Geely's Lean-burn Gasoline Engine with Brake Thermal Efficiency of 46%

The pursuit of more efficient and cleaner combustion has become the driving force behind the development of the internal combustion engine, while the combustion technology with higher efficiency and lower carbon emission provides a strong competitiveness for the power products in the new the new market and policy context. Geely's DHE engine with BTE of 43% has been put into mass production in 2022. In order to pursue higher engine thermal efficiency, a new type of engine has been developed synchronously. A lean-burn single-cylinder engine was taken as the prototype to optimize the combustion system and jet ignition system with an active pre-chamber. Subsequently, the combustion system of the single cylinder engine is transplanted to the multi-cylinder engine with the same cylinder diameter as the mass production model, which makes the newly developed ultra-efficient multi-cylinder engine feasible for mass production. Ultra-high compression ratio, Miller cycle, efficient supercharging system, intelligent thermal management and friction reduction technology are adopted to further improve the effective thermal efficiency of the engine. Finally, brake thermal efficiency of engine achieved more than 46% of the international advanced level, while the NOx concentration before catalytic converter could be controlled within 250 ppm. At the same time, the engine is equipped with a special after-treatment system for lean-burn technology, so emission would meet the requirements laws and regulations. In the future, the engine will realize full map lean-burn combustion to reduce the cost of after-treatment. The engine serves as an important technical reserve for Geely's future continuous low-carbon technology.