EP1529934B1 - Catalyst body and method for its manufacturing - Google Patents

Abstract

Producing a catalyst structure for gas treatment, comprising an assembly of catalyst-coated metal sheets in which at least one of each pair of adjacent sheets is corrugated and adjacent sheets are bonded together in uncoated areas, comprises providing the sheets with coated and uncoated areas before they are assembled and bonding the uncoated areas together. An independent claim is also included for a catalyst structure for gas treatment comprising an assembly of catalyst-coated metal sheets in which at least one of each pair of adjacent sheets is corrugated and the corrugation peaks have uncoated areas with contact zones through which the sheets are bonded together, where the contact zones are smaller than the corresponding uncoated areas.

Description

The invention relates to a method for producing a catalyst body for the catalytic treatment of gas, in particular for the catalytic purification of exhaust gas of an internal combustion engine. Such catalyst bodies intended for installation in a housing of a catalyst are often referred to as a substrate. The internal combustion engine may, for example, belong to an automobile or other motor vehicle or be arranged stationary.

From the EP 0 674 944 A and the corresponding US 5,628,925 It is known to apply to form a catalyst body such coatings on at least one smooth, wave-free metal strip and at least one corrugated metal strip that sheet metal elements arise with bare, coating-free strip-shaped areas that cross the waves in the finished catalyst body. The sheet metal elements are then, for example, wound or stacked or folded, so that a winding or a stack is formed with adjacent sheet metal element layers. These are firmly connected to one another at the wave crests by electron beam or laser or rolling wheel resistance welding or soldering. However, these known methods have the disadvantage that the sheet metal element layers lying adjacent to each other, while resting on one another substantially along the entire wave crests, however, they are joined together only in those partial areas of the crest peaks where the non-overlapping areas intersect the crests of the crests. Furthermore, and above all, the sheet-metal elements also have coatings on the wave peaks next to the coating-free regions, so that the coating-free regions of the adjacent sheet-metal layers are at small distances apart even at the wave crests at least before the joining of the sheet-metal element layers. This can make it difficult to connect the sheet metal element layers, in particular the connection by welding. For these reasons, the sheet metal layers are not very stable connected. The sheet element layers can therefore move against each other when using the catalyst body as a result of thermal stresses, vibrations and other accelerations and thereby cause abrasion of the coating material. Furthermore, the connections of the sheet metal layers may eventually become loose over time. Furthermore, the catalyst bodies produced in accordance with the two cited documents have the disadvantage that the coating-free areas also have partial areas lying between the neighboring wave peaks, which are rather wide and, of course, do not give any catalytic treatment of the exhaust gas.

The EP 0 049 489 A discloses a method for producing a catalyst body from two sheet metal elements, namely a sheet metal strip with trapezoidal waves and an originally flat sheet metal strip. In this manufacturing process, an adhesive is first applied to the approximately flat surface areas of the corrugated sheet metal strip at the wave crests. Thereafter, a solder powder is sprayed against the corrugated tape so that solder powder adheres to the previously adhesive surface areas. In places with Adhesive and solder powder provided corrugated sheet metal strip and the originally flat sheet metal strip are now merged and wound together to form a spiral winding so that pairs adjacent sheet metal layers arise, each of which consists of a turn of one of the two metal bands. The two metal strips are then soldered together in the contact areas of the corrugated metal strip formed by the flat surfaces of the corrugation peaks in a vacuum soldering furnace. Thereafter, noble metal coatings are applied to the brazed metal strips, so that a catalyst body is formed. In the case of a catalyst body produced in this way, the applied coatings extend as far as directly into the corners between the corrugation flanks and the approximately planar crests of the corrugated sheet-metal strip in which it is soldered to the other sheet-metal strip. Since the application of the coatings takes place only after soldering the metal strips, the coatings are substantially thicker at and in said corners than in the other, smooth, more or less flat or slightly curved surface areas of the two metal strips. Furthermore, the thickness of the coatings often varies uncontrollably and undesirably along the passageways of the catalyst body parallel to the waves. This is particularly the case when the bands have a width measured along the waves, which is relatively large compared to the cross-sectional dimensions of the passages, ie the wave height and the wavelength of the waves. Uneven thicknesses of the coatings lead to the disadvantage that the catalytically active noble metal is not optimally distributed and can be exploited poorly. This in turn means that more expensive precious metal is needed for the preparation of a catalyst body than with an optimal, for example, uniform distribution of the noble metal and / or that the effect of the catalyst body is reduced.

The US 5 094 074 A discloses various catalysts with electrically heatable catalyst bodies and processes for their preparation. The catalyst body has a sheet metal element, which consists of a meandering band with flat, mutually parallel sections. Between two adjacent, planar sections each serving as a spacer, corrugated sheet metal element is arranged. The sheet metal elements together form a stack of alternating successive, planar and corrugated sheet metal element layers, which abut each other at the wave crests. All sheet metal elements have a metallic core and coatings. In the manufacture of a catalyst body at least the sheet metal element consisting of a meandering strip is provided with coatings of electrically insulating ceramic prior to assembly with the corrugated sheet metal elements such that these coatings completely cover both surfaces of the metallic core of the strip and the metallic core of the strip after Insemble electrically with the corrugated sheet metal elements against their metallic cores. The first in the US 5 094 074 A described manufacturing method, the corrugated sheet metal elements are also provided prior to assembly with ceramic, electrically insulating coatings that completely cover their surfaces. After assembling the sheet metal elements additional coatings are again applied to this, which consist of ceramic and catalytically active material and also serve to connect the sheet metal elements. At another in the US 5 094 074 A described manufacturing method, the corrugated sheet metal elements are used in the uncoated state between the planar portions of the previously coated with meandering sheet metal element. Thereafter, coatings of ceramic and catalytically active material are applied to the composite Applied sheet metal elements. In the case of both described production methods, therefore, the catalytically active coating material and a part of the ceramic coating material are first applied to the sheet metal elements when they have been assembled to form a catalyst body. The from the US 5 094 074 A known manufacturing processes therefore have the same as that from the previously commented EP 0 049 489 A known manufacturing method has the disadvantage that the coatings containing the catalytically active material are unevenly thick. In addition, the according to US 5 094 073 A probably formed by partially ceramic and probably porous coating material compounds of the sheet metal elements not stable and not durable.

