WO2018015148A1

WO2018015148A1 - Mixer device for an exhaust gas aftertreatment system of a motor vehicle, exhaust gas aftertreatment system, and motor vehicle

Info

Publication number: WO2018015148A1
Application number: PCT/EP2017/066718
Authority: WO
Inventors: Volker BECHER; Matthias Kruse
Original assignee: Robert Bosch Gmbh
Priority date: 2016-07-22
Filing date: 2017-07-05
Publication date: 2018-01-25
Also published as: DE102016213409A1

Abstract

The invention relates to a mixer device (1) for an exhaust gas aftertreatment system of a motor vehicle, having a housing (2) which has a lateral wall (3), a first end face (4) and a second end face (5), the first end face (4) having an inlet opening (7) and the second end face (5) having at least one outlet opening (17) for an exhaust gas flow of an internal combustion engine, and an injection opening (12) for an in particular liquid exhaust gas aftertreatment agent being formed in the lateral wall (3). According to the invention, the second end face (5) has an end wall which has an outlet funnel (9), which extends in a tapering manner into the housing (2).

Description

Description title

Mixer device for an exhaust aftertreatment system of a motor vehicle, exhaust aftertreatment system and motor vehicle

The invention relates to a mixer device for a

Exhaust after-treatment system of a motor vehicle, comprising a housing, which has a jacket wall, a first end face and a second end face, wherein the first end face an inlet opening and the second end face a

Are associated with outlet for an exhaust gas flow, and wherein on the jacket wall an injection port for a particular liquid

Exhaust gas aftertreatment agent is formed.

Furthermore, the invention relates to an exhaust aftertreatment system for a

Motor vehicle, with a catalyst and a catalyst upstream of the mixer device.

Furthermore, the invention relates to a motor vehicle with such

Aftertreatment system.

State of the art

Exhaust aftertreatment systems and mixer devices are known in the art. For the reduction of pollutants in the exhaust gas of

Internal combustion engines in motor vehicles are used catalysts, through which the exhaust gas stream of the internal combustion engine is passed, so that the exhaust gas in the catalyst reacts to reduce pollutants. In which

So-called SCR process (SCR = selective catalytic reduction) is added to the exhaust gas as exhaust aftertreatment agent, an aqueous urea solution upstream of a catalyst, which together with the exhaust gas in the catalyst reacts to remove nitrogen oxides from the exhaust gas. So that the catalyst is optimally utilized, it is known this one

Vorzuschalten mixer device which advantageously mixes the exhaust gas with the injected exhaust gas aftertreatment agent and the catalyst such that it as evenly as possible from the

Exhaust gas aftertreatment agent-exhaust gas stream mixture is applied. So mixer devices are known, which put the exhaust gas flow in a swirling motion, for example by a spiral course, and on its jacket wall having an injection port through which the

Exhaust gas treatment agent in the direction of a secant of the cylindrical

Housing is injected.

It turns out, however, that without additional measures, such as the increase of a back pressure or implementation of a local excess ammonia by means of an ammonia slip catalyst, the currently permissible

Limits for pollutants in the exhaust are barely reachable. One reason for this is the uneven loading of the catalyst with respect to the concentration of the exhaust aftertreatment agent and the flow rate.

Disclosure of the invention

The mixer device according to the invention with the features of claim 1 has the advantage that the loading of the catalyst by the

In particular, the catalyst is uniformly charged with respect to the concentration of the exhaust aftertreatment agent and the flow velocity. This is achieved by the mixer device according to the invention in that the second

End face has an end wall, which has an outlet opening forming outlet funnel, which extends into the housing in a tapered manner.

The effluent exhaust stream with the contained therein

Exhaust aftertreatment agent is thus guided on exit from the mixer device along the outlet funnel. In the outflow direction, the discharge funnel expands, so that the exhaust gas flow due to the

Funnel effect distributed over a larger area and thus an improved Uniform distribution guaranteed. This applies both to the exhaust gas flow and to the exhaust gas aftertreatment agent entrained with the exhaust gas flow. The discharge hopper is arranged centrally or coaxially in the housing according to a first embodiment. According to a further embodiment, it is preferably provided that the outlet hopper is arranged off-center or eccentrically on the second end face of the housing. This is particularly advantageous if in the housing at least one

Arranging is arranged, which extends spirally to the

Exhaust gas flow to apply a twist.

According to a preferred embodiment of the invention, it is provided that the outlet funnel extends to the shell wall of the housing or almost to the shell wall. Thus, the maximum possible opening width of the outlet funnel is guaranteed and correspondingly an improved

Equal distribution allows.

