WO2008046681A1

WO2008046681A1 - Connecting unit for assembly in an exhaust strand of an internal combustion engine

Info

Publication number: WO2008046681A1
Application number: PCT/EP2007/058599
Authority: WO
Inventors: Rainer Haeberer; Matthias Horn; Michael Krause
Original assignee: Robert Bosch Gmbh
Priority date: 2006-10-20
Filing date: 2007-08-20
Publication date: 2008-04-24
Also published as: DE102006049531A1

Abstract

The invention relates to a connecting unit (100) for assembly in an exhaust strand of an internal combustion engine, having a tube piece (110) which has two end sides (116, 118), characterized in that the tube piece comprises an inlet (114) which leads from the outer side of the tube piece into the interior of the tube piece and which is designed to introduce additives into the tube piece, which additives originate from a metering module which can be connected to the tube piece. The invention also relates to an exhaust pipe having a connecting unit according to the invention.

Description

description

title

Connection unit for mounting in an exhaust system of an internal combustion engine

State of the art

Internal combustion engine vehicles produce nitrogen oxides and soot-containing exhaust gases. To remove the nitrogen oxides, a storage catalyst or an SCR catalyst is used. To reduce the soot particles, a particulate filter and an upstream oxidation catalyst are used. The exhaust gas flow leading to these catalysts is aftertreated by injecting various substances. While the storage catalyst and the oxidation catalyst receive an exhaust gas stream to which diesel has been added, a reducing agent, for example aqueous urea solution, is added to the exhaust gas stream leading to the catalyst in the SCR process.

In all exhaust aftertreatment systems, therefore, the exhaust gas discharge pipe for mixing the respective substance must be interrupted. Furthermore, individual, arranged in the exhaust stream mixer modules must be provided to distribute the respective added substance homogeneously in the exhaust gas. This ensures high efficiency and, in the case of reducing the soot particles, enables high durability of the oxide catalyst.

The prior art provides complete exhaust systems with suitable ports and discrete discrete mixer modules connected thereto. This leads to a high assembly cost and potential sources of error. Other systems include multiple discrete components that are expensive to assemble.

Advantages of the invention

The solution according to the invention has the advantage over the prior art that the construction and assembly are less expensive, less complicated and more compact. The installation the individual modules, such as the mixer and the dosing, is easier. Further, unlike the prior art, a single system may be used for all of the abovementioned exhaust gas manipulation systems. Consequently, there is a uniform manufacturing process for all the above systems, which costs and effort in production, installation and maintenance can be significantly reduced.

According to the invention, a connection unit is provided for mounting in an exhaust line of an internal combustion engine having a pipe section for interposition in the exhaust line, wherein the pipe section comprises a further access from the outside of the pipe section, which leads into the interior of the pipe section and is intended to additives in to introduce the pipe section coming from a dosing module. In an advantageous embodiment, the metering module can be connected directly to the connection unit via an adapter, via which the metering module can introduce the additives into the interior of the pipe section. Preferably, the adapter is integrally formed with the connection unit or non-positively, for example, plugged, connected to this separable. Advantageously, the connection unit comprises a metering valve and thus forms a metering module. Alternatively, the adapter for the metering valve is connected directly to the exhaust pipe or attached to a flange of the pipe section form fit. Preferably, the tube piece of the connection unit comprises a mixer, which is non-positively connected to the pipe piece, or which is formed integrally with the pipe piece, wherein the mixer is connected either before or after the access. The pipe section may also include two mixers arranged before and after access, respectively. The access is in this case arranged between the upstream and the downstream front end of the pipe section.

With these optional mixers, a more homogeneous distribution of the additive is achieved in the exhaust stream, at the same time no additional assembly steps are necessary because the two or the individual mixers are simultaneously introduced into the exhaust stream by the assembly of the pipe section.

The dosing module can be connected directly via the access or via a flange to the connection unit. The flange provided for the metering module can be provided in one piece with the connection unit, or can be frictionally connected thereto.

