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ELEVATE (European Low Emission V4 Automotive Two-stroke Engine) was a research project part funded by the European Commission to design and develop a compact and efficient gasoline two-stroke automotive engine. Five partners were involved in the project, IFP (Institut Français Du Pétrole) who were the project leaders, Lotus, Opcon (Autorotor and SEM), Politecnico di Milano and Queen's University Belfast. The general project targets were to achieve Euro 3 emissions compliance without DeNOx catalisation, and a power output of 120 kW at 5000 rev/min with maximum torque of 250 Nm at 2000 rev/min. Specific targets were a 15% reduction in fuel consumption compared to its four-stroke counterpart and a size and weight advantage over the four-stroke diesel with significant reduction in particulate and NOx emissions. This paper describes the design philosophy of the engine as well as the application of the various partner technologies used.

The control of Homogeneous Charge Compression Ignition (HCCI) (also known as Controlled Auto Ignition (CAI)) has been a major research topic recently, since this type of combustion has the potential to be highly efficient and to produce low NOx and particulate matter emissions. Ion current has proven itself as a closed loop control feedback for SI engines. Based on previous work by the authors, ion current was acquired through HCCI operation too, with promising results. However, for best utilization of this feedback signal, advanced interpretation techniques such as artificial neural networks can be used. In this paper the use of these advanced techniques on experimental data is explored and discussed. The experiments are performed on a single cylinder cam-less (equipped with a Fully Variable Valve Timing (FVVT) system) research engine fueled with commercially available gasoline (95 ON).

The Homogeneous Charge Compression Ignition (HCCI) engine combustion uses heat energy from trapped exhaust gases enhanced by the piston compression heating to auto ignite a premixed air/gasoline mixture. As the HCCI combustion is controlled by the charge temperature, composition and pressure, it therefore, prevents the use of a direct control mechanism such as in the spark and diesel combustion. Using a large amount of trapped residual gas (TRG), is seen as one of the ways to achieve and control HCCI in a certain operating range. By varying the amount of TRG in the fresh air/fuel mixture (inside the cylinder), the charge mixture temperature, composition and pressure can be controlled and hence, the auto ignition timing and heat release rate. The controlled auto ignition (HCCI) engine concept has the potential to be highly efficient and to produce low NOx, carbon dioxide and particulate matter emissions.

The homogeneous charge compression ignition-HCCI (also to be known as controlled auto ignition-CAI) engine concept has the potential to be highly efficient and to produce low NOx, carbon dioxide and particulate matter emissions. It experiences, however, problems with cold start, running at idle and high loads that together with controlling the combustion over the entire speed/load range limits its practical application. A solution to overcome these problems is to operate the engine in ‘hybrid mode’, where the engine operates in HCCI mode at low, medium and cruising loads and switch to spark ignition (SI) mode (or diesel mode-CI) at a cold start, idle and higher loads. To operate such ‘hybrid mode’ engine, a transition between SI and HCCI and SI modes, as a result of changes in engine speed and load must be seamless in operation, whilst keeping all relevant engine and combustion parameters in an acceptable range.

Homogeneous charge compression ignition (HCCI), combustion has the potential to be highly efficient and to produce low NOx, carbon dioxide and particulate matter emissions, but experiences problems with cold start, running at idle and producing high power density. A solution to these is to operate the engine in a ‘hybrid mode’, where the engine operates in spark ignition mode at cold start, idle and high loads and HCCI mode elsewhere during the drive cycle, demanding a seamless transition between the two modes of combustion through spark assisted controlled auto ignition. Moreover; HCCI requires considerable control to maintain consistent start of combustion and heat release rate, which has thus far limited HCCI's practical application. In order to provide a suitable control method, a feedback signal is required.