In-Cylinder Pressure Based Gasoline Engine Combustion Control

Authors

S. Choi PhD, H. Im MSc, K. Choi MSc, Hyundai Kia Motor Group, Namyang, South Korea; S.-J. Kim MSc, Vitesco Technologies GmbH, Regensburg; B. Varoquie PhD, Vitesco Technologies, Toulouse:

Year

2021

Print Info

Production/Publication ÖVK

Summary

The latest gasoline engine has improved thermal efficiency significantly through higher compression ratio (CR), Atkinson cycle, and advanced intake port design for high speed combustion. Various technologies, such as variable valve actuation (VVA), EGR, and MPIGDI duel injection, have been implemented to optimize engine combustion for overall engine operation ranges. However, combustion control has become challenging, because combustion speed and knock tendency depend more sensitively on variations of engine hardware and in-cylinder charge condition. In addition, the control range of ignition angle gets wider primarily due to the EGR, and superposition of other factors affecting the combustion rate makes it difficult to optimize combustion by traditional open-loop ignition angle control, which causes worse vehicle fuel economy and incorrect torque model output. In-cylinder pressure sensor (ICPS) is the ultimate sensor to monitor combustion directly. By applying closed-loop ignition angle control based on cylinder pressure, combustion of each cylinder can be optimized. In this study, the closed-loop combustion control (ignition angle control based on both HR50 feedback and knock detection) was tested and validated in the state-of-art Hyundai Smartstream G2.5 engine framework using Vitesco ICPS, an in-cylinder pressure sensor with a cost compatible with mass production orientation and production-level ECU. The vehicle fuel economy benefits of the closed-loop combustion control were demonstrated for the standard fuel economy testing schedules, FTP-75, HWFET, and US06. The combustion of each cylinder could be controlled optimum MBT or DBL in both steady and transient conditions, and 1.5 ~ 3 % of vehicle fuel economy improvement were validated. Moreover, the robust engine control was possible even with deviated actuators (e.g. maximum flow rate EGR valve sample) and the deviation of vehicle fuel economy was reduced. Beyond the combustion control, we are expecting more potential of ICPS in other fields such as engine torque modelling and diagnostics.

Number of pages

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