CLOSED LOOP METHOD OF CONTROLLING EXHAUST CIRCULATION FOR INTERNAL COMBUSTION ENGINE AND CLOSED LOOP EXHAUST RECIRCULATION APPARATUS FOR INTERNAL COMBUSTION ENGINE

摘要

A closed loop exhaust gas recirculation system for an internal combustion engine having an intake system, an exhaust manifold, a throttle disposed within the intake system for controlling air flow therein, a conduit coupling the exhaust manifold to the intake system for supplying exhaust gases back to the intake system for controlling the generation and emission of oxides of nitrogen and for improving driveability. The system includes a first memory pre-programmed with a look-up table of optimal values of absolute manifold pressure (MAP0) as a function of engine speed (RPM) and throttle position ( theta ). The actual operating parameters of absolute manifold pressure (MAP), engine speed (RPM) and throttle position ( theta ), or alternatively air flow (AF), are accurately sensed. The actual values of throttle position or air flow and RPM are used to address the first memory which outputs the pre-programmed optimal value of MAP. The actual value of throttle angle or air flow may be compensated for ambient barometric pressure and/or altitude, if desired. The actual value of MAP is compared with the optimal value of MAP0. The output of the comparator is used to close the loop and control the position of a valve positioned at least partially within the conduit such that the amount of recirculated exhaust gas (EGR) supplied to the input system is increased if MAPMAP0.