US20090016923A1 - Method for manufacturing at least one area of a filter structure, in particular for a particulate filter in the exhaust gas system of an internal combustion engine - Google Patents
Method for manufacturing at least one area of a filter structure, in particular for a particulate filter in the exhaust gas system of an internal combustion engine Download PDFInfo
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- US20090016923A1 US20090016923A1 US11/632,737 US63273705A US2009016923A1 US 20090016923 A1 US20090016923 A1 US 20090016923A1 US 63273705 A US63273705 A US 63273705A US 2009016923 A1 US2009016923 A1 US 2009016923A1
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- XFJBGINZIMNZBW-CRAIPNDOSA-N 5-chloro-2-[4-[(1r,2s)-2-[2-(5-methylsulfonylpyridin-2-yl)oxyethyl]cyclopropyl]piperidin-1-yl]pyrimidine Chemical compound N1=CC(S(=O)(=O)C)=CC=C1OCC[C@H]1[C@@H](C2CCN(CC2)C=2N=CC(Cl)=CN=2)C1 XFJBGINZIMNZBW-CRAIPNDOSA-N 0.000 description 1
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Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D39/00—Filtering material for liquid or gaseous fluids
- B01D39/14—Other self-supporting filtering material ; Other filtering material
- B01D39/20—Other self-supporting filtering material ; Other filtering material of inorganic material, e.g. asbestos paper, metallic filtering material of non-woven wires
- B01D39/2027—Metallic material
- B01D39/2031—Metallic material the material being particulate
- B01D39/2034—Metallic material the material being particulate sintered or bonded by inorganic agents
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
- B01D46/0001—Making filtering elements
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
- B01D46/52—Particle separators, e.g. dust precipitators, using filters embodying folded corrugated or wound sheet material
- B01D46/521—Particle separators, e.g. dust precipitators, using filters embodying folded corrugated or wound sheet material using folded, pleated material
- B01D46/522—Particle separators, e.g. dust precipitators, using filters embodying folded corrugated or wound sheet material using folded, pleated material with specific folds, e.g. having different lengths
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/10—Sintering only
- B22F3/11—Making porous workpieces or articles
- B22F3/1103—Making porous workpieces or articles with particular physical characteristics
- B22F3/1115—Making porous workpieces or articles with particular physical characteristics comprising complex forms, e.g. honeycombs
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2279/00—Filters adapted for separating dispersed particles from gases or vapours specially modified for specific uses
- B01D2279/30—Filters adapted for separating dispersed particles from gases or vapours specially modified for specific uses for treatment of exhaust gases from IC Engines
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy
Definitions
- the present invention relates to a method for manufacturing at least one area of a filter structure, in particular for a particulate filter in the exhaust gas system of an internal combustion engine.
- Sintered metals are suitable for manufacturing metallic filter mats.
- the processing of powdered metal is advantageous, because a well-defined density and pore size of the sintered metal may be adjusted via the particle size and particle size distribution of the powder used, as well as via the sintering conditions.
- a substrate material e.g., a metallic mesh or metal fabric
- the substrate material or framework material has two functions: it helps to fix the sintering metal powder, and later stabilizes the filter pocket.
- Such a filtering device is described in German Published Patent Application No. 101 28 936.
- the particulate filter shown in this patent is built into the exhaust gas system of a diesel engine.
- the filter walls in the known filter device are made of sintered metal and arranged in such a way as to form wedge-shaped filter pockets.
- the edges tapering into a tip of the filter pockets point against the direction of flow of the exhaust gas; the back narrow side of a filter pocket viewed in the direction of flow is open.
- the filter pockets are situated next to one another in such a way that a rotation-symmetric, annular filter structure is formed overall.
- the filter walls are formed by unstable sintered metal sheets or sintered metal mats, which are bonded to separate carrier or supporting structures, for example, perforated metal sheets, metal fabrics or the like.
- a spreadable, mortar-like compound made of a sintering metal and a minimum amount of an organic binder is also known from the market. It is spread into the metal fabric or metal mesh by the bucket wheel principle. A smooth and thus relatively small filter surface is thus obtained.
- a flowable paste or a slurry may be produced from sintering metal powder, an organic binder, and a solvent.
- the powder prepared in this way may then be applied either by immersing the metallic fabric or metallic mesh into the paste or slurry or the slurry may be cast onto or the paste may be imprinted on the metal fabric or mesh (by the silk-screen method, for example).
- a subsequent drying step is required in which the solvent is evaporated and the sintering metal powder is fixed on the metal framework.
- sintering metal powder may be mixed with wax beads and this mixture may be blown onto the metallic mesh or metallic fabric. When heated, the melting wax beads cause the powder to adhere to the metallic framework.
