Control of very high efficiency spark-ignition engines
Most of the EU countries will reduce their CO2 emission per km at least by 40% until 2025. Achieving this ambitious objective requires reducing fuel consumption via new technology development in the automotive industry. Vehicle electrification is one of the main ways to participate to such a reduction and such a technology will be increasing in the future and especially through hybridization. This means that around 90% of the vehicles in 2030 worldwide will still be equipped with an internal combustion engine. Gasoline will represent the major part and some R&D efforts still need to be focused on thermal engine to further improve the efficiency of hybridized powertrains. The efficiency of spark-ignition engines can be significantly improved by using lean mixtures. However, the ignition and flame propagation processes are so much constrained in diluted mixtures that a maximal dilution limit for gasoline engines is usually reached for lambda values around 1.5. Reaching the 50% brake thermal efficiency target largely depends on the ability to extend the lean limit into regions that are not reached today (lambda 2). The limit is defined by the combustion stability limit. Above this critical value, cycle-to-cycle fluctuations during the ignition phase and the flame propagation phase lead not only to a decrease in the produced torque, but also to an increase in pollutant emissions. In order to take the most of this technology, advanced combustion control is mandatory.
Many control issues have to be addressed regarding this new technology:
- Combustion stability control limit to maximize efficiency. Use of in-cylinder pressure sensor could provide a real-time information of the level of stability.
- Transient control of air system. High level of boosting implies complex air system architecture (i.e. e-turbo).
- Extra-lean combustion is used on a limited engine operating range, good management of mode switching between lean and lambda 1 combustions is then on primary importance.
- Hybrid architecture implies large engine transients (i.e. engine starts), implying necessity of an efficient transient control.
IFP Energies nouvelles is currently leading a large European project aiming to develop a spark-ignition engine using extra-lean combustion. The engine is planned to be part of a hybrid powertrain. The internship will be part of this framework. Working in the Digital Science and Technology Division, the student will work in close collaboration with control, simulation and combustion engineers. The objective will be to develop engine model, design control strategies for extra-lean spark-ignition engines, with the possibility of publishing and patenting the produced work.
- general engineering degree
- interest in the field of control and engine technologies
- curiosity, taste of teamwork