Andre-Francisco Casal Kulzer

Closed-loop control of a multi-mode GDI engine with CAI

Abstract In order to transfer the benefits of gasoline controlled auto ignition (CAI) combustion from research to real driving in a vehicle, intelligent engine control is essential. In this paper, we present a control concept for successfully managing a gasoline direct injection (GDI) engine operated in multi-mode with CAI. This includes the necessity of determining the state of combustion per cycle via sensing, the algorithms in the engine control unit (ECU) to regulate combustion in order to meet the desired performance, and the actuation means through both the engine valve-train and the injection system. Understanding the nature of homogeneous combustion and the ability to encapsulate the most important dynamics in a model amenable for control implementation are indispensable for running CAI stably. The latter lacks a direct combustion trigger and hence ignition is strongly dependent upon ambient temperature, tolerances in actuators and fuel-quality. In this paper, we propose an in-cylinder-pressure based controls concept for a multi-mode GDI engine with CAI driven by internal exhaust gas trapping. Combustion is controlled via the fuel and the air path concomitantly. The work has been carried out on a one and a four-cylinder engine with direct-injection and flexible valve-train. We show the necessity of models, both data-driven and physically-based, for successful control strategy design. Finally, dynamic operation is evaluated on the engines at cycle relevant points. The benefits of the technology, including improved fuel efficiency and lower emissions, the limitations, and suggested engine management strategies implementable in a vehicle are presented.