The invention has for its object to provide a method for the preparation of a catalyst body, which allows to avoid disadvantages of the known methods. In particular, starting from the EP 0 049 489 A be made possible to produce a catalyst body with sheet metal layers, the catalytically active material containing coatings having a desired favorable, for example, uniform distribution. Furthermore, the catalyst body should be simple and economical to manufacture and can be joined together. Furthermore, the sheet metal element layers of the finished catalyst body should be stable and permanently connected to each other.

This object is achieved according to the invention by a method having the features of claims 1.

The invention further relates to a catalyst body according to claim 11.

Advantageous developments of the method and of the catalyst body are evident from the dependent claims.

According to the invention, the sheet-metal layers are produced in such a way and assembled to form a catalyst body that, after assembly, they lie against one another in coating-free areas with preferably bare metallic surfaces of contact areas formed therefrom. The sheet metal elements can then be joined together in an integral manner in the contact regions by a joining connection, namely preferably by welding or possibly by brazing or sintering, and can be firmly and non-detachably connected to one another.

According to a preferred development of the production method, the sheet metal element layers are firmly joined together by resistance welding without additional welding material. For resistance welding, a short electrical surge with high current through the sheet metal layers and their contact areas can be passed. This surge can be generated, for example, by discharging a previously charged electrical capacitor. In such a resistance welding process, the sheet metal layers at the contact areas can be heated to the temperature required for welding, while the remaining areas of the sheet element layers remain relatively cool. Resistance welding therefore makes it possible to connect the sheet metal elements firmly, solidly and permanently together quickly, gently and with relatively low energy consumption.

Each catalyst body may, for example, comprise a stack of sheet metal layers, each of which consists of a consists of separate sheet metal element. However, the sheet metal layers may also be formed by turns of two wound into a winding sheet metal elements. The catalyst body can furthermore have a stack of sheet-metal element layers, in which either one of each two adjacent sheet-metal element layers or all sheet-metal element layers are formed by sections of a meandering curved and / or folded sheet metal element.

• Fig. 1 eine Seitenansicht eines Abschnitts eines zur Bildung von wellenförmigen Blechelementen bestimmten Metallbands beim Aufbringen von Überzügen,
• Fig. 2 eine Schrägansicht von einem Abschnitt eines zur Bildung von wellenfreien Blechelementen dienenden, mit Überzügen versehenen Metallbands,
• Fig. 3 eine Draufsicht auf einen Abschnitt eines ebenen, zur Bildung von gewellten Blechelementen bestimmten Metallbands,
• Fig. 4 eine Seitenansicht eines Abschnitts des zur Bildung von gewellten Blechelementen dienenden Metallbands beim Aufbringen von Überzügen,
• Fig. 5 eine Schrägansicht von einem Abschnitt eines zur Bildung von gewellten Blechelementen dienenden, mit Überzügen versehenen Metallbands,
• Fig. 6 eine Seitenansicht von einem Abschnitt eines gewellten Blechelements,
• Fig. 7 eine Seitenansicht von einem Stapel von wellenfreien und gewellten Blechelementen und von Elektroden einer Schweissvorrichtung,
• Fig. 8 den im Schnitt gezeichneten Ausschnitt VIII aus der Fig. 7 in grösserem Massstab,
• Fig. 9 den im Schnitt gezeichneten Ausschnitt IX aus der Fig. 7 im gleichen Massstab wie Fig. 8,
• Fig. 10 eine Seitenansicht eines fertigen Katalysatorkörpers,
• Fig. 11 eine Schrägansicht von einem Teil eines anderen Katalysatorkörpers, dessen gewellte Blechelemente stärker gebogene Wellen aufweisen,
• Fig. 12 einen in Schrägansicht dargestellten Abschnitt aus einem Katalysatorkörper, der Blechelemente mit einander senkrecht kreuzenden Wellen aufweist,
• Fig. 13 einen in Seitenansicht dargestellten Ausschnitt aus einem Katalysatorkörper, der durch eine Wicklung gebildet ist,
• Fig. 14 eine Seitenansicht eines Katalysatorkörpers mit einem mäanderförmigen, ungewellten Blechelement,
• Fig. 15 eine Seitenansicht eines Abschnitts eines wellenförmigen Blechelements und einer Einrichtung zur Aufbringen von Überzügen,
• Fig. 16 eine Schrägansicht einiger zur Bildung eines Katalysatorkörpers dienender, wellenförmiger Blechelemente,
• Fig. 17 einen schematischen Schnitt durch einen Katalysatorkörper mit Blechelementen, die einander unter schiefen Winkeln kreuzende Wellen haben, und
• Fig. 18 einen schematischen Schnitt durch einen Bereich des in Fig. 17 dargestellten Katalysatorkörpers entlang der Linie XVIII - XVIII in Fig. 17 in grösserem Messstab.

The subject invention will be explained in more detail with reference to exemplary embodiments illustrated in the drawings. In the drawings show

• 1 is a side view of a portion of a designated for the formation of wave-shaped sheet metal elements metal strip when applying coatings,
• FIG. 2 is an oblique view of a portion of a coated metal strip used to form non-corrugated sheet metal elements; FIG.
• 3 is a plan view of a portion of a flat, intended for forming corrugated sheet metal elements metal strip,
• 4 shows a side view of a portion of the metal strip used to form corrugated sheet metal elements during the application of coatings,
• FIG. 5 is an oblique view of a portion of a corrugated sheet metal-forming coated metal strip; FIG.
• 6 is a side view of a portion of a corrugated sheet metal element,
• 7 is a side view of a stack of wave-free and corrugated sheet metal elements and electrodes of a welding apparatus,
• 8 is a sectional view taken on line VIII from FIG. 7 on a larger scale, FIG.
• 9 is a sectional view IX of FIG. 7 on the same scale as FIG. 8, FIG.
• 10 is a side view of a finished catalyst body,
• 11 is an oblique view of a part of another catalyst body whose corrugated sheet metal elements have more curved waves,
• FIG. 12 is an oblique view of a catalyst body having sheet metal elements with corrugations perpendicularly intersecting each other. FIG.
• 13 is a side view of a portion of a catalyst body, which is formed by a winding,
• 14 is a side view of a catalyst body with a meandering, non-corroding sheet metal element,
• 15 is a side view of a portion of a corrugated sheet metal element and a device for applying coatings,
• 16 shows an oblique view of a number of corrugated sheet metal elements serving to form a catalyst body,
• Fig. 17 is a schematic section through a catalyst body with sheet metal elements which have each other at oblique angles crossing waves, and
• 18 shows a schematic section through a region of the catalyst body shown in FIG. 17 along the line XVIII-XVIII in FIG. 17 in a larger measuring rod.

