Title of Invention | HONEYCOMB BODY WITH FISSURED END SIDES FOR PURIFICATION OF EXHAUST GAS OF AN INTERNAL COMBUSTION ENGINE |
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Abstract | The invention relates to a wound, lopped and/or coated honeycomb body (1) which is made of sheet steel (2,3). Said honeycomb body comprises a plurality of at least partially structured sheet metal layers (2), whereby the structure thereof forms channels (4) which lead from an inlet front side (5) to an outlet front side (6) of the honeycomb body (1). According to the invention, at least one part of the sheet metal layers (2,3) on the inlet front side (5) and/or the outlet front side (6) comprise recesses (9,10) which are arranged on the edges thereof (7, 8), such that a fissured structure of the inlet front side (5) and/or the outlet front side (6) is produced. As a result, only the smooth sheet steel (3) or only the structured sheet steel (2) or both recesses (9 and/or 10 ) can be provided. Also, at least one part of the sheet steel (2,3) can be made of a porous material, in particular compressed metal fibres (16). Deposition of rust particles (17) on the front sides (5,6) of the honeycomb body (1) is, to a large extent, prevented due to said recesses (9,10). |
Full Text | WO 2006/092238 PCT/EP2006/001670 Honeycomb body with fissured end sides The present invention relates to a metallic honeycomb body, in particular for the purification of exhaust gas of an internal combustion engine. A particular field of use is the removal of particles from an exhaust gas. A distinction is made primarily between two typical designs of metallic honeycomb bodies. An early design, of which DE 29 02 779 A1 shows typical examples, is the spiral design in which substantially one smooth and one corrugated metal sheet are placed one on top of the other and wound into a spiral shape. In another design, the honeycomb body is constructed from a plurality of alternately arranged smooth and corrugated or differently corrugated metal sheets, with the metal sheets initially forming one or more stacks which are twined with one another. Here, the ends of all the metal sheets are situated at the outside and can be connected to a housing or casing tube, as a result of which several connections are generated which increase the durability of the honeycomb body. Typical examples of this design are described in EP 0 245 737 B1 or WO 90/03220. It has also been long known to equip the metal sheets with additional structures in order to influence the flow and/or to obtain transverse mixing between the individual flow ducts. Typical examples of embodiments of said type are WO 91/01178, WO 91/01807 and WO 90/08249. Finally, there are also honeycomb bodies of conical design, if appropriate also with further additional structures for influencing flow. A honeycomb body of said type is for example described in WO 97/49905. Furthermore, it is also known to leave free a cutout in a honeycomb body for a sensor, in particular for accommodating a lambda probe. An example of this is described in DE 88 16 154 U1. All honeycomb bodies of said type have a plurality of WO 2006/092238 PCT/EP2006/001670 - 2 - at least partially structured metal sheet layers whose structuring forms ducts which lead from an inlet face to an outlet face of the honeycomb body. Metal sheet layers mean the successive layers of the honeycomb body, regardless of whether said metal sheet layers are constructed from one or more separate metal sheets. It is pointed out that it is fundamentally possible to construct a honeycomb body from only a single metal sheet by virtue of for example a part of the sheet metal strip being corrugated and the remaining, smooth part of the sheet metal strip being folded onto said corrugated part by bending. The structure which is formed in this way can be wound in a spiral shape proceeding from the bend line to form a honeycomb body. The next possibility is to use one smooth and one corrugated metal sheet for producing a spiral-shaped wound honeycomb body. Multiple spirals formed from three or more metal sheets are also possible. There are finally a large number of designs which are produced from one or more stacks of alternating smooth and corrugated metal sheets. Honeycomb bodies of said type contain a plurality of metal sheets, with it however not being strictly necessary for the number of the metal sheets and the number of metal sheet layers, which are placed one on top of the other, to be equal. For this reason, a distinction is made in principle between a metal sheet and a metal sheet layer, even if this is often not possible for example in drawings which show only a detail of a honeycomb body. Tests have shown that honeycomb bodies in an exhaust gas flow which contains soot particles can become completely or partially clogged at the end side as a result of deposited soot particles. This adversely affects the normal