Development of a 1-Liter Advanced Turbocharged Gasoline Direct Injection 3-Cylinder Engine 2017-01-0632
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 engine systems, especially for 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 influence into account. Comparing pre-ignition events, oil dilution, combustion stability and especially particulate (PN) emissions, 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.
Besides, low friction design was kept in mind thoroughly, steel crankshaft with smaller journal diameter, low tension force ring pack, belt-in-oil timing system, ball bearing application on camshaft, all contribute to friction reduction. With respect to thermal management, split cooling system was designed, which helps to realize fast engine warm-up, as a result, low friction and good fuel economy.
As a result, thanks to superior combustion system design and low friction optimization, excellent fuel economy was realized. 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 NEDC cycle.