Catalytic converter for exhaust gas aftertreatment, with improved structure

Abstract

A catalytic converter for aftertreatment of exhaust gases from an internal combustion engine, having a honeycomb body formed by wrapping from at least one metal foil, where the honeycomb body has a center axis that runs along its axial extent from a gas entry side of the honeycomb body up to a gas exit side of the honeycomb body, and the honeycomb body has a multitude of flow channels through which a flow can pass from a gas entry side of the honeycomb body to a gas exit side, wherein the honeycomb body is divided into individual axial sections along its axial extent along which the center axis runs, where the axial sections have flow channel sections that run along different angles relative to the center axis.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This is a U.S. national stage of Application No. PCT / EP2023 / 068013 filed Jun. 30, 2023. Priority is claimed on German Application No. DE 10 2022 206 950.1 filed Jul. 7, 2022, the contents of which are incorporated herein by reference.BACKGROUND OF THE INVENTION1. Field of the Invention

[0002] The disclosure relates to a catalytic converter for aftertreatment of exhaust gases from an internal combustion engine, having a honeycomb body formed by wrapping from at least one metal foil, where the honeycomb body has a center axis that runs along its axial extent from a gas entry side of the honeycomb body up to a gas exit side of the honeycomb body, and the honeycomb body has a multitude of flow channels through which a flow can pass from a gas entry side of the honeycomb body to a gas exit side.2. Description of the Related Art

[0003] Metallic catalytic converters are installed in the exhaust gas system for conversion of pollutants from the exhaust gas emitted by internal combustion engines. There may be an electrically heatable heated disk upstream of the catalytic converter for shortening of the heating time of the installed catalytic converters. This heating disk, in the case of catalytic converters having metallic honeycomb bodies, is retained by what are called support pins that are cohesively bonded to the support catalytic converter on one side and cohesively bonded to the heating disk on the other side. The support pins serve firstly for mechanical fixing of the heating disk relative to the catalytic converter, and secondly for electrical insulation of the heating disk from the catalytic converter.

[0004] Those catalytic converters that are used as support catalytic converters to support heating disks are regularly created by stacking and winding of a multitude of metal foils, where the metal foils are alternately executed in a smooth and structured manner. The honeycomb body created by the winding is inserted into a carrier shell, which gives the catalytic converter its ultimate shape. The flow channels formed between the smooth foils and the structured foils are straight and regularly run parallel to the center axis of the catalytic converter.

[0005] Alternatively, there are known catalytic converters that do not have smooth foils. In order nevertheless to form flow channels in the honeycomb body through which a flow can pass from a gas entry side to a gas exit side, the foils are structured such that resultant flow channels run at an angle to the center axis. This creates what are called cross-corrugations or what are called herringbone structures.

[0006] The stacking of structured foils with respectively opposite alignments of the corrugation prevents the structured foils from slipping into one another.

[0007] A particular disadvantage of the prior art devices is that the aforementioned catalytic converters that are formed without a smooth layer have oblique flow channels that do not run parallel to the center axis of the catalytic converter both on the gas entry side of the catalytic converter and on the gas exit side. The above-described support pins cannot be used in such oblique channels. Moreover, it is disadvantageous that the matrix of the honeycomb body that forms the catalytic converter the metal foils can be slightly damaged as a result of the small bending radii that are regularly used.

[0008] The use of a support catalytic converter having a smooth metal foil between the structured metal foils is disadvantageous since this increases the heat capacity of the honeycomb body. This in turn increases the heating time before attainment of the optimal operating temperature. Moreover, a honeycomb body having smooth metal foils is more costly to produce, since it has a higher material requirement.SUMMARY OF THE INVENTION

[0009] It is therefore an object of one aspect of the present invention to provide a catalytic converter for exhaust gas aftertreatment that has an optimized design 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 higher flexibility of the honeycomb body in axial and / or tangential direction.

