Presently, NOx, as well as other engine exhaust emissions, can be reduced through Exhaust Gas Recirculation (EGR) where engine exhaust gas is recirculated and mixed with intake air into the engine intake manifold. Cooled EGR (CEGR) systems may be used to increase engine fuel efficiency at high engine loads. However, the accuracy of present EGR flow metering techniques based on the pressure differential across the EGR valve significantly decreases as the pressure differential decreases, such as during high load and relatively low engine speed; this means that present methods are insufficient for metering CEGR flow. Accordingly, there is a need and desire for improved EGR metering methods and systems that incorporate them.
USPTO Backgrounds
USPTO Backgrounds