WO2024008577A1

WO2024008577A1 - Catalytic converter for exhaust gas aftertreatment, with improved structure

Info

Publication number: WO2024008577A1
Application number: PCT/EP2023/068013
Authority: WO
Inventors: Christian Schmidt; Peter Hirth; Sebastian DUNG; Sven Schepers; Michael Voit
Original assignee: Vitesco Technologies GmbH
Priority date: 2022-07-07
Filing date: 2023-06-30
Publication date: 2024-01-11
Also published as: DE102022206950A1

Abstract

The invention relates to a catalytic converter (1) for aftertreatment of exhaust gases of an internal combustion engine, comprising a honeycomb body (2) wound from at least one metal foil, wherein the honeycomb body (2) has a central axis which extends along its axial extent from a gas inlet side (6) of the honeycomb body (2) to a gas outlet side (7) of the honeycomb body (2), and the honeycomb body (2) has a plurality of flow channels, through which gas can flow from a gas inlet side (6) of the honeycomb body (2) to a gas outlet side (7), wherein the honeycomb body (2) is divided into individual axial sections (4, 5) along its axial extent, along which the central axis runs, wherein the axial sections (4, 5) have flow channel sections which run at different angles to the central axis.

Description

Catalyst for exhaust gas aftertreatment with improved structure

Technical area

The invention relates to a catalyst for the aftertreatment of exhaust gases from an internal combustion engine with a honeycomb body wound from at least one metal foil, the honeycomb body having a central axis which extends along its axial extent from a gas inlet side of the honeycomb body to a gas outlet side of the honeycomb body, and the honeycomb body has a Has a plurality of flow channels through which flow can flow from a gas inlet side of the honeycomb body to a gas outlet side.

State of the art

To convert pollutants from the exhaust gas emitted by combustion engines, metallic catalysts are installed in the exhaust system. To shorten the heating time of the installed catalytic converters, an electrically heated heating disk can be installed upstream of the catalytic converter. In catalytic converters with a metallic honeycomb body, this heating disk is held by so-called support pins, which are integrally connected to the support catalytic converter on one side and are integrally connected to the heating disk on the other side. The support pins serve, on the one hand, to mechanically fix the heating disk relative to the catalytic converter and, on the other hand, to electrically isolate the heating disk from the catalytic converter.

Such catalysts, which are used as supporting catalysts to support heating disks, are regularly produced by stacking and winding a plurality of metal foils on top of one another, the metal foils being alternately smooth and structured. The honeycomb body created by winding is inserted into a support shell, giving the catalyst its final shape. The one between the smooth foils and the structured ones Flow channels formed by foils are straight and run regularly parallel to the central axis of the catalyst.

Alternatively, catalysts are known which do not have smooth films. In order to still form flow channels in the honeycomb body through which flow can flow from a gas inlet side to a gas outlet side, the films are structured in such a way that the resulting flow channels run at an angle to the central axis. This creates so-called cross corrugations or so-called herringbone structures.

Stacking structured films on top of each other, each with the opposite orientation of the corrugation, prevents the structured films from slipping into one another.

A particular disadvantage of the devices in the prior art is that the aforementioned catalysts, which are constructed without a smooth layer, have inclined flow channels on both the gas inlet side of the catalyst and on the gas outlet side, which do not run parallel to the central axis of the catalyst. The support pins described above cannot be used in such inclined channels. It is also disadvantageous that the matrix of the honeycomb body forming the catalyst and the metal foils can be easily damaged due to the small bending radii that are regularly used.

The use of a supporting catalyst with a smooth metal foil between the structured metal foils is disadvantageous because the heat capacity of the honeycomb body is thereby increased. This in turn increases the heating time until the optimal operating temperature is reached. In addition, a honeycomb body with smooth metal foils is more expensive to produce because it requires more material. Presentation of the invention, task, solution, advantages

It is therefore the object of the present invention to create a catalyst for exhaust gas aftertreatment which has a design that is optimized with regard to the metal foils used, and in particular does not require the use of smooth metal foils between the structured metal foils and has a higher flexibility of the honeycomb body in the axial and/or tangential direction direction.

The problem with regard to the catalyst is solved by a catalyst with the features of claim 1.

