Defining a model-based calibration process for a twin-independent valve timing engine

Model-based calibration tools can be used to prototype a process for an advanced engine type, reducing the burden of developing optimal calibrations for complex modern engines. This paper is a practical example of using simulation to prototype a calibration process before the engine hardware is available. We produce optimized tables for spark and cam timings for a 2.2 L naturally aspirated 4-valve overhead-cam spark ignition engine with twin-independent variable valve timing. We use design of experiments techniques to minimize testing, and a novel boundary modeling technique to describe the surface of the engine operating envelope and to constrain optimizations to realistic bounds. Testing simulated prototypes rather than the real hardware can save time and money by catching process errors and clearly defining measurement data requirements early in the design cycle. Offline optimization can be carried out independently of the test bench, limiting expenditure. This can help obtain consistent results faster, strengthen the predictive capability of the design process, and increase test bed productivity.