- the object of the present invention is therefore to refine a method of the type in such a way as to allow a filtering device having precisely defined characteristics to be manufactured in a cost-effective manner without using a supporting structure.
- the use of a sheet has the advantage that its thickness, density, and the structuring of the sintering metal filling may be defined very precisely.
- the permeability of the sintered metal filter may be predefined precisely via these parameters.
- such a sheet may be manufactured by a technically simple and cost-effective process with a reproducible quality. Continuous quality control and storage of such a sheet is also possible, which also facilitates the manufacturing process and lowers the manufacturing costs.
- Structuring the sheet makes it possible to produce a defined surface structure and thus a controlled increase of the active filter surface area.
- the sheet is produced by sheet spreading, sheet casting, or sheet extrusion in step b. All above-named methods allow the sheet thickness to be precisely adjusted and a homogeneous, smooth, and air bubble-free sintered metal sheet to be manufactured.
- Structuring takes place in step c, preferably at a temperature in the range of 80° to 150° Celsius, preferably in the range of 80° to 90° Celsius.
- the structuring temperature at which the sintered metal sheet is plastically deformable may be easily adjusted via an appropriate selection and amount of organic binder.
- the given temperature range is therefore particularly advantageous because the required energy input is limited and yet a satisfactory effect is achieved using customary organic and thermoplastic binders. This is true in particular for the range of 80° to 90° Celsius.
- Structuring is preferably carried out with the help of embossing plates which are placed on and pressed into the sheet.
- a structured laminating roller may also be used or a plurality of rollers may be situated one behind the other. An arrangement of rollers on both sides is also possible.
- both sides of the sheet are subjected to a structuring step.
- a structuring step it is possible, for example, to obtain a double-sided waffle structure of the sheet, which has the advantage that not only a surface is produced, but also the mechanical stability of the sheet is improved via suitable geometries (waffle structures, honeycomb structures, see further below).
- a plurality of sheets may be laminated together in order to increase the layer thickness overall or locally. This may take place before or after the embossing step; however, initially a plurality of green sheets is advantageously laminated together in order to adjust the desired layer thickness or a desired gradient regarding powder size distribution and/or density distribution, and subsequently one surface or both surfaces is/are embossed. It is, however, also conceivable to laminate pre-structured, e.g., perforated, sheets together.
- sheets containing more or less fine or course sintering metal powder may be combined to influence the pore structure of the finished filter sheets.
- Course and fine powders have different tendencies to bind during sintering.
- the green density of the sheets also has a great influence, i.e., it is important how tightly the particles are packed and how fast and how strongly they bind to one another.
- laminate two sheets together one of which may have a particularly good structurability because of its composition, while the other is particularly stable mechanically, to thus make reliable handling in the production process possible. This is determined by the organic materials used during the sheet manufacture, i.e., the polymer binder, plasticizer additives, etc.
- a metallic fabric, a mesh, or a perforated sheet is advantageously used as a support structure. These are cost-effective, cover only a small surface area, and thus allow high gas throughput during operation.
- Optimum filter characteristics in particular when using the filtering device as a particulate filter in the exhaust gas system of an internal combustion engine, are achieved when the sintering metal powder has a grain size of approximately 1 ⁇ m to 150 ⁇ m, preferably 40 ⁇ m to 70 ⁇ m, even more preferably 50 ⁇ m to 60 ⁇ m.
- step a the sintering metal powder having approximately 8% by weight of acrylate binder and butyl acetate as a solvent is processed to form a spreadable slurry.
- FIG. 1 shows a schematic depiction of an internal combustion engine having a particulate filter having a filter structure.
- FIG. 2 shows a perspective view of the filter structure of FIG. 1 .
- FIG. 3 shows two filter pockets of the filter structure of FIG. 1 .
- FIG. 4 shows a flow diagram of a method for manufacturing a filter wall of the filter structure of FIG. 1 .
- FIG. 5 shows a section of the sintering metal sheet before the structuring step.
- FIG. 6 shows a section of the sintering metal sheet of FIG. 5 after structuring using a first embossing plate.
- FIG. 7 shows a section of the sintering metal sheet of FIG. 5 after structuring using a second embossing plate.
- FIG. 8 shows an embodiment of the structuring using waffle-shaped embossing plates.
- FIG. 9 shows different embodiments of the multilayer green sheets according to the present invention.
- An internal combustion engine is labeled with reference numeral 10 in FIG. 1 . It has an exhaust system 12 , in which a particulate filter 14 is situated. It is able to filter out soot particles, for example, from the exhaust gas of internal combustion engine 10 .
- Particulate filter 14 has a housing 16 and a filter structure 18 situated in housing 16 .
