Arrangement and method for igniting a combustible gas mixture for the exhaust system of an internal-combustion engine and corresponding exhaust system

#This application claims the priority of German Patent Document 100 38 743.8, filed Aug. 9, 2000, the disclosure of which is expressly incorporated by reference herein.

#The present invention relates to an arrangement for igniting a combustible gas mixture for the exhaust system of an internal-combustion engine and to a corresponding exhaust system.

#When aftertreating the exhaust gas of an internal-combustion engine of a motor vehicle, the reduction of pollutants in the exhaust gas during the cold start and the warm-up of the internal-combustion engine has priority as the most promising potential for reducing pollutants. Among others, methods are known for this purpose in which, during the cold start, a combustible air/fuel mixture is generated in the exhaust gas train and the heating value contained in the exhaust gas is utilized for the rapid heating of the pollutant-converting catalysts to their starting temperature or usage temperature. This takes place in that the combustible air/fuel mixture is ignited again at an appropriate point in the direct proximity of the catalyst.

#FIG. 1a is a schematic view in flow direction A of FIG. 1b, depicting an ignition arrangement for an engine exhaust system constructed according to a preferred embodiment of the present invention;

#FIG. 1b is a schematic sectional view of a part of an engine exhaust system constructed according to a preferred embodiment of the present invention; and

#FIG. 2 is an enlarged cutout showing the heating wire anchoring of the arrangement according to FIG. 1.

#In the drawing figures, the same reference numbers indicate identical elements or elements having the same function.

#FIGS. 1a and 1b are schematic representations of an arrangement according to a preferred embodiment of the present invention.

#In FIGS. 1a and 1b and 2, reference numbers 1a and 1b indicate a first and a second frame made of metal in a monolith shape, which, separated by an insulation device 2, are placed upon one another and are virtually endlessly wound alternately with heating wire 3 (in a “racetrack shape”). Wire section 3A is representative of the wire sections of the wire grid, electrically contacting at the top in FIGS. 1a and 1b with the frame 1a and contacting at the bottom in FIGS. 1a and 1b with the frame 1b. The winding forms a flow area 300 through which exhaust gas can flow and which has a heating wire grid, whose mesh width can be determined virtually freely according to the requirements.