DE102020100165A1 - Exhaust aftertreatment device with improved temperature distribution - Google Patents

Abstract

The present invention relates to an exhaust gas aftertreatment device (1), in particular for motor vehicles (14), with a housing (2), at least one inlet opening (3) and at least one outlet opening (4), with at least one of a gaseous in the housing (2) Fluid is arranged in a flow direction (5) through which the exhaust gas aftertreatment component (11) can flow, and a heating device (10) for heating the exhaust gas aftertreatment component (11). It is characterized in that a fluid guide device (6) is provided upstream of the exhaust gas aftertreatment component (11) in the flow direction (5), the fluid guide device (6) being designed to equalize a fluid flow of the gaseous fluid.

Description

The present invention relates to an exhaust gas aftertreatment device, in particular for motor vehicles, with a housing, at least one inlet opening and at least one outlet opening, with at least one exhaust gas aftertreatment component through which a gaseous fluid can flow in one flow direction being arranged in the housing, as well as a heating device for heating the exhaust gas aftertreatment component.

In the prior art, exhaust gas aftertreatment devices are already known in a wide variety of embodiments. The task of exhaust gas aftertreatment devices of this type is to subject exhaust gases that arise in an internal combustion engine to a specific treatment before they are released into the environment. For example, diesel particles contained in the exhaust gases can be filtered out using diesel particle filters.

The aim is regularly to increase the efficiency of the exhaust gas aftertreatment devices in order to be able to meet further reduced pollutant limit values that will apply in the future. One problem here is that the (catalytic) exhaust gas aftertreatment devices only achieve a sufficiently high degree of efficiency and work efficiently from a certain temperature, the so-called “light-off temperature”.

A known possibility of bringing an exhaust gas aftertreatment device to the required temperature is to use an additional heater. By means of such an additional heater, the temperature of the exhaust gas can be increased in a noteworthy manner. In addition to the temperature of the exhaust gas, the temperature of the exhaust gas aftertreatment device is also increased in direct or indirect heating, so that its efficiency, for example after a cold start, increases more quickly, so that an effective exhaust gas aftertreatment can take place.

The disadvantage of the known solutions is that the additional heaters used must have relatively high heating capacities in order to achieve satisfactory results. At the same time, it is difficult to reliably control these relatively high heating outputs, given the frequently strongly changing exhaust gas flows, in order to avoid damage to the exhaust gas aftertreatment devices due to overheating. In the case of low mass flows of the exhaust gas, it can happen that the heat generated by means of the additional heater leads to a melting of the materials used in the exhaust gas aftertreatment device.

The object of the present invention is therefore to at least partially solve the problems arising from the prior art. In particular, the reliability of the exhaust gas aftertreatment device should be increased and the energy expenditure required for heating should be reduced as far as possible.

To solve these problems, an exhaust gas aftertreatment device with the features according to patent claim 1 is proposed.

Advantageous further developments are the subject of the dependent claims. The features listed individually in the patent claims can be combined with one another in a technologically sensible manner and can be supplemented by explanatory facts from the description and / or details from the figures, with further design variants of the invention being shown.

Contributing to this is an exhaust gas aftertreatment device that has a housing, at least one inlet opening and at least one outlet opening, with at least one exhaust gas aftertreatment component through which a gaseous fluid can flow in one flow direction being arranged in the housing, as well as a heating device for heating the exhaust gas aftertreatment component. A fluid guide device is provided upstream of the exhaust gas aftertreatment component in the direction of flow, the fluid guide device being designed to equalize a fluid flow of the gaseous fluid.

In the proposed exhaust gas aftertreatment device, the exhaust gases present as gaseous fluids first flow into a housing of the exhaust gas aftertreatment device via an inlet opening. The gaseous fluids usually come from an internal combustion engine, such as a piston-driven internal combustion engine. The gaseous fluids can optionally be delivered to the exhaust gas aftertreatment device immediately after exiting the internal combustion engine or indirectly by first passing the gaseous fluids through an exhaust gas turbocharger before they are then fed to the exhaust gas aftertreatment device.

Within the exhaust gas aftertreatment device, the gaseous fluids encounter a fluid guide device which is designed to equalize a fluid flow of the gaseous fluid. In this context, equalizing means to homogenize the fluid flow by considering a cross-section that is as similar as possible in all areas of this cross-section Flow velocities and mass flows of the gaseous fluids to be treated are present.

For this purpose, the fluid guide device is arranged inside the exhaust gas aftertreatment device upstream of the exhaust gas aftertreatment component through which a flow can flow.