[0010] One working example of one aspect of the invention relates to a catalytic converter for aftertreatment of exhaust gases from an internal combustion engine, having a honeycomb body formed by wrapping from at least one metal foil, where the honeycomb body has a center axis that runs along its axial extent from a gas entry side of the honeycomb body up to a gas exit side of the honeycomb body, and the honeycomb body has a multitude of flow channels through which a flow can pass from a gas entry side of the honeycomb body to a gas exit side, wherein the honeycomb body is divided into individual axial sections along its axial extent along which the center axis runs, where the axial sections have flow channel sections that run along different angles relative to the center axis.

[0011] The axial sections describe regions along the axial extent of the honeycomb body. The totality of the axial sections forms the overall honeycomb with its axial extent. The individual axial sections are created by specifically shaped regions in the metal foils used. The honeycomb body is preferably created from a single wound-up stack of layers, such that all axial sections formed in the honeycomb body are formed by the same metal foils.

[0012] The multitude of flow channels formed between the metal foils runs from the gas entry side of the honeycomb body to the gas exit side. According to one aspect of the invention, the flow channels are characterized in that they may have different alignments in relation to the center axis of the honeycomb body within the individual axial sections. The flow channels within an axial section may, for example, run parallel to the center axis, be set at a positive angle to the center axis, or be set at a negative angle to the center axis.

[0013] At the transitions between the individual axial sections, deflections of the respective flow direction in the individual flow channels thus take place.

[0014] The switch from straight axial sections with flow channels running parallel to the center axis and axial sections having oblique flow channels increases the radius at the deflection points and hence reduces material stress resulting from the corrugation process. This reduces the occurrence of damage to the metal foils in the production process.

[0015] The catalytic converter of one aspect of the invention has a honeycomb body formed without a smooth layer that is regularly used for separation of the structured metal foils in order to prevent the metal foils from slipping into one another. This simplifies the construction of the honeycomb body and means that less material is required.

[0016] According to the configuration, the alignment of the flow channels in the axial sections may be different in each case, with alternation of flow channels aligned parallel to the center axis and flow channels set at an angle to the center axis.

[0017] It is particularly advantageous when each flow channel, in accordance with the number of axial sections, has flow channel sections that each extend along one of the axial sections. The flow channels all run from the gas entry side to the gas exit side of the catalytic converter. Each flow channel thus also runs through all axial sections of the catalytic converter. Since the honeycomb body is created only from one stack of layers in axial direction, and hence the metal foils are uninterrupted, each flow channel extends through the axial sections without being interrupted by the transitions between the axial sections. The aim is to enable maximum flow through the honeycomb body, and therefore as few flow channels as possible should be blocked. For manufacturing reasons, it may be the case that individual flow channels become deformed and hence are blocked. But these cases are insignificant side effects that do not fundamentally alter the function and construction of the honeycomb body.

[0018] It is also advantageous when the flow channel sections of the axial section that begins on the gas entry side of the honeycomb body run parallel to the center axis of the honeycomb body and / or the flow channel sections of the axial section that ends on the gas exit side of the honeycomb body run parallel to the center axis.

[0019] This is advantageous especially when an upstream or downstream element is to be fixed with respect to the catalytic converter. In particular, a heating disk, which is fixed with straight support pins that are inserted into the flow channels and permanently bonded thereto, can thus be positioned in a particularly simple manner with respect to the catalytic converter.

[0020] A preferred working example is characterized in that the flow direction of the respective flow channel sections relative to the center axis is different in directly adjacent axial sections.

[0021] The flow channels preferably have angles to the center axis of between 1 and 15 degrees, more preferably between 1 and 10 degrees. A catalytic converter of the invention preferably has a cell density of 600 cpsi to 1200 cpsi (cells per square inch).

[0022] It is also preferable when the length of the axial sections is between 5 mm and 50 mm along the center axis.

[0023] The length of the axial sections is preferably between 5 mm and 50 mm. Axial sections having straight flow channel sections that run parallel to the center axis on the gas entry side and / or the gas exit side preferably have a length of 5 mm to 10 mm. The short length of these axial sections ensures that, in the gluing process and soldering process, the solder will also penetrate efficiently into the downstream axial sections and hence a cohesive bond between the metal foils will form in the subsequent soldering operation.

