Novel direct injection electro-hydraulic model-based controller for high efficiency internal combustion engines

During the past years, automotive industries developed several technologies suitable to increase efficiency and reduce emissions from Internal Combustion Engines (ICEs). Among them, the adoption of high-pressure injection systems is considered crucial to optimize air-fuel mixture formation. However, the use of these technologies also promotes the formation of particulate matter (PM), which is a direct result of charge stratification and fluid film on the cylinder walls. Therefore, to obtain a proper mixture formation without the risk of wall impingement, the utilization of consecutive injections is mandatory. Since modern Gasoline Direct Injection (GDI) systems are typically characterized by electrical-actuated injectors connected to a single high-pressure rail, a deep understanding of electrical and hydraulic effects among two close injection events becomes essential. This paper analyzes the combinations of electrical and hydraulic effects that occur in a high-pressure GDI system performing multiple injections. By using a specifically developed open vessel flushing bench, the injection system has been characterized in terms of pressure wave propagation as well as electrical distortions of the driving current profile of the injectors. The analysis of the experimental data has allowed for the calibration of the residual magnetization characteristic map in addition to the development of a pressure wave propagation control-oriented model. Finally, a Magnetization and Pressure Wave (MPW) correction strategy, easily implementable on an Electronic Control Unit (ECU) without the need for additional sensors, has been proposed. By running the MPW strategy, the error between the actual and expected injected mass has been reduced below 5% in all tested conditions.