The cross section of the exhaust gas aftertreatment device to be considered corresponds to the normal plane to the direction of flow of the fluids flowing through in the area before, in or immediately after the exhaust gas aftertreatment component.

For this purpose, the fluid guide device is preferably equipped with at least one guide plate, a perforated disk or a flow grille. Basically, the fluid guide device has the task of reducing or even preventing a main flow in the middle of the cross section from developing with higher flow velocities, while edge flows with lower flow velocities develop in the edge regions of the cross section. The fluid guide device effectively counteracts this formation of main and secondary flows, which can otherwise be observed. It is of great importance here that the fluid guide device does not aim to mix the fluids, but rather to make the fluid flow more uniform. For example, within the scope of the equalization, it is not necessary to pass partial flows of the fluid crosswise for thorough mixing, which would increase the flow resistance. Rather, the present fluid guide device can be designed in such a way that it achieves the desired effect of homogenizing / equalizing the fluid flow with a relatively low flow resistance and without mixing.

If, for example, a flow grid is arranged upstream of an electrically operated heating device as a fluid guide device, the gaseous fluid flowing through strikes the heating device with a significantly improved uniform distribution of the fluid flow. Both the heating device and the fluid-conducting device preferably extend over the entire cross section of the exhaust gas aftertreatment device. The flow grille causes the fluid flowing through the housing to flow through the housing in all areas of the cross section at approximately the same speed. As a result, the heat input from the heating device to the fluid can then also take place particularly homogeneously. The heat input from the heating device to the fluid usually takes place by convection.

The proposed solution thus creates, among other things, the prerequisites for the maximum required heating power of the heating device to be able to be reduced. For example, while so far particularly high flow velocities of the flowing fluid and thus also particularly high mass flows have occurred in the middle of the cross section in the main flow forming there, this is no longer the case with the present invention. The particularly high mass flows made it necessary in the past to design the maximum heating output of the heating device for precisely these high mass flows in order to ensure that the fluid is heated to the required temperatures. With the present invention, on the other hand, these maximum flow velocities are now reduced and evened out over the entire cross section.

This makes it possible to design the heating device with a lower heating power than was previously the case, since no power reserve needs to be taken into account for over-supplied zones.

In addition, the equalization of the mass flows and flow velocities over the cross section has the further advantage that no undersupplied zones arise in which no or only very small mass flows of the fluid to be cleaned occur. Such undersupplied zones can lead to the fact that in these areas the heat input of the heating device into the fluid does not take place to the required extent and this can lead to overheating or destruction of the heating device. With the avoidance of undersupplied zones by the present invention, the operational safety and reliability of the exhaust gas aftertreatment device are significantly improved.

Another technical aspect that is improved relates to the determination of the actual exhaust gas mass flow within the exhaust gas aftertreatment device. While this was previously very difficult to determine due to the inhomogeneous distribution of the flow velocities and thus also the mass flows over the cross-section, with the present invention, due to the homogeneity of the mass flow, conclusions can now be drawn very easily from the total exhaust gas mass flow to the exhaust gas mass flow in the individual areas. This is an important aspect, for example, for regulating the heating power of the heating device, because this is greatly simplified.

Finally, the improved heating of the flowing fluid also ensures improved efficiency of the exhaust gas aftertreatment, because both the fluid and the exhaust gas aftertreatment component are optimally heated to the required temperature over the entire cross section, which means that the effective exhaust gas aftertreatment almost simultaneously over the entire area Can use cross-section of the exhaust aftertreatment component. In particular, a so-called breakthrough of pollutant emissions can also be effectively prevented by means of the present invention if the exhaust gas aftertreatment component, for example after a cold start of the internal combustion engine, does not initially have the required temperature.

It is particularly advantageous if the exhaust gas aftertreatment device is designed in such a way that the fluid guide device is arranged downstream of an exhaust gas turbocharger.

A fluid guide device which is arranged downstream of an exhaust gas turbocharger and upstream of an exhaust gas aftertreatment component can contribute in a special way to the homogenization of the fluid flow. In principle, the fluid guide device can be used wherever an inhomogeneous flow occurs upstream of a heating device and upstream of an exhaust gas aftertreatment component. Since particularly inhomogeneous flows occur downstream of the exhaust gas turbocharger, it is advantageous to arrange the fluid guide device there and to homogenize the fluid flow at this point.

