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Various methods are available to predict future cylinder air charge for improved air/fuel control. However, there can never be perfect prediction. This paper presents an algorithm to correct for imperfect cylinder charge prediction. This is done by expanding the air/fuel control boundary to include the catalyst, and correcting prediction errors as soon as possible using small corrective changes to later cylinder fuel inputs. The method was experimentally tested and showed improved air/fuel control as indicated by reduced variability of catalyst downstream air/fuel ratio. Additional vehicle testing showed potential to further reduce emissions.

A time-efficient throttle flow data collection method is described. It uses a sonic nozzle flow bench to measure air flow as a function of throttle angle and pressure in a manner analogous to on-engine dynamometer throttle flow characterization. Opening each sonic nozzle combination, then recording throttle downstream pressure and computed nozzle flow allows data to be taken in a fraction of the time normally needed. Throttle flow modeling considerations are then discussed.

As part of a general EGR system model, an adiabatic thermodynamic vacuum EGR valve actuator model was developed and validated. The long term goal of the work is improved system operation by correctly specifying and allocating EGR system component requirements.

A dynamic model for the coupled engine-torque converter-vehicle system was developed to allow mathematical analysis and performance prediction for engine or powertrain controls in torque converter equipped vehicles. The principal contribution of this work is the derivation and justification of a static nonlinear terminal model of the torque converter. This model, when approximated, allows simple coupling of available engine, geartrain, and vehicle models. The resulting differential equations provide a reasonably simple, physically justified model for engine and vehicle behavior when driven by large signal variations in either engine net torque output or vehicle load.

A microprocessor based vehicular engine control system testbed has been developed to make possible complex, interactive engine control experiments in the vehicle environment. Designed for flexibility, the on-board vehicle system incorporates two microprocessors, a variety of engine instrumentation, and controls over spark advance, air-fuel ratio, and exhaust gas recirculation. The two microprocessors have been linked to form an efficient computational network with sufficient capacity to implement most, if not all, engine control experiments. Also included in the vehicle are video displays which provide operator control and interaction with experimental engine control systems.