[0024] Individual axial sections may additionally have a specific corrugation, where the corrugation maximum or the corrugation minimum is truncated and a bulge of the metal foil is provided in the opposite direction of the respective corrugation. This enables exhaust gas to flow across between mutually adjacent flow channels. Furthermore, it is possible thereby to achieve improved conversion over the catalytic converter, since the bulge improves gas flow and in particular makes it more turbulent. Especially in combination with a heating disk mounted on the catalytic converter, the bulges are advantageous since they enable multipoint solder binding between the support pins and the catalytic converter.

[0025] The bulges may electively be arranged in axial sections with flow channels running parallel to the center axis and / or on axial sections with flow channels at an angle to the center axis. More preferably, the bulges are disposed in the region of the gas entry side and, more preferably, the axial commencement of the bulge is disposed within a range from 1 mm to 10 mm, more preferably within a range from 1 mm to 5 mm, downstream of the gas entry side.

[0026] Furthermore, it is advantageous when at least one metal foil in at least one axial section has slots running in circumferential direction of the honeycomb body.

[0027] The slots are preferably introduced into the metal foils before the corrugating operation. The slots in particular distinctly reduce material stresses during the corrugating operation and hence reduce the risk of damage to the metal foils.

[0028] A further positive side effect of the slots, which run in circumferential direction in the wound-up honeycomb body, is that the catalytic converter has elevated flexibility both in axial and in tangential direction, which reduces cell deformation that regularly occurs as a result of thermal shocks in a continuous slot-free honeycomb body. In axial direction, the slots may be disposed in straight axial sections or preferably at deflection points or transition points between axial sections with different alignment of the flow channel sections.

[0029] In addition, it is advantageous when the axial section adjoining the gas entry side has flow channel sections that run parallel to the center axis, where support pins are inserted into individual flow channels and are permanently bonded to the honeycomb body. This especially facilitates binding of a heating disk to the catalytic converter.

[0030] It is also appropriate when the honeycomb body, along its axial extent, has alternating axial sections having a flow direction running parallel to the center axis and axial sections having a flow direction running at an angle to the center axis. In this way, the radius at the deflection points, or the transitions between the axial sections, is specifically increased, which results in a reduction in stress on the metal foils and hence likewise in a reduction in stress on the honeycomb body.

[0031] It is additionally advantageous when the honeycomb body is formed from a multitude of metal foils stacked one on top of another, which are wound around at least one center of rotation.

[0032] In addition, it is appropriate when the transition between two directly adjacent axial sections in each case constitutes 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.

[0033] Advantageous developments of the present invention are described in the dependent claims and the description of figures that follows.BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The invention is elucidated in detail hereinafter by working examples with reference to the drawings. The drawings show:

[0035] FIG. 1 is a section view through a catalytic converter having a honeycomb body;

[0036] FIG. 2 is a detail view of a specific shape of a corrugated foil, where the corrugation has a region at the corrugation maximum that has a bulge in the opposite direction;

[0037] FIG. 3 is a section view through a catalytic converter, showing a support catalytic converter where a heating disk is attached on the gas entry side by support pins;

[0038] FIG. 4 is a section view through a support catalytic converter and a heating disk, with a configuration of the successive axial regions;

[0039] FIG. 5 is a section view through a catalytic converter, where the honeycomb body has slots running in circumferential direction within individual axial sections; and

[0040] FIG. 6 is a section view through a catalytic converter, where the honeycomb body has slots running in circumferential direction at the transitions between mutually adjacent axial sections.DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

[0041] FIG. 1 shows a catalytic converter 1, where the honeycomb body 2 is accommodated in a shell tube 3. The honeycomb body has several axial sections 4, 5, through which exhaust gas can flow from the gas entry side 6 to the gas exit side 7.

[0042] The working example of FIG. 1 shows, in alternation, axial sections 5 with flow channel sections set at an angle to the center axis and axial sections 6 having flow channel sections running parallel to the center axis. The axial sections 5 have, in alternation, a positive angle to the center axis and a negative angle to the center axis, which gives rise to upward and downward movement of the flow channels in the section image of FIG. 1 along the axial extent of the honeycomb body 2.

