METHOD AND APPARATUS FOR EXHAUST GAS RECIRCULATION VIA REVERSE FLOW MOTORING.

摘要

One way of reducing nitrogen oxide emissions from an engine having a plurality of combustion chambers is through exhaust gas recirculation. The present invention provides an apparatus for exhaust gas recirculation by causing at least a selected subset of the combustion chambers to be operated in a four-stroke reverse flow motoring mode of operation while the remaining combustion chambers are operated is a normal four-stroke mode. In the four-stroke reverse flow motoring mode of operation, exhaust gas is inducted into the combustion chamber of a selected subset of combustion chambers. The exhaust gas is then compressing and expanded in the combustion chambers. Cooling of the exhaust gas is achieved during the compression and expansion strokes. The cooled exhaust gas is then expelled from the combustion chambers to be mixed with fresh charge air.