Control of HCCI engine fueled with gasoline with electro-hydraulic variable valve system

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 emissions whilst conventional engine suffered from consumption and emission penalty. In this paper, HCCI was realized by negative overlapping strategy. The mode transition from HCCI to SI and back to HCCI was investigated on a single cylinder engine, without major modifications, equipped with a newly developed electro-controlled fully variable valve train system. The transition smoothness was improved by applying the strategy in which the fuelling consumption was compensated. Due to the cycle-synchronous control of valve timings, injection and ignition offered by the control system, transitions between the HCCI and SI operating modes can be realized without misfire or negative torque response. The results indicated that mode-to-mode pressure fluctuation was improved significantly with spark assisted when operated with HCCI to SI or SI to HCCI transition. In order to control the HCCI combustion, negative overlapping strategy were studied by GT-POWER coupled with CHEMKIN, which consists of one-dimensional fluid dynamics code and a detailed chemical kinetics code. HCCI combustion was achieved in a modified single cylinder mass production engine through trapping residual gases.