In a further advantageous embodiment, the connection unit according to the invention is connected to an exhaust pipe by being positively or non-positively connected to the exhaust pipe. Alternatively, the connection unit may be provided integrally with the exhaust pipe. In this way, further assembly steps can be save by the assembly unit for the dosing module is mounted by the assembly of the exhaust pipe at the same time.

For installation of the connection unit according to the invention, the exhaust pipe on flanges, which can be mounted on flanges, which in turn are provided at the two ends of the insertion unit to be inserted.

The connection unit according to the invention thus simplifies the assembly and can also be used universally for the two denitrification methods mentioned above and for the particle filter method.

drawings

The invention will be explained in more detail with reference to the drawings.

FIG. 1 shows the basic circuit diagram of an exhaust gas line to which additives are supplied.

Figures 2 - 4 show embodiments of the connecting unit according to the invention in longitudinal section.

variants

1 shows the schematic diagram of an exhaust system of an internal combustion engine 10, wherein the exhaust system additives are added. An engine 10 generates exhaust gases, which are fed via an exhaust pipe 14 to a downstream catalyst 12.

Depending on the application, this catalyst 12 may be a storage catalyst in which nitrogen oxides are stored. Here, the exhaust gas is transferred from the lean state to the rich state at regular time intervals by a special addition of fuel (eg diesel) into the exhaust gas. With the aid of this rich exhaust gas mixture, the nitrogen oxides (NO _x ) stored in the storage catalytic converter are decomposed. Therefore, in this method, feed 16 supplies additional diesel fuel to the exhaust gas stream. In an alternative method, the pollutant NO _x with the aid of reducing agents (for example, aqueous urea solution, gaseous ammonia, ..., solid carbamate) is reduced to N ₂ and H ₂ O. This process is called SCR (Selective Catalytic Reduction). In this case, the reducing agent is injected into the exhaust gas before it is fed to a special SCR catalytic converter 12. By this method, the off-catalyst exhaust gas 20 is purged of nitrogen oxides. One Another field of use according to the invention is the reduction of the particles in diesel exhaust gas, for which purpose a particle filter is used, in which the particles are accumulated and burnt off at regular time intervals. This regenerates the particle filter. One method of burning off the particulate filter is to add fuel into the exhaust gas 14 after the engine 10. This fuel oxidizes in the oxidation catalyst 12 upstream of the particulate filter and thus produces a high temperature for burning off the particulate matter collected in the particulate filter. The downstream Partikelfϊlter (not shown) thus receives from the oxidation catalyst 12, the purified of this exhaust 20th

These three exemplary exhaust aftertreatment methods have in common that a medium is added to the exhaust gas of the internal combustion engine 10 via a device 14, 16, which leads to a change in the exhaust gas in a subsequent device 12 (catalyst, downstream Partikelfϊlter). Preferably, to increase the durability of the oxidation catalyst and the efficiency of the SCR catalyst, the additive is not only supplied to the exhaust stream, but also mixed with it. As a result, the added medium is distributed homogeneously over the cross section of the device 12 (catalyst, particle filter).

For simplified assembly and retrofitting, according to the invention a feeder 16 is provided for the respective medium to be added, wherein the feeder is arranged to be connected to a metering module for the medium to be added. For this purpose, the erfϊndungsgemäße connection unit is provided, which can be mounted in the exhaust system, and comprising a piece of pipe with a lateral access to which the dosing module can be connected.

FIG. 2 shows a connection unit 100 according to the invention, which comprises a pipe section 110. The pipe section 110 serves as an exhaust pipe and leads exhaust gases 112, which come from an internal combustion engine (not shown). On an outside of the pipe section, an access 114 is provided which leads from the outside of the pipe section 110 into the interior of the pipe section. By means of this access additives can be introduced into the pipe section 110. These additives come from a metering module (not shown) which can be connected to the pipe section 110. The pipe section has a first front end 116 and a second front end 118. Preferably flanges (not shown) are arranged at these front ends 116, 118, with which the connection unit can be mounted in an existing pipe system of an exhaust line. According to one embodiment, the access 114 comprises a port 124 with which the dosing module can be connected directly or via an adapter 122. In FIG. 2, the connection therefore comprises an outwardly directed connection, which serves as flange 122 is trained. An adapter 122 can be connected to this flange, wherein the adapter preferably also comprises a flange which is designed to match the feed line of a metering module or additive delivery system. Instead of the flange connection shown, other positive or non-positive connections can be used which are suitable for connecting the metering valve to be connected to the access 114. For example, plug, screw or bayonet locks can be used.

