Catalyst – solid sorbent – or support therefor: product or process – Monolith with specified shape or dimension of cell opening
Reexamination Certificate
1999-12-09
2001-08-21
Bell, Mark L. (Department: 1755)
Catalyst, solid sorbent, or support therefor: product or process
Monolith with specified shape or dimension of cell opening
C502S439000, C502S527140, C502S527160, C502S527170, C502S527180, C029S890000, C422S177000, C422S181000
Reexamination Certificate
active
06277784
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a metallic catalyst carrier body or support structure for the cleaning or treatment of an exhaust gas flow, in particular of a small engine, having a longitudinal axis and a honeycomb structure formed by a multiplicity of strip-shaped foils. The invention also relates to a foil assembly structure which is used in particular as a catalyst carrier body, preferably for small engines. The invention additionally relates to a method for manufacturing a metallic catalyst carrier body.
Metallic catalyst carrier bodies with a radial type of construction are known. Such a radial catalytic converter is described, for example, in International Publication No. WO 96/09893. The known radial catalytic converter includes individual disks which are disposed in series one against the other, which lie one on top of the other and in which radially extending flow channels are incorporated. The radial catalytic converter described therein is constructed as a hollow body into which the exhaust-gas flow to be treated flows. The flow enters into its interior, is deflected there and is directed outward in a radial direction through the flow channels between the individual disks.
The disadvantage of the radial catalytic converters described therein is that they include a multiplicity of individual, partially structured disks which have to be handled during production and held together as an assembly. They are therefore also relatively cost-intensive in their manufacture and, for that reason, not unreservedly suitable as a catalyst carrier body for use for small engines.
German Patent DE 36 22 115 C1 discloses a catalyst carrier body with an axial type of construction which includes an expanded partial laminated composite. However, that type of structure is relatively complicated to manufacture and secure in place and that prior art does not allow an application for radial catalytic converters.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a metallic catalyst carrier body, especially for small engines, which provides a compact, efficient, radial catalytic converter that can be used in particular for small engines, does not require any increase in dimensions of an exhaust system and can be manufactured at low cost, a prefabricated semifinished product in the form of a foil assembly structure which can easily be formed into a hollow catalyst carrier body, in particular for small engines, and a simple method for manufacturing a metallic catalyst carrier body without significant additional manufacturing devices, which overcome the hereinafore-mentioned disadvantages of the heretofore-known devices and methods of this general type.
With the foregoing and other objects in view there is provided, in accordance with the invention, a metallic catalyst carrier body for cleaning or treating an exhaust-gas flow, in particular of a small engine, comprising a longitudinal axis; a honeycomb structure having a multiplicity of strip-shaped foils resistant to high temperatures and corrosion, including adjacent foils securely interconnected at mutually spaced apart and alternatingly offset connecting locations; the foils forming a foil assembly structure or foil packet body which in the completed state has a block-like formation and is wound about the longitudinal axis into a hollow body stretching the foil assembly structure and forming flow channels in the honeycomb structure; and the flow channels extending in a perpendicular direction with respect to the longitudinal axis of the carrier body or having at least a radial directional component pointing in a direction perpendicular to the longitudinal axis.
A major advantage of the catalyst carrier body according to the invention is that the use of a prefabricated semifinished product in the form of a foil assembly has the effect on one hand of avoiding numerous individual parts in the form of disks, as are known in the prior art, and on the other hand of requiring no complicated manufacturing processes for manufacturing the actual catalyst carrier body by simply laying the inherently flexible foil assembly around a mandrel, a tube or the like to form an essentially cylindrical or frustoconical hollow body. When the foil assembly has been formed into a hollow body, all that is required is to interconnect the two end foils, then butting one against the other, without further devices being required for holding the catalyst carrier body together or keeping the catalyst carrier body in its form as a whole. This makes it possible, in particular, for relatively small catalytic converters for treating exhaust-gas flows of small engines to be manufactured at low cost and easily adapted to the dimensions of an existing, laid-out exhaust pipe system.
With the objects of the invention in view there is also provided a foil assembly structure to be formed into a hollow body of rotation, in particular for use as a catalyst carrier body, preferably for small engines, comprising a multiplicity of strip-shaped foils formed of a material resistant to high temperature corrosion, the foils having a catalytically active coating, the foils securely interconnected at spaced apart connecting locations producing a block-like assembly in a manufactured state in which foils disposed alongside one another touch, and the foils including mutually alternatingly offset adjacent foils producing an essentially flat flexible honeycomb structure through which an exhaust gas can flow upon stretching the foil assembly structure.
The flexible honeycomb structure according to the invention may preferably also be stretched by winding a honeycomb structure with an inherently flat form around a mandrel or a tube. As a result, with a corresponding connection of end pieces of the flexible honeycomb structure, an essentially cylindrical or frustoconical hollow body is produced. This cylindrical hollow body is inherently stable and requires no further retaining elements to keep it in its form. Therefore, it can be readily integrated into corresponding exhaust systems, in particular for small engines, to be precise in such a way that there is no need to change the dimensions of an existing exhaust system. Such a catalyst carrier body manufactured from a foil assembly structure according to the invention is also very inexpensive to manufacture.
In accordance with another feature of the invention, the foils which are respectively disposed alongside one another are provided with connecting locations of a linear form over the width of the foil. Such linear connecting locations, which run obliquely or essentially at right angles with respect to the longitudinal side edge of the strip-shaped foils, offer the advantage of making the foil assembly structure that is produced very stretchable and consequently producing a very flexible honeycomb structure, which can also be wound onto a mandrel having a relatively small diameter.
In accordance with a further feature of the invention, the connecting locations are constructed in the form of surface areas. The connecting locations are preferably constructed as rectangular areas, which run essentially perpendicularly with respect to the longitudinal side edges of the strip-shaped foils or, according to a further preferred exemplary embodiment, may also be disposed obliquely thereto.
In accordance with an added feature of the invention, the connecting locations have a triangular or trapezoidal form. Triangular or trapezoidal connecting locations have the advantage that, when the foil assembly structure is wound into a cylindrical hollow body, its form does not have any barrel-shaped deviations from the cylindrical form, as is the case with connecting locations running essentially perpendicularly with respect to the longitudinal side edge of the strip-like foil, of a linear or rectangular construction in the form of a surface area.
In accordance with an additional feature of the invention, in order to provide better adaptation to conical forms, the spacings between the individ
Bell Mark L.
Emitec Gesellschaft fuer Emissions-technologie mbH
Greenberg Laurence A.
Hailey Patricia L.
Lerner Herbert L.
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