Spark Ignition Engine Fuel Economy Control Optimization-Techniques and Procedures

An analysis is presented for the quantitative evaluation of spark ignition engine control parameters (spark advance, air-to-fuel ratio, exhaust gas recirculation) for optimal fuel economy, constrained emission levels and tradeoffs. Emphasis is placed on the procedures and techniques adopted for the off-line approach using steady state mapping dynamometer data of conventional engines in production. The analysis structure is composed primarily of existing documented tools, in particular, a) vehicle simulation programs, b) FTP-urban and highway drive cycle schedule, c) multiple regression techniques, and d) dynamic programming procedures. Analytical methods are evaluated along with illustrative examples, and discussions are presented on their sensitivities. Applications of engine control parameter optimizations are also illustrated with reference to two engine (one eight and one four cylinder) data bases.

Major factors are discussed. Results are presented on fuel economy as a function of three regulated emissions and engine settings, and on increase/decrease in fuel economy concerned with the emission contraint, emission control strategy, and vehicle drive cycle.