function, in particular as a soot filter, and/or makes regeneration more difficult. It is therefore an object of the present invention to create WO 2006/092238 PCT/EP2006/001670 - 3 - a honeycomb body in which there is a reduced probability of the deposition of soot particles at the end sides. A honeycomb body as claimed in claim 1 serves to achieve said object. Advantageous refinements and exemplary embodiments are described in the dependent claims. One reason for the deposition of soot particles at the end side of a honeycomb body is that the end faces of the honeycomb body structure are aligned perpendicularly with respect to the flow direction. Soot particles therefore impact almost exactly perpendicularly against the end faces of the honeycomb body. By creating a fissured structure at the inlet end side, two effects are obtained at the same time. On the one hand, purely from a geometric sense, considerable parts of the end face of the honeycomb body are now no longer aligned exactly perpendicularly with respect to the flow direction, and on the other hand, the profile of the flow as it enters the individual ducts is influenced such that only a few particles can impinge frontally against the end face. In addition, any soot depositions which are generated are already situated partially in the interior of the ducts, so that a catalytic reaction can be more easily initiated as a result of contact with catalytically coated duct walls. Any depositions which are generated can therefore be more easily eliminated again. It is fundamentally possible to obtain a fissured structure at the end sides of a honeycomb body by means of very different measures. One possibility is the use of metal sheet layers of different width in a honeycomb body, which can however lead to difficulties in production terms and with regard to reproducibility. It WO 2006/092238 PCT/EP2006/001670 - 4 - is more advantageous if metal sheet layers of identical width can be used. In order to nevertheless generate a fissured end side, at least a part of the metal sheet layers must be provided with end-side cutouts, with the size and the shape of the cutouts being variable within wide limits. For the achievement of the set object, it is fundamentally necessary only for the inlet-side end side of a honeycomb body to be fissured, but it is often undesirable for a honeycomb body to have a certain orientation when it is installed. For this reason, it can be advantageous to design a honeycomb body to be symmetrical so that it can be used in any desired installation direction. A honeycomb body according to the invention is therefore wound, twined and/or layered from metal sheets, having a plurality of at least partially structured metal sheet layers whose structuring forms ducts which lead from an inlet end side to an outlet end side of the honeycomb body. According to the invention, at least a part of the metal sheet layers has cutouts at their edges at the inlet end side and/or at the outlet end side, so as to generate a fissured structure of the inlet end side and/or of the outlet end side. Honeycomb bodies are typically constructed from alternating layers of substantially smooth and corrugated metal sheets, with it being possible according to the invention for only the smooth metal sheets, only the corrugated metal sheets or else both to have cutouts. In the case of honeycomb bodies which are designed as particle filters, in particular for the removal of soot particles, a part of the metal sheet layers is often composed of porous material, in particular of WO 2006/092238 PCT/EP2006/001670 —6- sides. The connection is preferably applied to honeycomb bodies which are formed from one or more stacks of metal sheets, with the metal sheets of each stack having a predefined length and a predefined width, where the length is greater than the width, and with the metal sheets of each stack in each case having several cutouts over the length. The cutouts are therefore situated at the longitudinal sides of the metal sheets, while the width sides are preferably, but not necessarily, formed without cutouts. Since, during the production of a honeycomb body, the width sides must typically be connected to the casing tube of said honeycomb body, cutouts are not necessarily advantageous here. According to one preferred embodiment of the invention, the cutouts have rounded boundary lines, thereby largely avoiding notching effects, that is to say the tearing of the metal sheet edges in the region of the cutouts. Cutouts are particularly preferably in the form of circular sections, preferably in each case a semicircle or smaller circular section. Since particle filters are for example produced from holed metal sheet layers, it is even possible if appropriate for the machines which are used in any case to generate holes in the metal sheet layers to also be used for generating the cutouts at the edges of the metal sheets. It is