Caterpillar Inc.

Scott T White

Aaron L Smith

William H Lane

Randy N Peterson

Daniel J Learned

The present invention is particularly applicable to lean burn engines that produce exhaust containing insufficient amounts of unburned hydrocarbons to satisfactorily reduce NOx emissions without undermining engine performance. In the exhaust purification system, ethanol or another suitable hydrocarbon is injected into the exhaust stream at an appropriate location between the engine and the catalytic converter. A deNOx catalytic converter is positioned within the exhaust downstream from the ethanol injection point. The combination engine application, ethanol injection and suitable deNOx catalyst combine to reduce NOx to satisfactory levels without producing significant amounts of undesirable secondary nitrogen containing compounds. An oxidation catalytic converter is positioned in the exhaust downstream from the deNOx catalytic converter. The oxidation catalyst serves to convert any remaining unburned hydrocarbons into carbon dioxide and water. At the same time, only small amounts of secondary nitrogen compounds are converted back into NOx compounds upon passage through the oxidation catalyst. The end result being an over all reduction in both HC and NOx compounds particularly for lean burn engines to satisfactory levels.

Series combination catalytic converter

A modular catalytic converter and muffler is used to purify exhaust from a relatively large diesel engine. The device includes various structural components that are mounted in the exhaust flow path within a housing having an inlet and an outlet. A plate mounted within the housing divides the housing into an inlet chamber and an outlet chamber. A plurality of catalytic converter sub-cans are mounted across the plate between the inlet chamber and the outlet chamber. A flow distributor is mounted within the housing upstream of the catalytic converter sub-cans. The flow distributor divides and directs a portion of the exhaust to each of the catalytic converter sub-cans. Some muffler structure is mounted within the housing between the catalytic converter sub-cans and the outlet in order to attenuate noise in the exhaust.

Modular catalytic converter and muffler for internal combustion engine

A catalytic converter exhaust section comprises a first mounting plate, a second mounting plate, a hollow cylindrically shaped metallic tube and a plurality of substantially identical metallic catalytic converter substrates arranged in a honeycomb pattern. Each of the catalytic converter substrates has a regular hexagonal cross section and an inlet end separated from an outlet end by six planer walls. The metallic substrates are attached in parallel to form a compound honeycomb cross section with an inlet side, an outlet side, and an outer border defined by a portion of the planer walls. The compound honeycomb cross section is affixed within the tube between the first mounting plate and the second mounting plate. The individual substrates are coated with an appropriate catalyst for treatment of a particular exhaust component. The present invention finds particular applicability to treating exhaust from relatively large internal combustion engines that require a catalytic converter cross section larger than that currently possible with monolithic catalytic converter substrates.

Catalytic converter exhaust section for an internal combustion engine

The present invention is particularly well suited for purifying exhaust from relatively large lean burn diesel engines. A computer controlled injector intermittently injects an optimal amount of NOx reducing fluid into the exhaust passageway from the engine. The optimal amount corresponds to an amount that will achieve optimal NOx reduction rates for the given engine operating condition and exhaust temperature. A computer periodically senses the engine operating condition and the exhaust temperature, and calculates the appropriate injection amount. With appropriate deNOx and oxidation catalysts located downstream from the injector, the exhaust purification system of the present invention has the ability to greatly reduce NOx content of the exhaust while maintaining HC emissions at acceptable levels.

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East Peoria, IL, United States of America

Scott T White