Multi-objective optimization of key technologies in gasoline direct-Injection engine based on fuel economy

Miller Cycle technology, High Compression Ratio technology and Variable Valve Timing (VVT) technology are the advanced technologies of the SI engine in hybrid vehicle at home and abroad. The best technical parameters under different operating conditions cannot be obtained easily through bench test due to the interaction among engine technologies. Therefore, this study picked up the above technologies on PSA 1.2THP engine simulation model, and the multi-objective optimization of the engine technologies scheme based on fuel economy was addressed. The optimization results which were selected based on fuel economy showed that with the increase of the geometric compression ratio, the knocking phenomenon was generated. However, the generation of knocking can be suppressed by adding the Miller Cycle technology, adjusting VVT and adjusting ignition timing. It was found that under the simultaneous action of Miller Cycle technology, High Compression Ratio technology and VVT, fuel economy and power can be balanced to achieve engine performance optimization.