Patent ID: 8996281
Filing Date: 2015-03-31
Classification: F01N,F02B,F02D,F02M,Y02T

Abstract:
1. A method of using exhaust gas recirculation (EGR) to decrease the light-off time of a catalytic exhaust aftertreatment device, in an internal combustion engine having a number of cylinders, comprising: using one or more of the cylinders as a dedicated EGR cylinder, such that all of the exhaust produced by EGR cylinder(s), during all or some engine cycles, may be recirculated via an EGR loop when the engine is in normal (non cold start) operation; operating the dedicated EGR cylinder at a first air-fuel ratio that is different from that of the cylinders that are not dedicated; determining whether the engine is in cold start condition; if the engine is in cold start condition, entering a cold start mode that includes the following steps; using an EGR bypass line to divert all or some of the dedicated EGR from the EGR loop to the main exhaust line to a point between the turbine and the exhaust aftertreatment device; operating the dedicated EGR cylinder(s) at a second air-fuel ratio that is also different from that of the cylinders that are not dedicated; and providing supplemental oxygen to the EGR bypass line; determining whether light-off of the aftertreatment device has occurred; and if light-off has occurred, ending the cold start mode.