Catalytic cleaning arrangement for exhaust from an internal combustion engine

Claim 1

Apparatus for catalytic cleaning of the exhaust gases of an internal combustion engine comprising an engine having a plurality of combustion chambers, first and second exhaust lines for receiving exhaust from different combustion chambers in the engine, each exhaust line including a catalyst assembly and being arranged to receive exhaust gases from at least one combustion chamber, a first flow connection between the two exhaust lines in the upstream direction from the catalyst assemblies, heater means for heating exhaust gases flowing through a portion of the first exhaust line upstream from the catalyst assembly therein and downstream from the first flow connection, cooling means for cooling hot exhaust gases flowing through a portion of the first exhaust line, the catalyst assembly in the second exhaust line being located at a distance from the engine which is far enough to avoid heating of the catalyst assembly above a selected temperature to inhibit catalyst aging, a second flow connection connecting the first and second exhaust lines downstream from the catalyst assembly in the first exhaust line and upstream from the catalyst assembly in the second exhaust line, valve means in the first and second exhaust lines and valve control means arranged to connect the catalyst assemblies in the first and second exhaust lines and the heater means in series when the temperature of the second catalyst assembly is below its start-up temperature and to connect each exhaust line to only one of the catalyst assemblies when both catalyst assemblies are above their start-up temperatures.