It is also particularly advantageous if the heating device is arranged downstream, upstream or within the exhaust gas aftertreatment components. In principle, different types of heating devices can be used to heat the fluid flow and the components of the exhaust gas aftertreatment device. This can be done, for example, by means of an auxiliary heater, in which fuel is burned with a burner to generate heat. An embodiment is particularly preferred in which the heating device is designed with an electrical heater. Such an electrical heater can be controlled safely and easily and is also particularly easy to regulate. In addition, an electric heater can be combined particularly well with an exhaust gas aftertreatment component. For this purpose, the electrical heater can be arranged upstream, downstream or within the exhaust gas aftertreatment components. In this way, for example, an electrically heated catalytic converter or an electrically heated diesel particulate filter can be created. The electrically heated exhaust gas aftertreatment component designed in this way can then be used for a particularly uniform and efficient heat input in the homogenized fluid flow.

It is particularly advantageous if the heating device is an electrical heating device. In this case, the heating device can be designed as a honeycomb body, the walls of which comprise metallic material or these are even made entirely of metal, and an electric current can be applied to them as required. As a result of the ohmic resistance heating, the desired heating power can be set.

In another advantageous embodiment, it is provided that the fluid guide device is designed as a perforated disk. A perforated disc has z. B. the advantage that it achieves a particularly good homogenization of the fluid flow and at the same time generates a relatively low flow resistance within the exhaust gas aftertreatment device. In addition, a perforated disk can be implemented with very little technical effort. Alternatively, however, other fluid guide devices, such as guide plates or flow grids arranged in the fluid flow, can also be used in order to achieve the homogenization of the fluid flow.

The present invention can be used particularly advantageously together with one or more different exhaust gas aftertreatment components combined with one another. For this purpose, different components can be used individually or in combination with one another in the exhaust gas aftertreatment device. For example, a diesel oxidation catalytic converter with or without a NOx adsorber, a NOx storage catalytic converter, an SCR (selective catalytic reduction) catalytic converter, a diesel particulate filter, a diesel particulate filter with an SCR coating or a diesel particulate filter with a catalytic coating can be used as a component. All of the possible embodiments of the exhaust gas aftertreatment components listed have in common that they are filters or catalysts, the efficiency of which can be further increased with an improved heat input. In addition, exhaust gas aftertreatment components other than those listed can also be used, provided that the improved heat input increases their efficiency.

In particular, it can also be provided that the fluid guide device is permanently connected to the housing or is designed to be exchangeable. Thus, the fluid guide device can contribute to the structural strength of the exhaust gas aftertreatment device if it is firmly connected to it. For this purpose, the connection between the fluid guide device and the housing of the exhaust gas aftertreatment device can be made, for example, by means of a soldered or welded connection. Alternatively, however, the fluid guide device can also be exchangeable, d. H. be detachable, mounted. This can be advantageous if, for example, due to the very high mileage of a motor vehicle, the fluid guide device shows wear and has to be replaced.

It is particularly advantageous to have a motor vehicle with one proposed here Equip exhaust aftertreatment device. The vehicle designed in this way has exhaust gas aftertreatment with improved efficiency, so that the exhaust gas aftertreatment is improved. Furthermore, the operational safety and durability of the exhaust gas aftertreatment device are also improved by avoiding undersupplied zones with insufficient mass flows and thereby preventing damage to the heating device. Furthermore, in a motor vehicle designed in this way, a direct conclusion can be drawn from the total exhaust gas mass flow to the exhaust gas mass flow in the individual areas of the exhaust gas aftertreatment device. This in turn makes it possible to regulate or limit the maximum heating power of the heating device in a simple manner. Finally, the heating device only has to have the actually required heating power and does not require any power reserve for over-supplied zones.

1. a) Zuleiten des gasförmigen Fluids,
2. b) Vergleichmäßigen des Fluidstroms des gasförmigen Fluids,
3. c) Aufheizen des vergleichmäßigten Stroms des gasförmigen Fluids mittels einer Heizvorrichtung,
4. d) Behandlung des erwärmten und vergleichmäßigten Stroms mittels einer Abgasnachbehandlungskomponente,
5. e) Ableiten des behandelten Fluidstroms.

The advantages described above can also be achieved with a method for treating gaseous fluids of an internal combustion engine, which comprises the following steps:

1. a) supplying the gaseous fluid,
2. b) equalizing the fluid flow of the gaseous fluid,
3. c) heating the equalized flow of the gaseous fluid by means of a heating device,
4. d) Treatment of the heated and equalized stream by means of an exhaust gas aftertreatment component,
5. e) diverting the treated fluid stream.

