Algorithm-Calculated Multiple Injection Patterns to Meet Future Requirements to Direct-Injection Spark Ignited Engines 2022-01-1068

Future emission regulations require further development for internal combustion engines operating on gasoline. To comply with such regulations and simultaneously improve fuel efficiency, major development trends are found in reduced displacements, increased compression ratios and turbocharging. To counteract such engines’ increased tendencies to knocking combustion, direct fuel injection systems are necessarily applied. Compared to standard port fuel injection, direct injection systems cause increased particle emissions.

State-of-the-art magnet-driven gasoline direct injectors are capable of realizing various injection events of small injected mass per event and short dwell time between one another. Thereby, they facilitate multiple injection strategies, able to overcome the drawbacks of direct injection systems in relation to exhaust emissions. However, the full potential of multiple injection strategies is not yet taken advantage of. An algorithm-based approach was developed to automatically design multiple injection patterns following thermodynamical and geometrical considerations to make use of the possible advantages. In this manner, impingement of neither piston nor liner is ensured, suppressing one dominant mechanism for particle formation and incomplete combustion. Furthermore, adaptions to different operation strategies can be taken into account for the calculations.

This study describes the development and features of the before-mentioned algorithm and the different steps undertaken to calibrate it to a distinct gasoline direct injector. This study focuses on the methodology of calibration. A sequence of preliminary measurements was executed, including measurements in a spray chamber and an injection rate analyser. The calculated injection patterns have subsequently been used to operate a single-cylinder research engine. With those measurements, the feasibility of the approach was demonstrated. To present engine-operation related advantages of the approach, the section of results contains different view angles on combustion and emission behaviour.