Furthermore, it is preferably provided that in the outlet funnel a corresponding with the outlet funnel air guide is inserted such that between outlet funnel and air guide a funnel-shaped

Outlet channel is formed. The exhaust gas flow or the exhaust gas exhaust gas aftertreatment agent mixture is forced to follow the funnel shape by the air guide element, so that the desired uniform distribution is reliably ensured. The fact that the air guide is formed corresponding to the outlet funnel, resulting in a funnel-shaped ring

Outlet channel, the opposite side walls parallel or nearly parallel to each other. It is preferably provided that the air guide element encloses a smaller angle with a central axis than the outlet funnel, so that the funnel-shaped outlet channel in

Flow direction widens, causing the admission of the

downstream catalyst further improved.

The air guide element preferably has a V-shaped longitudinal section for this purpose. The air guide element is thus formed closed at its pointed, the outlet funnel end and ultimately conically shaped, in particular such that the outlet opening facing the funnel of the air guide element, seen in longitudinal section, projects into the flow channel leading to the outlet funnel. The flow behavior is thereby further improved. The top can also be rounded.

According to a preferred embodiment of the invention, it is provided that the air guide element has a collar which extends up to the jacket wall of the housing and has at least one outlet opening. Through the collar, the air guide element is held in particular on the housing. For this purpose, the collar is preferably attached to the shell wall, for example screwed, clamped, welded, glued or the like. The at least one

Exhaust opening ensures that the mixed with exhaust aftertreatment agent exhaust stream selectively leaves the mixer device and can leave. Otherwise, the air guide is in particular closed or free of openings designed to selectively guide the exhaust stream.

According to a further embodiment of the invention, it is preferably provided that the air guide element is designed as a perforated plate with a plurality of outlet openings. Due to the design as a perforated plate, the air-guiding element also has outlet openings in the region of the funnel shape or in the V-shaped longitudinal section, through which the exhaust gas flow can escape from the mixer device. As a result, the back pressure of the mixer device is reduced and can be optimally adapted to the boundary conditions of the exhaust aftertreatment system.

The contours of the outlet openings are preferably symmetrical or

asymmetrically formed. Additionally or alternatively, the outlet openings are arranged or formed distributed symmetrically or asymmetrically on the air guide element. The exact configuration is particularly dependent on the axial depth of the outlet funnel, the number of

Outlet openings and the actual exact shape of the outlet funnel and other factors, such as space, required sales, or manufacturability conditionally.

Furthermore, it is preferably provided that the inlet opening in the first end face, in particular in a first end wall of the first end face is trained. In particular, the inlet opening is formed off-center, in order to improve the swirl effect in the exhaust gas flow.

The exhaust aftertreatment system according to the invention with the features of claim 9 is characterized by the mixer device according to the invention. This results in the already mentioned advantages.

The motor vehicle according to the invention is characterized by the exhaust aftertreatment system according to the invention. Here too, the advantages already mentioned arise.

Further advantages and preferred features and combinations of features emerge in particular from the previously described and from the claims.

In the following, the invention will be discussed with reference to the drawing. Show this

Figure 1 shows a first embodiment of an advantageous

Mixer device for an exhaust aftertreatment system of a motor vehicle and

Figure 2 shows a second embodiment of the mixer device, each in a longitudinal sectional view.

1 shows a mixer device 1 of an exhaust gas aftertreatment system of a motor vehicle in a simplified longitudinal sectional view. The

Mixer device 1 has a substantially cylindrical housing 2, which has a jacket wall 3, which extends from a first end face 4 to a second end face 5 in the flow direction of an exhaust gas stream. The end face 4 in this case has a first end wall 6, in which an inlet opening 7 is formed eccentrically, through which an exhaust gas flow in the

Mixer device 1 is initiated, as shown by arrows in Figure 1. In the housing at least one air guide element 8 is designed in the form of a guide wall, which in particular spirals the exhaust gas flow through the housing 2, so that the exhaust gas stream receives a twist. The end face 5 of the housing 2 has an outlet funnel 9, which extends into the housing 2 in a tapered manner, so that it has a smaller inside width in the housing 2 than at the end face 5 facing the end. At its narrowest point, the outlet funnel 9 has an axial opening 10, through which the exhaust gas flow can escape from the housing 2. The outlet funnel 9 is itself formed continuously closed so that it leads out the exhaust gas flow from the housing 2.

On the jacket wall 3, a nozzle 11 is also formed in particular for receiving a metering valve or injection valve by a

Injection opening 12 opens into the housing 2. Through the injection port 12 is thus liquid in particular by the injection valve

Exhaust gas aftertreatment agent, preferably an aqueous urea solution, into the housing 2 and injected into the exhaust gas stream.