- Filter structure 18 is shown in more detail in FIG. 2 : It includes a plurality of wedge-shaped filter pockets 20 , which are situated with their wedge edges tapering to a tip against the direction of flow of the exhaust gas. Filter pockets 20 are situated next to one another around a shared longitudinal axis, so that a completely rotation-symmetric filter structure 18 is formed. The radially inner and outer narrow sides of filter pockets 20 are closed. The narrow sides of filter pockets 20 situated in the back in the flow direction are open. The filter pockets are connected to one another in the area of their back ends in the direction of flow.
- FIG. 3 Two adjacent filter pockets 20 a and 20 b are depicted in FIG. 3 .
- the exhaust gas enters an area between the two filter pockets 20 a and 20 b , passes through a lateral filter wall 22 , and thus enters the inside of the particular filter pockets 20 a and 20 b .
- the exhaust gas flow is represented by an arrow 24 .
- the particulates are separated from the exhaust gas and deposited on the upstream surface of side wall 22 .
- the walls, and in particular side walls 22 of filter pockets 20 are made of a porous sintered material.
- a method for manufacturing side walls 22 of filter pockets 20 is shown in FIG. 4 .
- sintering metal powder 26 having a grain size of approximately 50 ⁇ m to 60 ⁇ m, preferably 53 ⁇ m, is processed using approximately 2% to 8% by weight of acrylate binder 28 and a volatile organic solvent, for example, butyl acetate or alcohol 30 to a spreadable slurry 34 in a device 32 .
- the slurry is processed into a 100 ⁇ m to 500 ⁇ m thick sintering metal sheet 38 (green sheet) using a film spreading device 36 . If multilayer green sheets 39 are produced from these individual sheets, the thickness is preferably >450 ⁇ m.
- This metal sheet or the multilayer green sheets are then structured with the aid of a device 40 , either embossing plates or a structured laminating roller being able to be used here.
- the sintering sheets are heated to a temperature of approximately 80° C. for this purpose.
- Different embossing plates are placed onto and pressed in.
- the structure of the embossing plates shows clearly after being pressed onto the corresponding blank 42 .
- Blank 42 is then sintered in a furnace 44 , an almost single-piece composite 46 being obtained.
- Filter pockets 22 are subsequently manufactured from the sintered metal sheet by pressing, folding, and welding 48 .
- FIGS. 5 , 6 , and 7 show sections of a blank 42 used according to the present invention.
- FIG. 5 shows a blank 42 having a defined layer thickness and green thickness, which has been manufactured using a relatively thick sintered metal sheet 38 .
- Surface 52 of sintered metal sheet 38 is smooth overall.
- Blank 42 shown in FIG. 6 corresponds to the blank manufactured using the method described in FIG. 4 : It is apparent that the surface structure of embossing plate 40 is mapped on surface 52 of sintered metal sheet 38 .
- FIG. 7 shows a blank 42 , which has been manufactured with a differently structured embossing plate 40 and whose surface 52 has a pattern 54 embossed accordingly.
- a sintered metal sheet having a large surface area and high mechanical stability may thus be manufactured, for example, via the method described below for manufacturing a “waffle iron structure.”
- sintering metal powder 26 having a grain size of approximately 50 ⁇ m to 60 ⁇ m, preferably 53 ⁇ m, is processed by a device 32 with approximately 2% to 8% by weight of acrylate binder and a volatile organic solvent, for example, butyl acetate or alcohol 30 to form a spreadable slurry 34 .
- the slurry is processed into a 100 ⁇ m to 500 ⁇ m, preferably >450 ⁇ m thick sintering metal green sheet 38 using a film spreading device 36 .
- This sheet is then structured, for example, with the aid of embossing plates 56 shown in FIG. 8 .
- the tool is heated to a temperature of approximately 80° C., green sheet 38 is placed in it, and the tool is closed under pressure.
- green sheet 38 is removed again and now has the structure of the embossing plates.
- the blank is then sintered in a furnace 44 , the geometry of three-dimensionally structured sheet 38 being fully preserved.
- sintering metal powder in other geometries (tablets, roughly sectioned plates, flatcake, etc.) instead of a defined sheet 38 in the form of a thermoplastic compound 58 (see FIG. 8 ).
- the following example shows the manufacture of sintering metal sheets having a large surface area by using green sheets or multilayer sheets having a gradient.
- sintering metal powder 26 having a grain size of 50 ⁇ m is processed with approximately 2% to 8% acrylate binder and a volatile organic solvent, for example, butyl acetate or alcohol 30 with the aid of a device 32 to form a spreadable slurry 34 .
- This slurry is processed using a film spreader device 36 into a 100 ⁇ m to 500 ⁇ m, preferably ⁇ 200 ⁇ m thick sintered metal green sheet 38 .
- the same procedure is applied for powders, for example, of a grain size of 30 ⁇ m and 80 ⁇ m.
