A system and method for controlling an internal combustion engine for low emissions include an inner feedback control loop to control the engine fuel/air ratio with feedback provided by a first exhaust gas sensor and an outer feedback control loop that modifies the fuel/air ratio reference provided to the inner feedback control loop based on feedback signals provided by the first exhaust gas sensor and a second exhaust gas sensor. The fuel/air ratio reference signal controller adapts to the oxygen storage capacity of the catalyst by modeling the catalyst as an integrator with an unknown gain and estimating the catalyst gain based on the first and second exhaust gas sensor signals. Using the estimated catalyst gain, an adaptive controller gain factor is determined and subsequently used to determine the fuel/air ratio reference signal provided to the fuel/air ratio controller of the inner feedback control loop.
A control apparatus for an internal combustion engine, which makes it possible to ensure quick recovery of a storage amount of oxygen saturated due to a fuel cut, to restore the capacity of a catalytic converter to absorb air-fuel ratio disturbances, and to suppress torque fluctuations through prevention of overcorrection of the air-fuel ratio during normal operation. The control apparatus for an internal combustion engine according to the present invention is equipped with a proportional gain changeover unit. This unit makes a changeover in a proportional gain for proportional calculation in a downstream-side control unit for a predetermined period from a normal proportional gain to a post-fuel-cut proportional gain set larger than the normal proportional gain by a predetermined value, when a fuel cutoff unit starts cutting the fuel supply.
A system for controlling fuel to an engine to minimize emissions in an exhaust of the engine. There may be a controller connected to an actuator, for example a fuel control actuator, of the engine and to emissions sensors, such as an NOx and/or PM sensor, proximate to an exhaust output of the engine. The controller, for example a speed controller, may have an input connected to an output of a pedal or desired speed setting mechanism. A speed sensor at a power output of the engine may be connected to an input of the controller.