Due to the advantageous embodiment of the mixer device 1 it is achieved that initially the liquid exhaust gas aftertreatment agent is advantageously mixed / mixed with the exhaust gas stream. This is due to the swirl of the exhaust gas flow and the effecting by the guidance of the exhaust gas flow long

Flow path of the exhaust gas flow through the housing 2 achieved. The exhaust gas stream offset with the exhaust gas aftertreatment agent initially leaves the housing 2 through the axial opening 10 and follows the outlet funnel 9, which distributes the exhaust gas flow over a larger area through the funnel effect and thus a downstream catalyst, in particular S CR catalyst, with the exhaust gas flow and therein exhaust gas aftertreatment agent contained in particular evenly applied.

Figure 2 shows an advantageous development of the mixer device 1 according to a second embodiment. 1 already known elements are provided with the same reference numerals, so that reference is made to the above description. In the following, the differences should be dealt with essentially. In contrast to the previous embodiment, it is provided that the outlet funnel is assigned an air guide element 13. The air guide element 13 is formed corresponding to the outlet funnel 9, so that it is V-shaped in a longitudinal section 14 and projects into the outlet funnel 9, so that between the air guide element 13 and the

Outlet funnel 9 a funnel-shaped outlet channel 15 is formed, through which the exhaust stream is at least substantially passed. At its end facing the end face 5, the air guide element 13 has a collar 16, which extends radially outwards as far as the jacket wall 2 and is fastened thereto. For attachment, the collar 16 is welded to the jacket wall 2, for example, soldered or glued.

Expediently, at least one outlet opening 17, preferably a plurality of outlet openings 17, is formed in the collar 16, through which outlet the exhaust gas stream can exit from the mixer device 1 and be supplied to the catalytic converter. Conveniently, a plurality of outlet openings 17 are arranged uniformly distributed over the collar 16.

In particular, the air guide element 13 is formed as a perforated plate, so that outlet openings 17 are also located in the V-shaped region of the air guide element, as shown in Figure 2, through which the exhaust gas flow can escape. Preferably, the outlet openings 17 are uniformly distributed / arranged, in particular distributed symmetrically over the air guiding element 13.

Alternatively, the outlet openings 17 may also be arranged asymmetrically. The outer contour of the respective outlet opening 17 is preferably formed symmetrically or asymmetrically. By the likewise funnel-shaped

Design of the air guide element 13 with the outlet openings 17, the back pressure of the mixer device 1 is increased and at the same time ensures an advantageous gas flow from the exhaust gas flow, which uniform loading of the downstream SCR catalyst with the

Ensured exhaust stream and the exhaust aftertreatment agent contained therein. As a result, a favorable exhaust aftertreatment result is achieved in a simple and cost-effective manner.

Claims

claims

1. Mixer device (1) for an exhaust aftertreatment system of

Motor vehicle, comprising a housing (2) having a jacket wall (3), a first end face (4) and a second end face (5), wherein the first end face (4) an inlet opening (7) and the second end face (5) at least an outlet opening (17) for an exhaust gas stream of an internal combustion engine is assigned, wherein on the casing wall (3) an injection opening (12) for a particular liquid exhaust aftertreatment means is formed, characterized in that the second end face (5) has an end wall which is an outlet funnel (9) which tapers into the housing (2).

2. Mixer device according to claim 1, characterized in that extending the outlet funnel in the flow direction up to the jacket wall (3) or almost to the shell wall (3) of the housing (2).

3. Mixer device according to one of the preceding claims, characterized in that in the outlet funnel (9) with the outlet funnel (9) corresponding air guide element (13) is arranged such that between the outlet funnel (9) and the air guide element (13)

funnel-shaped outlet channel (15) is formed.

4. Mixer device according to one of the preceding claims, characterized in that the air guide element (13) has a V-shaped

Longitudinal section (14).

5. Mixer device according to one of the preceding claims, characterized in that the air guide element (13) has a substantially radially extending collar (16) which extends up to the jacket wall (3) of the housing (2) and at least one outlet opening ( 17) for the exhaust gas stream.

6. Mixer device according to one of the preceding claims, characterized in that the air guide element (13) is designed as a perforated plate with a plurality of outlet openings (17).

7. Mixer device according to one of the preceding claims, characterized in that the contours of the outlet openings (17) are formed symmetrically or asymmetrically, and / or that the outlet openings (17) are arranged distributed symmetrically or asymmetrically.

8. Mixer device according to one of the preceding claims, characterized in that the inlet opening 7 is formed on the first end face (4).

9. exhaust aftertreatment system for an internal combustion engine of a

Motor vehicle, with at least one catalyst and a catalyst upstream of the mixer device (1), characterized by the

Formation of the mixer device (1) according to one or more of claims 1 to 8.

10. Motor vehicle with an exhaust gas aftertreatment system according to claim 9.