- green sheet variants are sheet compositions having a higher proportion of organic material (e.g., 6% to 20% by weight of acrylic binder) or sheets having pore-forming additives, which evaporate completely during the sintering process. Sheets having different layer thicknesses also represent possible variants, as does the use of defined powder mixtures (narrow monomodal, bimodal, or trimodal grain size distributions) or different powder types (e.g., spherical, round powder types, irregular drop-shaped powder types, flake-type powders, etc.) in manufacturing the sheet.
- defined powder mixtures narrow monomodal, bimodal, or trimodal grain size distributions
- different powder types e.g., spherical, round powder types, irregular drop-shaped powder types, flake-type powders, etc.
- These sheet variants 38 may be combined in different ways to form multilayer green sheets 39 .
- the porosity and surface characteristics of sintered filter sheets 46 may thus be adjusted and defined in a controlled manner via suitable sintering profiles.
- a filter sheet having large pores on one side and fine pores on the other side may be achieved by laminating different sheet variants after sintering, or a filter sheet having a high degree of surface roughness may be obtained after sintering when using sheets of different green densities, since the side having a lower green density shrinks in a non-homogeneous manner during sintering, forming porous surface structures.
- sintered metal filters having a porosity gradient and a large surface area are obtained.
- the above-mentioned multilayer green sheets 39 manufactured by laminating individual sheets 38 together, are processed as green sheets 38 and may, if needed, like sheets 38 , be laminated onto a supporting framework such as a metallic mesh 62 and/or subjected to additional mechanical structuring by embossing.
- FIG. 9 shows different design options of multilayer green sheets 39 .
- FIG. 9A shows a triple laminate 60 made of three green sheets 38 of the same type with metallic mesh 62 as the supporting structure applied by lamination.
- FIG. 9B shows a double laminate 64 made of two different green sheets 38 , one having a fine powder and the other having a coarse powder ( 66 , 68 ). The surface of the sheet having a coarse powder 68 is additionally structured by embossing to increase the filtering surface area.
- FIG. 9C shows a green sheet having a “waffle structure,” manufactured using a multilayer green sheet 39 having three layers ( 70 , 72 , 74 ) each with different powder filling, and finally FIG.
- FIG. 9D shows a double laminate 76 made of two different green sheets 78 , 80 , one sheet being highly filled, and the other having a low degree of filling with metal powder, and also possibly containing pore-forming additives.
- FIG. 9D again shows a metallic mesh 62 applied by lamination.
Abstract
A method for manufacturing at least one area of a filter structure, in particular for a particulate filter in the exhaust gas system of an internal combustion engine, includes the following steps: a. manufacturing a mixture from a sintering metal powder and an organic binder; b. manufacturing a sheet from the mixture; c. structuring the sheet; and d. sintering.
Description
- The present invention relates to a method for manufacturing at least one area of a filter structure, in particular for a particulate filter in the exhaust gas system of an internal combustion engine.
- Sintered metals are suitable for manufacturing metallic filter mats. In particular the processing of powdered metal is advantageous, because a well-defined density and pore size of the sintered metal may be adjusted via the particle size and particle size distribution of the powder used, as well as via the sintering conditions.
- Currently, to manufacture filter mats made of sintered metal, a substrate material (e.g., a metallic mesh or metal fabric) is coated using sintering metal powder and sintered together. The substrate material or framework material has two functions: it helps to fix the sintering metal powder, and later stabilizes the filter pocket.
- Such a filtering device is described in German Published Patent Application No. 101 28 936. The particulate filter shown in this patent is built into the exhaust gas system of a diesel engine. The filter walls in the known filter device are made of sintered metal and arranged in such a way as to form wedge-shaped filter pockets. The edges tapering into a tip of the filter pockets point against the direction of flow of the exhaust gas; the back narrow side of a filter pocket viewed in the direction of flow is open. The filter pockets are situated next to one another in such a way that a rotation-symmetric, annular filter structure is formed overall.
- In the known particulate filter, the filter walls are formed by unstable sintered metal sheets or sintered metal mats, which are bonded to separate carrier or supporting structures, for example, perforated metal sheets, metal fabrics or the like.
- Manufacturing a spreadable, mortar-like compound made of a sintering metal and a minimum amount of an organic binder is also known from the market. It is spread into the metal fabric or metal mesh by the bucket wheel principle. A smooth and thus relatively small filter surface is thus obtained.
- Furthermore, a flowable paste or a slurry may be produced from sintering metal powder, an organic binder, and a solvent. The powder prepared in this way may then be applied either by immersing the metallic fabric or metallic mesh into the paste or slurry or the slurry may be cast onto or the paste may be imprinted on the metal fabric or mesh (by the silk-screen method, for example). In all variants of this process, a subsequent drying step is required in which the solvent is evaporated and the sintering metal powder is fixed on the metal framework.