[0043] FIG. 2 shows a perspective view of a corrugated metal foil 8, where the upward corrugation maxima have bulges 9 that bulge from the corrugation in the opposite direction. In the working example of FIG. 2, the bulging regions 9 in turn have lower corrugation compared to the main corrugation.

[0044] FIG. 3 shows an alternative configuration of a honeycomb body 2. A heating disk 12 is positioned upstream of the honeycomb body on the gas entry side, and is bonded to the honeycomb body via support pins 11.

[0045] The honeycomb body 5 has, on its gas entry side and on the gas exit side, a respective axial section 4 having flow channel sections running parallel to the center axis. The rest of the honeycomb body 2 is formed by axial sections 5 that each have flow channel sections set at an angle.

[0046] It is apparent that the axial sections 4 each have a distinctly shorter axial extent on the gas entry side and the gas exit side than the middle axial sections 5.

[0047] FIG. 4 shows a honeycomb body 2 with an upstream heating disk 12. The axial sections 4 and 5 are arranged alternately here, such that, beginning with an axial section 4, this is followed by an axial section 5, and so forth, before being followed again by an axial section 4 on the gas exit side. The flow channels thus created thus follow an upward and downward movement along the axial extent of the honeycomb body.

[0048] FIG. 5 shows a further alternative honeycomb body 2, again with an alternating arrangement of axial sections 5 and axial sections 4. By contrast with the preceding figures, the axial sections 4 now have additional slots 13 that run in circumferential direction of the honeycomb body 2. The slots 13 are disposed in the middle of the axial sections 4.

[0049] FIG. 6 shows a honeycomb body 2 as in FIG. 5. By contrast with FIG. 5, the slots 13 are now disposed directly in the transitions between the axial regions 4 and 5.

[0050] The different features of the individual working examples may also be combined with one another.

[0051] The working examples of FIGS. 1 to 6 especially do not have any limiting character and serve to illustrate the concept of the invention.

[0052] Thus, while there have shown and described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and / or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and / or elements and / or method steps shown and / or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.

Claims

1. -10. (canceled)11. A catalytic converter configured for aftertreatment of exhaust gases from an internal combustion engine, comprising:a honeycomb body formed by wrapping at least one metal foil;a gas entry side of the honeycomb body;a gas exit side of the honeycomb body;a center axis that runs along an axial extent of the honeycomb body from the gas entry side to the gas exit side;a multitude of flow channels through which a flow can pass from the gas entry side to the gas exit side; andindividual axial sections into which the honeycomb body is divided along the axial extent of the honeycomb body,wherein the individual axial sections have respective flow channel sections that run along different angles relative to the center axis that make up the multitude of flow channels.

12. The catalytic converter as claimed in claim 11, wherein each flow channel, in accordance with a number of axial sections, has flow channel sections that each extend along one of the axial sections.

13. The catalytic converter as claimed in claim 11, wherein the flow channel sections of the axial section that begins on the gas entry side of the honeycomb body run parallel to the center axis of the honeycomb body and / or the flow channel sections of the axial section that ends on the gas exit side of the honeycomb body run parallel to the center axis.

14. The catalytic converter as claimed in claim 11, wherein directly adjacent axial sections have a different flow direction relative to the center axis.

15. The catalytic converter as claimed in claim 11, wherein a length of the axial sections is between 5 mm and 50 mm measured along the center axis.

16. The catalytic converter as claimed in claim 11, wherein at least one metal foil, in at least one axial section, has slots that run in circumferential direction of the honeycomb body.

17. The catalytic converter as claimed in claim 11, whereinthe axial section adjoining the gas entry side has flow channel sections that run parallel to the center axis, andsupport pins inserted into individual flow channels are permanently bonded to the honeycomb body.

18. The catalytic converter as claimed in claim 11, wherein the honeycomb body, along its axial extent, has alternating axial sections having a first flow direction running parallel to the center axis and a second flow direction running at an angle to the center axis.

19. The catalytic converter as claimed in claim 11, wherein the honeycomb body is formed from a plurality of metal foils stacked one on top of another, which are wound around at least one center of rotation.

20. The catalytic converter as claimed in claim 11, wherein a transition between two directly adjacent axial sections in each case constitutes a deflection point for a flow direction of a flow channel.

Images