Design of a low NO{sub}x emission HCCI diesel prototype vehicle

摘要

A prototype vehicle using a dual-mode diesel engine has been developed by IFP in partnership with Faurecia and Valeo. It operates in HCCI (Homogeneous Charge Compression Ignition) combustion mode from low to medium loads and in conventional combustion mode at higher loads. HCCI combustion is obtained using high burned gas recirculation, which requires advanced air and EGR circuits design and high cooling capabilities. A specific NADITM combustion chamber is used. Very low NO{sub}x emission levels can be achieved owing to the low combustion temperature. The torque control system includes a specific air path controller based on a gas composition observer, combined with a fuel path controller allowing to adapt injection settings to air path dynamics. This prototype architecture is used to control the highly sensitive combustion process in homogeneous mode and during the transition to conventional mode, which are major challenges for the concept vehicle. This paper presents the engine architecture and control system design, and describes preliminary tuning on an engine test bed. It also describes the integration of the engine into the vehicle demonstrator and set-up of the control structure in an embedded rapid prototyping system developed by IFP. Hot NEDC (New European Driving Cycle) results are presented and compared to simulated values.