An exemplary embodiment of the invention relates to a catalyst for the aftertreatment of exhaust gases from an internal combustion engine with a honeycomb body wound from at least one metal foil, the honeycomb body having a central axis which extends along its axial extent from a gas inlet side of the honeycomb body to a gas outlet side of the honeycomb body, and the The honeycomb body has a plurality of flow channels through which flow can flow from a gas inlet side of the honeycomb body to a gas outlet side, the honeycomb body being divided into individual axial sections along its axial extent, along which the central axis runs, the axial sections having flow channel sections which run along run at different angles to the central axis.

The axial sections describe areas along the axial extent of the honeycomb body. The entirety of the axial sections forms the entire honeycomb body with its axial extent. The individual axial sections are created by specially shaped areas in the metal foils used. The honeycomb body is preferably produced from a single wound stack of layers, so that all axial sections formed in the honeycomb body are formed by the same metal foils.

The large number of flow channels, which are formed between the metal foils, run from the gas inlet side of the honeycomb body to the gas outlet side. According to the invention, the flow channels are characterized in that they can have different orientations within the individual axial sections with respect to the central axis of the honeycomb body. The flow channels within an axial section can, for example, run parallel to the central axis, be set at a positive angle to the central axis, or be set at a negative angle to the central axis.

At the transitions between the individual axial sections, deflections of the respective flow direction in the individual flow channels take place.

By alternating straight axial sections with flow channels running parallel to the central axis and axial sections with oblique flow channels, the radius at the deflection points is increased and the material load caused by the corrugation process is thus reduced. This reduces the occurrence of damage to the metal foils during the manufacturing process.

The catalyst according to the invention has a honeycomb body which is constructed without a smooth layer, which is regularly used to separate the structured metal foils in order to prevent the metal foils from slipping into one another. This makes the construction of the honeycomb body easier and less material is required.

Depending on the design, the orientation of the flow channels in the axial sections can be different, with flow channels aligned parallel to the central axis alternating with flow channels positioned at an angle to the central axis.

It is particularly advantageous if each flow channel has flow channel sections corresponding to the number of axial sections, which each extend along one of the axial sections. The flow channels all run from the gas inlet side to the gas outlet side of the catalytic converter. Each flow channel therefore runs through all axial sections of the catalytic converter. Since the honeycomb body is only created from a stack of layers in the axial direction, and therefore the metal foils are not interrupted, each flow channel extends through the axial sections without being interrupted by the transitions between the axial sections. The aim is to enable the highest possible flow through the honeycomb body, which is why as few flow channels as possible should be blocked. For manufacturing reasons, it can happen that individual flow channels are deformed and thus blocked. However, these cases are insignificant side effects that fundamentally do not change the function and structure of the honeycomb body.

It is also advantageous if the flow channel sections of the axial section, which begins on the gas inlet side of the honeycomb body, run parallel to the central axis of the honeycomb body and / or the flow channel sections of the axial section, which ends on the gas outlet side of the honeycomb body, run parallel to the central axis.

This is particularly advantageous if an upstream or downstream element is to be fixed relative to the catalyst. In particular, a heating disk, which is fixed with straight support pins inserted into the flow channels and permanently connected to them, can be positioned particularly easily relative to the catalytic converter.

A preferred exemplary embodiment is characterized in that the flow direction of the respective flow channel sections is different relative to the central axis in axial sections that are directly adjacent to one another.

The flow channels preferably have angles to the central axis that are between 1 and 15 degrees, particularly preferably between 1 and 10 degrees. A catalyst according to the invention preferably has a cell density of 600 cpsi to 1200 cpsi (cells per square inch).

It is also preferable if the length of the axial sections is between 5mm and 50mm along the central axis. The length of the axial sections is preferably between 5mm and 50mm. Axial sections with straight flow channel sections running parallel to the central axis on the gas inlet side and/or the gas outlet side preferably have a length of 5mm to 10mm. The short length of these axial sections ensures that during the gluing and soldering process the solder also penetrates well into the subsequent axial sections and thus a cohesive connection is created between the metal foils in the subsequent soldering process.