- Finally, it is known that sintering metal powder may be mixed with wax beads and this mixture may be blown onto the metallic mesh or metallic fabric. When heated, the melting wax beads cause the powder to adhere to the metallic framework.
- Depending on the coating method used, there remains, however, the difficulty of accurately adjusting and controlling the coating thickness and coating density of the sintering metal layer. At the same time, a framework material considerably increases the weight and cost of a filter mat. It is therefore desirable to be able to omit a framework material, yet to produce defined and stable sintering metal sheets.
- The object of the present invention is therefore to refine a method of the type in such a way as to allow a filtering device having precisely defined characteristics to be manufactured in a cost-effective manner without using a supporting structure.
- This object is achieved with a method of the type named in the preamble in that the method includes the following steps:
-
- a. manufacturing a mixture from a sintering metal powder and an organic binder;
- b. manufacturing a sheet from the mixture;
- c. structuring the sheet; and
- d. sintering.
- The use of a sheet has the advantage that its thickness, density, and the structuring of the sintering metal filling may be defined very precisely. The permeability of the sintered metal filter may be predefined precisely via these parameters.
- In addition, such a sheet may be manufactured by a technically simple and cost-effective process with a reproducible quality. Continuous quality control and storage of such a sheet is also possible, which also facilitates the manufacturing process and lowers the manufacturing costs.
- Structuring the sheet makes it possible to produce a defined surface structure and thus a controlled increase of the active filter surface area.
- In a first refinement, the sheet is produced by sheet spreading, sheet casting, or sheet extrusion in step b. All above-named methods allow the sheet thickness to be precisely adjusted and a homogeneous, smooth, and air bubble-free sintered metal sheet to be manufactured.
- It is also possible to produce multilayer green sheets from these individual sheets after the manufacture of the sheets in step b (green sheets) and before structuring.
- Structuring takes place in step c, preferably at a temperature in the range of 80° to 150° Celsius, preferably in the range of 80° to 90° Celsius. The structuring temperature at which the sintered metal sheet is plastically deformable may be easily adjusted via an appropriate selection and amount of organic binder. The given temperature range is therefore particularly advantageous because the required energy input is limited and yet a satisfactory effect is achieved using customary organic and thermoplastic binders. This is true in particular for the range of 80° to 90° Celsius.
- Structuring is preferably carried out with the help of embossing plates which are placed on and pressed into the sheet. However, a structured laminating roller may also be used or a plurality of rollers may be situated one behind the other. An arrangement of rollers on both sides is also possible.
- In a further advantageous refinement of the method according to the present invention, both sides of the sheet are subjected to a structuring step. In this way, it is possible, for example, to obtain a double-sided waffle structure of the sheet, which has the advantage that not only a surface is produced, but also the mechanical stability of the sheet is improved via suitable geometries (waffle structures, honeycomb structures, see further below).
- In a particularly advantageous embodiment of the method according to the present invention, a plurality of sheets, even sheets structured differently, may be laminated together in order to increase the layer thickness overall or locally. This may take place before or after the embossing step; however, initially a plurality of green sheets is advantageously laminated together in order to adjust the desired layer thickness or a desired gradient regarding powder size distribution and/or density distribution, and subsequently one surface or both surfaces is/are embossed. It is, however, also conceivable to laminate pre-structured, e.g., perforated, sheets together.
- Furthermore, sheets containing more or less fine or course sintering metal powder may be combined to influence the pore structure of the finished filter sheets. Course and fine powders have different tendencies to bind during sintering. The green density of the sheets also has a great influence, i.e., it is important how tightly the particles are packed and how fast and how strongly they bind to one another. It is also possible to laminate two sheets together, one of which may have a particularly good structurability because of its composition, while the other is particularly stable mechanically, to thus make reliable handling in the production process possible. This is determined by the organic materials used during the sheet manufacture, i.e., the polymer binder, plasticizer additives, etc.
- In another embodiment of the method according to the present invention, it is possible to also bond the sheet to a support structure. A metallic fabric, a mesh, or a perforated sheet is advantageously used as a support structure. These are cost-effective, cover only a small surface area, and thus allow high gas throughput during operation.
- Optimum filter characteristics, in particular when using the filtering device as a particulate filter in the exhaust gas system of an internal combustion engine, are achieved when the sintering metal powder has a grain size of approximately 1 μm to 150 μm, preferably 40 μm to 70 μm, even more preferably 50 μm to 60 μm.
- Favorable manufacturing costs are achieved if, in step a, the sintering metal powder having approximately 8% by weight of acrylate binder and butyl acetate as a solvent is processed to form a spreadable slurry.