even possible to provide wide sheet metal strips uniformly with holes, and to thereafter cut the sheet metal strips to the desired width, wherein the cutting lines should preferably run through the center of rows of holes. In order to obtain the desired effect of avoiding soot WO 2006/092238 PCT/EP2006/001670 -7- depositions at the end sides, it is advantageous if more than 80% of the ducts end in the region of at least one cutout at at least one end side of a honeycomb body according to the invention. This should particularly preferably be even more than 90% of the ducts. It can be ensured in this way that even local accumulations of soot at the end side are avoided. Also proposed is a honeycomb body which has at least one cavity at the inlet end side. Said cavity is preferably arranged centrally and has in particular a conically narrowing section. One advantage of a design of said type is that ducts of different length are formed, which ducts result in pressure differences in relation to adjacent ducts. This promotes a mixture of partial exhaust gas flows within the honeycomb body. Also preferable is a design of the honeycomb body in which a part of the ducts is closed off close to the outlet end side. Such a closure of the ducts can be carried out by pressing together the duct walls and/or by providing a blocking element. It is particularly preferable for at least a part of the ducts which are arranged at the outer edge of the honeycomb body to be closed off, so that a flow which is forced within the honeycomb body enters through the cutouts into the inner partial volume. According to another refinement of the honeycomb body, said honeycomb body has a plurality of partial volumes which have a different number of ducts per unit of cross-sectional area from one another. Preferable here (for example for cylindrical designs of the honeycomb body) is a coaxial arrangement of two partial volumes. The field of use of honeycomb bodies according to the invention is primarily the purification of the exhaust WO 2006/092238 PCT/EP2006/001670 - 9 - constructed from a structured metal sheet 2 and a smooth metal sheet 3, with the structured metal sheet 2 having cutouts 9 at both longitudinal-side edges. The smooth metal sheet 3, with the width B and the length L, also has several cutouts 10 over the length L at its end-side edges 8. The boundary lines 12 of said cutouts 10 are rounded, so that the cutouts 10 have approximately the shape of circular segments. As the metal sheets 2, 3 are wound further, the ducts 4 of the honeycomb body 1 are formed, with sufficient end-side connecting points 11 between the smooth and corrugated metal sheet layers 2, 3 still being generated despite the cutouts 9, 10. The finished honeycomb body later has a fissured inlet end side 5 and a fissured outlet end side 6, but it is nevertheless possible if required for sufficient connecting points 11 to be brazed to one another by means of conventional methods. Figure 2 shows a corrugated metal sheet 2, with the width B, which is suitable for constructing a honeycomb body according to the invention. In this exemplary embodiment, only the inlet end side 5 has cutouts 9, while the outlet end side 6 has an edge strip 15 without cutouts. The end-side edge 7 of the corrugated metal sheet 2 has cutouts 9 with circular-section- shaped boundary lines 12. In addition, openings 13 are provided further in the interior of the structured metal sheet 2. For the present invention, the exact shape of the openings 13 and of the cutouts 9 is arbitrary, but it can be advantageous to select the shapes such that the projection of said openings or cutouts on the central plane of the structured metal sheet 2 is circular or circular-segment-shaped. Figure 3 shows, in a schematic perspective illustration, the typical conditions in a particle filter in which the exhaust gas is deflected through a WO 2006/092238 PCT/EP2006/001670 - 10 - porous, smooth layer 3 made from metallic fibers 16 by deflecting structures 14. The flow paths 19 are indicated by arrows. Soot particles 17 are deflected through openings 13 and by the deflecting structures 14 to the porous metal sheet layer 3, are held there and are converted. In this exemplary embodiment, too, the accumulation of soot particles 17 on the end-side metal sheet edge 7 of the structured metal sheet 2 or on the end-side metal sheet edge 8 of the smooth metal sheet 3 can be reduced by means of cutouts 10 in the smooth metal sheet 3. Here, too, the boundary line 12 of the cutout 10 has approximately the shape of a circular section. It can be seen that the cutout 10 influences the flow conditions as the flow enters into the adjoining ducts 4, and an accumulation of particles is therefore less likely. Figure 4 schematically shows different possibilities for the design of the edges of a metal sheet having cutouts. In the present exemplary embodiment, an end- side metal sheet edge 