It is important here that the fluid flow is made uniform before the gaseous fluid is heated in the heating device to the temperature required for exhaust gas aftertreatment.

The exhaust gas aftertreatment device designed in this way and the proposed method can be used in a wide variety of motor vehicles, such as, for example, passenger cars, commercial vehicles, but also watercraft and aircraft. Wherever exhaust aftertreatment components are used that must first be heated to a certain higher temperature before exhaust aftertreatment can take place efficiently.

As a precaution, it should be noted that the numerals used here (“first”, “second”, ...) primarily (only) serve to distinguish between several similar objects, sizes or processes, so in particular no dependency and / or sequence of these objects, sizes or prescribe processes to each other. Should a dependency and / or sequence be required, this is explicitly stated here or it is obvious to the person skilled in the art when studying the specifically described embodiment.

• 1: eine schematische Seitenansicht einer ersten Ausführungsform einer Abgasnachbehandlungsvorrichtung;
• 2: eine schematische Seitenansicht einer zweiten Ausführungsform einer Abgasnachbehandlungsvorrichtung;
• 3: eine erste Ausführungsform einer Fluidleiteinrichtung;
• 4: eine zweite Ausführungsform einer Fluidleiteinrichtung;
• 5: eine dritte Ausführungsform einer Fluidleiteinrichtung;
• 6: eine vierte Ausführungsform einer Fluidleiteinrichtung; und
• 7: ein Kraftfahrzeug mit einer erfindungsgemäßen Abgasnachbehandlungsvorrichtung.

The invention and the technical environment are explained in more detail below with reference to the accompanying figures. It should be pointed out that the invention is not intended to be restricted by the exemplary embodiments cited. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts explained in the figures and to combine them with other components and findings from the present description. In particular, it should be pointed out that the figures and in particular the size relationships shown are only schematic. Show it:

• 1 : a schematic side view of a first embodiment of an exhaust gas aftertreatment device;
• 2 : a schematic side view of a second embodiment of an exhaust gas aftertreatment device;
• 3 : a first embodiment of a fluid guide device;
• 4th : a second embodiment of a fluid guide device;
• 5 : a third embodiment of a fluid guide device;
• 6th : a fourth embodiment of a fluid guide device; and
• 7th : a motor vehicle with an exhaust gas aftertreatment device according to the invention.

In 1 is an exhaust gas aftertreatment device according to the invention 1 shown schematically in a side view. The exhaust aftertreatment device 1 has a housing 2 with an inlet port 3 and an outlet port 4th on.

In one direction of flow 5 becomes the exhaust aftertreatment device 1 traversed by a gaseous fluid. After entering the housing 2 the gaseous fluid reaches a fluid guide device 6th . The fluid guide device 6th is in the embodiment shown of three baffles 7th formed, which equalize and homogenize the inflowing fluid flow of the gaseous fluid and then into a conically widening interior 8th hand off. The conical interior 8th points in the normal plane to the direction of flow 5 lying an enlarged cross-section 9 on. In the interior 8th are still a heating device 10 and an exhaust aftertreatment component 11 arranged.

In the direction of flow 5 seen the housing tapers 2 then back to the outlet opening 4th . The heater shown 10 is designed as an electrically operated heater and is supplied with energy via electrical connections (not shown). If the fluid flow does not have the temperature required for effective exhaust gas aftertreatment, the heating device can 10 supplied with electrical energy and in this way the fluid flow is heated to the required temperature before it enters the exhaust gas aftertreatment component 11 entry. By means of the fluid guide device 6th it is achieved that the fluid to be treated over the entire cross-section 9 flows with the same mass flow. This causes the fluid from the heater 10 is heated evenly before it enters the exhaust aftertreatment component 11 occurs and this is also heated to the required temperature.

The exhaust aftertreatment component 11 can be any device for exhaust gas aftertreatment that benefits from the temperature increase by the heating device, that is, its efficiency is increased. These can be, for example, diesel oxidation catalysts, diesel oxidation catalysts with NOx absorber coating, NOx storage catalysts, components for selective catalytic reduction, diesel particle filters, diesel particle filters with catalytic coating or diesel particle filters with SCR coating.

The 2 shows a second possible embodiment of an exhaust gas aftertreatment device according to the invention 1 , in which the fluid guide device 6th as a perforated disc 12th is trained. The perforated disc 12th is in the area of the inlet opening 3 arranged and fixed to the housing 2 connected.

The 3 shows a fluid guide device according to the invention 6th that as a perforated disc 12th is trained. In the embodiment shown, the gaseous fluid to be treated flows through the perforated disk in the normal direction to the plane of the drawing 12th through it, the direction of the view on the perforated disc 12th the direction of flow 5 corresponds to.