It should be noted that various figures are not drawn to scale.

The catalyst body 1 shown in FIG. 10 serves for the catalytic treatment and purification of gas, namely exhaust gas of an internal combustion engine, and has a generally cuboid or cube-shaped stack 3 of sheet metal element layers, each of which consists of a separate sheet metal element 5 or 7. The stack has alternately successive first, smooth and even and wave-free sheet metal elements 5 and second, corrugated sheet metal elements 7. The sheet metal elements are joined together in a manner described in more detail and fixedly and permanently connected to each other, so that the stack 3 forms a solid block. The stack 3 is arranged and fastened, for example, in a substantially square-shaped, namely rectangular or square, metallic sleeve 9 which is open at both ends.

A spraying device 11, partly shown in FIG. 1, has at least one spray nozzle 13 and preferably at least two spray nozzles 13 in order to spray a first metal strip 15 which serves to form at least one first sheet metal element 5 and preferably several first sheet metal elements 5. The spraying device 11 has not yet shown transport means to the first metal strip 15th to transport in the direction indicated by an arrow transport direction 19 between the spray nozzles 13 therethrough. FIG. 4 also shows a spray device 11 for spraying a second metal strip 17, which serves to form at least one second sheet metal element 7 and preferably several of these. The spraying device 11 shown in FIG. 4 likewise has at least two spray nozzles 13 and transport means and can be formed for example by the same spraying device as the spraying device shown in FIG. 1 or by a separate spraying device. The or each spray device 11 further comprises means for supplying the spray nozzles at least one coating material and to control the spraying, for example, more or less similar to a printing operation of an ink jet printer, in particular turn on and off.

The first metal band 15 and the second metal band 17 have identical widths and thicknesses, consist of sheet metal made of the same material, for example stainless steel, and can be unwound, for example, by supply rolls not shown or also successively from the same supply roll. The two metal bands are smooth in the area of the spray device 11 and, for example, flat. When the metal strips 15, 17 are moved past the spray nozzles 13, they spray at least one coating material consisting, for example, of an aqueous solution and / or dispersion onto the two opposite sides or surfaces of the metal strips, so that they rest on one another along the metal strips following coatings are formed, which are referred to as first coatings 21 in the first metal band 15 and as second coatings 23 in the case of the second metal band and can also be seen in FIGS. 2 and 5. The coatings 21, 23 consist, as usual, for the most part of at least one porous metal oxide, for example Aluminum oxide, which forms a so-called "wash coat". The coatings also contain catalytically active material, namely at least one noble metal, for example platinum and rhodium. The "wash coat" and the noble metals can be contained during the spraying of the coatings, for example, in one and the same solution and / or dispersion and sprayed together on the metal strips. However, it is also possible first to spray a first coating material containing the "wash coat" and then a second coating material containing the precious metals. Maybe even the different precious metals can be sprayed on separately. The coatings 21, 23 extend over the whole widths of the metal bands and, for example, have substantially the same thicknesses and the same compositions substantially everywhere. However, the sprays may also be controlled so that the thicknesses of the coatings and / or the concentration of precious metals in the coatings and / or the precious metal composition vary locally. For example, it could be envisaged that the thickness of the coatings or at least the amount of precious metal contained in the coatings per unit area of the surfaces of the metal bands will change at least along a portion of the general flow path of the exhaust gas resulting from the use of the catalyst body and, for example, in general Flow direction of the exhaust gas increases or decreases.

The metal strips are sprayed in such a way that stripe-shaped, uncoated, ie coating-free, metallic areas result between the coatings which follow one another on their two surfaces in the longitudinal direction. These run perpendicular to the longitudinal edges of the metal bands. In the case of the first metal band 15, the bare, coating-free regions are denoted by 25 and all have the same in the longitudinal direction of the first Metal bands measured width s. The second metal strip 17 is followed alternately along the metal strip by bare, coating-free regions 33 and 35, which have different widths t and u measured in the longitudinal direction of the metal strip. The width u of the strip-shaped regions 35 is greater, for example at least 30% and for example at most 100% greater than the width t of the strip-shaped regions 33. In FIGS. 1 and 2, a grid spacing a of the first metal strip is shown the longitudinal direction of the metal strip is measured, for example, from center to center of successive, bare, coating-free regions 25. In FIGS. 4 and 5, a grid spacing b of the second metal strip is shown, which is measured, for example, from center to center of successive, blank, coating-free areas 33, 35. The first and second metal bands 15 and 17 both have the same width c and the same thickness.

In the case of the first metal strip 15, the coatings applied to the two sides or surfaces of the metal strip facing away from each other and, accordingly, also the bare, non-coated regions 25 present on the two sides or surfaces are half the grid spacing, that is to say the distance a / 2 added. The bare areas 25 present on the lower side of the first metal strip are thus located in each case in the middle between two bright areas 25 following one another on the upper side of the metal strip. The second metal strip 17 overlaps those on the lower and upper sides of the metal strip existing bare areas 33, 35 in pairs, so that the center lines of a stacked pair of bare areas 33, 35 coincide in a direction perpendicular to the surfaces of the metal strip projection. In this case, there is a blank area 35 underneath each blank area 33 and a blank area below each blank area 35 Area 33, so that therefore the narrower areas 33 and the wider areas 35 facing each other in pairs.