-
FIG. 1 shows a schematic depiction of an internal combustion engine having a particulate filter having a filter structure. -
FIG. 2 shows a perspective view of the filter structure ofFIG. 1 . -
FIG. 3 shows two filter pockets of the filter structure ofFIG. 1 . -
FIG. 4 shows a flow diagram of a method for manufacturing a filter wall of the filter structure ofFIG. 1 . -
FIG. 5 shows a section of the sintering metal sheet before the structuring step. -
FIG. 6 shows a section of the sintering metal sheet ofFIG. 5 after structuring using a first embossing plate. -
FIG. 7 shows a section of the sintering metal sheet ofFIG. 5 after structuring using a second embossing plate. -
FIG. 8 shows an embodiment of the structuring using waffle-shaped embossing plates. -
FIG. 9 shows different embodiments of the multilayer green sheets according to the present invention. - An internal combustion engine is labeled with
reference numeral 10 inFIG. 1 . It has anexhaust system 12, in which aparticulate filter 14 is situated. It is able to filter out soot particles, for example, from the exhaust gas ofinternal combustion engine 10.Particulate filter 14 has ahousing 16 and afilter structure 18 situated inhousing 16. -
Filter structure 18 is shown in more detail inFIG. 2 : It includes a plurality of wedge-shaped filter pockets 20, which are situated with their wedge edges tapering to a tip against the direction of flow of the exhaust gas. Filter pockets 20 are situated next to one another around a shared longitudinal axis, so that a completely rotation-symmetric filter structure 18 is formed. The radially inner and outer narrow sides of filter pockets 20 are closed. The narrow sides of filter pockets 20 situated in the back in the flow direction are open. The filter pockets are connected to one another in the area of their back ends in the direction of flow. - Two adjacent filter pockets 20 a and 20 b are depicted in
FIG. 3 . During operation, the exhaust gas enters an area between the two filter pockets 20 a and 20 b, passes through alateral filter wall 22, and thus enters the inside of the particular filter pockets 20 a and 20 b. The exhaust gas flow is represented by anarrow 24. When passing throughside wall 22, the particulates are separated from the exhaust gas and deposited on the upstream surface ofside wall 22. - The walls, and in
particular side walls 22 of filter pockets 20, are made of a porous sintered material. A method for manufacturingside walls 22 of filter pockets 20, for example, is shown inFIG. 4 . First, sinteringmetal powder 26 having a grain size of approximately 50 μm to 60 μm, preferably 53 μm, is processed using approximately 2% to 8% by weight ofacrylate binder 28 and a volatile organic solvent, for example, butyl acetate oralcohol 30 to aspreadable slurry 34 in a device 32. The slurry is processed into a 100 μm to 500 μm thick sintering metal sheet 38 (green sheet) using afilm spreading device 36. If multilayergreen sheets 39 are produced from these individual sheets, the thickness is preferably >450 μm. - This metal sheet or the multilayer green sheets are then structured with the aid of a
device 40, either embossing plates or a structured laminating roller being able to be used here. The sintering sheets are heated to a temperature of approximately 80° C. for this purpose. Different embossing plates are placed onto and pressed in. The structure of the embossing plates shows clearly after being pressed onto the corresponding blank 42.Blank 42 is then sintered in afurnace 44, an almost single-piece composite 46 being obtained. Filter pockets 22 are subsequently manufactured from the sintered metal sheet by pressing, folding, andwelding 48. -
FIGS. 5 , 6, and 7 show sections of a blank 42 used according to the present invention.FIG. 5 shows a blank 42 having a defined layer thickness and green thickness, which has been manufactured using a relatively thicksintered metal sheet 38.Surface 52 ofsintered metal sheet 38 is smooth overall.Blank 42 shown inFIG. 6 corresponds to the blank manufactured using the method described inFIG. 4 : It is apparent that the surface structure of embossingplate 40 is mapped onsurface 52 ofsintered metal sheet 38.FIG. 7 shows a blank 42, which has been manufactured with a differently structuredembossing plate 40 and whosesurface 52 has apattern 54 embossed accordingly. - As mentioned previously, the mechanical stability of the sheet may be improved via suitable geometries. A sintered metal sheet having a large surface area and high mechanical stability may thus be manufactured, for example, via the method described below for manufacturing a “waffle iron structure.”
- First, sintering
metal powder 26 having a grain size of approximately 50 μm to 60 μm, preferably 53 μm, is processed by a device 32 with approximately 2% to 8% by weight of acrylate binder and a volatile organic solvent, for example, butyl acetate oralcohol 30 to form aspreadable slurry 34. The slurry is processed into a 100 μm to 500 μm, preferably >450 μm thick sintering metalgreen sheet 38 using afilm spreading device 36. This sheet is then structured, for example, with the aid ofembossing plates 56 shown inFIG. 8 . For this purpose, the tool is heated to a temperature of approximately 80° C.,green sheet 38 is placed in it, and the tool is closed under pressure. After opening the tool,green sheet 38 is removed again and now has the structure of the embossing plates. The blank is then sintered in afurnace 44, the geometry of three-dimensionallystructured sheet 38 being fully preserved. Using this tool, it is also possible to use the sintering metal powder in other geometries (tablets, roughly sectioned plates, flatcake, etc.) instead of a definedsheet 38 in the form of a thermoplastic compound 58 (seeFIG. 8 ). - The following example shows the manufacture of sintering metal sheets having a large surface area by using green sheets or multilayer sheets having a gradient.