The use of the perforated disc 12th as a fluid guide device 6th has the advantage that both a particularly good homogenization of the fluid flow and a particularly low flow resistance can be achieved in this way. In addition, the perforated disc is 12th easy and cheap to manufacture.

In 4th is a further embodiment of a fluid guide device according to the invention 6th shown, in the case of the grid bars arranged at right angles to one another, a flow grid 13th form. Also with this grid-shaped fluid guide device 6th excellent homogenization of the fluid flow can be achieved.

In the 5 and 6th are further embodiments of fluid guide devices 6th shown, the baffles 7th use. The embodiment is used according to 5 horizontal baffles 7th while the embodiment according to 6th additionally vertically arranged baffles 7th uses. The direction of flow 5 of the gaseous fluid is directed into the image plane. It can also be clearly seen that the middle guide plates 7th exactly parallel to this direction of flow 5 are aligned, while the side baffles 7th divert the fluid flowing past it towards the outside. This deflection of the fluid outwards in the direction of the housing 2 , a particularly good homogenization and equalization of the mass flows of the gaseous fluid flowing through is achieved.

In 7th is finally a motor vehicle according to the invention 14th with an internal combustion engine 15th is the fluid that occurs during combustion shown through a line? 16 to an exhaust gas turbocharger 17th ejects. After flowing through the exhaust gas turbocharger 17th the fluid arrives via a second line means 18th to the exhaust gas aftertreatment device according to the invention 1 , where a homogenization of the fluid flow, heating and exhaust gas aftertreatment take place. After flowing out of the exhaust gas aftertreatment device 1 the fluid then arrives via third line means 19th and a muffler device 20th in the cleaned state into the environment.

List of reference symbols

1

Exhaust aftertreatment device

2

casing

3

Inlet opening

4th

Outlet opening

5

Direction of flow

6th

Fluid guide device

7th

Baffle

8th

inner space

9

cross-section

10

Heater

11

Exhaust aftertreatment component

12th

Perforated disc

13th

Flow grid

14th

Motor vehicle

15th

Internal combustion engine

16

Conduit means

17th

Exhaust gas turbocharger

18th

second line means

19th

third line means

20th

Silencer device

Claims (9)

Exhaust gas aftertreatment device (1) with a housing (2), at least one inlet opening (3) and at least one outlet opening (4), at least one exhaust gas aftertreatment component (11) through which a gaseous fluid can flow in a flow direction (5) is arranged in the housing (2) and a heating device (10) for heating the exhaust gas aftertreatment component (11), characterized in that a fluid guide device (6) is provided upstream of the exhaust gas aftertreatment component (11) in the flow direction (5), the fluid guide device (6) for equalizing a fluid flow of the gaseous fluid is formed. Exhaust gas aftertreatment device (1) according to the preceding claim, characterized in that the fluid guide device (6) is arranged downstream of an exhaust gas turbocharger (17). Exhaust gas aftertreatment device (1) according to one of the preceding claims, characterized in that the heating device (10) is an electrical heating device. Exhaust gas aftertreatment device (1) according to one of the preceding claims, characterized in that the fluid guide device (6) is designed as a perforated disk (12) or a flow grille (13). Exhaust gas aftertreatment device (1) according to one of the preceding claims, characterized in that the heating device (10) is arranged downstream, upstream or within the exhaust gas aftertreatment component (11). Exhaust aftertreatment device (1) according to one of the preceding claims, characterized in that the exhaust aftertreatment component (11) has at least one component from the following group: diesel oxidation catalytic converter with or without NOx adsorber, a NOx storage catalytic converter, an SCR catalytic converter, a diesel particulate filter , a diesel particulate filter with an SCR coating, a diesel particulate filter with a catalytic coating. Exhaust gas aftertreatment device (1) according to one of the preceding claims, characterized in that the fluid guide device (6) is permanently connected to the housing (2) or is designed to be exchangeable. Motor vehicle (14) with an exhaust gas aftertreatment device (1) according to one of the preceding claims. Method for treating gaseous fluids of a motor vehicle (14) comprising the steps: a) supplying the gaseous fluid, b) equalizing the fluid flow of the gaseous fluid c) heating of the equalized fluid flow of the gaseous fluid by means of a heating device (10) d) Treatment of the heated and equalized fluid flow by means of an exhaust gas aftertreatment component (11) e) diverting the treated fluid stream.

Images