The pitches a and b are for example approximately the same size, but could also be different from each other and are expediently at least 2 mm, more preferably at most 5 mm and for example about 3 mm. The width c can be varied within wide limits, depending on the size of the catalyst body to be produced, and is normally at least 20 mm, normally at most 100 mm, and for example approximately 30 mm. The width s of the bare areas of the first metal strip 15 is preferably at least 0.05 mm, preferably at most 0.3 mm, and for example about 0.15 mm to 0.2 mm. The widths of the bare portions 33 and 35 of the second metal strip are preferably at least 0.05 mm, preferably at most 0.3 mm, and for example about 0.1 mm and about 0.15 mm, respectively. The thickness of the coating-free metal strips 15, 17 is for example about 50 μm. The thicknesses of the coatings 21 and 23 are preferably in the range of 15 microns to 50 microns and are for example about 30 microns.

The second metal strip 17 is provided, for example, prior to the application of the coatings in the subsequently to be formed bare, coating-free areas 33, 35 with holes 31 which are formed for example by punching. In this case, for example, each pair of subsequently opposing regions 33, 35 forms a straight row of holes 31 distributed over the width of the metal strip 17. However, for each pair of opposing areas, only two holes located near one of the longitudinal edges of the metal strip, or even a single hole or no hole, could possibly be formed.

The second metal band 17 is corrugated after application of the coatings 23, i. by forming with corrugations that the waves and their crests are perpendicular to the longitudinal edges of the metal strip and that each crest of the wave is in a pair of mutually gegenüberliegendes, bare, coating-free areas 33, 35. The holes 31 can be used during forming of the second metal strip to ensure the proper positioning of the metal strip by means of a suitable device, so that the wave crests are formed precisely at bare areas 33, 35.

The provided with coatings 21 first metal strip 15 and provided with coatings 23 and waves second metal strip 17 are cut with a cutting device, not shown in first sheet metal elements 5 and second sheet metal elements 7, so that the sheet metal elements have a the catalyst body 1 to be formed corresponding length, the can be varied within wide limits. Each sheet metal element has in a plan view a quadrangular, namely preferably rectangular or square outline. Each sheet metal element has accordingly four pairs mutually parallel edges.

One of the second corrugated sheet metal elements is shown separately in FIG. Furthermore, sections of first sheet metal elements 5 and a second sheet metal element 7 in FIGS. 8 and 9 can be seen. Each second sheet metal element 8 has waves with wave peaks 37 and wave flanks 39. The wave peaks 37 run parallel to two edges of the sheet metal element and are bent and / or angled in cross section and - as can be seen particularly clearly in Figures 8 and 9 - at the highest or deepest points outside flattened so that they are there - ie on the outside of the respective upper or lower Shaft crest forming half wave - have a narrow, strip-shaped, at least approximately flat surface. The wave flanks 39 are at least for the most part approximately flat, so that each wave has approximately the shape of a triangle. Incidentally, in the formation of the corrugations, the second metal strip 15 is reshaped such that the successive corrugation peaks 37 located on the same side of the second metal strip 15 and on the same side of a second sheet metal element 7 cut off from it have a distance e from one another, which is equal to the pitch a of the first metal strip 15 and one of which is cut off, first sheet metal element 5.

Each first sheet metal element 5 has a metallic core which is formed from the original, coating-free part of the first metal strip 15 and designated 41 in FIGS. 8, 9. Each first sheet metal element 5 also has first coatings, which are designated 21 in FIGS. 8 and 9, like the coatings of the first metal strip. Each first sheet metal element further has bright, coating-free areas, which are designated as 25 as in the first metal strip. Each second sheet metal element 7 has a metallic core 43, which is formed from the original, coating-free part of the second metal strip 17, second coatings 23 and bare, coating-free regions 33 and 35. The narrower, bare regions 33 are located on the inner side of the wave crest 37 The broader, blank regions 35 are on the outer side of the crest of the wave.

For the formation of a catalyst body, first and second sheet metal elements are alternately stacked on each other, so that the apparent in Figure 7 stack 3 is formed. The sheet metal elements are arranged in stacking such that the existing on the outside of the wave crest 37 of the second sheet metal elements 7, bare, coating-free areas 35 on bare, coating-free areas 25 of first sheet metal elements rest, as can be seen in Figures 8 and 9. The strip-shaped, bare, coating-free regions 25 and 35 then form contact regions in which the metal elements resting on one another touch in pairs. Accordingly, these contact areas are metallically bright over their entire lengths and in particular also over the entire lengths of the wave crest. The contact areas of the adjacent sheet metal elements 5, 7 are narrower in cross sections perpendicular to the wave crests than the non-coating regions 25 and 35 forming them. Each non-coated region 35 extends in directions perpendicular to the wave crests 37 on both sides of the wave crest having it beyond the contact area available at this crest. At least when a wave crest 37 according to FIGS. 8 and 9 rests at least approximately in the center of a coating-free region 25 of a first sheet metal element 5, the coating-free region 25 also extends beyond the crest on both sides of the wave crest in directions perpendicular to the crest apex. The wave height measured from wave crest to wave crest is preferably at least 0.5 mm, preferably at most 3 mm, and for example 1 mm to 2 mm.

In Figure 7 are still parts of an electrical welding device 51 can be seen, which is designed for electrical resistance welding. The welding apparatus 51 has, for example, a fixed electrode 53 at the bottom and an electrode 55 at the top which is vertically adjustable and can be pressed against the lower electrode 53. The two electrodes have flat, mutually facing surfaces. The stack 3 formed of sheet metal elements is arranged between the two electrodes 53, 55 and has preferably at the bottom and at the top each a second corrugated sheet metal element 7, which rests with the located on the lower or upper side of the respective sheet metal element, bare areas 35 on the mutually facing surfaces of the electrodes. The adjustable electrode 55 is now pressed in the direction of arrows 57 against the stack 3 and the electrode 53, whereby the sheet metal elements 5 and 7 of the stack 3 are pressed against each other. The welding device 51 then generates an electric current surge, so that for a short time a large electric current flows through the stack 3 of sheet metal elements. The surge can be generated, for example, by discharging a previously charged electrical capacitor. For example, the capacitor may be charged to an electrical voltage of approximately 3 kV, then at least substantially discharged within a few milliseconds, and at least for the most part. As a result, all sheet metal elements are welded together over the entire length of the wave crests at all wave crests, in which sheet metal elements rest on each other. The stack 3 forms after this welding a solid unit and can now for example still in the already mentioned, shown in Figure 10 sleeve 9 used and fixed in this in any way, for example, by some welding connections. Since the stack 3 of sheet metal elements already forms itself a solid, stable unit, the sleeve can be very thin-walled and, for example, have wall thicknesses that are less than 1 mm and, for example, at most or approximately 0.5 mm.