8 of the smooth metal sheet 3 is provided with individual cutouts 10, while the opposite metal sheet edge has the shape of a corrugated line 18. A corrugated line 18 should also be considered within the context of the present invention as a metal sheet edge having cutouts. A typical installation situation of a honeycomb body 1 according to the invention is illustrated in figure 5. Exhaust gases pass from an internal combustion engine 20 into an exhaust system 21 which has the honeycomb body 1 according to the invention and if appropriate further components, in particular an oxidation catalytic converter 22 connected downstream. Figure 6 shows a honeycomb body 1 placed in a housing 23, which honeycomb body 1 has a centrally-arranged WO 2006/092238 PCT/EP2006/001670 - 11 - cavity 25 at the inlet end side 5. Said cavity 25 has a conically narrowing section. The ducts 4, which are of different length on account of the cavity 25, create pressure differences, so that the exhaust gas which enters in the illustrated flow direction 24 is deflected in the interior of the honeycomb body as is schematically illustrated by the arrows. In order to intensify this effect, a part of the ducts 4 is additionally closed off close to the outlet end side 6 by means of a ring-shaped blocking element 26. Figure 7 illustrates two honeycomb bodies 1 in one housing 23, which honeycomb bodies 1 have in each case two concentric partial volumes 27, 28 which have a different number of ducts 4 per unit of cross-sectional area from one another. Here, the honeycomb bodies 1 are spaced apart from one another with a gap 29 for example of less than 10 mm, and have an inverse arrangement of the partial volumes 27, 28, so that the partial volume 27, with a high duct density, of the first honeycomb body, and the partial volume 28, with the relatively low duct density, of the second honeycomb body are situated opposite one another (as viewed in the flow direction 24) . Here, the illustrated variant is preferred, in which the first honeycomb body has a first partial volume 27, with a high duct density, at the outside. The first partial volume 27 has in particular a duct density which is greater, at least by a factor of 1.5, than that of the second partial volume 28. The first partial volume preferably has a duct density in the region of at least 800 cpsi (cells per square inch; 1 cpsi corresponds approximately to 6.4516 cells per square centimeter). It is additionally advantageous, with regard to the considerable thermal and dynamic loadings of the honeycomb body 1 in the exhaust system of a vehicle, WO 2006/092238 PCT/EP2006/001670 - 12 - for at least one support element 3 0 to be provided at least partially between the partial volumes 27, 28. In the concentric arrangement illustrated here, said support element 3 0 can for example be a tube section. The present invention serves to further improve metallic honeycomb bodies when used as exhaust gas purification components, in particular for removing harmful particles from an exhaust gas. The invention prevents or reduces the deposition of particles, in particular soot, at the end sides of a honeycomb body. WO2006/092238 PCT/EP2006/001670 - 13 - List of reference symbols 1 Honeycomb body 2 Structured metal sheet 3 Substantially smooth metal sheet 4 Duct 5 Inlet end side 6 Outlet end side 7 End-side metal sheet edge of the structured metal sheet 8 End-side metal sheet edge of the substantially smooth metal sheet 9 Cutout in corrugated metal sheet 10 Cutout in smooth metal sheet 11 Connecting point 12 Boundary line 13 Opening 14 Deflecting structure 15 Edge strips 16 Metal fibers 17 Soot particles 18 Corrugation line 19 Flow paths 20 Internal combustion engine 21 Exhaust gas purification system 22 Catalytic converter 23 Housing 24 Flow direction 25 Cavity 26 Blocking element 27 First partial volume 28 Second partial volume 29 Gap 30 Support element L Length B Width WO 2006/092238 PCT/EP2006/001670 - 14 - Patent claims 1. A honeycomb body (1) which is wound, twined and/or layered from metal sheets (2,3), having a plurality of at least partially structured metal sheet layers (2) whose structuring forms ducts (4) which lead from an inlet end side (5) to an outlet end side (6) of the honeycomb body (1), characterized in that at least a part of the metal sheet layers (2, 3) has cutouts (9, 10) at their edges (7, 8) at the inlet end side (5) and/or at the outlet end side (6) , so as to generate a fissured structure of the inlet end side (5) and of the outlet end side (6), respectively. 2. The honeycomb body (1) as claimed in claim 1, which honeycomb body (1) is constructed from alternating layers of substantially smooth (2) and corrugated (3) metal sheets, characterized in that only the smooth metal sheets (2) have cutouts. 3. The honeycomb body (1) as claimed in claim 1, which honeycomb body (1) is constructed from alternating layers of substantially smooth (2) and corrugated (3) metal sheets, characterized in that only the corrugated metal sheets (3) have cutouts. 