Individual axial sections can additionally have a special corrugation, with the corrugation maximum or the corrugation minimum being cut and a protuberance of the metal foil in the opposite direction of the respective corrugation being provided. This allows exhaust gas to flow between adjacent flow channels. In addition, improved conversion on the catalyst can be achieved in this way, since the protuberance improves the gas flow, in particular making it more turbulent. The protuberances are particularly advantageous in combination with a heating disk attached to the catalytic converter, as they enable a multi-point soldering connection between the support pins and the catalytic converter.

The protuberances can optionally be arranged in axial sections with flow channels running parallel to the central axis and/or in axial sections with flow channels set at an angle to the central axis. The protuberances are particularly preferably arranged in the region of the gas inlet side and particularly preferably the axial start of the protuberance is arranged in a range of 1 mm to 10 mm, particularly preferably in a range of 1 mm to 5 mm, after the gas inlet side.

In addition, it is advantageous if at least one metal foil has slits running in at least one axial section in the circumferential direction of the honeycomb body. The slots are preferably made into the metal foils before the corrugation process. In particular, the slots significantly reduce the material loads during the corrugation process and thus reduce the risk of damage to the metal foils.

Another positive side effect of the slots, which run in the circumferential direction in the wound honeycomb body, is that the catalyst has increased flexibility in both the axial and tangential directions, whereby cell deformations, which regularly occur due to thermal shocks in a continuous slot-free honeycomb body, are avoided. The slots can be arranged in the axial direction in straight axial sections or preferably at deflection points or transition points between axial sections with unequal alignment of the flow channel sections.

Furthermore, it is advantageous if the axial section adjacent to the gas inlet side has flow channel sections which run parallel to the central axis, with support pins being inserted into individual flow channels and permanently connected to the honeycomb body. This makes it particularly easier to connect a heating disk to the catalytic converter.

It is also expedient if the honeycomb body has alternating axial sections along its axial extent with a flow direction running parallel to the central axis and axial sections with a flow direction running at an angle to the central axis. This specifically increases the radius at the deflection points or the transitions between the axial sections, which relieves the load on the metal foils and thus also relieves the load on the honeycomb body.

In addition, it is advantageous if the honeycomb body is formed from a plurality of metal foils stacked on top of one another and wound around at least one pivot point. Furthermore, it is expedient if the transition between two directly adjacent axial sections each represents a deflection point for the flow direction of a flow channel. This ensures that the flow channels are not interrupted by the transitions between the axial sections.

Advantageous developments of the present invention are described in the subclaims and in the following description of the figures.

Brief description of the drawings

The invention is explained in detail below using exemplary embodiments with reference to the drawings. Shown in the drawings:

1 shows a sectional view through a catalytic converter with a honeycomb body according to the invention,

2 shows a detailed view of a special shape of a corrugated film, the corrugation having an area in the corrugation maximum that is turned out in the opposite direction,

3 shows a sectional view through a catalytic converter, showing a supporting catalytic converter to which a heating disk is connected to the gas inlet side by means of supporting pins,

4 shows a sectional view through a supporting catalytic converter and a heating disk, with an alternative configuration of the successive axial areas,

5 shows a sectional view through a catalytic converter, the honeycomb body having circumferentially extending slots within individual of the axial sections, and Fig. 6 is a sectional view through a catalytic converter, the honeycomb body having circumferentially extending slots at the transitions between mutually adjacent axial sections.

Preferred embodiment of the invention

Figure 1 shows a catalytic converter 1, with the honeycomb body 2 being accommodated in a casing tube 3. The honeycomb body has several axial sections 4, 5 through which exhaust gas can flow from the gas inlet side 6 to the gas outlet side 7.

In the exemplary embodiment of Figure 1, alternating axial sections 5 with flow channel sections set at an angle to the central axis and axial sections 6 with flow channel sections running parallel to the central axis are shown. The axial sections 5 alternately have a positive angle of attack to the central axis and a negative angle of attack to the central axis, which creates an up and down movement of the flow channels along the axial extent of the honeycomb body 2 in the sectional view of Figure 1.

Figure 2 shows a perspective view of a corrugated metal foil 8, the upwardly projecting wave maxima having protuberances 9, which are protruded from the corrugation in the opposite direction. In the exemplary embodiment of FIG. 2, the protruded areas 9 in turn have a smaller corrugation compared to the main corrugation.