The sleeve 9 has an axis and four substantially parallel walls parallel thereto, which together define a continuous hole whose axis coincides with that of the sleeve. The stack 3 is arranged in the sleeve 9 such that a pair of edges of each sheet metal element and the Wave crest of the corrugated sheet metal elements parallel to the axis and to the hole of the sleeve. The catalyst body 1 then has bounded by the adjacent sheet metal elements, parallel to the waves passages for the exhaust gas. The catalyst body 1 may be used alone or together with at least one other catalyst body of the same or similar design to form a catalyst and be installed in a housing having an inlet and an outlet for the exhaust gas.

The catalyst body 1 is very stable and durable. Further, the surface portions of the sheet members adjacent to the passages, which come into contact with the exhaust gas in use of the catalyst body, are almost completely formed by the coatings containing catalytically active material, so that the catalyst body also provides effective catalytic treatment and purification of the exhaust gas.

The apparent in Figure 11 stack 73 of sheet metal elements has alternately successive first, flat sheet metal elements 75 and second, corrugated sheet metal elements 77. However, the waves of the latter are not triangular in cross-section, but more bent at the wave crests and, for example, at the wave edges and could be approximately sinusoidal, for example. Incidentally, the sheet metal element stack 73 may be formed similar to the sheet metal element stack 3.

In FIG. 12, parts of two sheet-metal elements 83, 85 can be seen, which are both corrugated, have crests 87 and 89, which cross each other approximately at right angles, and rest on one another at the points of intersection of the crests of the waves. The two sheet metal elements have coatings and either along the entire wave crests or only straight in the areas of contact where the crests of the waves lie on top of each other, and in the vicinity of these areas of contact, bare, non-coated areas. Additional sheet metal elements 83, 85 with intersecting waves can now be stacked on one another and then welded together by resistance welding. Each pair of adjacent sheet metal elements 83, 85 is firmly joined together after welding at a plurality of contact areas. The stack of sheet metal elements therefore forms a stable unit in this variant, which has only corrugated sheet metal elements.

Each sheet metal element 83, 85 has a quadrangular, substantially rectangular or square outline and accordingly four pairs mutually parallel edges. The undulations and crests of each sheet metal element are parallel to two of the edges of the sheet metal element and perpendicular to the other two edges of the sheet metal element. The stack formed of sheet metal elements of such is arranged in a sleeve 9, that the crests of each one sheet metal element of each pair of adjacent and locally abutting sheet metal elements parallel to the walls of the sleeve and the axis of the sleeve and in particular to the axis of this cross-sectioned hole run. The waves and crests of the other sheet metal elements then of course run perpendicular to the walls and the axis of the sleeve. Each pair of adjacent sheet metal elements then defines a passage for the exhaust gas generally parallel to the axis and to the wave crests of the one sheet metal elements.

FIG. 13 shows a part of a catalyst body which, instead of a stack of sheet metal elements, has a winding 93 which is formed by winding up a first, smooth, wave-free sheet metal element 95 and a second, corrugated sheet metal element 97 is formed. The first, smooth wave-free sheet metal element 95 is then not flat, but bent spirally. The second corrugated sheet metal element is located at least to a large extent between two successive turns of the first sheet metal element and rests with the wave crests on these turns of the first sheet metal element. The winding may be full in cross-section or have a cavity in the central region. The latter may be approximately circular in cross-section, for example, or approximately oval and / or for example flattened in places. In this catalyst body, each turn of one of the two sheet metal elements 95, 97 forms a sheet-metal element layer. Incidentally, the two sheet metal elements have coatings and partially touching, bare, coating-free areas and are firmly connected to each other in the contact areas formed by these, for example, welded. The welding can - depending on the type and shape of the winding - for example, sector by sector or possibly done in a single operation by resistance welding.

The catalyst body partly shown in FIG. 14 has a stack 103 of sheet metal elements which has a first, smooth, undulating, meander-shaped bent and / or folded sheet metal element 105 and a plurality of second corrugated sheet metal elements 107. The first sheet metal element forms loops with flat sections. The second, corrugated sheet metal elements are - apart from at most at the two ends of the stack located, second sheet metal elements - each disposed between two planar portions of the first, non-corrugated sheet metal element. In this catalyst body, each planar portion of the plate member 105 and each plate member 107 form a sheet member layer. The sheet metal elements in turn have coatings and bare touch areas where they abut each other and are welded together.

FIG. 15 shows parts of a device 131 for treating a metal strip 135, which serves to form a catalyst body 121 shown in FIG. 17. The catalyst body 121 has a stack 123 of sheet metal elements 125, 127. The latter comprise alternately successive first sheet metal elements 125 and second sheet metal elements 127 and each form a sheet metal element layer. The first and second sheet metal elements are all corrugated, but have different waves running at oblique angles. The stack 123 of sheet metal elements 125, 127 is firmly seated in a metallic sleeve 129th

The metal strip 135 is made of a sheet blank before treatment with the device 131, namely, for example, stainless steel. The metal strip 135 was corrugated in the blank state and prior to treatment with the device 131. The metal strip 135 has mutually parallel longitudinal edges and shafts. The waves form with the longitudinal direction and the longitudinal edges of the metal strip an angle β different from 90 °.

