A Simulation-Based Approach for Developing Optimal Calibrations for Engines with Variable Valve Actuation

• Published in: Oil & gas science and technology 2007-07, Vol.62 (4), p.539-553
• Main Authors: Wu, B., Filipi, Z., Prucka, R., Kramer, D., Ohl, G.
• Format: Article
• Language: English
• Subjects: Applied sciences; Crude oil, natural gas and petroleum products; Energy; Exact sciences and technology; Fuels; Physics
• ISSN: 1294-4475; 1953-8189
• DOI: 10.2516/ogst:2007047

Variable Valve Actuation (VVA) technology provides high potential for achieving improved performance, fuel economy and pollutant reduction. Benefits of VVA stem from better breathing and the ability to control internal residual. However, additional independent control variables in a VVA engine increase the complexity of the system, and achieving its full benefit depends critically on devising an optimum control strategy. The traditional approach relying on experimentation is in this case prohibitively costly, since the number of tests increases exponentially. Instead, this work formulates the task of defining actuator set-points as an optimization problem. It identifies simulation needs for supporting development of a generic methodology, capable of handling increased number of degrees of freedom. A high-fidelity tool predicts effects of various devices being considered. Since solving an optimization problem requires hundreds of function evaluations, direct use of the high-fidelity simulation leads to unacceptably long computational times. Instead, the Artificial Neural Networks (ANN) are trained with high-fidelity simulation results and used to represent engine s response to different control variable combinations with greatly reduced computational time. The paper describes a comprehensive simulation-based methodology, provides details of high-fidelity and surrogate modeling techniques, and then demonstrates application on a prototype four-cylinder spark-ignition engine with dual independent cam-phasers. La technologie d'actionnement variable de soupape (Variable Valve Actuation, VVA) présente un fort potentiel pour augmenter les performances et réduire consommation et pollution. Les avantages du VVA proviennent d'une meilleure aération et de la possibilité de contrôler les résidus internes. Par contre, l'addition de variables de contrôle supplémentaires dans un moteur VVA augmente la complexité du système, ce qui nécessite la mise au point d'une stratégie de contrôle optimale afin d'en tirer tous les bénéfices. L'approche traditionnelle reposant sur l'expérimentation s'avère trop onéreuse dans ce cas du fait de l'augmentation exponentielle du nombre de tests. Ce projet propose comme alternative de définir le réglage des soupapes comme un problème d'optimisation. Il identifie les simulations nécessaires au développement d'une méthode générique capable d'intégrer un nombre croissant de degrés de liberté afin de développer un outil degrande fidélité pour la