Figure 3 shows an alternative embodiment of a honeycomb body 2. On the gas inlet side, the honeycomb body is preceded by a heating slide 12, which is connected to the honeycomb body via support pins 11. The honeycomb body 5 has an axial section 4 with flow channel sections running parallel to the central axis on its gas inlet side and the gas outlet side. The remaining honeycomb body 2 is formed by axial sections 5, each of which has flow channel sections set at an angle.

It can be seen that the axial sections 4 on the gas inlet side and the gas outlet side each have a significantly shorter axial extent than the middle axial sections 5.

Figure 4 shows a honeycomb body 2 with an upstream heating disk 12. The axial sections 4 and 5 are arranged here alternately, so that starting with an axial section 4, an axial section 5 follows and so on until an axial section 4 follows again on the gas outlet side . The flow channels created in this way follow an up and down movement along the axial extent of the honeycomb body.

Figure 5 shows a further alternative honeycomb body 2, with axial sections 5 and axial sections 4 being arranged alternately. In contrast to the previous figures, the axial sections 4 now have additional slots 13 which run in the circumferential direction of the honeycomb body 2. The slots 13 are arranged centrally in the axial sections 4.

Figure 6 shows a honeycomb body 2 as in Figure 5. In contrast to Figure 5, the slots 13 are now arranged directly in the transitions between the axial areas 4 and 5.

The different features of the individual exemplary embodiments can also be combined with one another.

The exemplary embodiments of FIGS. 1 to 6 in particular do not have a restrictive character and serve to illustrate the idea of the invention. Reference symbol list

1 . catalyst

2. Honeycomb body 3. Casing tube

4. Axial section

5. axial section

6. Gas inlet side

7. Gas outlet side 8. Metal foil

9. Protuberance

11. Support pins

12. Heating disc

13. Slots

Claims

Patent claims

1. Catalyst (1) for the aftertreatment of exhaust gases from an internal combustion engine with a honeycomb body (2) wound from at least one metal foil, the honeycomb body (2) having a central axis which extends along its axial extent from a gas inlet side (6) of the honeycomb body (2 ) extends to a gas outlet side (7) of the honeycomb body (2), and the honeycomb body (2) has a plurality of flow channels through which flow can flow from a gas inlet side (6) of the honeycomb body (2) to a gas outlet side (7), so that there is no sign in that the honeycomb body (2) is divided into individual axial sections (4, 5) along its axial extent, along which the central axis runs, the axial sections (4, 5) having flow channel sections which run along different angles to the central axis.

2. Catalyst (1) according to claim 1, characterized in that each flow channel has flow channel sections corresponding to the number of axial sections (4, 5), each of which extends along one of the axial sections (4, 5).

3. Catalyst (1) according to one of the preceding claims, characterized in that the flow channel sections of the axial section (4), which begins on the gas inlet side (6) of the honeycomb body (2), run parallel to the central axis of the honeycomb body (2) and / or the flow channel sections of the axial section (4), which ends on the gas outlet side (7) of the honeycomb body (2), run parallel to the central axis.

4. Catalyst (1) according to one of the preceding claims, characterized in that the flow direction of the respective flow channel sections is different relative to the central axis in directly adjacent axial sections (4, 5). 5. Catalyst (1) according to one of the preceding claims, characterized in that the length of the axial sections (4,

5) between 5mm and 50mm along the central axis.

6. Catalyst (1) according to one of the preceding claims, so that at least one metal foil has slots (13) running in at least one axial section (4, 5) in the circumferential direction of the honeycomb body (2).

7. Catalyst (1) according to one of the preceding claims, characterized in that the axial section (4) adjacent to the gas inlet side (6) has flow channel sections which run parallel to the central axis, with support pins (11) inserted into individual flow channels and connected to the Honeycomb bodies (2) are permanently connected.

8. Catalyst (1) according to one of the preceding claims, characterized in that the honeycomb body (2) has alternating axial sections (4) along its axial extent with a flow direction running parallel to the central axis and axial sections (5) with an angle to the Central axis flow direction.

9. Catalyst (1) according to one of the preceding claims, so that the honeycomb body (2) is formed from a plurality of stacked metal foils which are wound around at least one pivot point.

10. Catalyst (1) according to one of the preceding claims, characterized in that the transition between two directly adjacent axial sections (4, 5) each represents a deflection point for the flow direction of a flow channel.