The adapter 122 preferably has a passage into which a metering valve 120 can be introduced. In a preferred embodiment, the metering valve is positively or positively connected to the adapter, for example via a snug fit or one of the above-mentioned non-positive connection variants.

In a preferred embodiment, the tubing includes a first mixer 130 located downstream of the access 114 within the tubing. Thus, the first mixer 130 is disposed between the access 114 and the second front end 118. Alternatively or additionally, another mixer 132 may be provided in the pipe section upstream of the access 114. The second mixer is thus arranged between the first front end and the input 114. The mixers can each be firmly connected to the pipe section. The first mixer 130 is a separate mixer arranged between the one metering valve 120 and the downstream device 140, for example one of the above-mentioned catalysts, in the exhaust gas stream within the tube piece. This separate mixer distributes the injected medium homogeneously over the cross section and thus improves the functioning of the downstream catalyst. The second mixer is preferably a static mixer located in front of a metering position. This generates turbulences even before metering through the feed 114, whereby the uniform distribution of the injected medium over the pipe cross-section is further improved.

FIG. 3 shows a cross-sectional view of a further preferred embodiment of the connection unit according to the invention. The connection unit 200 comprises a pipe section 210 which carries an exhaust gas flow 212. The connection unit comprises an access 214, which leads from the outside of the pipe section 210 into the interior of the pipe section 210. By means of this access it is possible to introduce additives into the pipe section. The connected to the access adapter 222 is integrally connected to the access 214, ie, the connection 224 between adapter 222 and access 214 or pipe section 210 is carried out in that the adapter is integral with the access and the pipe section 210. Thus, the connection unit comprises the pipe section and the Adapter, and differs from the embodiment shown in Figure 2, characterized in that the tube piece in Figure 2 comprises a flange 124 which is suitable for connection of an adapter 122.

As in the embodiment shown in Figure 2, the adapter 222 comprises a passage 220 into which a metering valve can be introduced. Preferably, the metering valve is connected via a frictional or positive connection with the adapter 222.

As in the embodiment shown in Figure 2, the exhaust stream 212 passes through a first face end, i. Eintrittssstirnende, 216 in the pipe section, is interspersed with substances, which are introduced via the access 214, and occurs over a second front end, i. Ausgangsstirnende, 218 again from the pipe section. The first face end operates as an exhaust flow inlet and the second face end 218 operates as the exhaust flow outlet. Connected to the connection unit 200 according to the invention is a downstream device 240, for example a catalyst, preferably via flanges which are attached to one or both ends and to a corresponding connection of the catalyst. Alternatively, the connection unit may be connected by one-piece design with the exhaust line with this. In one embodiment, the exhaust gas supply connected to the first front end 216 and / or the downstream catalytic converter 240 and the exhaust gas supply line leading to it are formed integrally with the connection unit according to the invention. Alternatively, flange or other non-positive or positive releasable connections for mounting the connection unit can be used, for example, bayonet locks, screw or plug-in connections with fit.

Preferably, the embodiment illustrated in Figure 3 includes first and second mixers disposed in the length of tubing before and after access 214, respectively, in the cross-section of the tubing. Alternatively, the embodiment shown in Figure 3 includes only one of these mixers.

4 shows a longitudinal section through a further embodiment of the connection unit 300 according to the invention. The connection unit 300 comprises a tube piece 310 which comprises an access 314. The access 314 is connected via a one-piece design with an adapter 322 having a passage into which a metering valve 320 can be releasably inserted.