- First, sintering
metal powder 26 having a grain size of 50 μm, for example, is processed with approximately 2% to 8% acrylate binder and a volatile organic solvent, for example, butyl acetate oralcohol 30 with the aid of a device 32 to form aspreadable slurry 34. This slurry is processed using afilm spreader device 36 into a 100 μm to 500 μm, preferably <200 μm thick sintered metalgreen sheet 38. The same procedure is applied for powders, for example, of a grain size of 30 μm and 80 μm. - Other green sheet variants are sheet compositions having a higher proportion of organic material (e.g., 6% to 20% by weight of acrylic binder) or sheets having pore-forming additives, which evaporate completely during the sintering process. Sheets having different layer thicknesses also represent possible variants, as does the use of defined powder mixtures (narrow monomodal, bimodal, or trimodal grain size distributions) or different powder types (e.g., spherical, round powder types, irregular drop-shaped powder types, flake-type powders, etc.) in manufacturing the sheet.
- These
sheet variants 38 may be combined in different ways to form multilayergreen sheets 39. The porosity and surface characteristics ofsintered filter sheets 46 may thus be adjusted and defined in a controlled manner via suitable sintering profiles. Thus, for example, a filter sheet having large pores on one side and fine pores on the other side may be achieved by laminating different sheet variants after sintering, or a filter sheet having a high degree of surface roughness may be obtained after sintering when using sheets of different green densities, since the side having a lower green density shrinks in a non-homogeneous manner during sintering, forming porous surface structures. In both cases, sintered metal filters having a porosity gradient and a large surface area are obtained. - The above-mentioned multilayer
green sheets 39, manufactured by laminatingindividual sheets 38 together, are processed asgreen sheets 38 and may, if needed, likesheets 38, be laminated onto a supporting framework such as ametallic mesh 62 and/or subjected to additional mechanical structuring by embossing. -
FIG. 9 shows different design options of multilayergreen sheets 39.FIG. 9A shows atriple laminate 60 made of threegreen sheets 38 of the same type withmetallic mesh 62 as the supporting structure applied by lamination.FIG. 9B shows adouble laminate 64 made of two differentgreen sheets 38, one having a fine powder and the other having a coarse powder (66, 68). The surface of the sheet having acoarse powder 68 is additionally structured by embossing to increase the filtering surface area.FIG. 9C shows a green sheet having a “waffle structure,” manufactured using a multilayergreen sheet 39 having three layers (70, 72, 74) each with different powder filling, and finallyFIG. 9D shows adouble laminate 76 made of two differentgreen sheets FIG. 9D again shows ametallic mesh 62 applied by lamination.
Claims (15)
1-14. (canceled)
15. A method for manufacturing at least one area of a filter structure in an exhaust gas system of an internal combustion engine, comprising:
manufacturing a mixture from a sintering metal powder and an organic binder;
manufacturing a sheet from the mixture;
structuring the sheet; and
performing a sintering operation.
16. The method as recited in claim 15 , further comprising:
before the structuring step, manufacturing multilayer green sheets from the sheet manufactured; and
structuring the multilayer green sheets.
17. The method as recited in claim 15 , wherein the sheet and/or the multilayer green sheet have a sintering metal powder size distribution gradient and/or density distribution gradient.
18. The method as recited in claim 15 , wherein the sheet is produced by sheet spreading, sheet casting, or sheet extrusion.
19. The method as recited in claim 15 , wherein the structuring takes place at a temperature in the range of 80° C. to 150° C., preferably in the range of 80° C. to 90° C.
20. The method as recited in claim 15 , wherein the structuring is achieved by embossing.
21. The method as recited in claim 20 , wherein embossing plates and/or structured laminating rollers whose surface structure is mapped on the sheet or the multilayer green sheet are used for embossing.
22. The method as recited in claim 15 , wherein a sintering metal powder having a grain size of approximately 1 μm to 150 μm, preferably 40 μm to 70 μm, more preferably 50 μm to 60 μm, is used.
23. The method as recited in claim 15 , wherein the sintering metal powder is processed in step a with approximately 2% to 8% by weight of acrylate binder and a volatile organic solvent to form a spreadable slurry.
