Development of Combustion System for a 1-Liter Advanced Turbocharged Gasoline Direct Injection 3-Cylinder Engine 2016-01-2243

In recent years, more attention has been focused on environment pollution and energy source issues. As a result, increasingly stringent fuel consumption and emission legislations have been implemented all over the world. For automakers, enhancing engine’s efficiency as a must contributes to lower vehicle fuel consumption. To reach this goal, Geely auto started the development of a 3-cylinder 1.0L turbocharged direct injection (TGDI) gasoline engine to achieve a challenging fuel economy target while maintaining fun-to-drive and NVH performance.

Demanding development targets for performance (specific torque 205Nm/L and specific power 100kW/L) and excellent part-load BSFC were defined, which lead to a major challenge for the design of the combustion system. Considering air/fuel mixture, fuel wall impingement and even future potential for lean burn combustion, a symmetrical layout and a central position for the injector with 200bar injection pressure was determined. For the injector, several spray pattern proposals were investigated using CFD. The top-3 best ones were extensively tested on engine dyno, taking injector aging into account. Comparing pre-ignition events, oil dilution, combustion stability and especially particulate number (PN) emission, a 5-hole injector was finally selected. Dual cam phasers were introduced to optimize intake and exhaust valve timing to reduce pumping losses and consequently improve fuel economy. To ensure performance output and responsiveness, an efficient but with very low inertia turbocharger was well mated.

As a result, thanks to superior combustion system design and low friction optimization, excellent fuel economy was realized. For instance, BSFC at 2000rpm/2bar BMEP was only around 360g/kWh, which represents new benchmark in the database. Compared to the predecessor a 1.3L TC PFI engine, 13.7% fuel consumption reduction was achieved in the NEDC cycle.