4. The honeycomb body as claimed in claim 1, 2 or 3, characterized in that at least a part of the metal sheets (2, 3)' is composed of porous material, in particular of compressed metal fibers (16). 5. The honeycomb body as claimed in one of the preceding claims, characterized in that the metal sheets (2,3) have sections at their end-side edges (7,8) without cutouts (9,10),which sections are long enough and frequent enough that WO 2006/092238 PCT/EP2006/001670 - 15 - a plurality of contact points (11) are provided statistically distributed between the foremost and rearmost edges (7, 8) of the metal sheet layers (2, 3) . 6. The honeycomb body (1) as claimed in one of the preceding claims, characterized in that the honeycomb body (1) is formed from one or more stacks of metal sheets (2, 3), with the metal sheets (2, 3) of each stack having a length (L) and a width (B) , where L > B, and with the metal sheets (2, 3) of each stack in each case having a plurality of cutouts (9, 10) over the length (L). 7. The honeycomb body (1) as claimed in one of the preceding claims, characterized in that the cutouts (9, 10) have rounded boundary lines (12). 8. The honeycomb body as claimed in one of the preceding claims, characterized in that the cutouts (9, 10) have the shape of circular sections, preferably semicircles or smaller circular sections. 9. The honeycomb body (1) as claimed in one of the preceding claims, characterized in that more than 80% of the ducts (4), preferably more than 90% of the ducts (4) , end in the region of at least one cutout (9, 10) at at least one end side (5, 6) . 10. The honeycomb body (1) as claimed in one of the preceding claims, characterized in that it is part of an exhaust gas purification system (21) of an internal combustion engine (20), in particular of a diesel engine, and contributes to the removal of soot particles (17) from the exhaust gas of the internal combustion engine (20). WO 2006/092238 PCT/EP2006/001670 - 16 - 11. The honeycomb body (1) as claimed in one of the preceding claims, characterized in that said honeycomb body (1) has additional openings (13) in the metal sheets (2, 3) and/or deflecting structures (14) in the ducts (4). 12. The honeycomb body (1) as claimed in one of the preceding claims, characterized in that said honeycomb body (1) has at least one cavity (25) at the inlet end side (5) . 13. The honeycomb body (1) as claimed in one of the preceding claims, characterized in that a part of the ducts (4) is closed off close to the outlet end side (6) . 14. The honeycomb body (1) as claimed in one of the preceding claims, characterized in that said honeycomb body (1) has a plurality of partial volumes (27,28) which have a different number of ducts (4) per unit of cross-sectional area from one another. Date the 13th day of August, 2007 The invention relates to a wound, lopped and/or coated honeycomb body (1) which is made of sheet steel (2,3). Said honeycomb body comprises a plurality of at least partially structured sheet metal layers (2), whereby the structure thereof forms channels (4) which lead from an inlet front side (5) to an outlet front side (6) of the honeycomb body (1). According to the invention, at least one part of the sheet metal layers (2,3) on the inlet front side (5) and/or the outlet front side (6) comprise recesses (9,10) which are arranged on the edges thereof (7, 8), such that a fissured structure of the inlet front side (5) and/or the outlet front side (6) is produced. As a result, only the smooth sheet steel (3) or only the structured sheet steel (2) or both recesses (9 and/or 10 ) can be provided. Also, at least one part of the sheet steel (2,3) can be made of a porous material, in particular compressed metal fibres (16). Deposition of rust particles (17) on the front sides (5,6) of the honeycomb body (1) is, to a large extent, prevented due to said recesses (9,10). |
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Patent Number | 248086 | ||||||||||||||||||
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Indian Patent Application Number | 2952/KOLNP/2007 | ||||||||||||||||||
PG Journal Number | 24/2011 | ||||||||||||||||||
Publication Date | 17-Jun-2011 | ||||||||||||||||||
Grant Date | 15-Jun-2011 | ||||||||||||||||||
Date of Filing | 13-Aug-2007 | ||||||||||||||||||
Name of Patentee | EMITEC GESELLSCHAFT FUR EMISSIONS-TECHNOLOGIE MBH | ||||||||||||||||||
Applicant Address | HAUPTSTRASSE 128, 53797 LOHMAR | ||||||||||||||||||
Inventors:
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PCT International Classification Number | F01N 3/28,F01N 3/022 | ||||||||||||||||||
PCT International Application Number | PCT/EP2006/001670 | ||||||||||||||||||
PCT International Filing date | 2006-02-23 | ||||||||||||||||||
PCT Conventions:
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