Combined steady state and transient optimization for dynamic smoke reduction on Heavy Duty engine (TIER3 Applications)

This paper describes a methodology to investigate the whole set of engine performance requested by off-road vehicles in order to define many sub-ratings with different speed and load ranges:

• DoE screening for parameter range evaluation on the whole map
• DoE with Map border lines
• Boundary conditions to get reliable test results
• Raw data plausibility
• Modeling based on torque / injected quantity
• Optimization (TIER3 calibrations) and Verifications
• Development decisions / Map calculations

The method has been tested on real case: NEF 6 cylinder Common Rail aftercooled engine with internal EGR and free floating turbocharger where also the intake manifold temperature is a DoE parameter able to simulate different customer cooler solutions.

Particular attention has been dedicated to the prediction of fuel consumption as well as NOx, HC and smoke emissions. A “zone” approach (a technique to differentiate most likely steady state regions from transient ones) has been implemented to study in deep detail the emissions control speed ranges vs rated power and peak torque.

The Global model was demonstrated to be a powerful tool to define multiple ratings from one DoE plan and to allow subsequent optimisation based on customer engine mission data (datalogged directly from the field) without further testing activity. The correlation to end customer data was remarkably good.

The method is currently under further development to take into consideration transient effects for typical off-highway working cycles.