A Contribution to Predictive Engine Calibration Based on Vehicle Drive Cycle Performance

Both the automotive and truck industry are facing further regulated emissions legislation in the near future. Understanding the emissions and fuel consumption attributes of an engine/vehicle application during a drive cycle early in an engine development program is a critical step to steer the engine development program to a successful final product. The generally accepted approach is to calibrate an engine on a dynamometer and to adjust the operation of the engine to meet performance targets. With the current build and test approach, these adjustments may not be made until well into the development program, and this calibration is a costly and time consuming step in the engine development process. Furthermore, the increasing complexity of state of the art engines under development today (continuously adjustable cam phasers on both intake and exhaust cams, variable intake systems, EGR valves, variable geometry turbines, etc.) has increased the test bed time required for calibration resulting in increased development time which may represent the critical path in the overall engine development program. This time is increased further by the considerable time necessary for adjustments under transient conditions.

This paper discusses the necessary tools and procedures to utilize co-simulation techniques with regard to predicting engine drive cycle performance for a typical vehicle. Furthermore, the paper describes an example of predicting both intake and exhaust cam phaser positions for a small SUV type vehicle equipped with a V6 gasoline engine and compares the results to measured calibration maps. The predicted cam phaser positions allowed reducing the elapsed time for the calibration on the test bed by approximately 2 months.