24. The method as recited in claim 23 , wherein the volatile organic solvent is butyl acetate or alcohol.
25. The method as recited in claim 15 , wherein the sheet or the multilayer green sheet is structured on both sides.
26. The method as recited in claim 25 , wherein the sheet or the multilayer green sheet is given a double-sided waffle structure.
27. The method as recited in claim 15 , wherein the sheet or the multilayer green sheet is additionally bonded to a supporting structure.
28. The method as recited in claim 27 , wherein a metallic fabric, a metallic mesh, or a perforated sheet is used as the supporting structure.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE102004035311.5 | 2004-07-21 | ||
DE102004035311A DE102004035311A1 (en) | 2004-07-21 | 2004-07-21 | Method for producing at least one region of a filter structure, in particular for a particle filter in the exhaust system of an internal combustion engine |
PCT/EP2005/052958 WO2006008222A1 (en) | 2004-07-21 | 2005-06-24 | Method for producing an area of a filter structure, especially for a particle filter in the exhaust gas system of an internal combustion engine |
Publications (1)
Publication Number | Publication Date |
---|---|
US20090016923A1 true US20090016923A1 (en) | 2009-01-15 |
Family
ID=34979584
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US11/632,737 Abandoned US20090016923A1 (en) | 2004-07-21 | 2005-06-24 | Method for manufacturing at least one area of a filter structure, in particular for a particulate filter in the exhaust gas system of an internal combustion engine |
Country Status (5)
Country | Link |
---|---|
US (1) | US20090016923A1 (en) |
EP (1) | EP1771236A1 (en) |
JP (1) | JP2008506523A (en) |
DE (1) | DE102004035311A1 (en) |
WO (1) | WO2006008222A1 (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20090160105A1 (en) * | 2006-07-06 | 2009-06-25 | Plansee Se | Process for Producing an Extruded Shaped Body |
US20140291326A1 (en) * | 2011-07-29 | 2014-10-02 | Fachhochschule Muenster | Method for applying a protective layer for protecting against impact stresses |
US10494970B2 (en) | 2017-07-05 | 2019-12-03 | Denso International America, Inc. | Emissions control substrate |
CN115487604A (en) * | 2022-09-23 | 2022-12-20 | 东莞市名创传动科技有限公司 | Composite sintered filtering material |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102008042415B3 (en) * | 2008-09-26 | 2010-05-20 | Andreas Hofenauer | Metallic semi-finished product, process for the production of materials and semi-finished products and their uses |
DE102013016226A1 (en) | 2012-10-01 | 2014-04-03 | Mann + Hummel Gmbh | Semi finished product useful for producing metallic material, and as eg, filter for gases or liquids, catalyst support, catalyst, and heat exchanger, comprises organic fibers, binders, metallic fillers, and non metallic inorganic fillers |
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DE10128936A1 (en) * | 2001-06-18 | 2003-01-02 | Hjs Fahrzeugtechnik Gmbh & Co | Exhaust gas particle filter used for removing particles from exhaust gas stream of diesel engine comprises metal support with openings and on which porous sintered metal powder is bound by sintering process |
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2004
- 2004-07-21 DE DE102004035311A patent/DE102004035311A1/en not_active Ceased
-
2005
- 2005-06-24 US US11/632,737 patent/US20090016923A1/en not_active Abandoned
- 2005-06-24 EP EP05764002A patent/EP1771236A1/en not_active Withdrawn
- 2005-06-24 WO PCT/EP2005/052958 patent/WO2006008222A1/en active Application Filing
- 2005-06-24 JP JP2007521933A patent/JP2008506523A/en not_active Withdrawn
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US2792302A (en) * | 1955-08-29 | 1957-05-14 | Connecticut Metals Inc | Process for making porous metallic bodies |
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Publication number | Priority date | Publication date | Assignee | Title |
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US20090160105A1 (en) * | 2006-07-06 | 2009-06-25 | Plansee Se | Process for Producing an Extruded Shaped Body |
US20140291326A1 (en) * | 2011-07-29 | 2014-10-02 | Fachhochschule Muenster | Method for applying a protective layer for protecting against impact stresses |
US9752235B2 (en) * | 2011-07-29 | 2017-09-05 | Fachhochschule Muenster | Workpiece comprising a laminate to protect against an impact stress |
US10494970B2 (en) | 2017-07-05 | 2019-12-03 | Denso International America, Inc. | Emissions control substrate |
CN115487604A (en) * | 2022-09-23 | 2022-12-20 | 东莞市名创传动科技有限公司 | Composite sintered filtering material |
Also Published As
Publication number | Publication date |
---|---|
WO2006008222A1 (en) | 2006-01-26 |
EP1771236A1 (en) | 2007-04-11 |
DE102004035311A1 (en) | 2006-02-16 |
JP2008506523A (en) | 2008-03-06 |
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