The device 131 has a device for applying in places, namely at the wave crests 161 of the corrugations of the metal strip 135, an anti-adhesive agent to the metal strip 135. This device comprises, for example, two opposing rollers 137 and rollers 137, respectively, which are rotatable about mutually parallel and perpendicular to the longitudinal edges of the metal strip 135 axes. The two rollers have cylindrical peripheral surfaces whose diameters are substantially larger than the wavelength of the corrugated metal strip. The closest to each other circumferential points of these cylindrical peripheral surfaces are at a distance which is approximately equal to the wave crest to crest wave measured wave height of the corrugated metal strip 135 so that it can be moved between the two roles and thereby touches the two rollers at the wave crests. The two rollers 137 are rotated during treatment of the corrugated metal strip by a drive device not shown in opposite, indicated by arrows directions of rotation 141, so that they have the metal strip together with additional, not shown, for example, transport rollers having transport in the direction indicated by an arrow transport direction 143rd in Fig. 15 from left to right transport. The device 131 further includes a not shown feeding device to supply the two rollers 137 an anti-adhesive agent. This consists for example of an organic, water-repellent, more or less flowable substance when applied, such as a wax, which may be slightly heated before applying to improve the fluidity. The anti-adhesive agent is applied with the two rollers 137 at the wave peaks 161 on the outer sides of the respective wave peak forming half-wave. The non-stick agent then forms non-stick pads 145 which cover the outer surfaces of the crest-crest forming and / or embossing surface portions of the metal strip 135 over its entire width, ie along the entire length of the crests of the crests.

The device 131 further comprises a spray device 151 with at least one spray nozzle 153 and namely with at least two spray nozzles 153 arranged on different sides of the metal strip 131 in order to spray the metal strip 135. The two spray nozzles are arranged downstream of the rollers 137 with respect to the transport direction 143. As the metal strip passes the spray nozzles 153, spray these at least one existing of an aqueous solution and / or dispersion coating material on the two opposite sides or surfaces of the metal strip 131 on. The coating material 155 contains at least one metal oxide serving for the formation of a porous "wash coat" and catalytically active material, namely at least one noble metal. Incidentally, the at least one metal oxide and the at least one noble metal may be contained in one and the same solution and / or dispersion and sprayed together onto the metal strip 135. However, it is also possible to spray the at least one metal oxide and the at least one noble metal successively with different spray nozzles on the metal strip. The anti-adhesive pads 145 previously applied to the two surfaces of the metal belt 135 repel the sprayed aqueous coating material so that the coating material sprayed on the two surfaces of the metal belt 135 does not abrade on the anti-adhesive pads 145 but only on the bare surface areas of the Metal bands 135 clings. The coating material adhered to the metal strip is then dried to form solid coatings 157. For example, the coating material 155 may be sprayed such that the coatings 157 are approximately the same thickness throughout and have approximately the same composition throughout. However, the spraying may possibly also take place in such a way that the thicknesses of the coatings and / or the quantities of the catalytically active material present per unit area vary in a desired, predetermined manner. Incidentally, the coatings 157 may be similarly made, and similarly composed and constructed as those described for the coatings 21 and 23. The anti-adhesive pads 145 are removed after spraying and drying the coating material 155 and before joining the already mentioned sheet metal elements 125, 127 and / or possibly when connecting the sheet metal elements. Removing the anti-adhesive pads can be done for example by means of a solvent or by heating and melting and possibly evaporation and / or burning.

The corrugated metal strip 135 provided with the coatings 157 is cut into pieces before or after the removal of the anti-adhesive coatings, all of which are of equal size and form the first sheet metal elements 125 and second sheet metal elements 127. Three of the sheet metal elements 125, 127 are partially visible in Figures 16 and 18. As already written and as it results from the manufacturing process, both the first sheet metal elements 125 and the second sheet metal elements 127 waves. The corrugations of the sheet metal elements have corrugation peaks which are denoted 161 in FIGS. 16 to 18 like those of the sheet metal strip 135 in FIG. 15. The corrugations also have corrugation sidewalls 163. Each sheet metal element 125, 127 has a metallic core 167 formed from the original bare metal strip 135, coatings applied thereto, like those of the metal strip 157, and coating free regions 159. The two surfaces of each sheet metal element define two planes parallel to each other at its wave crests. Each of the sheet metal elements 125, 127 is rectangular in a plan view of the planes defined by the wave crests, namely rectangular or square and accordingly has four edges, two of which are formed by the longitudinal edges of the metal strip 135 and hereinafter also as longitudinal edges or first Rims of the sheet metal element are called. The longitudinal edges or first edges of each sheet metal element 125, 127 are corrugated. The other, second edges of each sheet metal element extend in the aforementioned plan view at right angles to the longitudinal edges or first edges of the sheet metal element. The coatings 157 and the coating-free regions 159 extend from one longitudinal edge or first edge to the opposite longitudinal edge Of course, the same as the wave peaks 161 form an angle β different from 90 ° with the longitudinal edges or first edges of the sheet metal elements.

The cut sheet metal elements 125, 127 are arranged in the manner indicated in Fig. 16 to a stack 123 that alternately follow a first sheet member 125 and a second sheet member 127 to each other and each form a first and second sheet member layer and that the waves and in particular the wave crests 161 of the pairwise adjacent sheet metal elements intersect each other. When the sheet members 125, 127 are brought into contact with each other, they touch each other in pairs at contact areas, which are schematically shown in Fig. 17 and designated 165 and formed by parts of the outside on the wave peaks, coating-free regions 159.

The stack 123 formed by the sheet metal elements 125, 127 is arranged and compressed in the same way as the stack 3 of sheet metal elements 5 and 7 shown in FIG. 7 between two electrodes of a welding device. Then the sheet metal elements are welded together by resistance welding. The electric current required for welding can be generated, for example, as already mentioned in the description of FIG. 7, by discharging an electrical capacitor. The stack 123 of the welded-together sheet metal elements 125, 127 is then inserted into the metallic sleeve 129, which can be seen in FIG. 17. This is similar to the one shown in Fig. 10 sleeve 9 is formed, like these four walls, is open at both ends and rectangular or square in cross-section. The stack 123 is thereby inserted into the sleeve 129 such that the longitudinal direction of the four walls of the sleeve 129 and the from this limited, continuous hole perpendicular to the previously defined longitudinal edges or first edges of the sheet metal elements 125, 127 are. The stack 123 is fixed in the sleeve 129, for example, welded in some places with this.

