present.