A method of decreasing the light-off time of a catalytic exhaust aftertreatment device, using exhaust gas recirculation (EGR) in a turbocharged 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(s) may be operated to produce a differently compositioned exhaust gas than the other cylinders. During light-off, EGR gas is optimized for heat, diverted from the EGR loop and routed to a point directly upstream the aftertreatment device.
Jess W. Gingrich; Terrence F. Alger II