The adjacent sheet metal elements 125, 127 and sheet metal layers of the finished catalyst body limit in pairs together a passage for the exhaust gas. Each of these passages extends in the direction indicated by an arrow in Fig. 17 general through-direction 171 and / or general exhaust gas flow direction 171 parallel to the walls of the sleeve 129 perpendicular to the corrugated longitudinal edges or first edges of the sheet metal elements. The waves and wave crests 161 of the sheet metal elements 125, 127 or sheet metal layers lying in pairs against each other form an acute angle α different from 90 °. The corrugations and the corrugation vertex 161 of the adjacent sheet metal elements 125, 127 welded in pairs in pairs form the angle .alpha. / 2 with the general passage direction 171 and / or the general exhaust gas flow direction 171. The exhaust gas is therefore deflected locally differently when flowing through a passage through the waves and the existing in the passage at the contact areas 165 welds from the general direction of passage 171 and / or general exhaust gas flow direction. The angle β between the wave peaks 161 and the longitudinal edges or first edges of the sheet metal elements is preferably at least 60 °, preferably at most 85 ° and for example 70 ° to 80 °. The angle α / 2 is then preferably at least 5 °, preferably at most 30 ° and for example 10 ° to 20 °. The angle α is accordingly preferably at least 10 °, preferably at most 60 ° and for example 20 ° to 40 °.

The coatings 157 and coating-free regions 159 of the sheet metal elements 125, 127 can be seen particularly clearly in FIG. It should also be noted in this figure that the sheet metal elements in this figure are cut along a sectional plane which forms the angle α / 2 with the waves and thus does not run at right angles to the waves. The apexes 161 have on their outer side at their highest point a narrow surface portion which bent in a section perpendicular to the wave crests cut as well as in the apparent in Fig. 18 section rather flat or nearly flat or even - as in the in Figures 8, 9 visible wave crests 37 - is exactly the same. The longitudinal sections of the almost or exactly planar surface sections of the apex 161 at the intersections of the crests of the pairs of adjacent sheet metal elements 125, 127 then form the contact regions 165 with which the adjacent sheet metal elements touch each other and in which the sheet metal elements are welded together. In the section shown in FIG. 18 as well as in sections and directions perpendicular to the waves and wave peaks, the contacting and welded contact areas 165 of the adjacent sheet metal elements are narrower than the strip-shaped, coating-free areas 159 forming them and thus have these cuts and directions have a smaller dimension than the non-coating regions 159. The bare, coating-free regions 159 extend in these sections and directions, in particular also on both sides of the contact regions 165 a little beyond them to the curved transition sections, the wave crest 161 with the connect these adjacent wave flanks, and / or even a little into the ripples into it. Since the bare, non-coated areas 159 of the surfaces of the corrugated sheet metal elements 125, 127 over the entire length of the Shaft and wave crest 161 extend, the coating-free areas also in the direction parallel to the waves and crests apex direction of the respective sheet metal element has a greater extent than the contact areas. The coating-free regions 159 therefore protrude beyond the entire contact region beyond all contact regions 165, which are not located at one edge of a sheet-metal element. This ensures that the sheet metal elements abut each other during welding at the contact areas with bare surface portions of the metallic cores 167 and can be easily, well, solidly and permanently welded together. As can be seen in FIG. 18, the coatings at the wave peaks 161 are interrupted only by a coating-free region 159 on the outer, convex side of a half-wave forming the wave peak. In contrast, on the inner, concave side of the crest a portion of a coating is present, which is related to the coating portions on the inner, mutually facing sides of the associated with the respective apex 161 wave edges 163.

Unless previously stated otherwise, the production method and catalyst body described with reference to FIGS. 11 to 18 can be carried out similarly or be designed and dimensioned similar to the production method or the catalyst body described with reference to FIGS. 1 to 10, for example.

The processes and the catalyst bodies produced can still be changed in other ways. For example, certain features of various described processes and the manufactured catalyst body parts could be combined. So can the formation of corrugated metal elements serving metal bands may also be wavy in the embodiments described with reference to Figures 1 to 14, before the coatings are applied. The winding partially shown in FIG. 13 could be formed of two corrugated sheet metal elements with intersecting shafts instead of one corrugated and one corrugated sheet metal element. Instead of spraying the coating material used to form the coatings on metal strips in one of the ways described with reference to FIGS. 1, 4, 15, the coating material can be printed or applied to metal strips, as in other printing processes known from printing technology, in such a way that the desired coatings and Coating-free areas arise. The method described with reference to FIGS. 15 to 18 could be modified such that the sheet metal elements 125, 127 consisting of separate pieces are replaced by alternately successive, first and second sheet metal layers consisting of sections of a single contiguous sheet metal element, analogous to FIG 14, the first sheet metal element 105 shown in FIG. 14 is bent and / or folded in a zigzag or meander shape. Furthermore, the corrugated sheet metal elements 125, 127 - analogous to what was already mentioned as a possibility for the corrugated sheet metal elements 83, 85 - could be coating-free only at the contact areas and in the vicinity of these contact areas. The coating-free regions would then not extend over the entire lengths of the wave peaks, but should preferably also have a slightly larger dimension than the contact areas in the direction of the wave peaks and in any case be dimensioned so that the sheet metal elements rest on each other with bare, metallic surfaces. Furthermore, instead of resistance welding, the sheet metal elements could possibly be produced by another material joining process, for example by another welding process or by Brazing or sintering together at the contact areas and connected by joining compounds firmly and permanently. For example, in the case of the winding 93 shown in part in FIG. 13, it would be possible to connect the sheet-metal elements by brazing instead of welding.

