Abstract:

Hybrid vehicle is an effective solution to reduce vehicle CO₂ emission and pollutant emission. Improving the maximum thermal efficiency of engine and expanding the high thermal efficiency area under common working conditions can effectively reduce the fuel consumption of the hybrid vehicle. According to the requirements of hybrid technology platform， a 2.0T high-efficiency lean burn hybrid engine is developed. The engine adopts an ultra-high compression ratio， large stroke/bore ratio and a deep Miller cycle， and uses a high tumble port design to achieve ultra lean combustion with an excess air ratio of 1.8. With advanced combustion system and friction reduction design， the engine has achieved an effective thermal efficiency of 44%. At the same time， more than 41% of the thermal efficiency area covers the main engine operation points of hybrid engine from 1 000 to 4 000 r/min， ensuring excellent fuel economy of the hybrid vehicle. In addition， the high-efficiency lean burn engine also realizes the maximum power of 115 kW and the torque platform of 240 N·m， which ensures the power requirement of the hybrid system.

Key words: lean burn engine, high thermal efficiency, high compression ratio, hybrid vehicle