Chemical apparatus and process disinfecting – deodorizing – preser – Chemical reactor – Waste gas purifier
Reexamination Certificate
1999-08-09
2002-11-26
Tran, Hien (Department: 1764)
Chemical apparatus and process disinfecting, deodorizing, preser
Chemical reactor
Waste gas purifier
C422S171000, C422S177000, C428S593000, C502S527190
Reexamination Certificate
active
06485694
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention concerns a catalytic converter in a housing for an exhaust gas system of an internal combustion engine, in particular a small engine. The catalytic converter has at least one structured metal sheet which is provided with a catalytically active material and which is wound or twisted, and is formed with passages through which exhaust gas can flow, and which at least partially bears against the housing. The invention also concerns a silencer or muffler for an exhaust gas system of an internal combustion engine and a process for the production of a catalytic converter carrier body which is disposed in an exhaust gas system of an internal combustion engine, in particular a silencer or muffler for a small engine.
It is known for catalytic converters for exhaust gas systems of an internal combustion engine to be in the form of a honeycomb body. The honeycomb bodies are produced from sheet metal layers that are stacked or wound or twisted together. Other honeycomb bodies in turn contain sintered or extruded material. Those catalytic converters are intended to ensure that the convertible gases that still remain in the exhaust gas are further converted. A large number of ever increasingly strict exhaust gas requirements, in particular in relation to motor vehicles, results in that the catalytic converters must be of a configuration that they ensure almost complete conversion, even when the catalytic converter is in use over a prolonged period of time. The development in the catalytic converter art is in particular along the lines of maximizing the catalytically active surface area. Therefore in particular honeycomb bodies which have a large number of passages over their cross-section are used. Besides the possibility of increasing the surface area involved however the length and volume of the catalytic converter and therewith its cross-section are also increased. That however requires a large amount of space to be available for the catalytic converter in the exhaust gas system. In addition, with the catalytic converter being of an increasing size, the working processes for the production thereof become more expensive. In addition, in relation to large catalytic converters, particular attention must be paid to the durability thereof in relation to mechanical and thermal changes in operation, which necessitates a particular mounting configuration.
Set out hereinafter are various configurations of catalytic converters, to the features of which the present invention refers in respect of the configuration and form of the catalytic converter. Published, British Patent Application GB 2 231 283 A discloses a honeycomb body which has one layer. That layer is formed from a flat metal sheet and a structured metal sheet and is then shaped in a spiral to form a multi-layer catalytic converter. It has an internal cylindrical cross-section, the size of which is dependent on the outside diameter of the honeycomb body. The large number of mutually stabilizing layers which bear against each other is intended to ensure adequate stiffness for the honeycomb body constructed in that way. Published, Non-Prosecuted German Patent Application DE 37 15 040 A1 discloses another catalytic converter which contains a strip with non-cutting stampings therein. Those stampings are intended to increase the surface area involved. European Patent Application EP 0 473 081 A1 discloses mounting a catalytic converter in the bend of a motorcycle exhaust gas system. An apertured plate is used as the catalytic converter. The plate can be straight or also round. Published, Non-Prosecuted German Patent Application DE 24 36 559 Al in turn discloses a catalytic converter which is disposed directly in a bend of an internal combustion engine. The bend itself is in the form of a catalytic converter. Besides a catalytic coating on the inside wall of the bend, it is additionally possible to disposed catalytic shaped portions, in particular in screw form. Japanese Patent JP 61 65 940 discloses a catalytic converter which is made up of smooth and corrugated metal foils. Disposed upstream of that full catalytic converter is a further catalytic converter which is heatable. U.S. Pat. No. 4,195,063 in turn discloses a main catalytic converter with an additional, upstream-disposed catalytic converter. The catalytic converter contains primarily two catalytically coated mesh configurations that are each held between two mesh carriers. The catalytic converter can be disposed in the bend, but also in a conical configuration. Japanese Patent JP 61 096 120 discloses two tubes which are mounted in the proximity of an engine block in a curved configuration. The interior of the two tubes has holes. A catalytically active layer is disposed between those two tubes.
A particularly preferred area of use of a catalytic converter according to the invention is in relation to small engines. The term small engines is used hereinafter to denote engines with a cubic capacity of less than 250 cc. Such engines are used in particular in lawnmowers, motor-driven saws, transportable power generators, two-wheelers and similar uses. In the case of motor-driven saws, lawnmowers and other garden equipment the person operating the apparatus is often disposed over a prolonged period of time directly in the exhaust gas region of the small engine, and for that reason catalytic exhaust gas cleaning is particularly important there.
Attention is also directed to Published, Non-Prosecuted German Patent Application DE 38 29 668 A1 in which the catalytic converter, in a small engine, is used in a partitioning wall which extends approximately perpendicularly to the through-flow direction. European Patent EP 0 470 113 B1 also discloses a configuration of the catalytic converter, in which it is disposed with a spacing at all sides in an exhaust gas silencer or muffler for two-stroke engines. European Patent EP 0 049 489 B1 also discloses a process for the production of a carrier matrix for an exhaust gas catalytic converter. The features disclosed in those three documents can also be applied to this invention.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a honeycomb body with a cross-sectional region which is bordered in the interior, in particular for small engines that overcome the above-mentioned disadvantages of the prior art devices and methods of this general type, which can be produced in a small number of working steps, which is extremely compact, and which nonetheless makes available a sufficient catalytically active surface area so that limit values which are prescribed by statute in respect of the exhaust gas characteristics of an internal combustion engine are observed. A further object of the invention is to provide a housing for the catalytic converter, which does not nullify again the space gained by virtue of the compact catalytic converter. Another object of the invention is to provide a process for the production of a compact catalytic converter carrier body, which ensures continuous production thereof while avoiding a high level of production expenditure.
With the foregoing and other objects in view there is provided, in accordance with the invention, a catalytic converter assembly for an exhaust gas system of an internal combustion engine, including a small engine, the catalytic converter assembly including:
a housing having a cross-section with a cross-sectional area;
and
a catalytic converter having at most two layers formed of sheets and disposed in the housing, the catalytic converter containing:
an at least partially curved elongated body; and
at least one structured sheet having a structuring and a catalytically active material, the at least one structured sheet being wound on inclinedly around the at least partially curved elongated body and at least partially bears against the housing, the structuring of the at least one structured sheet in addition with one of the housing and a sheet of a layer of the at most two layers define closed passages there-
Maus Wolfgang
Reck Alfred
Siepmann Uwe
Emitec Gesellschaft fuer Emissions-technologie mbH
Greenberg Laurence A.
Mayback Gregory L.
Stemer Werner H.
Tran Hien
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