Claims (17)

1. Method for the production of a catalyst body (1, 121) for a catalytic treatment of gas, in particular of exhaust gas of an internal combustion engine, comprising sheet metal element layers, each of which has a metallic core (41, 43, 167) and coats (21, 23, 157) containing catalytically active material, at least one of two sheet metal element layers adjacent to one another in the finished catalyst body (1, 121) being corrugated, and the sheet metal element layers adjacent to one another resting against one another and being joined to one another in coating-free regions (25, 35, 159), characterized in that the sheet metal element layers are provided with the coats (21, 23, 157) and coating-free regions (25, 33, 35, 159) before they are caused to rest against one another and are joined to one another in coating-free regions (25, 35, 159).
2. Method according to claim 1, characterized in that each corrugated sheet metal element layer has wave summits (37, 87, 89, 161) having coating-free regions (25, 35, 159) which extend over the entire length of the wave summits (37, 87, 89, 161).
3. Method according to claim 2, characterized in that the sheet metal element layers comprise first, smooth, wave-free sheet metal element layers and second, corrugated sheet metal element layers, that a stack (73, 103) comprising alternating first sheet metal element layers and second sheet metal element layers is formed and that the coats (21, 23) are applied, before the joining of the sheet metal element layers, to the first, smooth, wave-free sheet metal element layers so as to form strip-like, straight, coating-free regions (25) which, in the finished catalyst body (1), along the entire length of the wave summits (37) of a second sheet metal element layer, rest against these wave summits (37).
4. Method according to claim 1 or 2, characterized in that all sheet metal element layers are corrugated and are stacked in such a way that wave summits (87, 89, 161) of the successive sheet metal element layers intersect one another so as to form, at the intersection points, contact regions (165) which are formed by parts of the coating-free regions (159).
5. Method according to any of claims 1 to 4, characterized in that the coats (21, 23, 157) are applied to the sheet metal element layers only after the formation of the waves of the corrugated sheet metal element layers.
6. Method according to any of claims 1 to 5, characterized in that the coats (21, 23, 157) are applied by spraying on or printing on of coating material (155) in such a way that no coating material reaches those surface regions of the cores (41, 43) which are intended for the formation of the coating-free regions (25, 33, 35), and/or that at least no coating material (155) adheres to these surface regions of the cores (41, 43).
7. Method according to any of claims 1 to 6,
   characterized in that, before the coats (157) are applied, an antiadhesion coating (145) is applied to the surface regions of the metallic core (167) of each sheet metal element layer which are intended for the formation of the coating-free regions (159), ana that the antiadhesion coating (145) prevents a coating material (155) subsequently applied for the formation of the coats (157) to the core (167) of the sheet metal element layers from adhering to the core (167), the antiadhesion coatings (145) comprising, preferably, at least one organic substance, for example, a wax, the coating material (155) being preferably applied in the form of an aqueous solution and/or dispersion to the cores (167), and the antiadhesion coatings (145) preferably being removed after the application of the coats (157) and preferably before the joining and/or, possibly, during the joining of the sheet metal element layers adjacent to one another.
8. Method according to any of claims 1 to 7, characterized in that the sheet metal element layers adjacent to one another are caused to rest against one another in the coating-free regions (25, 35, 159) with metallic surfaces and are joined to one another by material closure, for example, by welding, brazing or sintering.
9. Method according to any of claims 1 to 8, characterized in that the sheet metal element layers are simultaneously joined to one another in the coating-free regions (25, 35, 159) in which they rest against one another.
10. Method according to any of claims 1 to 9, characterized in that, for joining the sheet metal element layers, two electrodes (53, 55) are pressed against those sides of a stack (3, 73, 103, 123) or of a coil (93) of sheet metal element layers which are opposite one another, and that the sheet metal element layers are joined to one another by resistance welding, an electrical current serving for resistance welding being, for example, generated by discharge of an electrical capacitor.
11. Catalyst body for a catalytic treatment of gas, in particular of exhaust gas of an internal combustion engine, the catalyst body, for example, being producible by the method according to any of claims 1 to 10, the catalyst body comprising sheet metal element layers having a metallic core (41, 43, 167) and having coats (21, 23, 157) containing catalytically active material, at least one of two sheet metal element layers adjacent to one another in the finished catalyst body being corrugated and having wave summits (37, 87, 89, 161), and the sheet metal element layers adjacent to one another having coating-free regions (25, 35, 159) at wave summits (37, 87, 89, 161), resting against one another in contact regions (165) formed by said coating-free regions and being joined to one another in said contact regions, characterized in that each contact region (165) has, in a direction perpendicular to the wave summit (37, 87, 89, 161) of the sheet metal element layer comprising or touching it, a smaller dimension than the coating-free region (25, 35, 159) forming it.
12. Catalyst body according to claim 11,
    characterized in that the sheet metal element layers rest against one another with metallic surfaces in the contact regions and are joined to one another by a join which is produced by welding or brazing or sintering, and that each coating-free region (35, 159) of a corrugated sheet metal element layer which is present at a wave summit (37, 87, 89, 161) projects on both sides of the wave summit (37, 87, 89, 161) beyond the contact region and beyond the surface region connected by a joint to an adjacent sheet metal element layer.
13. Catalyst body according to claim 11 or 12, characterized in that the sheet metal element layers are joined to one another by weld joints in the contact regions.
14. Catalyst body according to any of claims 11 to 13, characterized in that all sheet metal element layers are corrugated and that the wave summits (87, 89, 161) of the sheet metal element layers adjacent to one another make an angle (α) with one another.
15. Catalyst body according to claim 14,
    characterized in that said angle (α) made by the wave summits of adjacent sheet metal element layers with one another is at least 10°, at most 60° and, for example, 20° to 40°, and that the adjacent sheet metal element layers together bound passages having a general passage direction (171) which makes an angle (α/2) of at most 30° with the wave summits (161).
16. Catalyst body according to claim 14,
    characterized in that the angle made by the wave summits (87, 89) of the sheet metal element layers adjacent to one another is about 90°, the sheet metal element layers, preferably, being arranged in such a way that they bound passages for the gas which are approximately parallel to the wave summits of, in each case, one sheet metal element layer of the sheet metal element layers adjacent to one another in pairs.
17. Catalyst body according to any of claims 11 to 16, characterized in that each sheet metal element layer consists of a separate sheet metal element (5, 7, 75, 77, 83, 85, 125, 127) and the sheet metal element layers together form a stack (3, 73, 123) or that the sheet metal element layers consist of windings of a coil (93) formed from two sheet metal elements (95, 97), or that a meandering and/or folded sheet metal element (105) is present which forms sheet metal element layers of a stack (103) of sheet metal element layers.

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