In the cross section of the pipe section, an exhaust gas flow 312 is guided, which first passes through a static mixer 332 before the dosing position, ie before the access 314. This static mixer 332 creates turbulence. As a result, the substance supplied via the metering valve 320 is homogeneously mixed with the exhaust gas flow 312. After access 314, the exhaust stream 312 passes through a separate mixer 330, which is located after the injection position, ie after the access 314, in the cross section of the pipe section 310. Thereby, the homogenization of the mixture is provided, which consists of the exhaust gas 312 and the supplied substance. Alternatively, the connection unit may be equipped only with the separate mixer 330.

The mixture thus produced is supplied via a further connection to the device 340, for example one of the abovementioned catalysts or particle filters. The connection between connection unit 300 and the downstream device 340 can be provided via releasable non-positive or positive connections. Alternatively, the tube piece is made integral with the feed leading to the downstream device 340. In the same way, the connection between the motor and the pipe section can be in one piece, or designed to be non-positive or positive, for example via a flange, a screw connection or a bayonet lock. In a further preferred embodiment, the metering valve 320, the adapter 322 and the pipe section 310 are integrally formed, wherein the metering valve has a connection leading to the outside. This connection is set up to be connected to a dosing module, for example via a detachable connection, for example a flange connection, screw connection, bayonet closure or a plug connection with a snug fit. According to a further, not shown embodiment, the metering valve is integrally formed in the adapter, which in turn is made in one piece with the pipe section and the access to the interior of the pipe section.

Advantageously, the connection unit is comprised of an exhaust pipe, wherein the connection unit is connected in one piece, positive or non-positive with the exhaust pipe.

Claims

claims

A connection unit (100, 200, 300) for mounting in an exhaust line of an internal combustion engine, comprising a pipe section (110, 210, 310) having two front ends, characterized in that the pipe section (110, 210, 310) has an access ( 114, 214, 314) which leads from the outside of the pipe section (110, 210, 310) into the interior of the pipe section (110, 210, 310) and which is adapted to add additives into the pipe section (110, 210, 310). which originate from a dosing module which can be connected to the pipe section (110, 210, 310).

The connection unit (100, 200, 300) according to claim 1, wherein the pipe section (110, 210, 310) is provided at one or both ends (116, 216, 316, 118, 218, 318) with connecting flanges.

The connection unit (100, 200, 300) according to claim 1, further comprising an adapter (122, 222, 322) arranged to connect the dosing module directly to the connection unit (100, 200, 300) via the access (114, 214, 314), wherein the adapter (122, 222, 322) is integrally formed with the connection unit (100, 200, 300) or is non-positively connected thereto.

The connection unit (100, 200, 300) according to claim 1, wherein the connection unit (100, 200, 300) comprises a flange (124) adapted for mounting the adapter (122, 222, 322).

5. connecting unit (100, 200, 300) according to claim 1, wherein the pipe section (110, 210, 310) at least one in the pipe section (110, 210, 310) provided mixer (130, 132, 330, 332), the non-positively connected to the pipe section (1 10, 210, 310) or integrally formed with pipe section (1 10, 210, 310).

6. Connection unit (100, 200, 300) according to claim 1, comprising a mixer (130, 330) provided in the pipe section (110, 210, 310) and arranged between the downstream front end (118, 318) and the access (1 14, 214, 314), and / or with a mixer (132, 332) provided in the pipe section (110, 210, 310) and arranged between the upstream front end (116, 316) and the access (1 14, 214, 314). is arranged.

7. connection unit (100, 200, 300) according to claim 1, wherein the connection unit (100, 200, 300) directly via the access (114, 214, 314) is connectable to the dosing.

The connection unit (100, 200, 300) according to claim 1, wherein the connection unit (100, 200, 300) is directly frictionally connected directly to a dosing module flange (124) or integrally connected to a dosing module flange (124) Dosing module flange (124) is set up for mounting the dosing module.

9. exhaust pipe with a connection unit (100, 200, 300) according to one of the preceding claims, wherein the connection unit (100, 200, 300) is integrally, positively or non-positively connected to the exhaust pipe (110, 210, 310).