A method using exhaust gas recirculation (EGR) in an internal combustion engine. The engine has at least one "dedicated EGR cylinder", whose entire exhaust is recirculated back to all the engine cylinders. The dedicated EGR cylinder is operated at a rich air-fuel ratio, and the other cylinders are operated stoichiometrically so that a conventional three way catalyst may be used to treat the exhaust. A fuel injector is used to inject fuel into the combustion chamber of the dedicated EGR cylinder after initiation of the main combustion event. This post injection method overcomes flammability limits of a dedicated EGR cylinder, and increases the hydrogen (H2) and carbon monoxide (CO) in its exhaust.
Jess W. Gingrich; Terrence F. Alger II; Raphael Gukelberger