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In-cylinder boosting of turbocharged spark-ignited engines. Part 1: Model-based design of the charge valve

Downsizing and turbocharging for retaining the maximal power is a widely used approach to decrease the fuel consumption of spark ignited engines. In general, the trade-off is a substantial driveability loss. In-cylinder boosting has proven to be an effective way to eliminate this problem. Thus far, expensive and complex fully variable valve-trains have been proposed for the air exchange between the air tank and the combustion chamber. This paper is the first of a two-part study that examines the use of a deactivatable camshaft-driven valve with respect to the achievable transient engine performance. The system characteristics and limitations are discussed by using a mean value engine model that is adapted for in-cylinder boosting. A model-based design framework is presented which links the valve system design to a desired engine performance. The companion paper covers control issues and provides experimental verifications.