Southwest Research Institute

Chad P Koci

Charles Edward Roberts, Jr

Darius Mehta

Magdi K Khair

Gary Dale Neely

Stefan Simescu

Vlad L C Ulmet

A method for controlling emissions in the exhaust gas of a diesel engine, the engine having an exhaust gas recirculation (EGR) system. The engine's exhaust aftertreatment system need have only an oxidation catalyst and a particulate filter (with no NOx reduction or adsorption device). In 'normal' engine conditions, the engine is operated with a lean air-fuel ratio, with 'normal' engine conditions being engine conditions other than transient load increase engine conditions. Also, during normal engine conditions, the EGR system is used to reduce engine-out NOx. During transient load increase engine conditions, the engine is operated stoichiometrically or near stoichiometrically and the use of EGR is interrupted.

Diesel engine operation for fast transient response and low emissions

A method of stoichiometrically operating a diesel-fueled internal combustion engine. During a main (conventional) fuel injection event, fuel is injected into the cylinders. The air-fuel ratio during this main fuel injection event is stoichiometric. The cylinders are operated by either advancing the exhaust valve closing or modifying the phasing of the exhaust and intake valve lift events, to achieve a negative valve overlap period between the end of the exhaust phase and the beginning of the intake phase of the engine cycle. Fuel is injected into the cylinders during the negative valve overlap period, which results in highly reactive fuel and reduces ignition delay during the main fuel injection event.

Fuel injection during negative valve overlap for stoichiometric diesel operations

A method of stoichiometrically operating a diesel-fueled internal combustion engine. A control unit is provide with stored data representing, within a range of exhaust valve timing or event modifications, an amount of fresh air flow and exhaust gas residuals resulting from each modification. During operation of the engine, the control unit is used to determine a desired amount of exhaust gas residuals for a given engine load; to access the stored data to determine a modification that will provide the desired amount of exhaust gas residuals; and to generate a control signal that will result in the desired modification.

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San Antonio, TX, United States of America

Chad P Koci